From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 88356 invoked by alias); 17 Jul 2017 12:10:57 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 85361 invoked by uid 89); 17 Jul 2017 12:10:54 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 spammy=Respect X-HELO: mx1.suse.de Received: from mx2.suse.de (HELO mx1.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 17 Jul 2017 12:10:51 +0000 Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C3CB6AABA; Mon, 17 Jul 2017 12:10:48 +0000 (UTC) Date: Mon, 17 Jul 2017 12:10:00 -0000 From: Torsten Duwe To: "Richard Earnshaw (lists)" Cc: Sandra Loosemore , Maxim Kuvyrkov , Marek Polacek , Maxim Kuvyrkov , GCC Patches , Szabolcs Nagy , nd@arm.com, Li Bin , Jiri Kosina , Marcus Shawcroft , Takahiro Akashi , Andrew Wafaa Subject: Re: [PATCH v12] add -fpatchable-function-entry=N,M option Message-ID: <20170717121046.GA22056@suse.de> References: <20170706140311.GA20710@suse.de> <20170707193028.GA17752@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170707193028.GA17752@suse.de> User-Agent: Mutt/1.5.24 (2015-08-30) X-SW-Source: 2017-07/txt/msg00967.txt.bz2 What is the next step now? Is anybody going to commit that patch? Torsten On Fri, Jul 07, 2017 at 02:57:55PM +0100, Richard Earnshaw (lists) wrote: > On 06/07/17 15:03, Torsten Duwe wrote: > +#if TARGET_HAVE_NAMED_SECTIONS No, this is a hook. You need to test targetm_common.have_named_sections. OK with that change. R. On Fri, Jul 07, 2017 at 09:30:28PM +0200, Torsten Duwe wrote: > Change since v11: > > < +#if TARGET_HAVE_NAMED_SECTIONS > > > + if (record_p && targetm_common.have_named_sections) > > (plus > +#include "common/common-target.h" ) > > Torsten > > > gcc/c-family/ChangeLog > 2017-07-07 Torsten Duwe > > * c-attribs.c (c_common_attribute_table): Add entry for > "patchable_function_entry". > > gcc/lto/ChangeLog > 2017-07-07 Torsten Duwe > > * lto-lang.c (lto_attribute_table): Add entry for > "patchable_function_entry". > > gcc/ChangeLog > 2017-07-07 Torsten Duwe > > * common.opt: Introduce -fpatchable-function-entry > command line option, and its variables function_entry_patch_area_size > and function_entry_patch_area_start. > * opts.c (common_handle_option): Add -fpatchable_function_entry_ case, > including a two-value parser. > * target.def (print_patchable_function_entry): New target hook. > * targhooks.h (default_print_patchable_function_entry): New function. > * targhooks.c (default_print_patchable_function_entry): Likewise. > * toplev.c (process_options): Switch off IPA-RA if > patchable function entries are being generated. > * varasm.c (assemble_start_function): Look at the > patchable-function-entry command line switch and current > function attributes and maybe generate NOP instructions by > calling the print_patchable_function_entry hook. > * doc/extend.texi: Document patchable_function_entry attribute. > * doc/invoke.texi: Document -fpatchable_function_entry > command line option. > * doc/tm.texi.in (TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY): > New target hook. > * doc/tm.texi: Likewise. > > gcc/testsuite/ChangeLog > 2017-07-07 Torsten Duwe > > * c-c++-common/patchable_function_entry-default.c: New test. > * c-c++-common/patchable_function_entry-decl.c: Likewise. > * c-c++-common/patchable_function_entry-definition.c: Likewise. > > diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c > index 626ffa1cde7..ecb00c1d5b9 100644 > --- a/gcc/c-family/c-attribs.c > +++ b/gcc/c-family/c-attribs.c > @@ -142,6 +142,8 @@ static tree handle_bnd_variable_size_attribute (tree *, tree, tree, int, bool *) > static tree handle_bnd_legacy (tree *, tree, tree, int, bool *); > static tree handle_bnd_instrument (tree *, tree, tree, int, bool *); > static tree handle_fallthrough_attribute (tree *, tree, tree, int, bool *); > +static tree handle_patchable_function_entry_attribute (tree *, tree, tree, > + int, bool *); > > /* Table of machine-independent attributes common to all C-like languages. > > @@ -351,6 +353,9 @@ const struct attribute_spec c_common_attribute_table[] = > handle_bnd_instrument, false }, > { "fallthrough", 0, 0, false, false, false, > handle_fallthrough_attribute, false }, > + { "patchable_function_entry", 1, 2, true, false, false, > + handle_patchable_function_entry_attribute, > + false }, > { NULL, 0, 0, false, false, false, NULL, false } > }; > > @@ -3260,3 +3265,10 @@ handle_fallthrough_attribute (tree *, tree name, tree, int, > *no_add_attrs = true; > return NULL_TREE; > } > + > +static tree > +handle_patchable_function_entry_attribute (tree *, tree, tree, int, bool *) > +{ > + /* Nothing to be done here. */ > + return NULL_TREE; > +} > diff --git a/gcc/common.opt b/gcc/common.opt > index e81165c488b..78cfa568a95 100644 > --- a/gcc/common.opt > +++ b/gcc/common.opt > @@ -163,6 +163,13 @@ bool flag_stack_usage_info = false > Variable > int flag_debug_asm > > +; How many NOP insns to place at each function entry by default > +Variable > +HOST_WIDE_INT function_entry_patch_area_size > + > +; And how far the real asm entry point is into this area > +Variable > +HOST_WIDE_INT function_entry_patch_area_start > > ; Balance between GNAT encodings and standard DWARF to emit. > Variable > @@ -2030,6 +2037,10 @@ fprofile-reorder-functions > Common Report Var(flag_profile_reorder_functions) > Enable function reordering that improves code placement. > > +fpatchable-function-entry= > +Common Joined Optimization > +Insert NOP instructions at each function entry. > + > frandom-seed > Common Var(common_deferred_options) Defer > > diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi > index 5cb512fe575..9c171abc121 100644 > --- a/gcc/doc/extend.texi > +++ b/gcc/doc/extend.texi > @@ -3105,6 +3105,27 @@ that affect more than one function. > This attribute should be used for debugging purposes only. It is not > suitable in production code. > > +@item patchable_function_entry > +@cindex @code{patchable_function_entry} function attribute > +@cindex extra NOP instructions at the function entry point > +In case the target's text segment can be made writable at run time by > +any means, padding the function entry with a number of NOPs can be > +used to provide a universal tool for instrumentation. > + > +The @code{patchable_function_entry} function attribute can be used to > +change the number of NOPs to any desired value. The two-value syntax > +is the same as for the command-line switch > +@option{-fpatchable-function-entry=N,M}, generating @var{N} NOPs, with > +the function entry point before the @var{M}th NOP instruction. > +@var{M} defaults to 0 if omitted e.g. function entry point is before > +the first NOP. > + > +If patchable function entries are enabled globally using the command-line > +option @option{-fpatchable-function-entry=N,M}, then you must disable > +instrumentation on all functions that are part of the instrumentation > +framework with the attribute @code{patchable_function_entry (0)} > +to prevent recursion. > + > @item pure > @cindex @code{pure} function attribute > @cindex functions that have no side effects > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > index d0b90503ced..dc93f0ccd50 100644 > --- a/gcc/doc/invoke.texi > +++ b/gcc/doc/invoke.texi > @@ -11520,6 +11520,34 @@ of the function name, it is considered to be a match. For C99 and C++ > extended identifiers, the function name must be given in UTF-8, not > using universal character names. > > +@item -fpatchable-function-entry=@var{N}[,@var{M}] > +@opindex fpatchable-function-entry > +Generate @var{N} NOPs right at the beginning > +of each function, with the function entry point before the @var{M}th NOP. > +If @var{M} is omitted, it defaults to @code{0} so the > +function entry points to the address just at the first NOP. > +The NOP instructions reserve extra space which can be used to patch in > +any desired instrumentation at run time, provided that the code segment > +is writable. The amount of space is controllable indirectly via > +the number of NOPs; the NOP instruction used corresponds to the instruction > +emitted by the internal GCC back-end interface @code{gen_nop}. This behavior > +is target-specific and may also depend on the architecture variant and/or > +other compilation options. > + > +For run-time identification, the starting addresses of these areas, > +which correspond to their respective function entries minus @var{M}, > +are additionally collected in the @code{__patchable_function_entries} > +section of the resulting binary. > + > +Note that the value of @code{__attribute__ ((patchable_function_entry > +(N,M)))} takes precedence over command-line option > +@option{-fpatchable-function-entry=N,M}. This can be used to increase > +the area size or to remove it completely on a single function. > +If @code{N=0}, no pad location is recorded. > + > +The NOP instructions are inserted at---and maybe before, depending on > +@var{M}---the function entry address, even before the prologue. > + > @end table > > > diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi > index 795e49246af..23e85c7afea 100644 > --- a/gcc/doc/tm.texi > +++ b/gcc/doc/tm.texi > @@ -4573,6 +4573,15 @@ will select the smallest suitable mode. > This section describes the macros that output function entry > (@dfn{prologue}) and exit (@dfn{epilogue}) code. > > +@deftypefn {Target Hook} void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *@var{file}, unsigned HOST_WIDE_INT @var{patch_area_size}, bool @var{record_p}) > +Generate a patchable area at the function start, consisting of > +@var{patch_area_size} NOP instructions. If the target supports named > +sections and if @var{record_p} is true, insert a pointer to the current > +location in the table of patchable functions. The default implementation > +of the hook places the table of pointers in the special section named > +@code{__patchable_function_entries}. > +@end deftypefn > + > @deftypefn {Target Hook} void TARGET_ASM_FUNCTION_PROLOGUE (FILE *@var{file}, HOST_WIDE_INT @var{size}) > If defined, a function that outputs the assembler code for entry to a > function. The prologue is responsible for setting up the stack frame, > diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in > index 98f2e6bce5f..6df08a2c477 100644 > --- a/gcc/doc/tm.texi.in > +++ b/gcc/doc/tm.texi.in > @@ -3650,6 +3650,8 @@ will select the smallest suitable mode. > This section describes the macros that output function entry > (@dfn{prologue}) and exit (@dfn{epilogue}) code. > > +@hook TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY > + > @hook TARGET_ASM_FUNCTION_PROLOGUE > > @hook TARGET_ASM_FUNCTION_END_PROLOGUE > diff --git a/gcc/lto/lto-lang.c b/gcc/lto/lto-lang.c > index 58935172b2c..6e9a138fa3b 100644 > --- a/gcc/lto/lto-lang.c > +++ b/gcc/lto/lto-lang.c > @@ -48,6 +48,8 @@ static tree handle_sentinel_attribute (tree *, tree, tree, int, bool *); > static tree handle_type_generic_attribute (tree *, tree, tree, int, bool *); > static tree handle_transaction_pure_attribute (tree *, tree, tree, int, bool *); > static tree handle_returns_twice_attribute (tree *, tree, tree, int, bool *); > +static tree handle_patchable_function_entry_attribute (tree *, tree, tree, > + int, bool *); > static tree ignore_attribute (tree *, tree, tree, int, bool *); > > static tree handle_format_attribute (tree *, tree, tree, int, bool *); > @@ -76,6 +78,9 @@ const struct attribute_spec lto_attribute_table[] = > handle_nonnull_attribute, false }, > { "nothrow", 0, 0, true, false, false, > handle_nothrow_attribute, false }, > + { "patchable_function_entry", 1, 2, true, false, false, > + handle_patchable_function_entry_attribute, > + false }, > { "returns_twice", 0, 0, true, false, false, > handle_returns_twice_attribute, false }, > { "sentinel", 0, 1, false, true, true, > @@ -473,6 +478,13 @@ handle_returns_twice_attribute (tree *node, tree ARG_UNUSED (name), > return NULL_TREE; > } > > +static tree > +handle_patchable_function_entry_attribute (tree *, tree, tree, int, bool *) > +{ > + /* Nothing to be done here. */ > + return NULL_TREE; > +} > + > /* Ignore the given attribute. Used when this attribute may be usefully > overridden by the target, but is not used generically. */ > > diff --git a/gcc/opts.c b/gcc/opts.c > index 7555ed55434..fecf97978fc 100644 > --- a/gcc/opts.c > +++ b/gcc/opts.c > @@ -2199,6 +2199,33 @@ common_handle_option (struct gcc_options *opts, > opts->x_flag_ipa_reference = false; > break; > > + case OPT_fpatchable_function_entry_: > + { > + char *patch_area_arg = xstrdup (arg); > + char *comma = strchr (patch_area_arg, ','); > + if (comma) > + { > + *comma = '\0'; > + function_entry_patch_area_size = > + integral_argument (patch_area_arg); > + function_entry_patch_area_start = > + integral_argument (comma + 1); > + } > + else > + { > + function_entry_patch_area_size = > + integral_argument (patch_area_arg); > + function_entry_patch_area_start = 0; > + } > + if (function_entry_patch_area_size < 0 > + || function_entry_patch_area_start < 0 > + || function_entry_patch_area_size > + < function_entry_patch_area_start) > + error ("invalid arguments for %<-fpatchable_function_entry%>"); > + free (patch_area_arg); > + } > + break; > + > case OPT_ftree_vectorize: > if (!opts_set->x_flag_tree_loop_vectorize) > opts->x_flag_tree_loop_vectorize = value; > diff --git a/gcc/target.def b/gcc/target.def > index bbd9c015189..6d67b1fe8ba 100644 > --- a/gcc/target.def > +++ b/gcc/target.def > @@ -288,6 +288,17 @@ hidden, protected or internal visibility as specified by @var{visibility}.", > void, (tree decl, int visibility), > default_assemble_visibility) > > +DEFHOOK > +(print_patchable_function_entry, > + "Generate a patchable area at the function start, consisting of\n\ > +@var{patch_area_size} NOP instructions. If the target supports named\n\ > +sections and if @var{record_p} is true, insert a pointer to the current\n\ > +location in the table of patchable functions. The default implementation\n\ > +of the hook places the table of pointers in the special section named\n\ > +@code{__patchable_function_entries}.", > + void, (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p), > + default_print_patchable_function_entry) > + > /* Output the assembler code for entry to a function. */ > DEFHOOK > (function_prologue, > diff --git a/gcc/targhooks.c b/gcc/targhooks.c > index 940deec67f9..6a8fae656d0 100644 > --- a/gcc/targhooks.c > +++ b/gcc/targhooks.c > @@ -73,6 +73,7 @@ along with GCC; see the file COPYING3. If not see > #include "calls.h" > #include "expr.h" > #include "output.h" > +#include "common/common-target.h" > #include "reload.h" > #include "intl.h" > #include "opts.h" > @@ -1610,6 +1611,51 @@ default_compare_by_pieces_branch_ratio (machine_mode) > return 1; > } > > +/* Write PATCH_AREA_SIZE NOPs into the asm outfile FILE around a function > + entry. If RECORD_P is true and the target supports named sections, > + the location of the NOPs will be recorded in a special object section > + called "__patchable_function_entries". This routine may be called > + twice per function to put NOPs before and after the function > + entry. */ > + > +void > +default_print_patchable_function_entry (FILE *file, > + unsigned HOST_WIDE_INT patch_area_size, > + bool record_p) > +{ > + const char *nop_templ = 0; > + int code_num; > + rtx_insn *my_nop = make_insn_raw (gen_nop ()); > + > + /* We use the template alone, relying on the (currently sane) assumption > + that the NOP template does not have variable operands. */ > + code_num = recog_memoized (my_nop); > + nop_templ = get_insn_template (code_num, my_nop); > + > + if (record_p && targetm_common.have_named_sections) > + { > + char buf[256]; > + static int patch_area_number; > + section *previous_section = in_section; > + > + patch_area_number++; > + ASM_GENERATE_INTERNAL_LABEL (buf, "LPFE", patch_area_number); > + > + switch_to_section (get_section ("__patchable_function_entries", > + 0, NULL)); > + fputs (integer_asm_op (POINTER_SIZE_UNITS, false), file); > + assemble_name_raw (file, buf); > + fputc ('\n', file); > + > + switch_to_section (previous_section); > + ASM_OUTPUT_LABEL (file, buf); > + } > + > + unsigned i; > + for (i = 0; i < patch_area_size; ++i) > + fprintf (file, "\t%s\n", nop_templ); > +} > + > bool > default_profile_before_prologue (void) > { > diff --git a/gcc/targhooks.h b/gcc/targhooks.h > index 1ddb8891fe4..c73ea0bda20 100644 > --- a/gcc/targhooks.h > +++ b/gcc/targhooks.h > @@ -203,6 +203,9 @@ extern bool default_use_by_pieces_infrastructure_p (unsigned HOST_WIDE_INT, > bool); > extern int default_compare_by_pieces_branch_ratio (machine_mode); > > +extern void default_print_patchable_function_entry (FILE *, > + unsigned HOST_WIDE_INT, > + bool); > extern bool default_profile_before_prologue (void); > extern reg_class_t default_preferred_reload_class (rtx, reg_class_t); > extern reg_class_t default_preferred_output_reload_class (rtx, reg_class_t); > diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-decl.c b/gcc/testsuite/c-c++-common/patchable_function_entry-decl.c > new file mode 100644 > index 00000000000..8514b10e820 > --- /dev/null > +++ b/gcc/testsuite/c-c++-common/patchable_function_entry-decl.c > @@ -0,0 +1,16 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fpatchable-function-entry=3,1" } */ > +/* { dg-final { scan-assembler-times "nop" 2 } } */ > + > +extern int a; > + > +/* Respect overriding attributes in the declaration. */ > +int f3 (void) __attribute__((patchable_function_entry(2))); > + > +/* F3 should now get 2 NOPs. */ > +int > +__attribute__((noinline)) > +f3 (void) > +{ > + return 5*a; > +} > diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-default.c b/gcc/testsuite/c-c++-common/patchable_function_entry-default.c > new file mode 100644 > index 00000000000..0dcf1181dde > --- /dev/null > +++ b/gcc/testsuite/c-c++-common/patchable_function_entry-default.c > @@ -0,0 +1,16 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fpatchable-function-entry=3,1" } */ > +/* { dg-final { scan-assembler-times "nop" 3 } } */ > + > +extern int a; > + > +/* Nothing declared must not mean anything. */ > +int f3 (void); > + > +/* F3 should get a default-sized NOP area. */ > +int > +__attribute__((noinline)) > +f3 (void) > +{ > + return 5*a; > +} > diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-definition.c b/gcc/testsuite/c-c++-common/patchable_function_entry-definition.c > new file mode 100644 > index 00000000000..a007867dcb0 > --- /dev/null > +++ b/gcc/testsuite/c-c++-common/patchable_function_entry-definition.c > @@ -0,0 +1,16 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fpatchable-function-entry=3,1" } */ > +/* { dg-final { scan-assembler-times "nop" 1 } } */ > + > +extern int a; > + > +int f3 (void); > + > +/* F3 should now get 1 NOP. */ > +int > +__attribute__((noinline)) > +__attribute__((patchable_function_entry(1))) > +f3 (void) > +{ > + return 5*a; > +} > diff --git a/gcc/toplev.c b/gcc/toplev.c > index e6c69a4ba93..b28f1847c83 100644 > --- a/gcc/toplev.c > +++ b/gcc/toplev.c > @@ -1630,8 +1630,10 @@ process_options (void) > } > > /* Do not use IPA optimizations for register allocation if profiler is active > + or patchable function entries are inserted for run-time instrumentation > or port does not emit prologue and epilogue as RTL. */ > - if (profile_flag || !targetm.have_prologue () || !targetm.have_epilogue ()) > + if (profile_flag || function_entry_patch_area_size > + || !targetm.have_prologue () || !targetm.have_epilogue ()) > flag_ipa_ra = 0; > > /* Enable -Werror=coverage-mismatch when -Werror and -Wno-error > diff --git a/gcc/varasm.c b/gcc/varasm.c > index fbaebc1b5c0..ec1640ea378 100644 > --- a/gcc/varasm.c > +++ b/gcc/varasm.c > @@ -1825,6 +1825,46 @@ assemble_start_function (tree decl, const char *fnname) > if (DECL_PRESERVE_P (decl)) > targetm.asm_out.mark_decl_preserved (fnname); > > + unsigned HOST_WIDE_INT patch_area_size = function_entry_patch_area_size; > + unsigned HOST_WIDE_INT patch_area_entry = function_entry_patch_area_start; > + > + tree patchable_function_entry_attr > + = lookup_attribute ("patchable_function_entry", DECL_ATTRIBUTES (decl)); > + if (patchable_function_entry_attr) > + { > + tree pp_val = TREE_VALUE (patchable_function_entry_attr); > + tree patchable_function_entry_value1 = TREE_VALUE (pp_val); > + > + if (tree_fits_uhwi_p (patchable_function_entry_value1)) > + patch_area_size = tree_to_uhwi (patchable_function_entry_value1); > + else > + gcc_unreachable (); > + > + patch_area_entry = 0; > + if (list_length (pp_val) > 1) > + { > + tree patchable_function_entry_value2 = > + TREE_VALUE (TREE_CHAIN (pp_val)); > + > + if (tree_fits_uhwi_p (patchable_function_entry_value2)) > + patch_area_entry = tree_to_uhwi (patchable_function_entry_value2); > + else > + gcc_unreachable (); > + } > + } > + > + if (patch_area_entry > patch_area_size) > + { > + if (patch_area_size > 0) > + warning (OPT_Wattributes, "Patchable function entry > size"); > + patch_area_entry = 0; > + } > + > + /* Emit the patching area before the entry label, if any. */ > + if (patch_area_entry > 0) > + targetm.asm_out.print_patchable_function_entry (asm_out_file, > + patch_area_entry, true); > + > /* Do any machine/system dependent processing of the function name. */ > #ifdef ASM_DECLARE_FUNCTION_NAME > ASM_DECLARE_FUNCTION_NAME (asm_out_file, fnname, current_function_decl); > @@ -1833,6 +1873,12 @@ assemble_start_function (tree decl, const char *fnname) > ASM_OUTPUT_FUNCTION_LABEL (asm_out_file, fnname, current_function_decl); > #endif /* ASM_DECLARE_FUNCTION_NAME */ > > + /* And the area after the label. Record it if we haven't done so yet. */ > + if (patch_area_size > patch_area_entry) > + targetm.asm_out.print_patchable_function_entry (asm_out_file, > + patch_area_size-patch_area_entry, > + patch_area_entry == 0); > + > if (lookup_attribute ("no_split_stack", DECL_ATTRIBUTES (decl))) > saw_no_split_stack = true; > }