From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org
Cc: Florian Weimer <fweimer@redhat.com>, Carlos O'Donell <carlos@redhat.com>
Subject: [PATCH 3/3] ld.so: Add --list-tunables to print tunable values
Date: Sat, 12 Sep 2020 06:44:41 -0700 [thread overview]
Message-ID: <20200912134441.2407884-4-hjl.tools@gmail.com> (raw)
In-Reply-To: <20200912134441.2407884-1-hjl.tools@gmail.com>
Pass --list-tunables to ld.so to print tunables with min and max values.
---
NEWS | 2 ++
elf/Makefile | 6 +++++-
elf/dl-tunables.c | 36 ++++++++++++++++++++++++++++++++++++
elf/dl-tunables.h | 2 ++
elf/rtld.c | 37 +++++++++++++++++++++++++++++++++++--
manual/tunables.texi | 37 +++++++++++++++++++++++++++++++++++++
6 files changed, 117 insertions(+), 3 deletions(-)
diff --git a/NEWS b/NEWS
index 878221639b..3ad798c4e3 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,8 @@ Version 2.33
Major new features:
+* Pass --list-tunables to ld.so to print tunable values.
+
* Add <sys/platform/x86.h> to provide query macros for x86 CPU features.
* Support for the RISC-V ISA running on Linux has been expanded to run on
diff --git a/elf/Makefile b/elf/Makefile
index 0b78721848..7943a684ab 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -414,7 +414,7 @@ endif
ifeq (yes,$(build-shared))
ifeq ($(run-built-tests),yes)
tests-special += $(objpfx)tst-pathopt.out $(objpfx)tst-rtld-load-self.out \
- $(objpfx)tst-rtld-preload.out
+ $(objpfx)tst-rtld-preload.out $(objpfx)list-tunables.out
endif
tests-special += $(objpfx)check-textrel.out $(objpfx)check-execstack.out \
$(objpfx)check-wx-segment.out \
@@ -962,6 +962,10 @@ $(objpfx)tst-rtld-preload.out: tst-rtld-preload.sh $(objpfx)ld.so \
'$(rpath-link)' '$(tst-rtld-preload-OBJS)' > $@; \
$(evaluate-test)
+$(objpfx)list-tunables.out: $(objpfx)ld.so
+ $(objpfx)ld.so --list-tunables > $@; \
+ $(evaluate-test)
+
$(objpfx)initfirst: $(libdl)
$(objpfx)initfirst.out: $(objpfx)firstobj.so
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index b44174fe71..53226ef258 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -368,6 +368,42 @@ __tunables_init (char **envp)
}
}
+void
+__tunables_print (void)
+{
+ for (int i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++)
+ {
+ tunable_t *cur = &tunable_list[i];
+ _dl_printf ("%s: ", cur->name);
+ switch (cur->type.type_code)
+ {
+ case TUNABLE_TYPE_INT_32:
+ _dl_printf ("%d (min: %d, max: %d)\n",
+ (int) cur->val.numval,
+ (int) cur->type.min,
+ (int) cur->type.max);
+ break;
+ case TUNABLE_TYPE_UINT_64:
+ _dl_printf ("0x%lx (min: 0x%lx, max: 0x%lx)\n",
+ (long int) cur->val.numval,
+ (long int) cur->type.min,
+ (long int) cur->type.max);
+ break;
+ case TUNABLE_TYPE_SIZE_T:
+ _dl_printf ("0x%Zx (min: 0x%Zx, max: 0x%Zx)\n",
+ (size_t) cur->val.numval,
+ (size_t) cur->type.min,
+ (size_t) cur->type.max);
+ break;
+ case TUNABLE_TYPE_STRING:
+ _dl_printf ("%s\n", cur->val.strval ? cur->val.strval : "");
+ break;
+ default:
+ __builtin_unreachable ();
+ }
+ }
+}
+
/* Set the tunable value. This is called by the module that the tunable exists
in. */
void
diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
index b1add3184f..a2c728f0dd 100644
--- a/elf/dl-tunables.h
+++ b/elf/dl-tunables.h
@@ -69,9 +69,11 @@ typedef struct _tunable tunable_t;
# include "dl-tunable-list.h"
extern void __tunables_init (char **);
+extern void __tunables_print (void);
extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
extern void __tunable_set_val (tunable_id_t, void *, void *, void *);
rtld_hidden_proto (__tunables_init)
+rtld_hidden_proto (__tunables_print)
rtld_hidden_proto (__tunable_get_val)
rtld_hidden_proto (__tunable_set_val)
diff --git a/elf/rtld.c b/elf/rtld.c
index 5b882163fa..705bca504f 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -48,6 +48,10 @@
#include <array_length.h>
#include <libc-early-init.h>
+#if HAVE_TUNABLES
+# include <dl-tunables.h>
+#endif
+
#include <assert.h>
/* Only enables rtld profiling for architectures which provides non generic
@@ -168,7 +172,7 @@ static void audit_list_add_dynamic_tag (struct audit_list *,
static const char *audit_list_next (struct audit_list *);
/* This is a list of all the modes the dynamic loader can be in. */
-enum mode { normal, list, verify, trace };
+enum mode { normal, list, verify, trace, list_tunables };
/* Process all environments variables the dynamic linker must recognize.
Since all of them start with `LD_' we are a bit smarter while finding
@@ -1263,13 +1267,37 @@ dl_main (const ElfW(Phdr) *phdr,
_dl_argc -= 2;
_dl_argv += 2;
}
+#if HAVE_TUNABLES
+ else if (! strcmp (_dl_argv[1], "--list-tunables"))
+ {
+ mode = list_tunables;
+
+ ++_dl_skip_args;
+ --_dl_argc;
+ ++_dl_argv;
+ }
+#endif
else
break;
+#if HAVE_TUNABLES
+ if (__builtin_expect (mode, normal) == list_tunables)
+ {
+ __tunables_print ();
+ _exit (0);
+ }
+#endif
+
/* If we have no further argument the program was called incorrectly.
Grant the user some education. */
if (_dl_argc < 2)
- _dl_fatal_printf ("\
+ {
+#if HAVE_TUNABLES
+ _dl_printf
+#else
+ _dl_fatal_printf
+#endif
+ ("\
Usage: ld.so [OPTION]... EXECUTABLE-FILE [ARGS-FOR-PROGRAM...]\n\
You have invoked `ld.so', the helper program for shared library executables.\n\
This program usually lives in the file `/lib/ld.so', and special directives\n\
@@ -1293,6 +1321,11 @@ of this helper program; chances are you did not intend to run this program.\n\
in LIST\n\
--audit LIST use objects named in LIST as auditors\n\
--preload LIST preload objects named in LIST\n");
+#if HAVE_TUNABLES
+ _dl_fatal_printf ("\
+ --list-tunables list all tunables with minimum and maximum values\n");
+#endif
+ }
++_dl_skip_args;
--_dl_argc;
diff --git a/manual/tunables.texi b/manual/tunables.texi
index 23ef0d40e7..38c8578229 100644
--- a/manual/tunables.texi
+++ b/manual/tunables.texi
@@ -28,6 +28,43 @@ Finally, the set of tunables available may vary between distributions as
the tunables feature allows distributions to add their own tunables under
their own namespace.
+Passing @option{--list-tunables} to the dynamic loader to print all
+tunables with minimum and maximum values:
+
+@example
+$ /lib64/ld-linux-x86-64.so.2 --list-tunables
+glibc.rtld.nns: 0x4 (min: 0x1, max: 0x10)
+glibc.elision.skip_lock_after_retries: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.trim_threshold: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.perturb: 0 (min: 0, max: 255)
+glibc.cpu.x86_shared_cache_size: 0x100000 (min: 0x0, max: 0xffffffffffffffff)
+glibc.elision.tries: 3 (min: -2147483648, max: 2147483647)
+glibc.elision.enable: 0 (min: 0, max: 1)
+glibc.cpu.x86_rep_movsb_threshold: 0x800 (min: 0x100, max: 0xffffffffffffffff)
+glibc.malloc.mxfast: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.elision.skip_lock_busy: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.top_pad: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_rep_stosb_threshold: 0x800 (min: 0x1, max: 0xffffffffffffffff)
+glibc.cpu.x86_non_temporal_threshold: 0x600000 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_shstk:
+glibc.cpu.hwcap_mask: 0x6 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.mmap_max: 0 (min: -2147483648, max: 2147483647)
+glibc.elision.skip_trylock_internal_abort: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.tcache_unsorted_limit: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_ibt:
+glibc.cpu.hwcaps:
+glibc.elision.skip_lock_internal_abort: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.arena_max: 0x0 (min: 0x1, max: 0xffffffffffffffff)
+glibc.malloc.mmap_threshold: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_data_cache_size: 0x8000 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.tcache_count: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.arena_test: 0x0 (min: 0x1, max: 0xffffffffffffffff)
+glibc.pthread.mutex_spin_count: 100 (min: 0, max: 32767)
+glibc.rtld.optional_static_tls: 0x200 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.tcache_max: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.check: 0 (min: 0, max: 3)
+@end example
+
@menu
* Tunable names:: The structure of a tunable name
* Memory Allocation Tunables:: Tunables in the memory allocation subsystem
--
2.26.2
next prev parent reply other threads:[~2020-09-12 13:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-12 13:44 [PATCH 0/3] " H.J. Lu
2020-09-12 13:44 ` [PATCH 1/3] x86: Initialize CPU info via IFUNC relocation [BZ 26203] H.J. Lu
2020-09-18 8:06 ` Florian Weimer
2020-09-18 13:55 ` H.J. Lu
2020-09-18 13:59 ` Florian Weimer
2020-09-18 14:18 ` H.J. Lu
2020-09-18 14:22 ` Florian Weimer
2020-09-18 14:30 ` H.J. Lu
2020-09-21 8:21 ` Florian Weimer
2020-09-21 11:31 ` H.J. Lu
2020-09-25 12:55 ` Florian Weimer
2020-09-12 13:44 ` [PATCH 2/3] Set tunable value as well as min/max values H.J. Lu
2020-09-18 8:29 ` Florian Weimer
2020-09-18 15:11 ` H.J. Lu
2020-09-12 13:44 ` H.J. Lu [this message]
2020-09-18 8:13 ` [PATCH 3/3] ld.so: Add --list-tunables to print tunable values Florian Weimer
2020-09-18 15:24 ` H.J. Lu
-- strict thread matches above, loose matches on Subject: below --
2020-07-12 14:24 [PATCH 0/3] " H.J. Lu
2020-07-12 14:24 ` [PATCH 3/3] " H.J. Lu
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