[PATCH tracing/kprobes v3 0/7] tracing/kprobes, perf: perf probe support take 3

[PATCH tracing/kprobes v3 0/7] tracing/kprobes, perf: perf probe support take 3

[Masami Hiramatsu]

Hi,

These patches introduce 'perf probe' command and update kprobe-tracer.
perf probe command allows you to add new probe points by C line number
and local variable names.

This version fixes some bugs, remove -r option (because perf always be
used for online kernel) and rename kprobe-tracer special vars.

Usage
-----
 perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
                          probe point definition, where
		p:	kprobe probe
		r:	kretprobe probe
		GRP:	Group name (optional)
		NAME:	Event name
		FUNC:	Function name
		OFFS:	Offset from function entry (in byte)
		SRC:	Source code path
		LINE:	Line number
		ARG:	Probe argument (local variable name or
			kprobe-tracer argument format is supported.)

Examples
--------
1) Add a new kprobe probe on a line of C source code.
./perf probe -P 'p:myprobe @fs/read_write.c:285 file buf count'
Adding new event: p:myprobe vfs_read+57 file=%bx buf=%si count=%ax

2) Add a new kretprobe probe on a function return.
./perf probe -P 'r:myretprobe vfs_read $retval'
Adding new event: r:myretprobe vfs_read+0 $retval

3) Check it in the perf list.
./perf list
...
  rNNN                                       [raw hardware event descriptor]

  kprobes:myprobe                            [Tracepoint event]
  kprobes:myretprobe                         [Tracepoint event]
  skb:kfree_skb                              [Tracepoint event]
...

4) Record the event by perf
./perf record -f -e kprobes:myprobe:record  -F 1 -a ls
...
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.081 MB perf.data (~3540 samples) ]

5) Trace the event
./perf trace
            perf-11445 [000] 95862.048894383: myprobe: (c04bbed5) file=dae15e80 buf=b78b2000 count=400
            perf-11445 [000] 95862.049066533: myprobe: (c04bbed5) file=dae15d80 buf=b78b2000 count=400
            perf-11445 [000] 95862.049134394: myprobe: (c04bbed5) file=dae15d80 buf=b78b2000 count=400
            perf-11445 [000] 95862.049171495: myprobe: (c04bbed5) file=dae15a80 buf=b78b2000 count=400

NOTE
----
 perf still fails to parse format if arguments have special charactors
(e.g. $retval, +16($stack) etc.) So, tracing myretprobe will fail with this
version. This will be solved by naming arguments automatically if it
doesn't have C-language name.

TODO
----
 - Support sys_perf_counter_open (non-root)
 - Input from stdin/output to stdout
 - 64-bits return value on x86-32
 - Static variable
 - Fields of data structures (var->field)
 - Type support
   - Bit fields
 - Array (var[N])
 - Dynamic array indexing (var[var2])
 - String/dynamic arrays (var:string, var[N..M])
 - Force Type casting ((type)var)
 - Non-inline search
 - libdw, libdwfl
 - etc.

Thank you,

---

Masami Hiramatsu (7):
      perf: perf probe command supports without libdwarf
      perf: Add perf probe subcommand for kprobe-event setup helper
      tracing/kprobes: Rename fixed field name
      tracing/kprobes: Avoid field name confliction
      tracing/kprobes: Rename special variables
      tracing/kprobes: Remove '$ra' special variable
      tracing/kprobes: Add $ prefix to special variables


 Documentation/trace/kprobetrace.txt |   27 +
 kernel/trace/trace_kprobe.c         |  158 +++++---
 tools/perf/Makefile                 |   10 +
 tools/perf/builtin-probe.c          |  385 ++++++++++++++++++++
 tools/perf/builtin.h                |    1 
 tools/perf/perf.c                   |    1 
 tools/perf/util/probe-finder.c      |  690 +++++++++++++++++++++++++++++++++++
 tools/perf/util/probe-finder.h      |   70 ++++
 8 files changed, 1269 insertions(+), 73 deletions(-)
 create mode 100644 tools/perf/builtin-probe.c
 create mode 100644 tools/perf/util/probe-finder.c
 create mode 100644 tools/perf/util/probe-finder.h

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH tracing/kprobes v3 1/7] tracing/kprobes: Add $ prefix to special variables

[Masami Hiramatsu]

Add $ prefix to the special variables(e.g. sa, rv) of kprobe-tracer.
This resolves consistency issue between kprobe_events and perf-kprobe.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 Documentation/trace/kprobetrace.txt |   20 ++++++------
 kernel/trace/trace_kprobe.c         |   60 ++++++++++++++++++++++-------------
 2 files changed, 47 insertions(+), 33 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 9b8f7c6..33f5318 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -36,13 +36,13 @@ Synopsis of kprobe_events
 
  FETCHARGS	: Arguments. Each probe can have up to 128 args.
   %REG	: Fetch register REG
-  sN	: Fetch Nth entry of stack (N >= 0)
-  sa	: Fetch stack address.
   @ADDR	: Fetch memory at ADDR (ADDR should be in kernel)
   @SYM[+|-offs]	: Fetch memory at SYM +|- offs (SYM should be a data symbol)
-  aN	: Fetch function argument. (N >= 0)(*)
-  rv	: Fetch return value.(**)
-  ra	: Fetch return address.(**)
+  $sN	: Fetch Nth entry of stack (N >= 0)
+  $sa	: Fetch stack address.
+  $aN	: Fetch function argument. (N >= 0)(*)
+  $rv	: Fetch return value.(**)
+  $ra	: Fetch return address.(**)
   +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
   NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
 
@@ -85,13 +85,13 @@ Usage examples
 To add a probe as a new event, write a new definition to kprobe_events
 as below.
 
-  echo p:myprobe do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > /sys/kernel/debug/tracing/kprobe_events
+  echo p:myprobe do_sys_open dfd=$a0 filename=$a1 flags=$a2 mode=$a3 > /sys/kernel/debug/tracing/kprobe_events
 
  This sets a kprobe on the top of do_sys_open() function with recording
 1st to 4th arguments as "myprobe" event. As this example shows, users can
 choose more familiar names for each arguments.
 
-  echo r:myretprobe do_sys_open rv ra >> /sys/kernel/debug/tracing/kprobe_events
+  echo r:myretprobe do_sys_open $rv $ra >> /sys/kernel/debug/tracing/kprobe_events
 
  This sets a kretprobe on the return point of do_sys_open() function with
 recording return value and return address as "myretprobe" event.
@@ -138,11 +138,11 @@ events, you need to enable it.
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
            <...>-1447  [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
-           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) rv=fffffffffffffffe ra=ffffffff81367a3a
+           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe $ra=ffffffff81367a3a
            <...>-1447  [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6
-           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a
+           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a
            <...>-1447  [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10
-           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a
+           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a
 
 
  Each line shows when the kernel hits an event, and <- SYMBOL means kernel
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 97309d4..f63ead0 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -220,24 +220,24 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
 	int ret = -EINVAL;
 
 	if (ff->func == fetch_argument)
-		ret = snprintf(buf, n, "a%lu", (unsigned long)ff->data);
+		ret = snprintf(buf, n, "$a%lu", (unsigned long)ff->data);
 	else if (ff->func == fetch_register) {
 		const char *name;
 		name = regs_query_register_name((unsigned int)((long)ff->data));
 		ret = snprintf(buf, n, "%%%s", name);
 	} else if (ff->func == fetch_stack)
-		ret = snprintf(buf, n, "s%lu", (unsigned long)ff->data);
+		ret = snprintf(buf, n, "$s%lu", (unsigned long)ff->data);
 	else if (ff->func == fetch_memory)
 		ret = snprintf(buf, n, "@0x%p", ff->data);
 	else if (ff->func == fetch_symbol) {
 		struct symbol_cache *sc = ff->data;
 		ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
 	} else if (ff->func == fetch_retvalue)
-		ret = snprintf(buf, n, "rv");
+		ret = snprintf(buf, n, "$rv");
 	else if (ff->func == fetch_ip)
-		ret = snprintf(buf, n, "ra");
+		ret = snprintf(buf, n, "$ra");
 	else if (ff->func == fetch_stack_address)
-		ret = snprintf(buf, n, "sa");
+		ret = snprintf(buf, n, "$sa");
 	else if (ff->func == fetch_indirect) {
 		struct indirect_fetch_data *id = ff->data;
 		size_t l = 0;
@@ -429,12 +429,10 @@ static int split_symbol_offset(char *symbol, unsigned long *offset)
 #define PARAM_MAX_ARGS 16
 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 
-static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
 {
 	int ret = 0;
 	unsigned long param;
-	long offset;
-	char *tmp;
 
 	switch (arg[0]) {
 	case 'a':	/* argument */
@@ -456,14 +454,6 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 		} else
 			ret = -EINVAL;
 		break;
-	case '%':	/* named register */
-		ret = regs_query_register_offset(arg + 1);
-		if (ret >= 0) {
-			ff->func = fetch_register;
-			ff->data = (void *)(unsigned long)ret;
-			ret = 0;
-		}
-		break;
 	case 's':	/* stack */
 		if (arg[1] == 'a') {
 			ff->func = fetch_stack_address;
@@ -478,6 +468,31 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 			}
 		}
 		break;
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+}
+
+static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+{
+	int ret = 0;
+	unsigned long param;
+	long offset;
+	char *tmp;
+
+	switch (arg[0]) {
+	case '$':
+		ret = parse_probe_vars(arg + 1, ff, is_return);
+		break;
+	case '%':	/* named register */
+		ret = regs_query_register_offset(arg + 1);
+		if (ret >= 0) {
+			ff->func = fetch_register;
+			ff->data = (void *)(unsigned long)ret;
+			ret = 0;
+		}
+		break;
 	case '@':	/* memory or symbol */
 		if (isdigit(arg[1])) {
 			ret = strict_strtoul(arg + 1, 0, &param);
@@ -489,8 +504,7 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 			ret = split_symbol_offset(arg + 1, &offset);
 			if (ret)
 				break;
-			ff->data = alloc_symbol_cache(arg + 1,
-							      offset);
+			ff->data = alloc_symbol_cache(arg + 1, offset);
 			if (ff->data)
 				ff->func = fetch_symbol;
 			else
@@ -544,11 +558,11 @@ static int create_trace_probe(int argc, char **argv)
 	 *  - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
 	 *  - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
 	 * Fetch args:
-	 *  aN	: fetch Nth of function argument. (N:0-)
-	 *  rv	: fetch return value
-	 *  ra	: fetch return address
-	 *  sa	: fetch stack address
-	 *  sN	: fetch Nth of stack (N:0-)
+	 *  $aN	: fetch Nth of function argument. (N:0-)
+	 *  $rv	: fetch return value
+	 *  $ra	: fetch return address
+	 *  $sa	: fetch stack address
+	 *  $sN	: fetch Nth of stack (N:0-)
 	 *  @ADDR	: fetch memory at ADDR (ADDR should be in kernel)
 	 *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 	 *  %REG	: fetch register REG


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 1/7] tracing/kprobes: Add $ prefix to special variables

[Masami Hiramatsu]

Masami Hiramatsu wrote:
> Add $ prefix to the special variables(e.g. sa, rv) of kprobe-tracer.
> This resolves consistency issue between kprobe_events and perf-kprobe.
>
> Signed-off-by: Masami Hiramatsu<mhiramat@redhat.com>
> Cc: Frederic Weisbecker<fweisbec@gmail.com>
> Cc: Ingo Molnar<mingo@elte.hu>
> Cc: Thomas Gleixner<tglx@linutronix.de>
> Cc: Arnaldo Carvalho de Melo<acme@redhat.com>
> Cc: Steven Rostedt<rostedt@goodmis.org>
> Cc: Mike Galbraith<efault@gmx.de>
> Cc: Paul Mackerras<paulus@samba.org>
> Cc: Peter Zijlstra<a.p.zijlstra@chello.nl>
> Cc: Christoph Hellwig<hch@infradead.org>
> Cc: Ananth N Mavinakayanahalli<ananth@in.ibm.com>
> Cc: Jim Keniston<jkenisto@us.ibm.com>
> Cc: Frank Ch. Eigler<fche@redhat.com>
> ---
>
>   Documentation/trace/kprobetrace.txt |   20 ++++++------
>   kernel/trace/trace_kprobe.c         |   60 ++++++++++++++++++++++-------------
>   2 files changed, 47 insertions(+), 33 deletions(-)


Oops, I've forgotten to update self-test code...

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH tracing/kprobes v3 7/7] perf: perf probe command supports without libdwarf

[Masami Hiramatsu]

Enables 'perf probe' even if libdwarf is installed. If libdwarf is not found,
'perf probe' just disables dwarf support. Users can use 'perf probe' to set
up new events by using kprobe_events format.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 tools/perf/Makefile            |    6 +++---
 tools/perf/builtin-probe.c     |   42 +++++++++++++++++++++++++++++++++-------
 tools/perf/perf.c              |    2 --
 tools/perf/util/probe-finder.h |    2 ++
 4 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 6dabcf1..52b1f43 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -385,6 +385,7 @@ BUILTIN_OBJS += builtin-stat.o
 BUILTIN_OBJS += builtin-timechart.o
 BUILTIN_OBJS += builtin-top.o
 BUILTIN_OBJS += builtin-trace.o
+BUILTIN_OBJS += builtin-probe.o
 
 PERFLIBS = $(LIB_FILE)
 
@@ -420,13 +421,12 @@ ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf *
 endif
 
 ifneq ($(shell sh -c "(echo '\#include <libdwarf/dwarf.h>'; echo '\#include <libdwarf/libdwarf.h>'; echo 'int main(void) { Dwarf_Debug dbg; Dwarf_Error err; dwarf_init(0, DW_DLC_READ, 0, 0, &dbg, &err); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -ldwarf -lelf -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
-	msg := $(warning No libdwarf.h found, disables probe subcommand. Please install libdwarf-dev/libdwarf-devel);
+	msg := $(warning No libdwarf.h found, disables dwarf support. Please install libdwarf-dev/libdwarf-devel);
+	BASIC_CFLAGS += -DNO_LIBDWARF
 else
 	EXTLIBS += -lelf -ldwarf
 	LIB_H += util/probe-finder.h
 	LIB_OBJS += util/probe-finder.o
-	BUILTIN_OBJS += builtin-probe.o
-	BASIC_CFLAGS += -DSUPPORT_DWARF
 endif
 
 ifdef NO_DEMANGLE
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index c74249f..13f308b 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -53,6 +53,7 @@ const char *default_search_path[NR_SEARCH_PATH] = {
 static struct {
 	char *vmlinux;
 	char *release;
+	int need_dwarf;
 	int nr_probe;
 	struct probe_point probes[MAX_PROBES];
 	char *events[MAX_PROBES];
@@ -161,6 +162,8 @@ static int parse_probepoint(const struct option *opt __used,
 		      pp->function, pp->file, pp->offset);
 	}
 	free(argv[1]);
+	if (pp->file)
+		session.need_dwarf = 1;
 
 	/* Copy arguments */
 	pp->nr_args = argc - 2;
@@ -172,15 +175,19 @@ static int parse_probepoint(const struct option *opt __used,
 	}
 
 	/* Ensure return probe has no C argument */
-	if (retp)
-		for (i = 0; i < pp->nr_args; i++)
-			if (is_c_varname(pp->args[i]))
+	for (i = 0; i < pp->nr_args; i++)
+		if (is_c_varname(pp->args[i])) {
+			if (retp)
 				semantic_error("You can't specify local"
 						" variable for kretprobe");
+			session.need_dwarf = 1;
+		}
+
 	debug("%d arguments\n", pp->nr_args);
 	return 0;
 }
 
+#ifndef NO_LIBDWARF
 static int open_default_vmlinux(void)
 {
 	struct utsname uts;
@@ -208,6 +215,7 @@ static int open_default_vmlinux(void)
 	}
 	return fd;
 }
+#endif
 
 static const char * const probe_usage[] = {
 	"perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]",
@@ -215,10 +223,16 @@ static const char * const probe_usage[] = {
 };
 
 static const struct option options[] = {
+#ifndef NO_LIBDWARF
 	OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
 		"vmlinux/module pathname"),
+#endif
 	OPT_CALLBACK('P', "probe", NULL,
+#ifdef NO_LIBDWARF
+		"p|r:[GRP/]NAME FUNC[+OFFS] [ARG ...]",
+#else
 		"p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
+#endif
 		"probe point definition, where\n"
 		"\t\tp:\tkprobe probe\n"
 		"\t\tr:\tkretprobe probe\n"
@@ -226,9 +240,13 @@ static const struct option options[] = {
 		"\t\tNAME:\tEvent name\n"
 		"\t\tFUNC:\tFunction name\n"
 		"\t\tOFFS:\tOffset from function entry (in byte)\n"
+#ifdef NO_LIBDWARF
+		"\t\tARG:\tProbe argument (only \n"
+#else
 		"\t\tSRC:\tSource code path\n"
 		"\t\tLINE:\tLine number\n"
 		"\t\tARG:\tProbe argument (local variable name or\n"
+#endif
 		"\t\t\tkprobe-tracer argument format is supported.)\n",
 		parse_probepoint),
 	OPT_END()
@@ -278,7 +296,7 @@ error:
 
 int cmd_probe(int argc, const char **argv, const char *prefix __used)
 {
-	int i, j, fd, ret, need_dwarf = 0;
+	int i, j, fd, ret;
 	struct probe_point *pp;
 	char buf[MAX_CMDLEN];
 
@@ -287,12 +305,19 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 	if (argc || session.nr_probe == 0)
 		usage_with_options(probe_usage, options);
 
-	/* Synthesize return probes */
+#ifdef NO_LIBDWARF
+	if (session.need_dwarf)
+		semantic_error("Dwarf-analysis is not supported");
+#endif
+
+	/* Synthesize probes without dwarf */
 	for (j = 0; j < session.nr_probe; j++) {
+#ifndef NO_LIBDWARF
 		if (session.events[j][0] != 'r') {
-			need_dwarf = 1;
+			session.need_dwarf = 1;
 			continue;
 		}
+#endif
 		ret = synthesize_probepoint(&session.probes[j]);
 		if (ret == -E2BIG)
 			semantic_error("probe point is too long.");
@@ -302,7 +327,8 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 		}
 	}
 
-	if (!need_dwarf)
+#ifndef NO_LIBDWARF
+	if (!session.need_dwarf)
 		goto setup_probes;
 
 	if (session.vmlinux)
@@ -331,6 +357,8 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 	close(fd);
 
 setup_probes:
+#endif /* !NO_LIBDWARF */
+
 	/* Settng up probe points */
 	snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
 	fd = open(buf, O_WRONLY, O_APPEND);
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index f598120..c570d17 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -295,9 +295,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "version", cmd_version, 0 },
 		{ "trace", cmd_trace, 0 },
 		{ "sched", cmd_sched, 0 },
-#ifdef SUPPORT_DWARF
 		{ "probe", cmd_probe, 0 },
-#endif
 	};
 	unsigned int i;
 	static const char ext[] = STRIP_EXTENSION;
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index af920de..306810c 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -44,6 +44,7 @@ struct probe_point {
 	char	*probes[MAX_PROBES];	/* Output buffers (will be allocated)*/
 };
 
+#ifndef NO_LIBDWARF
 extern int find_probepoint(int fd, struct probe_point *pp);
 
 #include <libdwarf/dwarf.h>
@@ -64,5 +65,6 @@ struct probe_finder {
 	char		*buf;		/* Current output buffer */
 	int		len;		/* Length of output buffer */
 };
+#endif /* NO_LIBDWARF */
 
 #endif /*_PROBE_FINDER_H */


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Masami Hiramatsu]

Check whether the argument name is conflict with other field names.

Changes in v3:
 - Check strcmp() == 0 instead of !strcmp().

Changes in v2:
 - Add common_lock_depth to reserved name list.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 kernel/trace/trace_kprobe.c |   65 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 030f28c..e3b824a 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -38,6 +38,25 @@
 #define MAX_EVENT_NAME_LEN 64
 #define KPROBE_EVENT_SYSTEM "kprobes"
 
+/* Reserved field names */
+#define FIELD_STRING_IP "ip"
+#define FIELD_STRING_NARGS "nargs"
+#define FIELD_STRING_RETIP "ret_ip"
+#define FIELD_STRING_FUNC "func"
+
+const char *reserved_field_names[] = {
+	"common_type",
+	"common_flags",
+	"common_preempt_count",
+	"common_pid",
+	"common_tgid",
+	"common_lock_depth",
+	FIELD_STRING_IP,
+	FIELD_STRING_NARGS,
+	FIELD_STRING_RETIP,
+	FIELD_STRING_FUNC,
+};
+
 /* currently, trace_kprobe only supports X86. */
 
 struct fetch_func {
@@ -537,6 +556,20 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
 	return ret;
 }
 
+/* Return 1 if name is reserved or already used by another argument */
+static int conflict_field_name(const char *name,
+			       struct probe_arg *args, int narg)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
+		if (strcmp(reserved_field_names[i], name) == 0)
+			return 1;
+	for (i = 0; i < narg; i++)
+		if (strcmp(args[i].name, name) == 0)
+			return 1;
+	return 0;
+}
+
 static int create_trace_probe(int argc, char **argv)
 {
 	/*
@@ -637,6 +670,12 @@ static int create_trace_probe(int argc, char **argv)
 			*arg++ = '\0';
 		else
 			arg = argv[i];
+
+		if (conflict_field_name(argv[i], tp->args, i)) {
+			ret = -EINVAL;
+			goto error;
+		}
+
 		tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
 
 		/* Parse fetch argument */
@@ -1039,8 +1078,8 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
 	if (!ret)
 		return ret;
 
-	DEFINE_FIELD(unsigned long, ip, "ip", 0);
-	DEFINE_FIELD(int, nargs, "nargs", 1);
+	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+	DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
 	/* Set argument names as fields */
 	for (i = 0; i < tp->nr_args; i++)
 		DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
@@ -1057,9 +1096,9 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
 	if (!ret)
 		return ret;
 
-	DEFINE_FIELD(unsigned long, func, "func", 0);
-	DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
-	DEFINE_FIELD(int, nargs, "nargs", 1);
+	DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
+	DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
+	DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
 	/* Set argument names as fields */
 	for (i = 0; i < tp->nr_args; i++)
 		DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
@@ -1108,15 +1147,16 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
 	int ret, i;
 	struct trace_probe *tp = (struct trace_probe *)call->data;
 
-	SHOW_FIELD(unsigned long, ip, "ip");
-	SHOW_FIELD(int, nargs, "nargs");
+	SHOW_FIELD(unsigned long, ip, FIELD_STRING_IP);
+	SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);
 
 	/* Show fields */
 	for (i = 0; i < tp->nr_args; i++)
 		SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
 	trace_seq_puts(s, "\n");
 
-	return __probe_event_show_format(s, tp, "(%lx)", "REC->ip");
+	return __probe_event_show_format(s, tp, "(%lx)",
+					 "REC->" FIELD_STRING_IP);
 }
 
 static int kretprobe_event_show_format(struct ftrace_event_call *call,
@@ -1126,9 +1166,9 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
 	int ret, i;
 	struct trace_probe *tp = (struct trace_probe *)call->data;
 
-	SHOW_FIELD(unsigned long, func, "func");
-	SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
-	SHOW_FIELD(int, nargs, "nargs");
+	SHOW_FIELD(unsigned long, func, FIELD_STRING_FUNC);
+	SHOW_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP);
+	SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);
 
 	/* Show fields */
 	for (i = 0; i < tp->nr_args; i++)
@@ -1136,7 +1176,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
 	trace_seq_puts(s, "\n");
 
 	return __probe_event_show_format(s, tp, "(%lx <- %lx)",
-					  "REC->func, REC->ret_ip");
+					 "REC->" FIELD_STRING_FUNC
+					 ", REC->" FIELD_STRING_RETIP);
 }
 
 #ifdef CONFIG_EVENT_PROFILE


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Frédéric Weisbecker]

2009/10/8 Masami Hiramatsu <mhiramat@redhat.com>:
> Check whether the argument name is conflict with other field names.
>
> Changes in v3:
>  - Check strcmp() == 0 instead of !strcmp().
>
> Changes in v2:
>  - Add common_lock_depth to reserved name list.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Jim Keniston <jkenisto@us.ibm.com>
> Cc: Frank Ch. Eigler <fche@redhat.com>
> ---
>
>  kernel/trace/trace_kprobe.c |   65 +++++++++++++++++++++++++++++++++++--------
>  1 files changed, 53 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 030f28c..e3b824a 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -38,6 +38,25 @@
>  #define MAX_EVENT_NAME_LEN 64
>  #define KPROBE_EVENT_SYSTEM "kprobes"
>
> +/* Reserved field names */
> +#define FIELD_STRING_IP "ip"
> +#define FIELD_STRING_NARGS "nargs"
> +#define FIELD_STRING_RETIP "ret_ip"
> +#define FIELD_STRING_FUNC "func"


If it might conflict, then we should minimize the possibilities for
that to happen.

What if we prefix these fields with kprobed_ ?

kprobed_ip
kprobed_nargs
kprobed_ret_ip
kprobed_func

We are lucky there in that kprobe functions in the kernel can't be kprobed
so it's safe wrt the conflict in the same namespace.

And we can further schrink the kprobed prefixes in userspace post processing.

(If you agree with the above, that can be done incrementally).

Thanks.


> +
> +const char *reserved_field_names[] = {
> +       "common_type",
> +       "common_flags",
> +       "common_preempt_count",
> +       "common_pid",
> +       "common_tgid",
> +       "common_lock_depth",
> +       FIELD_STRING_IP,
> +       FIELD_STRING_NARGS,
> +       FIELD_STRING_RETIP,
> +       FIELD_STRING_FUNC,
> +};
> +
>  /* currently, trace_kprobe only supports X86. */
>
>  struct fetch_func {
> @@ -537,6 +556,20 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
>        return ret;
>  }
>
> +/* Return 1 if name is reserved or already used by another argument */
> +static int conflict_field_name(const char *name,
> +                              struct probe_arg *args, int narg)
> +{
> +       int i;
> +       for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
> +               if (strcmp(reserved_field_names[i], name) == 0)
> +                       return 1;
> +       for (i = 0; i < narg; i++)
> +               if (strcmp(args[i].name, name) == 0)
> +                       return 1;
> +       return 0;
> +}
> +
>  static int create_trace_probe(int argc, char **argv)
>  {
>        /*
> @@ -637,6 +670,12 @@ static int create_trace_probe(int argc, char **argv)
>                        *arg++ = '\0';
>                else
>                        arg = argv[i];
> +
> +               if (conflict_field_name(argv[i], tp->args, i)) {
> +                       ret = -EINVAL;
> +                       goto error;
> +               }
> +
>                tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
>
>                /* Parse fetch argument */
> @@ -1039,8 +1078,8 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
>        if (!ret)
>                return ret;
>
> -       DEFINE_FIELD(unsigned long, ip, "ip", 0);
> -       DEFINE_FIELD(int, nargs, "nargs", 1);
> +       DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
> +       DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
>        /* Set argument names as fields */
>        for (i = 0; i < tp->nr_args; i++)
>                DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
> @@ -1057,9 +1096,9 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
>        if (!ret)
>                return ret;
>
> -       DEFINE_FIELD(unsigned long, func, "func", 0);
> -       DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
> -       DEFINE_FIELD(int, nargs, "nargs", 1);
> +       DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
> +       DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
> +       DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
>        /* Set argument names as fields */
>        for (i = 0; i < tp->nr_args; i++)
>                DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
> @@ -1108,15 +1147,16 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
>        int ret, i;
>        struct trace_probe *tp = (struct trace_probe *)call->data;
>
> -       SHOW_FIELD(unsigned long, ip, "ip");
> -       SHOW_FIELD(int, nargs, "nargs");
> +       SHOW_FIELD(unsigned long, ip, FIELD_STRING_IP);
> +       SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);
>
>        /* Show fields */
>        for (i = 0; i < tp->nr_args; i++)
>                SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
>        trace_seq_puts(s, "\n");
>
> -       return __probe_event_show_format(s, tp, "(%lx)", "REC->ip");
> +       return __probe_event_show_format(s, tp, "(%lx)",
> +                                        "REC->" FIELD_STRING_IP);
>  }
>
>  static int kretprobe_event_show_format(struct ftrace_event_call *call,
> @@ -1126,9 +1166,9 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
>        int ret, i;
>        struct trace_probe *tp = (struct trace_probe *)call->data;
>
> -       SHOW_FIELD(unsigned long, func, "func");
> -       SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
> -       SHOW_FIELD(int, nargs, "nargs");
> +       SHOW_FIELD(unsigned long, func, FIELD_STRING_FUNC);
> +       SHOW_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP);
> +       SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);
>
>        /* Show fields */
>        for (i = 0; i < tp->nr_args; i++)
> @@ -1136,7 +1176,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
>        trace_seq_puts(s, "\n");
>
>        return __probe_event_show_format(s, tp, "(%lx <- %lx)",
> -                                         "REC->func, REC->ret_ip");
> +                                        "REC->" FIELD_STRING_FUNC
> +                                        ", REC->" FIELD_STRING_RETIP);
>  }
>
>  #ifdef CONFIG_EVENT_PROFILE
>
>
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America), Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com
>

Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Frédéric Weisbecker]

Le 12 octobre 2009 12:10, Frédéric Weisbecker <fweisbec@gmail.com> a écrit :
> 2009/10/8 Masami Hiramatsu <mhiramat@redhat.com>:
>> Check whether the argument name is conflict with other field names.
>>
>> Changes in v3:
>>  - Check strcmp() == 0 instead of !strcmp().
>>
>> Changes in v2:
>>  - Add common_lock_depth to reserved name list.
>>
>> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> Cc: Ingo Molnar <mingo@elte.hu>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Cc: Mike Galbraith <efault@gmx.de>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> Cc: Christoph Hellwig <hch@infradead.org>
>> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
>> Cc: Jim Keniston <jkenisto@us.ibm.com>
>> Cc: Frank Ch. Eigler <fche@redhat.com>
>> ---
>>
>>  kernel/trace/trace_kprobe.c |   65 +++++++++++++++++++++++++++++++++++--------
>>  1 files changed, 53 insertions(+), 12 deletions(-)
>>
>> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
>> index 030f28c..e3b824a 100644
>> --- a/kernel/trace/trace_kprobe.c
>> +++ b/kernel/trace/trace_kprobe.c
>> @@ -38,6 +38,25 @@
>>  #define MAX_EVENT_NAME_LEN 64
>>  #define KPROBE_EVENT_SYSTEM "kprobes"
>>
>> +/* Reserved field names */
>> +#define FIELD_STRING_IP "ip"
>> +#define FIELD_STRING_NARGS "nargs"
>> +#define FIELD_STRING_RETIP "ret_ip"
>> +#define FIELD_STRING_FUNC "func"
>
>
> If it might conflict, then we should minimize the possibilities for
> that to happen.
>
> What if we prefix these fields with kprobed_ ?
>
> kprobed_ip
> kprobed_nargs
> kprobed_ret_ip
> kprobed_func
>
> We are lucky there in that kprobe functions in the kernel can't be kprobed
> so it's safe wrt the conflict in the same namespace.
>
> And we can further schrink the kprobed prefixes in userspace post processing.
>
> (If you agree with the above, that can be done incrementally).
>
> Thanks.


I'm an idiot. I should have looked at the 5/7 patch before sending this reply.
Just forget about what I said :-)

Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Frederic Weisbecker]

On Wed, Oct 07, 2009 at 06:28:07PM -0400, Masami Hiramatsu wrote:
> Check whether the argument name is conflict with other field names.
> 
> Changes in v3:
>  - Check strcmp() == 0 instead of !strcmp().
> 
> Changes in v2:
>  - Add common_lock_depth to reserved name list.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Jim Keniston <jkenisto@us.ibm.com>
> Cc: Frank Ch. Eigler <fche@redhat.com>
> ---
> 
>  kernel/trace/trace_kprobe.c |   65 +++++++++++++++++++++++++++++++++++--------
>  1 files changed, 53 insertions(+), 12 deletions(-)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 030f28c..e3b824a 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -38,6 +38,25 @@
>  #define MAX_EVENT_NAME_LEN 64
>  #define KPROBE_EVENT_SYSTEM "kprobes"
>  
> +/* Reserved field names */
> +#define FIELD_STRING_IP "ip"
> +#define FIELD_STRING_NARGS "nargs"
> +#define FIELD_STRING_RETIP "ret_ip"
> +#define FIELD_STRING_FUNC "func"
> +
> +const char *reserved_field_names[] = {
> +	"common_type",
> +	"common_flags",
> +	"common_preempt_count",
> +	"common_pid",
> +	"common_tgid",
> +	"common_lock_depth",
> +	FIELD_STRING_IP,
> +	FIELD_STRING_NARGS,
> +	FIELD_STRING_RETIP,
> +	FIELD_STRING_FUNC,
> +};
> +
>  /* currently, trace_kprobe only supports X86. */
>  
>  struct fetch_func {
> @@ -537,6 +556,20 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
>  	return ret;
>  }
>  
> +/* Return 1 if name is reserved or already used by another argument */
> +static int conflict_field_name(const char *name,
> +			       struct probe_arg *args, int narg)
> +{
> +	int i;
> +	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
> +		if (strcmp(reserved_field_names[i], name) == 0)
> +			return 1;
> +	for (i = 0; i < narg; i++)
> +		if (strcmp(args[i].name, name) == 0)
> +			return 1;
> +	return 0;
> +}
> +
>  static int create_trace_probe(int argc, char **argv)
>  {
>  	/*
> @@ -637,6 +670,12 @@ static int create_trace_probe(int argc, char **argv)
>  			*arg++ = '\0';
>  		else
>  			arg = argv[i];
> +
> +		if (conflict_field_name(argv[i], tp->args, i)) {
> +			ret = -EINVAL;



The conflict issue might not be obvious for a user desperately trying to set
a kprobe. Even for other failcases, it might not be obvious (blacklisted
symbols, syntax errors...)

May be should you improve the error granularity and print a KERN_DEBUG
message?

Thanks.

Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Masami Hiramatsu]

Frederic Weisbecker wrote:
> The conflict issue might not be obvious for a user desperately trying to set
> a kprobe. Even for other failcases, it might not be obvious (blacklisted
> symbols, syntax errors...)
>
> May be should you improve the error granularity and print a KERN_DEBUG
> message?

Agreed, and kprobes error handling should be improved too (in the most cases,
it just returns -EINVAL).

Thank you.

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Frederic Weisbecker]

On Mon, Oct 12, 2009 at 03:13:51PM -0400, Masami Hiramatsu wrote:
> Frederic Weisbecker wrote:
>> The conflict issue might not be obvious for a user desperately trying to set
>> a kprobe. Even for other failcases, it might not be obvious (blacklisted
>> symbols, syntax errors...)
>>
>> May be should you improve the error granularity and print a KERN_DEBUG
>> message?
>
> Agreed, and kprobes error handling should be improved too (in the most cases,
> it just returns -EINVAL).
>
> Thank you.
>


And btw, I'm enable to create a probe, neither through ftrace nor perf:

	$ sudo ./perf probe -P 'p:sys_close sys_close $retval'
	Adding new event: p:sys_close sys_close+0 $retval

	Error: Failed to create event: Invalid argument


	# echo 'p:sys_open sys_open $retval' > /debug/tracing/kprobe_events 
	bash: echo: write error : Invalid argument

I suspect I missed something very obvious with the syntax :)

I've applied your patches in:

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	tracing/kprobes

Thanks.

Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Masami Hiramatsu]

Frederic Weisbecker wrote:
> On Mon, Oct 12, 2009 at 03:13:51PM -0400, Masami Hiramatsu wrote:
>> Frederic Weisbecker wrote:
>>> The conflict issue might not be obvious for a user desperately trying to set
>>> a kprobe. Even for other failcases, it might not be obvious (blacklisted
>>> symbols, syntax errors...)
>>>
>>> May be should you improve the error granularity and print a KERN_DEBUG
>>> message?
>>
>> Agreed, and kprobes error handling should be improved too (in the most cases,
>> it just returns -EINVAL).
>>
>> Thank you.
>>
>
>
> And btw, I'm enable to create a probe, neither through ftrace nor perf:
>
> 	$ sudo ./perf probe -P 'p:sys_close sys_close $retval'
> 	Adding new event: p:sys_close sys_close+0 $retval
>
> 	Error: Failed to create event: Invalid argument
>
>
> 	# echo 'p:sys_open sys_open $retval'>  /debug/tracing/kprobe_events
> 	bash: echo: write error : Invalid argument
>
> I suspect I missed something very obvious with the syntax :)

Ah, only kretprobe events can use $retval :-)
So, you should specify 'r' instead of 'p'.

-P 'r:sys_close sys_close $retval'


> I've applied your patches in:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
> 	tracing/kprobes
>
> Thanks.

Thank you!

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 4/7] tracing/kprobes: Avoid field name confliction

[Frederic Weisbecker]

On Mon, Oct 12, 2009 at 04:22:26PM -0400, Masami Hiramatsu wrote:
> Frederic Weisbecker wrote:
>> On Mon, Oct 12, 2009 at 03:13:51PM -0400, Masami Hiramatsu wrote:
>>> Frederic Weisbecker wrote:
>>>> The conflict issue might not be obvious for a user desperately trying to set
>>>> a kprobe. Even for other failcases, it might not be obvious (blacklisted
>>>> symbols, syntax errors...)
>>>>
>>>> May be should you improve the error granularity and print a KERN_DEBUG
>>>> message?
>>>
>>> Agreed, and kprobes error handling should be improved too (in the most cases,
>>> it just returns -EINVAL).
>>>
>>> Thank you.
>>>
>>
>>
>> And btw, I'm enable to create a probe, neither through ftrace nor perf:
>>
>> 	$ sudo ./perf probe -P 'p:sys_close sys_close $retval'
>> 	Adding new event: p:sys_close sys_close+0 $retval
>>
>> 	Error: Failed to create event: Invalid argument
>>
>>
>> 	# echo 'p:sys_open sys_open $retval'>  /debug/tracing/kprobe_events
>> 	bash: echo: write error : Invalid argument
>>
>> I suspect I missed something very obvious with the syntax :)
>
> Ah, only kretprobe events can use $retval :-)
> So, you should specify 'r' instead of 'p'.
>
> -P 'r:sys_close sys_close $retval'
>

Hehe, I was sure I was doing something silly but couldn't figure
out what :-)

So that works, at least without libdwarf, I can't test with it for
now but this tool looks very promising.

I really think it would be great to be able to cut the

	./perf probe
	./perf record
	./perf trace

batch into one step through a single

	./perf probe -t -P "probe definition" [-a|cmdline]

That would do the probe creation, the record, and stop
once the given process finishes, or once we Ctrl+C (especially
useful in wide tracing with -a, but sometimes also with processes).
Not a lot of changes are required to do that.

I can already see printk() whining on the horizon...

Thanks!

[PATCH tracing/kprobes v3 5/7] tracing/kprobes: Rename fixed field name

[Masami Hiramatsu]

Rename probe-common fixed field name to the name harder conflictable,
because current 'ip', 'func', and other probe field names are easy to
conflict with user-specified variable names.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 kernel/trace/trace_kprobe.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index e3b824a..6c11a09 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -39,10 +39,10 @@
 #define KPROBE_EVENT_SYSTEM "kprobes"
 
 /* Reserved field names */
-#define FIELD_STRING_IP "ip"
-#define FIELD_STRING_NARGS "nargs"
-#define FIELD_STRING_RETIP "ret_ip"
-#define FIELD_STRING_FUNC "func"
+#define FIELD_STRING_IP "__probe_ip"
+#define FIELD_STRING_NARGS "__probe_nargs"
+#define FIELD_STRING_RETIP "__probe_ret_ip"
+#define FIELD_STRING_FUNC "__probe_func"
 
 const char *reserved_field_names[] = {
 	"common_type",


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH tracing/kprobes v3 3/7] tracing/kprobes: Rename special variables

[Masami Hiramatsu]

Rename special variables to more self-explainable name as below:
- $rv to $retval
- $sa to $stack
- $aN to $argN
- $sN to $stackN

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 Documentation/trace/kprobetrace.txt |   22 ++++++++-------
 kernel/trace/trace_kprobe.c         |   50 ++++++++++++++++-------------------
 2 files changed, 34 insertions(+), 38 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 4208253..1541524 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -35,13 +35,13 @@ Synopsis of kprobe_events
  MEMADDR	: Address where the probe is inserted.
 
  FETCHARGS	: Arguments. Each probe can have up to 128 args.
-  %REG	: Fetch register REG
-  @ADDR	: Fetch memory at ADDR (ADDR should be in kernel)
+  %REG		: Fetch register REG
+  @ADDR		: Fetch memory at ADDR (ADDR should be in kernel)
   @SYM[+|-offs]	: Fetch memory at SYM +|- offs (SYM should be a data symbol)
-  $sN	: Fetch Nth entry of stack (N >= 0)
-  $sa	: Fetch stack address.
-  $aN	: Fetch function argument. (N >= 0)(*)
-  $rv	: Fetch return value.(**)
+  $stackN	: Fetch Nth entry of stack (N >= 0)
+  $stack	: Fetch stack address.
+  $argN		: Fetch function argument. (N >= 0)(*)
+  $retval	: Fetch return value.(**)
   +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
   NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
 
@@ -84,13 +84,13 @@ Usage examples
 To add a probe as a new event, write a new definition to kprobe_events
 as below.
 
-  echo p:myprobe do_sys_open dfd=$a0 filename=$a1 flags=$a2 mode=$a3 > /sys/kernel/debug/tracing/kprobe_events
+  echo p:myprobe do_sys_open dfd=$arg0 filename=$arg1 flags=$arg2 mode=$arg3 > /sys/kernel/debug/tracing/kprobe_events
 
  This sets a kprobe on the top of do_sys_open() function with recording
 1st to 4th arguments as "myprobe" event. As this example shows, users can
 choose more familiar names for each arguments.
 
-  echo r:myretprobe do_sys_open $rv >> /sys/kernel/debug/tracing/kprobe_events
+  echo r:myretprobe do_sys_open $retval >> /sys/kernel/debug/tracing/kprobe_events
 
  This sets a kretprobe on the return point of do_sys_open() function with
 recording return value as "myretprobe" event.
@@ -137,11 +137,11 @@ events, you need to enable it.
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
            <...>-1447  [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
-           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe
+           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $retval=fffffffffffffffe
            <...>-1447  [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6
-           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3
+           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3
            <...>-1447  [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10
-           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3
+           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3
 
 
  Each line shows when the kernel hits an event, and <- SYMBOL means kernel
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ba6d3bd..030f28c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -215,22 +215,22 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
 	int ret = -EINVAL;
 
 	if (ff->func == fetch_argument)
-		ret = snprintf(buf, n, "$a%lu", (unsigned long)ff->data);
+		ret = snprintf(buf, n, "$arg%lu", (unsigned long)ff->data);
 	else if (ff->func == fetch_register) {
 		const char *name;
 		name = regs_query_register_name((unsigned int)((long)ff->data));
 		ret = snprintf(buf, n, "%%%s", name);
 	} else if (ff->func == fetch_stack)
-		ret = snprintf(buf, n, "$s%lu", (unsigned long)ff->data);
+		ret = snprintf(buf, n, "$stack%lu", (unsigned long)ff->data);
 	else if (ff->func == fetch_memory)
 		ret = snprintf(buf, n, "@0x%p", ff->data);
 	else if (ff->func == fetch_symbol) {
 		struct symbol_cache *sc = ff->data;
 		ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
 	} else if (ff->func == fetch_retvalue)
-		ret = snprintf(buf, n, "$rv");
+		ret = snprintf(buf, n, "$retval");
 	else if (ff->func == fetch_stack_address)
-		ret = snprintf(buf, n, "$sa");
+		ret = snprintf(buf, n, "$stack");
 	else if (ff->func == fetch_indirect) {
 		struct indirect_fetch_data *id = ff->data;
 		size_t l = 0;
@@ -427,28 +427,17 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
 	int ret = 0;
 	unsigned long param;
 
-	switch (arg[0]) {
-	case 'a':	/* argument */
-		ret = strict_strtoul(arg + 1, 10, &param);
-		if (ret || param > PARAM_MAX_ARGS)
-			ret = -EINVAL;
-		else {
-			ff->func = fetch_argument;
-			ff->data = (void *)param;
-		}
-		break;
-	case 'r':	/* retval or retaddr */
-		if (is_return && arg[1] == 'v') {
+	if (strcmp(arg, "retval") == 0) {
+		if (is_return) {
 			ff->func = fetch_retvalue;
 			ff->data = NULL;
 		} else
 			ret = -EINVAL;
-		break;
-	case 's':	/* stack */
-		if (arg[1] == 'a') {
+	} else if (strncmp(arg, "stack", 5) == 0) {
+		if (arg[5] == '\0') {
 			ff->func = fetch_stack_address;
 			ff->data = NULL;
-		} else {
+		} else if (isdigit(arg[5])) {
 			ret = strict_strtoul(arg + 1, 10, &param);
 			if (ret || param > PARAM_MAX_STACK)
 				ret = -EINVAL;
@@ -456,11 +445,18 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
 				ff->func = fetch_stack;
 				ff->data = (void *)param;
 			}
+		} else
+			ret = -EINVAL;
+	} else if (strncmp(arg, "arg", 3) == 0 && isdigit(arg[4])) {
+		ret = strict_strtoul(arg + 1, 10, &param);
+		if (ret || param > PARAM_MAX_ARGS)
+			ret = -EINVAL;
+		else {
+			ff->func = fetch_argument;
+			ff->data = (void *)param;
 		}
-		break;
-	default:
+	} else
 		ret = -EINVAL;
-	}
 	return ret;
 }
 
@@ -548,10 +544,10 @@ static int create_trace_probe(int argc, char **argv)
 	 *  - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
 	 *  - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
 	 * Fetch args:
-	 *  $aN	: fetch Nth of function argument. (N:0-)
-	 *  $rv	: fetch return value
-	 *  $sa	: fetch stack address
-	 *  $sN	: fetch Nth of stack (N:0-)
+	 *  $argN	: fetch Nth of function argument. (N:0-)
+	 *  $retval	: fetch return value
+	 *  $stack	: fetch stack address
+	 *  $stackN	: fetch Nth of stack (N:0-)
 	 *  @ADDR	: fetch memory at ADDR (ADDR should be in kernel)
 	 *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 	 *  %REG	: fetch register REG


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 3/7] tracing/kprobes: Rename special variables

[Masami Hiramatsu]

Masami Hiramatsu wrote:
> @@ -427,28 +427,17 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>   	int ret = 0;
>   	unsigned long param;
>
> -	switch (arg[0]) {
> -	case 'a':	/* argument */
> -		ret = strict_strtoul(arg + 1, 10,&param);
> -		if (ret || param>  PARAM_MAX_ARGS)
> -			ret = -EINVAL;
> -		else {
> -			ff->func = fetch_argument;
> -			ff->data = (void *)param;
> -		}
> -		break;
> -	case 'r':	/* retval or retaddr */
> -		if (is_return&&  arg[1] == 'v') {
> +	if (strcmp(arg, "retval") == 0) {
> +		if (is_return) {
>   			ff->func = fetch_retvalue;
>   			ff->data = NULL;
>   		} else
>   			ret = -EINVAL;
> -		break;
> -	case 's':	/* stack */
> -		if (arg[1] == 'a') {
> +	} else if (strncmp(arg, "stack", 5) == 0) {
> +		if (arg[5] == '\0') {
>   			ff->func = fetch_stack_address;
>   			ff->data = NULL;
> -		} else {
> +		} else if (isdigit(arg[5])) {
>   			ret = strict_strtoul(arg + 1, 10,&param);
                                              ^^^^^^^ this should be arg + 5.

> @@ -456,11 +445,18 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>   				ff->func = fetch_stack;
>   				ff->data = (void *)param;
>   			}
> +		} else
> +			ret = -EINVAL;
> +	} else if (strncmp(arg, "arg", 3) == 0&&  isdigit(arg[4])) {
> +		ret = strict_strtoul(arg + 1, 10,&param);
                                      ^^^^^^^ here too, arg + 3.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 3/7] tracing/kprobes: Rename special variables

[Frederic Weisbecker]

On Mon, Oct 12, 2009 at 05:20:09PM -0400, Masami Hiramatsu wrote:
> Masami Hiramatsu wrote:
>> @@ -427,28 +427,17 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>>   	int ret = 0;
>>   	unsigned long param;
>>
>> -	switch (arg[0]) {
>> -	case 'a':	/* argument */
>> -		ret = strict_strtoul(arg + 1, 10,&param);
>> -		if (ret || param>  PARAM_MAX_ARGS)
>> -			ret = -EINVAL;
>> -		else {
>> -			ff->func = fetch_argument;
>> -			ff->data = (void *)param;
>> -		}
>> -		break;
>> -	case 'r':	/* retval or retaddr */
>> -		if (is_return&&  arg[1] == 'v') {
>> +	if (strcmp(arg, "retval") == 0) {
>> +		if (is_return) {
>>   			ff->func = fetch_retvalue;
>>   			ff->data = NULL;
>>   		} else
>>   			ret = -EINVAL;
>> -		break;
>> -	case 's':	/* stack */
>> -		if (arg[1] == 'a') {
>> +	} else if (strncmp(arg, "stack", 5) == 0) {
>> +		if (arg[5] == '\0') {
>>   			ff->func = fetch_stack_address;
>>   			ff->data = NULL;
>> -		} else {
>> +		} else if (isdigit(arg[5])) {
>>   			ret = strict_strtoul(arg + 1, 10,&param);
>                                              ^^^^^^^ this should be arg + 5.
>
>> @@ -456,11 +445,18 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>>   				ff->func = fetch_stack;
>>   				ff->data = (void *)param;
>>   			}
>> +		} else
>> +			ret = -EINVAL;
>> +	} else if (strncmp(arg, "arg", 3) == 0&&  isdigit(arg[4])) {



And this should be isdigit(arg[3]) actually, what you want to test is the
first character after arg, right?



>> +		ret = strict_strtoul(arg + 1, 10,&param);
>                                      ^^^^^^^ here too, arg + 3.

Re: [PATCH tracing/kprobes v3 3/7] tracing/kprobes: Rename special variables

[Masami Hiramatsu]

Frederic Weisbecker wrote:
> On Mon, Oct 12, 2009 at 05:20:09PM -0400, Masami Hiramatsu wrote:
>> Masami Hiramatsu wrote:
>>> @@ -427,28 +427,17 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>>>    	int ret = 0;
>>>    	unsigned long param;
>>>
>>> -	switch (arg[0]) {
>>> -	case 'a':	/* argument */
>>> -		ret = strict_strtoul(arg + 1, 10,&param);
>>> -		if (ret || param>   PARAM_MAX_ARGS)
>>> -			ret = -EINVAL;
>>> -		else {
>>> -			ff->func = fetch_argument;
>>> -			ff->data = (void *)param;
>>> -		}
>>> -		break;
>>> -	case 'r':	/* retval or retaddr */
>>> -		if (is_return&&   arg[1] == 'v') {
>>> +	if (strcmp(arg, "retval") == 0) {
>>> +		if (is_return) {
>>>    			ff->func = fetch_retvalue;
>>>    			ff->data = NULL;
>>>    		} else
>>>    			ret = -EINVAL;
>>> -		break;
>>> -	case 's':	/* stack */
>>> -		if (arg[1] == 'a') {
>>> +	} else if (strncmp(arg, "stack", 5) == 0) {
>>> +		if (arg[5] == '\0') {
>>>    			ff->func = fetch_stack_address;
>>>    			ff->data = NULL;
>>> -		} else {
>>> +		} else if (isdigit(arg[5])) {
>>>    			ret = strict_strtoul(arg + 1, 10,&param);
>>                                               ^^^^^^^ this should be arg + 5.
>>
>>> @@ -456,11 +445,18 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>>>    				ff->func = fetch_stack;
>>>    				ff->data = (void *)param;
>>>    			}
>>> +		} else
>>> +			ret = -EINVAL;
>>> +	} else if (strncmp(arg, "arg", 3) == 0&&   isdigit(arg[4])) {
>
>
>
> And this should be isdigit(arg[3]) actually, what you want to test is the
> first character after arg, right?

Right. I'll fix it...


Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 3/7] tracing/kprobes: Rename special variables

[Frederic Weisbecker]

On Mon, Oct 12, 2009 at 05:36:56PM -0400, Masami Hiramatsu wrote:
> Frederic Weisbecker wrote:
>> On Mon, Oct 12, 2009 at 05:20:09PM -0400, Masami Hiramatsu wrote:
>>> Masami Hiramatsu wrote:
>>>> @@ -427,28 +427,17 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>>>>    	int ret = 0;
>>>>    	unsigned long param;
>>>>
>>>> -	switch (arg[0]) {
>>>> -	case 'a':	/* argument */
>>>> -		ret = strict_strtoul(arg + 1, 10,&param);
>>>> -		if (ret || param>   PARAM_MAX_ARGS)
>>>> -			ret = -EINVAL;
>>>> -		else {
>>>> -			ff->func = fetch_argument;
>>>> -			ff->data = (void *)param;
>>>> -		}
>>>> -		break;
>>>> -	case 'r':	/* retval or retaddr */
>>>> -		if (is_return&&   arg[1] == 'v') {
>>>> +	if (strcmp(arg, "retval") == 0) {
>>>> +		if (is_return) {
>>>>    			ff->func = fetch_retvalue;
>>>>    			ff->data = NULL;
>>>>    		} else
>>>>    			ret = -EINVAL;
>>>> -		break;
>>>> -	case 's':	/* stack */
>>>> -		if (arg[1] == 'a') {
>>>> +	} else if (strncmp(arg, "stack", 5) == 0) {
>>>> +		if (arg[5] == '\0') {
>>>>    			ff->func = fetch_stack_address;
>>>>    			ff->data = NULL;
>>>> -		} else {
>>>> +		} else if (isdigit(arg[5])) {
>>>>    			ret = strict_strtoul(arg + 1, 10,&param);
>>>                                               ^^^^^^^ this should be arg + 5.
>>>
>>>> @@ -456,11 +445,18 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
>>>>    				ff->func = fetch_stack;
>>>>    				ff->data = (void *)param;
>>>>    			}
>>>> +		} else
>>>> +			ret = -EINVAL;
>>>> +	} else if (strncmp(arg, "arg", 3) == 0&&   isdigit(arg[4])) {
>>
>>
>>
>> And this should be isdigit(arg[3]) actually, what you want to test is the
>> first character after arg, right?
>
> Right. I'll fix it...
>
>
> Thank you,


No need to, I've rebased and pushed to the same tree :-)

[PATCH tracing/kprobes v3 2/7] tracing/kprobes: Remove '$ra' special variable

[Masami Hiramatsu]

Remove '$ra' because it is already shown at the head of each entry.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 Documentation/trace/kprobetrace.txt |   13 ++++++-------
 kernel/trace/trace_kprobe.c         |   11 -----------
 2 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 33f5318..4208253 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -1,4 +1,4 @@
-                         Kprobe-based Event Tracer
+                        Kprobe-based Event Tracer
                          =========================
 
                  Documentation is written by Masami Hiramatsu
@@ -42,7 +42,6 @@ Synopsis of kprobe_events
   $sa	: Fetch stack address.
   $aN	: Fetch function argument. (N >= 0)(*)
   $rv	: Fetch return value.(**)
-  $ra	: Fetch return address.(**)
   +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
   NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
 
@@ -91,10 +90,10 @@ as below.
 1st to 4th arguments as "myprobe" event. As this example shows, users can
 choose more familiar names for each arguments.
 
-  echo r:myretprobe do_sys_open $rv $ra >> /sys/kernel/debug/tracing/kprobe_events
+  echo r:myretprobe do_sys_open $rv >> /sys/kernel/debug/tracing/kprobe_events
 
  This sets a kretprobe on the return point of do_sys_open() function with
-recording return value and return address as "myretprobe" event.
+recording return value as "myretprobe" event.
  You can see the format of these events via
 /sys/kernel/debug/tracing/events/kprobes/<EVENT>/format.
 
@@ -138,11 +137,11 @@ events, you need to enable it.
 #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
 #              | |       |          |         |
            <...>-1447  [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
-           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe $ra=ffffffff81367a3a
+           <...>-1447  [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe
            <...>-1447  [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6
-           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a
+           <...>-1447  [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3
            <...>-1447  [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10
-           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a
+           <...>-1447  [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3
 
 
  Each line shows when the kernel hits an event, and <- SYMBOL means kernel
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f63ead0..ba6d3bd 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -85,11 +85,6 @@ static __kprobes unsigned long fetch_retvalue(struct pt_regs *regs,
 	return regs_return_value(regs);
 }
 
-static __kprobes unsigned long fetch_ip(struct pt_regs *regs, void *dummy)
-{
-	return instruction_pointer(regs);
-}
-
 static __kprobes unsigned long fetch_stack_address(struct pt_regs *regs,
 						   void *dummy)
 {
@@ -234,8 +229,6 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
 		ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
 	} else if (ff->func == fetch_retvalue)
 		ret = snprintf(buf, n, "$rv");
-	else if (ff->func == fetch_ip)
-		ret = snprintf(buf, n, "$ra");
 	else if (ff->func == fetch_stack_address)
 		ret = snprintf(buf, n, "$sa");
 	else if (ff->func == fetch_indirect) {
@@ -448,9 +441,6 @@ static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
 		if (is_return && arg[1] == 'v') {
 			ff->func = fetch_retvalue;
 			ff->data = NULL;
-		} else if (is_return && arg[1] == 'a') {
-			ff->func = fetch_ip;
-			ff->data = NULL;
 		} else
 			ret = -EINVAL;
 		break;
@@ -560,7 +550,6 @@ static int create_trace_probe(int argc, char **argv)
 	 * Fetch args:
 	 *  $aN	: fetch Nth of function argument. (N:0-)
 	 *  $rv	: fetch return value
-	 *  $ra	: fetch return address
 	 *  $sa	: fetch stack address
 	 *  $sN	: fetch Nth of stack (N:0-)
 	 *  @ADDR	: fetch memory at ADDR (ADDR should be in kernel)


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH tracing/kprobes v3 6/7] perf: Add perf probe subcommand for kprobe-event setup helper

[Masami Hiramatsu]

Add perf probe subcommand for kprobe-event setup helper to perf command.
This allows user to define kprobe events by C expressions (C line numbers,
C function names, and C local variables).

Usage
-----
 perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
                          probe point definition, where
		p:	kprobe probe
		r:	kretprobe probe
		GRP:	Group name (optional)
		NAME:	Event name
		FUNC:	Function name
		OFFS:	Offset from function entry (in byte)
		SRC:	Source code path
		LINE:	Line number
		ARG:	Probe argument (local variable name or
			kprobe-tracer argument format is supported.)

Changes in v3:
 - Remove -r option because perf always be used for online kernel.
 - Check malloc/calloc results.

Changes in v2:
 - Check synthesized string length.
 - Rename perf kprobe to perf probe.
 - Use spaces for separator and update usage comment.
 - Check error paths in parse_probepoint().
 - Check optimized-out variables.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 tools/perf/Makefile            |   10 +
 tools/perf/builtin-probe.c     |  357 +++++++++++++++++++++
 tools/perf/builtin.h           |    1 
 tools/perf/perf.c              |    3 
 tools/perf/util/probe-finder.c |  690 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/probe-finder.h |   68 ++++
 6 files changed, 1129 insertions(+), 0 deletions(-)
 create mode 100644 tools/perf/builtin-probe.c
 create mode 100644 tools/perf/util/probe-finder.c
 create mode 100644 tools/perf/util/probe-finder.h

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index b5f1953..6dabcf1 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -419,6 +419,16 @@ ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf *
 	msg := $(error No libelf.h/libelf found, please install libelf-dev/elfutils-libelf-devel);
 endif
 
+ifneq ($(shell sh -c "(echo '\#include <libdwarf/dwarf.h>'; echo '\#include <libdwarf/libdwarf.h>'; echo 'int main(void) { Dwarf_Debug dbg; Dwarf_Error err; dwarf_init(0, DW_DLC_READ, 0, 0, &dbg, &err); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -ldwarf -lelf -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
+	msg := $(warning No libdwarf.h found, disables probe subcommand. Please install libdwarf-dev/libdwarf-devel);
+else
+	EXTLIBS += -lelf -ldwarf
+	LIB_H += util/probe-finder.h
+	LIB_OBJS += util/probe-finder.o
+	BUILTIN_OBJS += builtin-probe.o
+	BASIC_CFLAGS += -DSUPPORT_DWARF
+endif
+
 ifdef NO_DEMANGLE
 	BASIC_CFLAGS += -DNO_DEMANGLE
 else
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
new file mode 100644
index 0000000..c74249f
--- /dev/null
+++ b/tools/perf/builtin-probe.c
@@ -0,0 +1,357 @@
+/*
+ * builtin-probe.c
+ *
+ * Builtin probe command: Set up probe events by C expression
+ *
+ * Written by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "perf.h"
+#include "builtin.h"
+#include "util/util.h"
+#include "util/parse-options.h"
+#include "util/parse-events.h"	/* For debugfs_path */
+#include "util/probe-finder.h"
+
+/* Default vmlinux search paths */
+#define NR_SEARCH_PATH 3
+const char *default_search_path[NR_SEARCH_PATH] = {
+"/lib/modules/%s/build/vmlinux",		/* Custom build kernel */
+"/usr/lib/debug/lib/modules/%s/vmlinux",	/* Red Hat debuginfo */
+"/boot/vmlinux-debug-%s",			/* Ubuntu */
+};
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBES 128
+
+/* Session management structure */
+static struct {
+	char *vmlinux;
+	char *release;
+	int nr_probe;
+	struct probe_point probes[MAX_PROBES];
+	char *events[MAX_PROBES];
+} session;
+
+static void semantic_error(const char *msg)
+{
+	fprintf(stderr, "Semantic error: %s\n", msg);
+	exit(1);
+}
+
+static void perror_exit(const char *msg)
+{
+	perror(msg);
+	exit(1);
+}
+
+#define MAX_PROBE_ARGS 128
+
+static int parse_probepoint(const struct option *opt __used,
+			    const char *str, int unset __used)
+{
+	char *argv[MAX_PROBE_ARGS + 2];	/* Event + probe + args */
+	int argc, i;
+	char *arg, *ptr;
+	struct probe_point *pp = &session.probes[session.nr_probe];
+	char **event = &session.events[session.nr_probe];
+	int retp = 0;
+
+	if (!str)	/* The end of probe points */
+		return 0;
+
+	debug("Probe-define(%d): %s\n", session.nr_probe, str);
+	if (++session.nr_probe == MAX_PROBES)
+		semantic_error("Too many probes");
+
+	/* Separate arguments, similar to argv_split */
+	argc = 0;
+	do {
+		/* Skip separators */
+		while (isspace(*str))
+			str++;
+
+		/* Add an argument */
+		if (*str != '\0') {
+			const char *s = str;
+
+			/* Skip the argument */
+			while (!isspace(*str) && *str != '\0')
+				str++;
+
+			/* Duplicate the argument */
+			argv[argc] = strndup(s, str - s);
+			if (argv[argc] == NULL)
+				perror_exit("strndup");
+			if (++argc == MAX_PROBE_ARGS)
+				semantic_error("Too many arguments");
+			debug("argv[%d]=%s\n", argc, argv[argc - 1]);
+		}
+	} while (*str != '\0');
+	if (argc < 2)
+		semantic_error("Need event-name and probe-point at least.");
+
+	/* Parse the event name */
+	if (argv[0][0] == 'r')
+		retp = 1;
+	else if (argv[0][0] != 'p')
+		semantic_error("You must specify 'p'(kprobe) or"
+				" 'r'(kretprobe) first.");
+	/* TODO: check event name */
+	*event = argv[0];
+
+	/* Parse probe point */
+	arg = argv[1];
+	if (arg[0] == '@') {
+		/* Source Line */
+		arg++;
+		ptr = strchr(arg, ':');
+		if (!ptr || !isdigit(ptr[1]))
+			semantic_error("Line number is required.");
+		*ptr++ = '\0';
+		if (strlen(arg) == 0)
+			semantic_error("No file name.");
+		pp->file = strdup(arg);
+		pp->line = atoi(ptr);
+		if (!pp->file || !pp->line)
+			semantic_error("Failed to parse line.");
+		debug("file:%s line:%d\n", pp->file, pp->line);
+	} else {
+		/* Function name */
+		ptr = strchr(arg, '+');
+		if (ptr) {
+			if (!isdigit(ptr[1]))
+				semantic_error("Offset is required.");
+			*ptr++ = '\0';
+			pp->offset = atoi(ptr);
+		} else
+			ptr = arg;
+		ptr = strchr(ptr, '@');
+		if (ptr) {
+			*ptr++ = '\0';
+			pp->file = strdup(ptr);
+		}
+		pp->function = strdup(arg);
+		debug("symbol:%s file:%s offset:%d\n",
+		      pp->function, pp->file, pp->offset);
+	}
+	free(argv[1]);
+
+	/* Copy arguments */
+	pp->nr_args = argc - 2;
+	if (pp->nr_args > 0) {
+		pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
+		if (!pp->args)
+			perror_exit("malloc");
+		memcpy(pp->args, &argv[2], sizeof(char *) * pp->nr_args);
+	}
+
+	/* Ensure return probe has no C argument */
+	if (retp)
+		for (i = 0; i < pp->nr_args; i++)
+			if (is_c_varname(pp->args[i]))
+				semantic_error("You can't specify local"
+						" variable for kretprobe");
+	debug("%d arguments\n", pp->nr_args);
+	return 0;
+}
+
+static int open_default_vmlinux(void)
+{
+	struct utsname uts;
+	char fname[MAX_PATH_LEN];
+	int fd, ret, i;
+
+	ret = uname(&uts);
+	if (ret) {
+		debug("uname() failed.\n");
+		return -errno;
+	}
+	session.release = uts.release;
+	for (i = 0; i < NR_SEARCH_PATH; i++) {
+		ret = snprintf(fname, MAX_PATH_LEN,
+			       default_search_path[i], session.release);
+		if (ret >= MAX_PATH_LEN || ret < 0) {
+			debug("Filename(%d,%s) is too long.\n", i, uts.release);
+			errno = E2BIG;
+			return -E2BIG;
+		}
+		debug("try to open %s\n", fname);
+		fd = open(fname, O_RDONLY);
+		if (fd >= 0)
+			break;
+	}
+	return fd;
+}
+
+static const char * const probe_usage[] = {
+	"perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]",
+	NULL
+};
+
+static const struct option options[] = {
+	OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
+		"vmlinux/module pathname"),
+	OPT_CALLBACK('P', "probe", NULL,
+		"p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
+		"probe point definition, where\n"
+		"\t\tp:\tkprobe probe\n"
+		"\t\tr:\tkretprobe probe\n"
+		"\t\tGRP:\tGroup name (optional)\n"
+		"\t\tNAME:\tEvent name\n"
+		"\t\tFUNC:\tFunction name\n"
+		"\t\tOFFS:\tOffset from function entry (in byte)\n"
+		"\t\tSRC:\tSource code path\n"
+		"\t\tLINE:\tLine number\n"
+		"\t\tARG:\tProbe argument (local variable name or\n"
+		"\t\t\tkprobe-tracer argument format is supported.)\n",
+		parse_probepoint),
+	OPT_END()
+};
+
+static int write_new_event(int fd, const char *buf)
+{
+	int ret;
+
+	printf("Adding new event: %s\n", buf);
+	ret = write(fd, buf, strlen(buf));
+	if (ret <= 0)
+		perror("Error: Failed to create event");
+
+	return ret;
+}
+
+#define MAX_CMDLEN 256
+
+static int synthesize_probepoint(struct probe_point *pp)
+{
+	char *buf;
+	int i, len, ret;
+	pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
+	if (!buf)
+		perror_exit("calloc");
+	ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
+	if (ret <= 0 || ret >= MAX_CMDLEN)
+		goto error;
+	len = ret;
+
+	for (i = 0; i < pp->nr_args; i++) {
+		ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
+			       pp->args[i]);
+		if (ret <= 0 || ret >= MAX_CMDLEN - len)
+			goto error;
+		len += ret;
+	}
+	pp->found = 1;
+	return pp->found;
+error:
+	free(pp->probes[0]);
+	if (ret > 0)
+		ret = -E2BIG;
+	return ret;
+}
+
+int cmd_probe(int argc, const char **argv, const char *prefix __used)
+{
+	int i, j, fd, ret, need_dwarf = 0;
+	struct probe_point *pp;
+	char buf[MAX_CMDLEN];
+
+	argc = parse_options(argc, argv, options, probe_usage,
+		PARSE_OPT_STOP_AT_NON_OPTION);
+	if (argc || session.nr_probe == 0)
+		usage_with_options(probe_usage, options);
+
+	/* Synthesize return probes */
+	for (j = 0; j < session.nr_probe; j++) {
+		if (session.events[j][0] != 'r') {
+			need_dwarf = 1;
+			continue;
+		}
+		ret = synthesize_probepoint(&session.probes[j]);
+		if (ret == -E2BIG)
+			semantic_error("probe point is too long.");
+		else if (ret < 0) {
+			perror("snprintf");
+			return -1;
+		}
+	}
+
+	if (!need_dwarf)
+		goto setup_probes;
+
+	if (session.vmlinux)
+		fd = open(session.vmlinux, O_RDONLY);
+	else
+		fd = open_default_vmlinux();
+	if (fd < 0) {
+		perror("vmlinux/module file open");
+		return -1;
+	}
+
+	/* Searching probe points */
+	for (j = 0; j < session.nr_probe; j++) {
+		pp = &session.probes[j];
+		if (pp->found)
+			continue;
+
+		lseek(fd, SEEK_SET, 0);
+		ret = find_probepoint(fd, pp);
+		if (ret <= 0) {
+			fprintf(stderr, "Error: No probe point found.\n");
+			return -1;
+		}
+		debug("probe event %s found\n", session.events[j]);
+	}
+	close(fd);
+
+setup_probes:
+	/* Settng up probe points */
+	snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
+	fd = open(buf, O_WRONLY, O_APPEND);
+	if (fd < 0) {
+		perror("kprobe_events open");
+		return -1;
+	}
+	for (j = 0; j < session.nr_probe; j++) {
+		pp = &session.probes[j];
+		if (pp->found == 1) {
+			snprintf(buf, MAX_CMDLEN, "%s %s\n",
+				session.events[j], pp->probes[0]);
+			write_new_event(fd, buf);
+		} else
+			for (i = 0; i < pp->found; i++) {
+				snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
+					session.events[j], i, pp->probes[i]);
+				write_new_event(fd, buf);
+			}
+	}
+	close(fd);
+	return 0;
+}
+
diff --git a/tools/perf/builtin.h b/tools/perf/builtin.h
index e11d8d2..ad5f0f4 100644
--- a/tools/perf/builtin.h
+++ b/tools/perf/builtin.h
@@ -25,5 +25,6 @@ extern int cmd_timechart(int argc, const char **argv, const char *prefix);
 extern int cmd_top(int argc, const char **argv, const char *prefix);
 extern int cmd_trace(int argc, const char **argv, const char *prefix);
 extern int cmd_version(int argc, const char **argv, const char *prefix);
+extern int cmd_probe(int argc, const char **argv, const char *prefix);
 
 #endif
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 19fc7fe..f598120 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -295,6 +295,9 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "version", cmd_version, 0 },
 		{ "trace", cmd_trace, 0 },
 		{ "sched", cmd_sched, 0 },
+#ifdef SUPPORT_DWARF
+		{ "probe", cmd_probe, 0 },
+#endif
 	};
 	unsigned int i;
 	static const char ext[] = STRIP_EXTENSION;
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
new file mode 100644
index 0000000..ec6f53f
--- /dev/null
+++ b/tools/perf/util/probe-finder.c
@@ -0,0 +1,690 @@
+/*
+ * probe-finder.c : C expression to kprobe event converter
+ *
+ * Written by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <ctype.h>
+#include "probe-finder.h"
+
+
+/* Dwarf_Die Linkage to parent Die */
+struct die_link {
+	struct die_link *parent;	/* Parent die */
+	Dwarf_Die die;			/* Current die */
+};
+
+static Dwarf_Debug __dw_debug;
+static Dwarf_Error __dw_error;
+
+static void msg_exit(int ret, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fprintf(stderr, "Error:  ");
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	fprintf(stderr, "\n");
+	exit(ret);
+}
+
+
+/*
+ * Generic dwarf analysis helpers
+ */
+
+#define X86_32_MAX_REGS 8
+const char *x86_32_regs_table[X86_32_MAX_REGS] = {
+	"%ax",
+	"%cx",
+	"%dx",
+	"%bx",
+	"$stack",	/* Stack address instead of %sp */
+	"%bp",
+	"%si",
+	"%di",
+};
+
+#define X86_64_MAX_REGS 16
+const char *x86_64_regs_table[X86_64_MAX_REGS] = {
+	"%ax",
+	"%dx",
+	"%cx",
+	"%bx",
+	"%si",
+	"%di",
+	"%bp",
+	"%sp",
+	"%r8",
+	"%r9",
+	"%r10",
+	"%r11",
+	"%r12",
+	"%r13",
+	"%r14",
+	"%r15",
+};
+
+/* TODO: switching by dwarf address size */
+#ifdef __x86_64__
+#define ARCH_MAX_REGS X86_64_MAX_REGS
+#define arch_regs_table x86_64_regs_table
+#else
+#define ARCH_MAX_REGS X86_32_MAX_REGS
+#define arch_regs_table x86_32_regs_table
+#endif
+
+/* Return architecture dependent register string (for kprobe-tracer) */
+static const char *get_arch_regstr(unsigned int n)
+{
+	return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
+}
+
+/*
+ * Compare the tail of two strings.
+ * Return 0 if whole of either string is same as another's tail part.
+ */
+static int strtailcmp(const char *s1, const char *s2)
+{
+	int i1 = strlen(s1);
+	int i2 = strlen(s2);
+	while (--i1 > 0 && --i2 > 0) {
+		if (s1[i1] != s2[i2])
+			return s1[i1] - s2[i2];
+	}
+	return 0;
+}
+
+/* Find the fileno of the target file. */
+static Dwarf_Unsigned die_get_fileno(Dwarf_Die cu_die, const char *fname)
+{
+	Dwarf_Signed cnt, i;
+	Dwarf_Unsigned found = 0;
+	char **srcs;
+	int ret;
+
+	if (!fname)
+		return 0;
+
+	ret = dwarf_srcfiles(cu_die, &srcs, &cnt, &__dw_error);
+	if (ret == DW_DLV_OK) {
+		for (i = 0; i < cnt && !found; i++) {
+			if (strtailcmp(srcs[i], fname) == 0)
+				found = i + 1;
+			dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
+		}
+		for (; i < cnt; i++)
+			dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
+		dwarf_dealloc(__dw_debug, srcs, DW_DLA_LIST);
+	}
+	if (found)
+		debug("found fno: %d\n", (int)found);
+	return found;
+}
+
+/* Compare diename and tname */
+static int die_compare_name(Dwarf_Die die, const char *tname)
+{
+	char *name;
+	int ret;
+	ret = dwarf_diename(die, &name, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = strcmp(tname, name);
+		dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
+	} else
+		ret = -1;
+	return ret;
+}
+
+/* Check the address is in the subprogram(function). */
+static int die_within_subprogram(Dwarf_Die sp_die, Dwarf_Addr addr,
+				 Dwarf_Signed *offs)
+{
+	Dwarf_Addr lopc, hipc;
+	int ret;
+
+	/* TODO: check ranges */
+	ret = dwarf_lowpc(sp_die, &lopc, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_NO_ENTRY)
+		return 0;
+	ret = dwarf_highpc(sp_die, &hipc, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	if (lopc <= addr && addr < hipc) {
+		*offs = addr - lopc;
+		return 1;
+	} else
+		return 0;
+}
+
+/* Check the die is inlined function */
+static Dwarf_Bool die_inlined_subprogram(Dwarf_Die die)
+{
+	/* TODO: check strictly */
+	Dwarf_Bool inl;
+	int ret;
+
+	ret = dwarf_hasattr(die, DW_AT_inline, &inl, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	return inl;
+}
+
+/* Get the offset of abstruct_origin */
+static Dwarf_Off die_get_abstract_origin(Dwarf_Die die)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Off cu_offs;
+	int ret;
+
+	ret = dwarf_attr(die, DW_AT_abstract_origin, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_formref(attr, &cu_offs, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+	return cu_offs;
+}
+
+/* Get entry pc(or low pc, 1st entry of ranges)  of the die */
+static Dwarf_Addr die_get_entrypc(Dwarf_Die die)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Addr addr;
+	Dwarf_Off offs;
+	Dwarf_Ranges *ranges;
+	Dwarf_Signed cnt;
+	int ret;
+
+	/* Try to get entry pc */
+	ret = dwarf_attr(die, DW_AT_entry_pc, &attr, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = dwarf_formaddr(attr, &addr, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+		return addr;
+	}
+
+	/* Try to get low pc */
+	ret = dwarf_lowpc(die, &addr, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK)
+		return addr;
+
+	/* Try to get ranges */
+	ret = dwarf_attr(die, DW_AT_ranges, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_formref(attr, &offs, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_get_ranges(__dw_debug, offs, &ranges, &cnt, NULL,
+				&__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	addr = ranges[0].dwr_addr1;
+	dwarf_ranges_dealloc(__dw_debug, ranges, cnt);
+	return addr;
+}
+
+/*
+ * Search a Die from Die tree.
+ * Note: cur_link->die should be deallocated in this function.
+ */
+static int __search_die_tree(struct die_link *cur_link,
+			     int (*die_cb)(struct die_link *, void *),
+			     void *data)
+{
+	Dwarf_Die new_die;
+	struct die_link new_link;
+	int ret;
+
+	if (!die_cb)
+		return 0;
+
+	/* Check current die */
+	while (!(ret = die_cb(cur_link, data))) {
+		/* Check child die */
+		ret = dwarf_child(cur_link->die, &new_die, &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		if (ret == DW_DLV_OK) {
+			new_link.parent = cur_link;
+			new_link.die = new_die;
+			ret = __search_die_tree(&new_link, die_cb, data);
+			if (ret)
+				break;
+		}
+
+		/* Move to next sibling */
+		ret = dwarf_siblingof(__dw_debug, cur_link->die, &new_die,
+				      &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
+		cur_link->die = new_die;
+		if (ret == DW_DLV_NO_ENTRY)
+			return 0;
+	}
+	dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
+	return ret;
+}
+
+/* Search a die in its children's die tree */
+static int search_die_from_children(Dwarf_Die parent_die,
+				    int (*die_cb)(struct die_link *, void *),
+				    void *data)
+{
+	struct die_link new_link;
+	int ret;
+
+	new_link.parent = NULL;
+	ret = dwarf_child(parent_die, &new_link.die, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK)
+		return __search_die_tree(&new_link, die_cb, data);
+	else
+		return 0;
+}
+
+/* Find a locdesc corresponding to the address */
+static int attr_get_locdesc(Dwarf_Attribute attr, Dwarf_Locdesc *desc,
+			    Dwarf_Addr addr)
+{
+	Dwarf_Signed lcnt;
+	Dwarf_Locdesc **llbuf;
+	int ret, i;
+
+	ret = dwarf_loclist_n(attr, &llbuf, &lcnt, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = DW_DLV_NO_ENTRY;
+	for (i = 0; i < lcnt; ++i) {
+		if (llbuf[i]->ld_lopc <= addr &&
+		    llbuf[i]->ld_hipc > addr) {
+			memcpy(desc, llbuf[i], sizeof(Dwarf_Locdesc));
+			desc->ld_s =
+				malloc(sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
+			ERR_IF(desc->ld_s == NULL);
+			memcpy(desc->ld_s, llbuf[i]->ld_s,
+				sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
+			ret = DW_DLV_OK;
+			break;
+		}
+		dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
+		dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
+	}
+	/* Releasing loop */
+	for (; i < lcnt; ++i) {
+		dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
+		dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
+	}
+	dwarf_dealloc(__dw_debug, llbuf, DW_DLA_LIST);
+	return ret;
+}
+
+/*
+ * Probe finder related functions
+ */
+
+/* Show a location */
+static void show_location(Dwarf_Loc *loc, struct probe_finder *pf)
+{
+	Dwarf_Small op;
+	Dwarf_Unsigned regn;
+	Dwarf_Signed offs;
+	int deref = 0, ret;
+	const char *regs;
+
+	op = loc->lr_atom;
+
+	/* If this is based on frame buffer, set the offset */
+	if (op == DW_OP_fbreg) {
+		deref = 1;
+		offs = (Dwarf_Signed)loc->lr_number;
+		op = pf->fbloc.ld_s[0].lr_atom;
+		loc = &pf->fbloc.ld_s[0];
+	} else
+		offs = 0;
+
+	if (op >= DW_OP_breg0 && op <= DW_OP_breg31) {
+		regn = op - DW_OP_breg0;
+		offs += (Dwarf_Signed)loc->lr_number;
+		deref = 1;
+	} else if (op >= DW_OP_reg0 && op <= DW_OP_reg31) {
+		regn = op - DW_OP_reg0;
+	} else if (op == DW_OP_bregx) {
+		regn = loc->lr_number;
+		offs += (Dwarf_Signed)loc->lr_number2;
+		deref = 1;
+	} else if (op == DW_OP_regx) {
+		regn = loc->lr_number;
+	} else
+		msg_exit(-EINVAL, "Dwarf_OP %d is not supported.\n", op);
+
+	regs = get_arch_regstr(regn);
+	if (!regs)
+		msg_exit(-EINVAL, "%lld exceeds max register number.\n", regn);
+
+	if (deref)
+		ret = snprintf(pf->buf, pf->len,
+				 " %s=%+lld(%s)", pf->var, offs, regs);
+	else
+		ret = snprintf(pf->buf, pf->len, " %s=%s", pf->var, regs);
+	ERR_IF(ret < 0);
+	ERR_IF(ret >= pf->len);
+}
+
+/* Show a variables in kprobe event format */
+static void show_variable(Dwarf_Die vr_die, struct probe_finder *pf)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Locdesc ld;
+	int ret;
+
+	ret = dwarf_attr(vr_die, DW_AT_location, &attr, &__dw_error);
+	if (ret != DW_DLV_OK)
+		goto error;
+	ret = attr_get_locdesc(attr, &ld, (pf->addr - pf->cu_base));
+	if (ret != DW_DLV_OK)
+		goto error;
+	/* TODO? */
+	ERR_IF(ld.ld_cents != 1);
+	show_location(&ld.ld_s[0], pf);
+	free(ld.ld_s);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+	return ;
+error:
+	msg_exit(-1, "Failed to find the location of %s at this address.\n"
+		 " Perhaps, it was optimized out.\n", pf->var);
+}
+
+static int variable_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	Dwarf_Half tag;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if ((tag == DW_TAG_formal_parameter ||
+	     tag == DW_TAG_variable) &&
+	    (die_compare_name(dlink->die, pf->var) == 0)) {
+		show_variable(dlink->die, pf);
+		return 1;
+	}
+	/* TODO: Support struct members and arrays */
+	return 0;
+}
+
+/* Find a variable in a subprogram die */
+static void find_variable(Dwarf_Die sp_die, struct probe_finder *pf)
+{
+	int ret;
+
+	if (!is_c_varname(pf->var)) {
+		/* Output raw parameters */
+		ret = snprintf(pf->buf, pf->len, " %s", pf->var);
+		ERR_IF(ret < 0);
+		ERR_IF(ret >= pf->len);
+		return ;
+	}
+
+	debug("Searching '%s' variable in context.\n", pf->var);
+	/* Search child die for local variables and parameters. */
+	ret = search_die_from_children(sp_die, variable_callback, pf);
+	if (!ret)
+		msg_exit(-1, "Failed to find '%s' in this function.\n",
+			 pf->var);
+}
+
+/* Get a frame base on the address */
+static void get_current_frame_base(Dwarf_Die sp_die, struct probe_finder *pf)
+{
+	Dwarf_Attribute attr;
+	int ret;
+
+	ret = dwarf_attr(sp_die, DW_AT_frame_base, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = attr_get_locdesc(attr, &pf->fbloc, (pf->addr - pf->cu_base));
+	ERR_IF(ret != DW_DLV_OK);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+}
+
+static void free_current_frame_base(struct probe_finder *pf)
+{
+	free(pf->fbloc.ld_s);
+	memset(&pf->fbloc, 0, sizeof(Dwarf_Locdesc));
+}
+
+/* Show a probe point to output buffer */
+static void show_probepoint(Dwarf_Die sp_die, Dwarf_Signed offs,
+			    struct probe_finder *pf)
+{
+	struct probe_point *pp = pf->pp;
+	char *name;
+	char tmp[MAX_PROBE_BUFFER];
+	int ret, i, len;
+
+	/* Output name of probe point */
+	ret = dwarf_diename(sp_die, &name, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%u", name,
+				(unsigned int)offs);
+		dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
+	} else {
+		/* This function has no name. */
+		ret = snprintf(tmp, MAX_PROBE_BUFFER, "0x%llx", pf->addr);
+	}
+	ERR_IF(ret < 0);
+	ERR_IF(ret >= MAX_PROBE_BUFFER);
+	len = ret;
+
+	/* Find each argument */
+	get_current_frame_base(sp_die, pf);
+	for (i = 0; i < pp->nr_args; i++) {
+		pf->var = pp->args[i];
+		pf->buf = &tmp[len];
+		pf->len = MAX_PROBE_BUFFER - len;
+		find_variable(sp_die, pf);
+		len += strlen(pf->buf);
+	}
+	free_current_frame_base(pf);
+
+	pp->probes[pp->found] = strdup(tmp);
+	pp->found++;
+}
+
+static int probeaddr_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	Dwarf_Half tag;
+	Dwarf_Signed offs;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	/* Check the address is in this subprogram */
+	if (tag == DW_TAG_subprogram &&
+	    die_within_subprogram(dlink->die, pf->addr, &offs)) {
+		show_probepoint(dlink->die, offs, pf);
+		return 1;
+	}
+	return 0;
+}
+
+/* Find probe point from its line number */
+static void find_by_line(Dwarf_Die cu_die, struct probe_finder *pf)
+{
+	struct probe_point *pp = pf->pp;
+	Dwarf_Signed cnt, i;
+	Dwarf_Line *lines;
+	Dwarf_Unsigned lineno = 0;
+	Dwarf_Addr addr;
+	Dwarf_Unsigned fno;
+	int ret;
+
+	ret = dwarf_srclines(cu_die, &lines, &cnt, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+
+	for (i = 0; i < cnt; i++) {
+		ret = dwarf_line_srcfileno(lines[i], &fno, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		if (fno != pf->fno)
+			continue;
+
+		ret = dwarf_lineno(lines[i], &lineno, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		if (lineno != (Dwarf_Unsigned)pp->line)
+			continue;
+
+		ret = dwarf_lineaddr(lines[i], &addr, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		debug("Probe point found: 0x%llx\n", addr);
+		pf->addr = addr;
+		/* Search a real subprogram including this line, */
+		ret = search_die_from_children(cu_die, probeaddr_callback, pf);
+		if (ret == 0)
+			msg_exit(-1,
+				 "Probe point is not found in subprograms.\n");
+		/* Continuing, because target line might be inlined. */
+	}
+	dwarf_srclines_dealloc(__dw_debug, lines, cnt);
+}
+
+/* Search function from function name */
+static int probefunc_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	struct probe_point *pp = pf->pp;
+	struct die_link *lk;
+	Dwarf_Signed offs;
+	Dwarf_Half tag;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (tag == DW_TAG_subprogram) {
+		if (die_compare_name(dlink->die, pp->function) == 0) {
+			if (die_inlined_subprogram(dlink->die)) {
+				/* Inlined function, save it. */
+				ret = dwarf_die_CU_offset(dlink->die,
+							  &pf->inl_offs,
+							  &__dw_error);
+				ERR_IF(ret != DW_DLV_OK);
+				debug("inline definition offset %lld\n",
+					pf->inl_offs);
+				return 0;
+			}
+			/* Get probe address */
+			pf->addr = die_get_entrypc(dlink->die);
+			pf->addr += pp->offset;
+			/* TODO: Check the address in this function */
+			show_probepoint(dlink->die, pp->offset, pf);
+			/* Continue to search */
+		}
+	} else if (tag == DW_TAG_inlined_subroutine && pf->inl_offs) {
+		if (die_get_abstract_origin(dlink->die) == pf->inl_offs) {
+			/* Get probe address */
+			pf->addr = die_get_entrypc(dlink->die);
+			pf->addr += pp->offset;
+			debug("found inline addr: 0x%llx\n", pf->addr);
+			/* Inlined function. Get a real subprogram */
+			for (lk = dlink->parent; lk != NULL; lk = lk->parent) {
+				tag = 0;
+				dwarf_tag(lk->die, &tag, &__dw_error);
+				ERR_IF(ret == DW_DLV_ERROR);
+				if (tag == DW_TAG_subprogram &&
+				    !die_inlined_subprogram(lk->die))
+					goto found;
+			}
+			msg_exit(-1, "Failed to find real subprogram.\n");
+found:
+			/* Get offset from subprogram */
+			ret = die_within_subprogram(lk->die, pf->addr, &offs);
+			ERR_IF(!ret);
+			show_probepoint(lk->die, offs, pf);
+			/* Continue to search */
+		}
+	}
+	return 0;
+}
+
+static void find_by_func(Dwarf_Die cu_die, struct probe_finder *pf)
+{
+	search_die_from_children(cu_die, probefunc_callback, pf);
+}
+
+/* Find a probe point */
+int find_probepoint(int fd, struct probe_point *pp)
+{
+	Dwarf_Half addr_size = 0;
+	Dwarf_Unsigned next_cuh = 0;
+	Dwarf_Die cu_die = 0;
+	int cu_number = 0, ret;
+	struct probe_finder pf = {.pp = pp};
+
+	ret = dwarf_init(fd, DW_DLC_READ, 0, 0, &__dw_debug, &__dw_error);
+	if (ret != DW_DLV_OK)
+		msg_exit(-1, "Failed to call dwarf_init(). "
+			 "Maybe, not a dwarf file?\n");
+
+	pp->found = 0;
+	while (++cu_number) {
+		/* Search CU (Compilation Unit) */
+		ret = dwarf_next_cu_header(__dw_debug, NULL, NULL, NULL,
+			&addr_size, &next_cuh, &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		if (ret == DW_DLV_NO_ENTRY)
+			break;
+
+		/* Get the DIE(Debugging Information Entry) of this CU */
+		ret = dwarf_siblingof(__dw_debug, 0, &cu_die, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+
+		/* Check if target file is included. */
+		if (pp->file)
+			pf.fno = die_get_fileno(cu_die, pp->file);
+
+		if (!pp->file || pf.fno) {
+			/* Save CU base address (for frame_base) */
+			ret = dwarf_lowpc(cu_die, &pf.cu_base, &__dw_error);
+			ERR_IF(ret == DW_DLV_ERROR);
+			if (ret == DW_DLV_NO_ENTRY)
+				pf.cu_base = 0;
+			if (pp->line)
+				find_by_line(cu_die, &pf);
+			if (pp->function)
+				find_by_func(cu_die, &pf);
+		}
+		dwarf_dealloc(__dw_debug, cu_die, DW_DLA_DIE);
+	}
+	ret = dwarf_finish(__dw_debug, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+
+	return pp->found;
+}
+
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
new file mode 100644
index 0000000..af920de
--- /dev/null
+++ b/tools/perf/util/probe-finder.h
@@ -0,0 +1,68 @@
+#ifndef _PROBE_FINDER_H
+#define _PROBE_FINDER_H
+
+#define _stringify(n)	#n
+#define stringify(n)	_stringify(n)
+
+#ifdef DEBUG
+#define debug(fmt ...)	\
+	fprintf(stderr, "DBG(" __FILE__ ":" stringify(__LINE__) "): " fmt)
+#else
+#define debug(fmt ...)	do {} while (0)
+#endif
+
+#define ERR_IF(cnd)	\
+	do { if (cnd) {	\
+		fprintf(stderr, "Error (" __FILE__ ":" stringify(__LINE__) \
+			"): " stringify(cnd) "\n");			\
+		exit(1);						\
+	} } while (0)
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBE_BUFFER 1024
+#define MAX_PROBES 128
+
+static inline int is_c_varname(const char *name)
+{
+	/* TODO */
+	return isalpha(name[0]) || name[0] == '_';
+}
+
+struct probe_point {
+	/* Inputs */
+	char	*file;		/* File name */
+	int	line;		/* Line number */
+
+	char	*function;	/* Function name */
+	int	offset;		/* Offset bytes */
+
+	int	nr_args;	/* Number of arguments */
+	char	**args;		/* Arguments */
+
+	/* Output */
+	int	found;		/* Number of found probe points */
+	char	*probes[MAX_PROBES];	/* Output buffers (will be allocated)*/
+};
+
+extern int find_probepoint(int fd, struct probe_point *pp);
+
+#include <libdwarf/dwarf.h>
+#include <libdwarf/libdwarf.h>
+
+struct probe_finder {
+	struct probe_point	*pp;	/* Target probe point */
+
+	/* For function searching */
+	Dwarf_Addr	addr;		/* Address */
+	Dwarf_Unsigned	fno;		/* File number */
+	Dwarf_Off	inl_offs;	/* Inline offset */
+
+	/* For variable searching */
+	Dwarf_Addr	cu_base;	/* Current CU base address */
+	Dwarf_Locdesc	fbloc;		/* Location of Current Frame Base */
+	const char	*var;		/* Current variable name */
+	char		*buf;		/* Current output buffer */
+	int		len;		/* Length of output buffer */
+};
+
+#endif /*_PROBE_FINDER_H */


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 6/7] perf: Add perf probe subcommand for kprobe-event setup helper

[Masami Hiramatsu]

Masami Hiramatsu wrote:
> Add perf probe subcommand for kprobe-event setup helper to perf command.
> This allows user to define kprobe events by C expressions (C line numbers,
> C function names, and C local variables).
>
> Usage
> -----
>   perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]
>
>      -k, --vmlinux<file>   vmlinux/module pathname
>      -P, --probe<p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
>                            probe point definition, where
> 		p:	kprobe probe
> 		r:	kretprobe probe
> 		GRP:	Group name (optional)
> 		NAME:	Event name
> 		FUNC:	Function name
> 		OFFS:	Offset from function entry (in byte)
> 		SRC:	Source code path
> 		LINE:	Line number
> 		ARG:	Probe argument (local variable name or
> 			kprobe-tracer argument format is supported.)

Oops, I found it caused compilation error on gcc < 4.4 as below:

     CC builtin-trace.o
     CC builtin-probe.o
cc1: warnings being treated as errors
builtin-probe.c: In function 'parse_probepoint':
builtin-probe.c:109: error: implicit declaration of function 'strndup'
builtin-probe.c:109: error: incompatible implicit declaration of built-in function 'strndup'

Since I forgot to add _GNU_SOURCE...


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

[PATCH tracing/kprobes v4] perf: Add perf probe subcommand for kprobe-event setup helper

[Masami Hiramatsu]

Add perf probe subcommand for kprobe-event setup helper to perf command.
This allows user to define kprobe events by C expressions (C line numbers,
C function names, and C local variables).

Usage
-----
 perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
                          probe point definition, where
		p:	kprobe probe
		r:	kretprobe probe
		GRP:	Group name (optional)
		NAME:	Event name
		FUNC:	Function name
		OFFS:	Offset from function entry (in byte)
		SRC:	Source code path
		LINE:	Line number
		ARG:	Probe argument (local variable name or
			kprobe-tracer argument format is supported.)

Changes in v4:
 - Add _GNU_SOURCE macro for strndup().

Changes in v3:
 - Remove -r option because perf always be used for online kernel.
 - Check malloc/calloc results.

Changes in v2:
 - Check synthesized string length.
 - Rename perf kprobe to perf probe.
 - Use spaces for separator and update usage comment.
 - Check error paths in parse_probepoint().
 - Check optimized-out variables.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---

 tools/perf/Makefile            |   10 +
 tools/perf/builtin-probe.c     |  358 +++++++++++++++++++++
 tools/perf/builtin.h           |    1 
 tools/perf/perf.c              |    3 
 tools/perf/util/probe-finder.c |  690 ++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/probe-finder.h |   68 ++++
 6 files changed, 1130 insertions(+), 0 deletions(-)
 create mode 100644 tools/perf/builtin-probe.c
 create mode 100644 tools/perf/util/probe-finder.c
 create mode 100644 tools/perf/util/probe-finder.h

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index b5f1953..6dabcf1 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -419,6 +419,16 @@ ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf *
 	msg := $(error No libelf.h/libelf found, please install libelf-dev/elfutils-libelf-devel);
 endif
 
+ifneq ($(shell sh -c "(echo '\#include <libdwarf/dwarf.h>'; echo '\#include <libdwarf/libdwarf.h>'; echo 'int main(void) { Dwarf_Debug dbg; Dwarf_Error err; dwarf_init(0, DW_DLC_READ, 0, 0, &dbg, &err); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -ldwarf -lelf -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
+	msg := $(warning No libdwarf.h found, disables probe subcommand. Please install libdwarf-dev/libdwarf-devel);
+else
+	EXTLIBS += -lelf -ldwarf
+	LIB_H += util/probe-finder.h
+	LIB_OBJS += util/probe-finder.o
+	BUILTIN_OBJS += builtin-probe.o
+	BASIC_CFLAGS += -DSUPPORT_DWARF
+endif
+
 ifdef NO_DEMANGLE
 	BASIC_CFLAGS += -DNO_DEMANGLE
 else
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
new file mode 100644
index 0000000..24b64b5
--- /dev/null
+++ b/tools/perf/builtin-probe.c
@@ -0,0 +1,358 @@
+/*
+ * builtin-probe.c
+ *
+ * Builtin probe command: Set up probe events by C expression
+ *
+ * Written by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+#define _GNU_SOURCE
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+#undef _GNU_SOURCE
+#include "perf.h"
+#include "builtin.h"
+#include "util/util.h"
+#include "util/parse-options.h"
+#include "util/parse-events.h"	/* For debugfs_path */
+#include "util/probe-finder.h"
+
+/* Default vmlinux search paths */
+#define NR_SEARCH_PATH 3
+const char *default_search_path[NR_SEARCH_PATH] = {
+"/lib/modules/%s/build/vmlinux",		/* Custom build kernel */
+"/usr/lib/debug/lib/modules/%s/vmlinux",	/* Red Hat debuginfo */
+"/boot/vmlinux-debug-%s",			/* Ubuntu */
+};
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBES 128
+
+/* Session management structure */
+static struct {
+	char *vmlinux;
+	char *release;
+	int nr_probe;
+	struct probe_point probes[MAX_PROBES];
+	char *events[MAX_PROBES];
+} session;
+
+static void semantic_error(const char *msg)
+{
+	fprintf(stderr, "Semantic error: %s\n", msg);
+	exit(1);
+}
+
+static void perror_exit(const char *msg)
+{
+	perror(msg);
+	exit(1);
+}
+
+#define MAX_PROBE_ARGS 128
+
+static int parse_probepoint(const struct option *opt __used,
+			    const char *str, int unset __used)
+{
+	char *argv[MAX_PROBE_ARGS + 2];	/* Event + probe + args */
+	int argc, i;
+	char *arg, *ptr;
+	struct probe_point *pp = &session.probes[session.nr_probe];
+	char **event = &session.events[session.nr_probe];
+	int retp = 0;
+
+	if (!str)	/* The end of probe points */
+		return 0;
+
+	debug("Probe-define(%d): %s\n", session.nr_probe, str);
+	if (++session.nr_probe == MAX_PROBES)
+		semantic_error("Too many probes");
+
+	/* Separate arguments, similar to argv_split */
+	argc = 0;
+	do {
+		/* Skip separators */
+		while (isspace(*str))
+			str++;
+
+		/* Add an argument */
+		if (*str != '\0') {
+			const char *s = str;
+
+			/* Skip the argument */
+			while (!isspace(*str) && *str != '\0')
+				str++;
+
+			/* Duplicate the argument */
+			argv[argc] = strndup(s, str - s);
+			if (argv[argc] == NULL)
+				perror_exit("strndup");
+			if (++argc == MAX_PROBE_ARGS)
+				semantic_error("Too many arguments");
+			debug("argv[%d]=%s\n", argc, argv[argc - 1]);
+		}
+	} while (*str != '\0');
+	if (argc < 2)
+		semantic_error("Need event-name and probe-point at least.");
+
+	/* Parse the event name */
+	if (argv[0][0] == 'r')
+		retp = 1;
+	else if (argv[0][0] != 'p')
+		semantic_error("You must specify 'p'(kprobe) or"
+				" 'r'(kretprobe) first.");
+	/* TODO: check event name */
+	*event = argv[0];
+
+	/* Parse probe point */
+	arg = argv[1];
+	if (arg[0] == '@') {
+		/* Source Line */
+		arg++;
+		ptr = strchr(arg, ':');
+		if (!ptr || !isdigit(ptr[1]))
+			semantic_error("Line number is required.");
+		*ptr++ = '\0';
+		if (strlen(arg) == 0)
+			semantic_error("No file name.");
+		pp->file = strdup(arg);
+		pp->line = atoi(ptr);
+		if (!pp->file || !pp->line)
+			semantic_error("Failed to parse line.");
+		debug("file:%s line:%d\n", pp->file, pp->line);
+	} else {
+		/* Function name */
+		ptr = strchr(arg, '+');
+		if (ptr) {
+			if (!isdigit(ptr[1]))
+				semantic_error("Offset is required.");
+			*ptr++ = '\0';
+			pp->offset = atoi(ptr);
+		} else
+			ptr = arg;
+		ptr = strchr(ptr, '@');
+		if (ptr) {
+			*ptr++ = '\0';
+			pp->file = strdup(ptr);
+		}
+		pp->function = strdup(arg);
+		debug("symbol:%s file:%s offset:%d\n",
+		      pp->function, pp->file, pp->offset);
+	}
+	free(argv[1]);
+
+	/* Copy arguments */
+	pp->nr_args = argc - 2;
+	if (pp->nr_args > 0) {
+		pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
+		if (!pp->args)
+			perror_exit("malloc");
+		memcpy(pp->args, &argv[2], sizeof(char *) * pp->nr_args);
+	}
+
+	/* Ensure return probe has no C argument */
+	if (retp)
+		for (i = 0; i < pp->nr_args; i++)
+			if (is_c_varname(pp->args[i]))
+				semantic_error("You can't specify local"
+						" variable for kretprobe");
+	debug("%d arguments\n", pp->nr_args);
+	return 0;
+}
+
+static int open_default_vmlinux(void)
+{
+	struct utsname uts;
+	char fname[MAX_PATH_LEN];
+	int fd, ret, i;
+
+	ret = uname(&uts);
+	if (ret) {
+		debug("uname() failed.\n");
+		return -errno;
+	}
+	session.release = uts.release;
+	for (i = 0; i < NR_SEARCH_PATH; i++) {
+		ret = snprintf(fname, MAX_PATH_LEN,
+			       default_search_path[i], session.release);
+		if (ret >= MAX_PATH_LEN || ret < 0) {
+			debug("Filename(%d,%s) is too long.\n", i, uts.release);
+			errno = E2BIG;
+			return -E2BIG;
+		}
+		debug("try to open %s\n", fname);
+		fd = open(fname, O_RDONLY);
+		if (fd >= 0)
+			break;
+	}
+	return fd;
+}
+
+static const char * const probe_usage[] = {
+	"perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]",
+	NULL
+};
+
+static const struct option options[] = {
+	OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
+		"vmlinux/module pathname"),
+	OPT_CALLBACK('P', "probe", NULL,
+		"p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
+		"probe point definition, where\n"
+		"\t\tp:\tkprobe probe\n"
+		"\t\tr:\tkretprobe probe\n"
+		"\t\tGRP:\tGroup name (optional)\n"
+		"\t\tNAME:\tEvent name\n"
+		"\t\tFUNC:\tFunction name\n"
+		"\t\tOFFS:\tOffset from function entry (in byte)\n"
+		"\t\tSRC:\tSource code path\n"
+		"\t\tLINE:\tLine number\n"
+		"\t\tARG:\tProbe argument (local variable name or\n"
+		"\t\t\tkprobe-tracer argument format is supported.)\n",
+		parse_probepoint),
+	OPT_END()
+};
+
+static int write_new_event(int fd, const char *buf)
+{
+	int ret;
+
+	printf("Adding new event: %s\n", buf);
+	ret = write(fd, buf, strlen(buf));
+	if (ret <= 0)
+		perror("Error: Failed to create event");
+
+	return ret;
+}
+
+#define MAX_CMDLEN 256
+
+static int synthesize_probepoint(struct probe_point *pp)
+{
+	char *buf;
+	int i, len, ret;
+	pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
+	if (!buf)
+		perror_exit("calloc");
+	ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
+	if (ret <= 0 || ret >= MAX_CMDLEN)
+		goto error;
+	len = ret;
+
+	for (i = 0; i < pp->nr_args; i++) {
+		ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
+			       pp->args[i]);
+		if (ret <= 0 || ret >= MAX_CMDLEN - len)
+			goto error;
+		len += ret;
+	}
+	pp->found = 1;
+	return pp->found;
+error:
+	free(pp->probes[0]);
+	if (ret > 0)
+		ret = -E2BIG;
+	return ret;
+}
+
+int cmd_probe(int argc, const char **argv, const char *prefix __used)
+{
+	int i, j, fd, ret, need_dwarf = 0;
+	struct probe_point *pp;
+	char buf[MAX_CMDLEN];
+
+	argc = parse_options(argc, argv, options, probe_usage,
+		PARSE_OPT_STOP_AT_NON_OPTION);
+	if (argc || session.nr_probe == 0)
+		usage_with_options(probe_usage, options);
+
+	/* Synthesize return probes */
+	for (j = 0; j < session.nr_probe; j++) {
+		if (session.events[j][0] != 'r') {
+			need_dwarf = 1;
+			continue;
+		}
+		ret = synthesize_probepoint(&session.probes[j]);
+		if (ret == -E2BIG)
+			semantic_error("probe point is too long.");
+		else if (ret < 0) {
+			perror("snprintf");
+			return -1;
+		}
+	}
+
+	if (!need_dwarf)
+		goto setup_probes;
+
+	if (session.vmlinux)
+		fd = open(session.vmlinux, O_RDONLY);
+	else
+		fd = open_default_vmlinux();
+	if (fd < 0) {
+		perror("vmlinux/module file open");
+		return -1;
+	}
+
+	/* Searching probe points */
+	for (j = 0; j < session.nr_probe; j++) {
+		pp = &session.probes[j];
+		if (pp->found)
+			continue;
+
+		lseek(fd, SEEK_SET, 0);
+		ret = find_probepoint(fd, pp);
+		if (ret <= 0) {
+			fprintf(stderr, "Error: No probe point found.\n");
+			return -1;
+		}
+		debug("probe event %s found\n", session.events[j]);
+	}
+	close(fd);
+
+setup_probes:
+	/* Settng up probe points */
+	snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
+	fd = open(buf, O_WRONLY, O_APPEND);
+	if (fd < 0) {
+		perror("kprobe_events open");
+		return -1;
+	}
+	for (j = 0; j < session.nr_probe; j++) {
+		pp = &session.probes[j];
+		if (pp->found == 1) {
+			snprintf(buf, MAX_CMDLEN, "%s %s\n",
+				session.events[j], pp->probes[0]);
+			write_new_event(fd, buf);
+		} else
+			for (i = 0; i < pp->found; i++) {
+				snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
+					session.events[j], i, pp->probes[i]);
+				write_new_event(fd, buf);
+			}
+	}
+	close(fd);
+	return 0;
+}
+
diff --git a/tools/perf/builtin.h b/tools/perf/builtin.h
index e11d8d2..ad5f0f4 100644
--- a/tools/perf/builtin.h
+++ b/tools/perf/builtin.h
@@ -25,5 +25,6 @@ extern int cmd_timechart(int argc, const char **argv, const char *prefix);
 extern int cmd_top(int argc, const char **argv, const char *prefix);
 extern int cmd_trace(int argc, const char **argv, const char *prefix);
 extern int cmd_version(int argc, const char **argv, const char *prefix);
+extern int cmd_probe(int argc, const char **argv, const char *prefix);
 
 #endif
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 19fc7fe..f598120 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -295,6 +295,9 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "version", cmd_version, 0 },
 		{ "trace", cmd_trace, 0 },
 		{ "sched", cmd_sched, 0 },
+#ifdef SUPPORT_DWARF
+		{ "probe", cmd_probe, 0 },
+#endif
 	};
 	unsigned int i;
 	static const char ext[] = STRIP_EXTENSION;
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
new file mode 100644
index 0000000..ec6f53f
--- /dev/null
+++ b/tools/perf/util/probe-finder.c
@@ -0,0 +1,690 @@
+/*
+ * probe-finder.c : C expression to kprobe event converter
+ *
+ * Written by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <ctype.h>
+#include "probe-finder.h"
+
+
+/* Dwarf_Die Linkage to parent Die */
+struct die_link {
+	struct die_link *parent;	/* Parent die */
+	Dwarf_Die die;			/* Current die */
+};
+
+static Dwarf_Debug __dw_debug;
+static Dwarf_Error __dw_error;
+
+static void msg_exit(int ret, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fprintf(stderr, "Error:  ");
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	fprintf(stderr, "\n");
+	exit(ret);
+}
+
+
+/*
+ * Generic dwarf analysis helpers
+ */
+
+#define X86_32_MAX_REGS 8
+const char *x86_32_regs_table[X86_32_MAX_REGS] = {
+	"%ax",
+	"%cx",
+	"%dx",
+	"%bx",
+	"$stack",	/* Stack address instead of %sp */
+	"%bp",
+	"%si",
+	"%di",
+};
+
+#define X86_64_MAX_REGS 16
+const char *x86_64_regs_table[X86_64_MAX_REGS] = {
+	"%ax",
+	"%dx",
+	"%cx",
+	"%bx",
+	"%si",
+	"%di",
+	"%bp",
+	"%sp",
+	"%r8",
+	"%r9",
+	"%r10",
+	"%r11",
+	"%r12",
+	"%r13",
+	"%r14",
+	"%r15",
+};
+
+/* TODO: switching by dwarf address size */
+#ifdef __x86_64__
+#define ARCH_MAX_REGS X86_64_MAX_REGS
+#define arch_regs_table x86_64_regs_table
+#else
+#define ARCH_MAX_REGS X86_32_MAX_REGS
+#define arch_regs_table x86_32_regs_table
+#endif
+
+/* Return architecture dependent register string (for kprobe-tracer) */
+static const char *get_arch_regstr(unsigned int n)
+{
+	return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
+}
+
+/*
+ * Compare the tail of two strings.
+ * Return 0 if whole of either string is same as another's tail part.
+ */
+static int strtailcmp(const char *s1, const char *s2)
+{
+	int i1 = strlen(s1);
+	int i2 = strlen(s2);
+	while (--i1 > 0 && --i2 > 0) {
+		if (s1[i1] != s2[i2])
+			return s1[i1] - s2[i2];
+	}
+	return 0;
+}
+
+/* Find the fileno of the target file. */
+static Dwarf_Unsigned die_get_fileno(Dwarf_Die cu_die, const char *fname)
+{
+	Dwarf_Signed cnt, i;
+	Dwarf_Unsigned found = 0;
+	char **srcs;
+	int ret;
+
+	if (!fname)
+		return 0;
+
+	ret = dwarf_srcfiles(cu_die, &srcs, &cnt, &__dw_error);
+	if (ret == DW_DLV_OK) {
+		for (i = 0; i < cnt && !found; i++) {
+			if (strtailcmp(srcs[i], fname) == 0)
+				found = i + 1;
+			dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
+		}
+		for (; i < cnt; i++)
+			dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
+		dwarf_dealloc(__dw_debug, srcs, DW_DLA_LIST);
+	}
+	if (found)
+		debug("found fno: %d\n", (int)found);
+	return found;
+}
+
+/* Compare diename and tname */
+static int die_compare_name(Dwarf_Die die, const char *tname)
+{
+	char *name;
+	int ret;
+	ret = dwarf_diename(die, &name, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = strcmp(tname, name);
+		dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
+	} else
+		ret = -1;
+	return ret;
+}
+
+/* Check the address is in the subprogram(function). */
+static int die_within_subprogram(Dwarf_Die sp_die, Dwarf_Addr addr,
+				 Dwarf_Signed *offs)
+{
+	Dwarf_Addr lopc, hipc;
+	int ret;
+
+	/* TODO: check ranges */
+	ret = dwarf_lowpc(sp_die, &lopc, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_NO_ENTRY)
+		return 0;
+	ret = dwarf_highpc(sp_die, &hipc, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	if (lopc <= addr && addr < hipc) {
+		*offs = addr - lopc;
+		return 1;
+	} else
+		return 0;
+}
+
+/* Check the die is inlined function */
+static Dwarf_Bool die_inlined_subprogram(Dwarf_Die die)
+{
+	/* TODO: check strictly */
+	Dwarf_Bool inl;
+	int ret;
+
+	ret = dwarf_hasattr(die, DW_AT_inline, &inl, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	return inl;
+}
+
+/* Get the offset of abstruct_origin */
+static Dwarf_Off die_get_abstract_origin(Dwarf_Die die)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Off cu_offs;
+	int ret;
+
+	ret = dwarf_attr(die, DW_AT_abstract_origin, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_formref(attr, &cu_offs, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+	return cu_offs;
+}
+
+/* Get entry pc(or low pc, 1st entry of ranges)  of the die */
+static Dwarf_Addr die_get_entrypc(Dwarf_Die die)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Addr addr;
+	Dwarf_Off offs;
+	Dwarf_Ranges *ranges;
+	Dwarf_Signed cnt;
+	int ret;
+
+	/* Try to get entry pc */
+	ret = dwarf_attr(die, DW_AT_entry_pc, &attr, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = dwarf_formaddr(attr, &addr, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+		return addr;
+	}
+
+	/* Try to get low pc */
+	ret = dwarf_lowpc(die, &addr, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK)
+		return addr;
+
+	/* Try to get ranges */
+	ret = dwarf_attr(die, DW_AT_ranges, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_formref(attr, &offs, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = dwarf_get_ranges(__dw_debug, offs, &ranges, &cnt, NULL,
+				&__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	addr = ranges[0].dwr_addr1;
+	dwarf_ranges_dealloc(__dw_debug, ranges, cnt);
+	return addr;
+}
+
+/*
+ * Search a Die from Die tree.
+ * Note: cur_link->die should be deallocated in this function.
+ */
+static int __search_die_tree(struct die_link *cur_link,
+			     int (*die_cb)(struct die_link *, void *),
+			     void *data)
+{
+	Dwarf_Die new_die;
+	struct die_link new_link;
+	int ret;
+
+	if (!die_cb)
+		return 0;
+
+	/* Check current die */
+	while (!(ret = die_cb(cur_link, data))) {
+		/* Check child die */
+		ret = dwarf_child(cur_link->die, &new_die, &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		if (ret == DW_DLV_OK) {
+			new_link.parent = cur_link;
+			new_link.die = new_die;
+			ret = __search_die_tree(&new_link, die_cb, data);
+			if (ret)
+				break;
+		}
+
+		/* Move to next sibling */
+		ret = dwarf_siblingof(__dw_debug, cur_link->die, &new_die,
+				      &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
+		cur_link->die = new_die;
+		if (ret == DW_DLV_NO_ENTRY)
+			return 0;
+	}
+	dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
+	return ret;
+}
+
+/* Search a die in its children's die tree */
+static int search_die_from_children(Dwarf_Die parent_die,
+				    int (*die_cb)(struct die_link *, void *),
+				    void *data)
+{
+	struct die_link new_link;
+	int ret;
+
+	new_link.parent = NULL;
+	ret = dwarf_child(parent_die, &new_link.die, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK)
+		return __search_die_tree(&new_link, die_cb, data);
+	else
+		return 0;
+}
+
+/* Find a locdesc corresponding to the address */
+static int attr_get_locdesc(Dwarf_Attribute attr, Dwarf_Locdesc *desc,
+			    Dwarf_Addr addr)
+{
+	Dwarf_Signed lcnt;
+	Dwarf_Locdesc **llbuf;
+	int ret, i;
+
+	ret = dwarf_loclist_n(attr, &llbuf, &lcnt, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = DW_DLV_NO_ENTRY;
+	for (i = 0; i < lcnt; ++i) {
+		if (llbuf[i]->ld_lopc <= addr &&
+		    llbuf[i]->ld_hipc > addr) {
+			memcpy(desc, llbuf[i], sizeof(Dwarf_Locdesc));
+			desc->ld_s =
+				malloc(sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
+			ERR_IF(desc->ld_s == NULL);
+			memcpy(desc->ld_s, llbuf[i]->ld_s,
+				sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
+			ret = DW_DLV_OK;
+			break;
+		}
+		dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
+		dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
+	}
+	/* Releasing loop */
+	for (; i < lcnt; ++i) {
+		dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
+		dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
+	}
+	dwarf_dealloc(__dw_debug, llbuf, DW_DLA_LIST);
+	return ret;
+}
+
+/*
+ * Probe finder related functions
+ */
+
+/* Show a location */
+static void show_location(Dwarf_Loc *loc, struct probe_finder *pf)
+{
+	Dwarf_Small op;
+	Dwarf_Unsigned regn;
+	Dwarf_Signed offs;
+	int deref = 0, ret;
+	const char *regs;
+
+	op = loc->lr_atom;
+
+	/* If this is based on frame buffer, set the offset */
+	if (op == DW_OP_fbreg) {
+		deref = 1;
+		offs = (Dwarf_Signed)loc->lr_number;
+		op = pf->fbloc.ld_s[0].lr_atom;
+		loc = &pf->fbloc.ld_s[0];
+	} else
+		offs = 0;
+
+	if (op >= DW_OP_breg0 && op <= DW_OP_breg31) {
+		regn = op - DW_OP_breg0;
+		offs += (Dwarf_Signed)loc->lr_number;
+		deref = 1;
+	} else if (op >= DW_OP_reg0 && op <= DW_OP_reg31) {
+		regn = op - DW_OP_reg0;
+	} else if (op == DW_OP_bregx) {
+		regn = loc->lr_number;
+		offs += (Dwarf_Signed)loc->lr_number2;
+		deref = 1;
+	} else if (op == DW_OP_regx) {
+		regn = loc->lr_number;
+	} else
+		msg_exit(-EINVAL, "Dwarf_OP %d is not supported.\n", op);
+
+	regs = get_arch_regstr(regn);
+	if (!regs)
+		msg_exit(-EINVAL, "%lld exceeds max register number.\n", regn);
+
+	if (deref)
+		ret = snprintf(pf->buf, pf->len,
+				 " %s=%+lld(%s)", pf->var, offs, regs);
+	else
+		ret = snprintf(pf->buf, pf->len, " %s=%s", pf->var, regs);
+	ERR_IF(ret < 0);
+	ERR_IF(ret >= pf->len);
+}
+
+/* Show a variables in kprobe event format */
+static void show_variable(Dwarf_Die vr_die, struct probe_finder *pf)
+{
+	Dwarf_Attribute attr;
+	Dwarf_Locdesc ld;
+	int ret;
+
+	ret = dwarf_attr(vr_die, DW_AT_location, &attr, &__dw_error);
+	if (ret != DW_DLV_OK)
+		goto error;
+	ret = attr_get_locdesc(attr, &ld, (pf->addr - pf->cu_base));
+	if (ret != DW_DLV_OK)
+		goto error;
+	/* TODO? */
+	ERR_IF(ld.ld_cents != 1);
+	show_location(&ld.ld_s[0], pf);
+	free(ld.ld_s);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+	return ;
+error:
+	msg_exit(-1, "Failed to find the location of %s at this address.\n"
+		 " Perhaps, it was optimized out.\n", pf->var);
+}
+
+static int variable_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	Dwarf_Half tag;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if ((tag == DW_TAG_formal_parameter ||
+	     tag == DW_TAG_variable) &&
+	    (die_compare_name(dlink->die, pf->var) == 0)) {
+		show_variable(dlink->die, pf);
+		return 1;
+	}
+	/* TODO: Support struct members and arrays */
+	return 0;
+}
+
+/* Find a variable in a subprogram die */
+static void find_variable(Dwarf_Die sp_die, struct probe_finder *pf)
+{
+	int ret;
+
+	if (!is_c_varname(pf->var)) {
+		/* Output raw parameters */
+		ret = snprintf(pf->buf, pf->len, " %s", pf->var);
+		ERR_IF(ret < 0);
+		ERR_IF(ret >= pf->len);
+		return ;
+	}
+
+	debug("Searching '%s' variable in context.\n", pf->var);
+	/* Search child die for local variables and parameters. */
+	ret = search_die_from_children(sp_die, variable_callback, pf);
+	if (!ret)
+		msg_exit(-1, "Failed to find '%s' in this function.\n",
+			 pf->var);
+}
+
+/* Get a frame base on the address */
+static void get_current_frame_base(Dwarf_Die sp_die, struct probe_finder *pf)
+{
+	Dwarf_Attribute attr;
+	int ret;
+
+	ret = dwarf_attr(sp_die, DW_AT_frame_base, &attr, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+	ret = attr_get_locdesc(attr, &pf->fbloc, (pf->addr - pf->cu_base));
+	ERR_IF(ret != DW_DLV_OK);
+	dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
+}
+
+static void free_current_frame_base(struct probe_finder *pf)
+{
+	free(pf->fbloc.ld_s);
+	memset(&pf->fbloc, 0, sizeof(Dwarf_Locdesc));
+}
+
+/* Show a probe point to output buffer */
+static void show_probepoint(Dwarf_Die sp_die, Dwarf_Signed offs,
+			    struct probe_finder *pf)
+{
+	struct probe_point *pp = pf->pp;
+	char *name;
+	char tmp[MAX_PROBE_BUFFER];
+	int ret, i, len;
+
+	/* Output name of probe point */
+	ret = dwarf_diename(sp_die, &name, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (ret == DW_DLV_OK) {
+		ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%u", name,
+				(unsigned int)offs);
+		dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
+	} else {
+		/* This function has no name. */
+		ret = snprintf(tmp, MAX_PROBE_BUFFER, "0x%llx", pf->addr);
+	}
+	ERR_IF(ret < 0);
+	ERR_IF(ret >= MAX_PROBE_BUFFER);
+	len = ret;
+
+	/* Find each argument */
+	get_current_frame_base(sp_die, pf);
+	for (i = 0; i < pp->nr_args; i++) {
+		pf->var = pp->args[i];
+		pf->buf = &tmp[len];
+		pf->len = MAX_PROBE_BUFFER - len;
+		find_variable(sp_die, pf);
+		len += strlen(pf->buf);
+	}
+	free_current_frame_base(pf);
+
+	pp->probes[pp->found] = strdup(tmp);
+	pp->found++;
+}
+
+static int probeaddr_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	Dwarf_Half tag;
+	Dwarf_Signed offs;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	/* Check the address is in this subprogram */
+	if (tag == DW_TAG_subprogram &&
+	    die_within_subprogram(dlink->die, pf->addr, &offs)) {
+		show_probepoint(dlink->die, offs, pf);
+		return 1;
+	}
+	return 0;
+}
+
+/* Find probe point from its line number */
+static void find_by_line(Dwarf_Die cu_die, struct probe_finder *pf)
+{
+	struct probe_point *pp = pf->pp;
+	Dwarf_Signed cnt, i;
+	Dwarf_Line *lines;
+	Dwarf_Unsigned lineno = 0;
+	Dwarf_Addr addr;
+	Dwarf_Unsigned fno;
+	int ret;
+
+	ret = dwarf_srclines(cu_die, &lines, &cnt, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+
+	for (i = 0; i < cnt; i++) {
+		ret = dwarf_line_srcfileno(lines[i], &fno, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		if (fno != pf->fno)
+			continue;
+
+		ret = dwarf_lineno(lines[i], &lineno, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		if (lineno != (Dwarf_Unsigned)pp->line)
+			continue;
+
+		ret = dwarf_lineaddr(lines[i], &addr, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+		debug("Probe point found: 0x%llx\n", addr);
+		pf->addr = addr;
+		/* Search a real subprogram including this line, */
+		ret = search_die_from_children(cu_die, probeaddr_callback, pf);
+		if (ret == 0)
+			msg_exit(-1,
+				 "Probe point is not found in subprograms.\n");
+		/* Continuing, because target line might be inlined. */
+	}
+	dwarf_srclines_dealloc(__dw_debug, lines, cnt);
+}
+
+/* Search function from function name */
+static int probefunc_callback(struct die_link *dlink, void *data)
+{
+	struct probe_finder *pf = (struct probe_finder *)data;
+	struct probe_point *pp = pf->pp;
+	struct die_link *lk;
+	Dwarf_Signed offs;
+	Dwarf_Half tag;
+	int ret;
+
+	ret = dwarf_tag(dlink->die, &tag, &__dw_error);
+	ERR_IF(ret == DW_DLV_ERROR);
+	if (tag == DW_TAG_subprogram) {
+		if (die_compare_name(dlink->die, pp->function) == 0) {
+			if (die_inlined_subprogram(dlink->die)) {
+				/* Inlined function, save it. */
+				ret = dwarf_die_CU_offset(dlink->die,
+							  &pf->inl_offs,
+							  &__dw_error);
+				ERR_IF(ret != DW_DLV_OK);
+				debug("inline definition offset %lld\n",
+					pf->inl_offs);
+				return 0;
+			}
+			/* Get probe address */
+			pf->addr = die_get_entrypc(dlink->die);
+			pf->addr += pp->offset;
+			/* TODO: Check the address in this function */
+			show_probepoint(dlink->die, pp->offset, pf);
+			/* Continue to search */
+		}
+	} else if (tag == DW_TAG_inlined_subroutine && pf->inl_offs) {
+		if (die_get_abstract_origin(dlink->die) == pf->inl_offs) {
+			/* Get probe address */
+			pf->addr = die_get_entrypc(dlink->die);
+			pf->addr += pp->offset;
+			debug("found inline addr: 0x%llx\n", pf->addr);
+			/* Inlined function. Get a real subprogram */
+			for (lk = dlink->parent; lk != NULL; lk = lk->parent) {
+				tag = 0;
+				dwarf_tag(lk->die, &tag, &__dw_error);
+				ERR_IF(ret == DW_DLV_ERROR);
+				if (tag == DW_TAG_subprogram &&
+				    !die_inlined_subprogram(lk->die))
+					goto found;
+			}
+			msg_exit(-1, "Failed to find real subprogram.\n");
+found:
+			/* Get offset from subprogram */
+			ret = die_within_subprogram(lk->die, pf->addr, &offs);
+			ERR_IF(!ret);
+			show_probepoint(lk->die, offs, pf);
+			/* Continue to search */
+		}
+	}
+	return 0;
+}
+
+static void find_by_func(Dwarf_Die cu_die, struct probe_finder *pf)
+{
+	search_die_from_children(cu_die, probefunc_callback, pf);
+}
+
+/* Find a probe point */
+int find_probepoint(int fd, struct probe_point *pp)
+{
+	Dwarf_Half addr_size = 0;
+	Dwarf_Unsigned next_cuh = 0;
+	Dwarf_Die cu_die = 0;
+	int cu_number = 0, ret;
+	struct probe_finder pf = {.pp = pp};
+
+	ret = dwarf_init(fd, DW_DLC_READ, 0, 0, &__dw_debug, &__dw_error);
+	if (ret != DW_DLV_OK)
+		msg_exit(-1, "Failed to call dwarf_init(). "
+			 "Maybe, not a dwarf file?\n");
+
+	pp->found = 0;
+	while (++cu_number) {
+		/* Search CU (Compilation Unit) */
+		ret = dwarf_next_cu_header(__dw_debug, NULL, NULL, NULL,
+			&addr_size, &next_cuh, &__dw_error);
+		ERR_IF(ret == DW_DLV_ERROR);
+		if (ret == DW_DLV_NO_ENTRY)
+			break;
+
+		/* Get the DIE(Debugging Information Entry) of this CU */
+		ret = dwarf_siblingof(__dw_debug, 0, &cu_die, &__dw_error);
+		ERR_IF(ret != DW_DLV_OK);
+
+		/* Check if target file is included. */
+		if (pp->file)
+			pf.fno = die_get_fileno(cu_die, pp->file);
+
+		if (!pp->file || pf.fno) {
+			/* Save CU base address (for frame_base) */
+			ret = dwarf_lowpc(cu_die, &pf.cu_base, &__dw_error);
+			ERR_IF(ret == DW_DLV_ERROR);
+			if (ret == DW_DLV_NO_ENTRY)
+				pf.cu_base = 0;
+			if (pp->line)
+				find_by_line(cu_die, &pf);
+			if (pp->function)
+				find_by_func(cu_die, &pf);
+		}
+		dwarf_dealloc(__dw_debug, cu_die, DW_DLA_DIE);
+	}
+	ret = dwarf_finish(__dw_debug, &__dw_error);
+	ERR_IF(ret != DW_DLV_OK);
+
+	return pp->found;
+}
+
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
new file mode 100644
index 0000000..af920de
--- /dev/null
+++ b/tools/perf/util/probe-finder.h
@@ -0,0 +1,68 @@
+#ifndef _PROBE_FINDER_H
+#define _PROBE_FINDER_H
+
+#define _stringify(n)	#n
+#define stringify(n)	_stringify(n)
+
+#ifdef DEBUG
+#define debug(fmt ...)	\
+	fprintf(stderr, "DBG(" __FILE__ ":" stringify(__LINE__) "): " fmt)
+#else
+#define debug(fmt ...)	do {} while (0)
+#endif
+
+#define ERR_IF(cnd)	\
+	do { if (cnd) {	\
+		fprintf(stderr, "Error (" __FILE__ ":" stringify(__LINE__) \
+			"): " stringify(cnd) "\n");			\
+		exit(1);						\
+	} } while (0)
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBE_BUFFER 1024
+#define MAX_PROBES 128
+
+static inline int is_c_varname(const char *name)
+{
+	/* TODO */
+	return isalpha(name[0]) || name[0] == '_';
+}
+
+struct probe_point {
+	/* Inputs */
+	char	*file;		/* File name */
+	int	line;		/* Line number */
+
+	char	*function;	/* Function name */
+	int	offset;		/* Offset bytes */
+
+	int	nr_args;	/* Number of arguments */
+	char	**args;		/* Arguments */
+
+	/* Output */
+	int	found;		/* Number of found probe points */
+	char	*probes[MAX_PROBES];	/* Output buffers (will be allocated)*/
+};
+
+extern int find_probepoint(int fd, struct probe_point *pp);
+
+#include <libdwarf/dwarf.h>
+#include <libdwarf/libdwarf.h>
+
+struct probe_finder {
+	struct probe_point	*pp;	/* Target probe point */
+
+	/* For function searching */
+	Dwarf_Addr	addr;		/* Address */
+	Dwarf_Unsigned	fno;		/* File number */
+	Dwarf_Off	inl_offs;	/* Inline offset */
+
+	/* For variable searching */
+	Dwarf_Addr	cu_base;	/* Current CU base address */
+	Dwarf_Locdesc	fbloc;		/* Location of Current Frame Base */
+	const char	*var;		/* Current variable name */
+	char		*buf;		/* Current output buffer */
+	int		len;		/* Length of output buffer */
+};
+
+#endif /*_PROBE_FINDER_H */


-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v4] perf: Add perf probe subcommand for kprobe-event setup helper

[Frédéric Weisbecker]

2009/10/8 Masami Hiramatsu <mhiramat@redhat.com>:
> Add perf probe subcommand for kprobe-event setup helper to perf command.
> This allows user to define kprobe events by C expressions (C line numbers,
> C function names, and C local variables).
>
> Usage
> -----
>  perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]
>
>    -k, --vmlinux <file>  vmlinux/module pathname
>    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
>                          probe point definition, where
>                p:      kprobe probe
>                r:      kretprobe probe
>                GRP:    Group name (optional)
>                NAME:   Event name
>                FUNC:   Function name
>                OFFS:   Offset from function entry (in byte)
>                SRC:    Source code path
>                LINE:   Line number
>                ARG:    Probe argument (local variable name or
>                        kprobe-tracer argument format is supported.)
>
> Changes in v4:
>  - Add _GNU_SOURCE macro for strndup().
>
> Changes in v3:
>  - Remove -r option because perf always be used for online kernel.
>  - Check malloc/calloc results.
>
> Changes in v2:
>  - Check synthesized string length.
>  - Rename perf kprobe to perf probe.
>  - Use spaces for separator and update usage comment.
>  - Check error paths in parse_probepoint().
>  - Check optimized-out variables.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> Cc: Jim Keniston <jkenisto@us.ibm.com>
> Cc: Frank Ch. Eigler <fche@redhat.com>
> ---
>
[...]
> +/* Default vmlinux search paths */
> +#define NR_SEARCH_PATH 3
> +const char *default_search_path[NR_SEARCH_PATH] = {
> +"/lib/modules/%s/build/vmlinux",               /* Custom build kernel */
> +"/usr/lib/debug/lib/modules/%s/vmlinux",       /* Red Hat debuginfo */
> +"/boot/vmlinux-debug-%s",                      /* Ubuntu */
> +};
[...]
> +static int open_default_vmlinux(void)
> +{
> +       struct utsname uts;
> +       char fname[MAX_PATH_LEN];
> +       int fd, ret, i;
> +
> +       ret = uname(&uts);
> +       if (ret) {
> +               debug("uname() failed.\n");
> +               return -errno;
> +       }
> +       session.release = uts.release;
> +       for (i = 0; i < NR_SEARCH_PATH; i++) {
> +               ret = snprintf(fname, MAX_PATH_LEN,
> +                              default_search_path[i], session.release);
> +               if (ret >= MAX_PATH_LEN || ret < 0) {
> +                       debug("Filename(%d,%s) is too long.\n", i, uts.release);
> +                       errno = E2BIG;
> +                       return -E2BIG;
> +               }
> +               debug("try to open %s\n", fname);
> +               fd = open(fname, O_RDONLY);
> +               if (fd >= 0)
> +                       break;
> +       }
> +       return fd;
> +}


We have a kind of kernel path finder already inside perf. It might be
encapsulated
inside the load_kernel() helper, I don't remember exactly.

It would be better to make use of such centralized and already
existing facility.

The patchset looks good. I'll apply and push it soon.

Thanks a lot!

Re: [PATCH tracing/kprobes v4] perf: Add perf probe subcommand for kprobe-event setup helper

[Masami Hiramatsu]

Frédéric Weisbecker wrote:
> 2009/10/8 Masami Hiramatsu <mhiramat@redhat.com>:
>> Add perf probe subcommand for kprobe-event setup helper to perf command.
>> This allows user to define kprobe events by C expressions (C line numbers,
>> C function names, and C local variables).
>>
>> Usage
>> -----
>>  perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]
>>
>>    -k, --vmlinux <file>  vmlinux/module pathname
>>    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
>>                          probe point definition, where
>>                p:      kprobe probe
>>                r:      kretprobe probe
>>                GRP:    Group name (optional)
>>                NAME:   Event name
>>                FUNC:   Function name
>>                OFFS:   Offset from function entry (in byte)
>>                SRC:    Source code path
>>                LINE:   Line number
>>                ARG:    Probe argument (local variable name or
>>                        kprobe-tracer argument format is supported.)
>>
>> Changes in v4:
>>  - Add _GNU_SOURCE macro for strndup().
>>
>> Changes in v3:
>>  - Remove -r option because perf always be used for online kernel.
>>  - Check malloc/calloc results.
>>
>> Changes in v2:
>>  - Check synthesized string length.
>>  - Rename perf kprobe to perf probe.
>>  - Use spaces for separator and update usage comment.
>>  - Check error paths in parse_probepoint().
>>  - Check optimized-out variables.
>>
>> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> Cc: Ingo Molnar <mingo@elte.hu>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Cc: Mike Galbraith <efault@gmx.de>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> Cc: Christoph Hellwig <hch@infradead.org>
>> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
>> Cc: Jim Keniston <jkenisto@us.ibm.com>
>> Cc: Frank Ch. Eigler <fche@redhat.com>
>> ---
>>
> [...]
>> +/* Default vmlinux search paths */
>> +#define NR_SEARCH_PATH 3
>> +const char *default_search_path[NR_SEARCH_PATH] = {
>> +"/lib/modules/%s/build/vmlinux",               /* Custom build kernel */
>> +"/usr/lib/debug/lib/modules/%s/vmlinux",       /* Red Hat debuginfo */
>> +"/boot/vmlinux-debug-%s",                      /* Ubuntu */
>> +};
> [...]
>> +static int open_default_vmlinux(void)
>> +{
>> +       struct utsname uts;
>> +       char fname[MAX_PATH_LEN];
>> +       int fd, ret, i;
>> +
>> +       ret = uname(&uts);
>> +       if (ret) {
>> +               debug("uname() failed.\n");
>> +               return -errno;
>> +       }
>> +       session.release = uts.release;
>> +       for (i = 0; i < NR_SEARCH_PATH; i++) {
>> +               ret = snprintf(fname, MAX_PATH_LEN,
>> +                              default_search_path[i], session.release);
>> +               if (ret >= MAX_PATH_LEN || ret < 0) {
>> +                       debug("Filename(%d,%s) is too long.\n", i, uts.release);
>> +                       errno = E2BIG;
>> +                       return -E2BIG;
>> +               }
>> +               debug("try to open %s\n", fname);
>> +               fd = open(fname, O_RDONLY);
>> +               if (fd >= 0)
>> +                       break;
>> +       }
>> +       return fd;
>> +}
> 
> 
> We have a kind of kernel path finder already inside perf. It might be
> encapsulated
> inside the load_kernel() helper, I don't remember exactly.
> 
> It would be better to make use of such centralized and already
> existing facility.

Agreed. AFAICS, load_kernel() is currently only for symbol resolver,
and we can make it for dwarf analyzer too.

> 
> The patchset looks good. I'll apply and push it soon.

Thanks!

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v4] perf: Add perf probe subcommand for kprobe-event setup helper

[Frederic Weisbecker]

On Thu, Oct 08, 2009 at 05:17:38PM -0400, Masami Hiramatsu wrote:
> +static void semantic_error(const char *msg)
> +{
> +	fprintf(stderr, "Semantic error: %s\n", msg);
> +	exit(1);
> +}
> +
> +static void perror_exit(const char *msg)
> +{
> +	perror(msg);
> +	exit(1);
> +}



We have that already btw:

tools/perf/util/util.h:
	extern void die(const char *err, ...) NORETURN __attribute__((format (printf, 1, 2)));


> +static void msg_exit(int ret, const char *fmt, ...)
> +{
> +	va_list ap;
> +
> +	va_start(ap, fmt);
> +	fprintf(stderr, "Error:  ");
> +	vfprintf(stderr, fmt, ap);
> +	va_end(ap);
> +
> +	fprintf(stderr, "\n");
> +	exit(ret);
> +}


And somehow ditto :)

Re: [PATCH tracing/kprobes v4] perf: Add perf probe subcommand for kprobe-event setup helper

[Frederic Weisbecker]

On Thu, Oct 08, 2009 at 05:17:38PM -0400, Masami Hiramatsu wrote:
> +#ifdef DEBUG
> +#define debug(fmt ...)	\
> +	fprintf(stderr, "DBG(" __FILE__ ":" stringify(__LINE__) "): " fmt)
> +#else
> +#define debug(fmt ...)	do {} while (0)
> +#endif



We have that too:

int eprintf(const char *fmt, ...) __attribute__((format(printf, 1, 2)));
int dump_printf(const char *fmt, ...) __attribute__((format(printf, 1, 2)));



> +#define ERR_IF(cnd)	\
> +	do { if (cnd) {	\
> +		fprintf(stderr, "Error (" __FILE__ ":" stringify(__LINE__) \
> +			"): " stringify(cnd) "\n");			\
> +		exit(1);						\
> +	} } while (0)


And that would be nice to have in util/debug.h but more
perhaps more as a DIE_IF()

Re: [PATCH tracing/kprobes v4] perf: Add perf probe subcommand for kprobe-event setup helper

[Masami Hiramatsu]

Frederic Weisbecker wrote:
> On Thu, Oct 08, 2009 at 05:17:38PM -0400, Masami Hiramatsu wrote:
>> +#ifdef DEBUG
>> +#define debug(fmt ...)	\
>> +	fprintf(stderr, "DBG(" __FILE__ ":" stringify(__LINE__) "): " fmt)
>> +#else
>> +#define debug(fmt ...)	do {} while (0)
>> +#endif
>
>
>
> We have that too:
>
> int eprintf(const char *fmt, ...) __attribute__((format(printf, 1, 2)));
> int dump_printf(const char *fmt, ...) __attribute__((format(printf, 1, 2)));

Thanks, I'll use that.

>> +#define ERR_IF(cnd)	\
>> +	do { if (cnd) {	\
>> +		fprintf(stderr, "Error (" __FILE__ ":" stringify(__LINE__) \
>> +			"): " stringify(cnd) "\n");			\
>> +		exit(1);						\
>> +	} } while (0)
>
>
> And that would be nice to have in util/debug.h but more
> perhaps more as a DIE_IF()
>

Sure :-)

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com

Re: [PATCH tracing/kprobes v3 6/7] perf: Add perf probe subcommand for kprobe-event setup helper

[Frederic Weisbecker]

On Thu, Oct 08, 2009 at 05:17:34PM -0400, Masami Hiramatsu wrote:
> Masami Hiramatsu wrote:
>> Add perf probe subcommand for kprobe-event setup helper to perf command.
>> This allows user to define kprobe events by C expressions (C line numbers,
>> C function names, and C local variables).
>>
>> Usage
>> -----
>>   perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]
>>
>>      -k, --vmlinux<file>   vmlinux/module pathname
>>      -P, --probe<p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
>>                            probe point definition, where
>> 		p:	kprobe probe
>> 		r:	kretprobe probe
>> 		GRP:	Group name (optional)
>> 		NAME:	Event name
>> 		FUNC:	Function name
>> 		OFFS:	Offset from function entry (in byte)
>> 		SRC:	Source code path
>> 		LINE:	Line number
>> 		ARG:	Probe argument (local variable name or
>> 			kprobe-tracer argument format is supported.)
>
> Oops, I found it caused compilation error on gcc < 4.4 as below:
>
>     CC builtin-trace.o
>     CC builtin-probe.o
> cc1: warnings being treated as errors
> builtin-probe.c: In function 'parse_probepoint':
> builtin-probe.c:109: error: implicit declaration of function 'strndup'
> builtin-probe.c:109: error: incompatible implicit declaration of built-in function 'strndup'
>
> Since I forgot to add _GNU_SOURCE...
>


No problem, I can add it, or rather include util/util.h as it includes
everything necessary for the string functions + _GNU_SOURCE :)

Re: [PATCH tracing/kprobes v3 6/7] perf: Add perf probe subcommand for kprobe-event setup helper

[Frederic Weisbecker]

On Wed, Oct 07, 2009 at 06:28:23PM -0400, Masami Hiramatsu wrote:
> Add perf probe subcommand for kprobe-event setup helper to perf command.
> This allows user to define kprobe events by C expressions (C line numbers,
> C function names, and C local variables).
>


My libdwarf.h and dwarf.h are available through <libdwarf.h> and
<dwarf.h>, these are in /usr/include

But even by fixing the include path in the makefile and probe-finder.h,
I get the following build error:

util/probe-finder.c: In function ‘die_get_entrypc’:
util/probe-finder.c:222: erreur: ‘Dwarf_Ranges’ undeclared (first use in this function)
util/probe-finder.c:222: erreur: (Each undeclared identifier is reported only once
util/probe-finder.c:222: erreur: for each function it appears in.)
util/probe-finder.c:222: erreur: ‘ranges’ undeclared (first use in this function)
cc1: warnings being treated as errors
util/probe-finder.c:223: erreur: ISO C90 forbids mixed declarations and code
util/probe-finder.c:247: erreur: implicit declaration of function ‘dwarf_get_ranges’
util/probe-finder.c:247: erreur: nested extern declaration of ‘dwarf_get_ranges’
util/probe-finder.c:251: erreur: implicit declaration of function ‘dwarf_ranges_dealloc’
util/probe-finder.c:251: erreur: nested extern declaration of ‘dwarf_ranges_dealloc’
make: *** [util/probe-finder.o] Erreur 1


I remember we talked about that before, but I don't remember well why it happened.
This is because of a libdwarf version or something, right?

Which one should I pick? Mine is:

    libdwarf.h  

    $Revision: #9 $ $Date: 2008/01/17 $

Re: [PATCH tracing/kprobes v3 6/7] perf: Add perf probe subcommand for kprobe-event setup helper

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> On Wed, Oct 07, 2009 at 06:28:23PM -0400, Masami Hiramatsu wrote:
> > Add perf probe subcommand for kprobe-event setup helper to perf command.
> > This allows user to define kprobe events by C expressions (C line numbers,
> > C function names, and C local variables).
> >
> 
> 
> My libdwarf.h and dwarf.h are available through <libdwarf.h> and
> <dwarf.h>, these are in /usr/include
> 
> But even by fixing the include path in the makefile and probe-finder.h,
> I get the following build error:
> 
> util/probe-finder.c: In function ‘die_get_entrypc’:
> util/probe-finder.c:222: erreur: ‘Dwarf_Ranges’ undeclared (first use in this function)
> util/probe-finder.c:222: erreur: (Each undeclared identifier is reported only once
> util/probe-finder.c:222: erreur: for each function it appears in.)
> util/probe-finder.c:222: erreur: ‘ranges’ undeclared (first use in this function)
> cc1: warnings being treated as errors
> util/probe-finder.c:223: erreur: ISO C90 forbids mixed declarations and code
> util/probe-finder.c:247: erreur: implicit declaration of function ‘dwarf_get_ranges’
> util/probe-finder.c:247: erreur: nested extern declaration of ‘dwarf_get_ranges’
> util/probe-finder.c:251: erreur: implicit declaration of function ‘dwarf_ranges_dealloc’
> util/probe-finder.c:251: erreur: nested extern declaration of ‘dwarf_ranges_dealloc’
> make: *** [util/probe-finder.o] Erreur 1
> 
> 
> I remember we talked about that before, but I don't remember well why it happened.
> This is because of a libdwarf version or something, right?
> 
> Which one should I pick? Mine is:
> 
>     libdwarf.h  
> 
>     $Revision: #9 $ $Date: 2008/01/17 $

if it's possible to still have a single set of APIs it would be nice to 
auto-detect and massage all these libdwarf versions into a single 
backend within perf.

	Ingo

Re: [PATCH tracing/kprobes v3 6/7] perf: Add perf probe subcommand for kprobe-event setup helper

[Masami Hiramatsu]

Ingo Molnar wrote:
>
> * Frederic Weisbecker<fweisbec@gmail.com>  wrote:
>
>> On Wed, Oct 07, 2009 at 06:28:23PM -0400, Masami Hiramatsu wrote:
>>> Add perf probe subcommand for kprobe-event setup helper to perf command.
>>> This allows user to define kprobe events by C expressions (C line numbers,
>>> C function names, and C local variables).
>>>
>>
>>
>> My libdwarf.h and dwarf.h are available through<libdwarf.h>  and
>> <dwarf.h>, these are in /usr/include
>>
>> But even by fixing the include path in the makefile and probe-finder.h,
>> I get the following build error:
>>
>> util/probe-finder.c: In function ‘die_get_entrypc’:
>> util/probe-finder.c:222: erreur: ‘Dwarf_Ranges’ undeclared (first use in this function)
>> util/probe-finder.c:222: erreur: (Each undeclared identifier is reported only once
>> util/probe-finder.c:222: erreur: for each function it appears in.)
>> util/probe-finder.c:222: erreur: ‘ranges’ undeclared (first use in this function)
>> cc1: warnings being treated as errors
>> util/probe-finder.c:223: erreur: ISO C90 forbids mixed declarations and code
>> util/probe-finder.c:247: erreur: implicit declaration of function ‘dwarf_get_ranges’
>> util/probe-finder.c:247: erreur: nested extern declaration of ‘dwarf_get_ranges’
>> util/probe-finder.c:251: erreur: implicit declaration of function ‘dwarf_ranges_dealloc’
>> util/probe-finder.c:251: erreur: nested extern declaration of ‘dwarf_ranges_dealloc’
>> make: *** [util/probe-finder.o] Erreur 1
>>
>>
>> I remember we talked about that before, but I don't remember well why it happened.
>> This is because of a libdwarf version or something, right?

Yeah, you may use an old version.

>>
>> Which one should I pick? Mine is:
>>
>>      libdwarf.h
>>
>>      $Revision: #9 $ $Date: 2008/01/17 $

AFAICS, the revision tag is not updated :(
I'm usually using libdwarf later than 20090324, and dwarf_get_ranges()
was introduced from 20081231.

>
> if it's possible to still have a single set of APIs it would be nice to
> auto-detect and massage all these libdwarf versions into a single
> backend within perf.

Sure, it's not so hard to check APIs.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com