[PATCH] Support profiling PIE [BZ #22284]
H.J. Lu
hjl.tools@gmail.com
Thu Oct 12 10:47:00 GMT 2017
On 10/11/17, Carlos O'Donell <carlos@redhat.com> wrote:
> On 10/11/2017 07:19 PM, H.J. Lu wrote:
>> Since PIE can be loaded at any address, we need to subtract load address
>> from PCs.
>>
>> Tested on i686 and x86-64. OK for master?
>
> OK, with one added comment, see below.
>
> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
>
>>
>> H.J.
>> ---
>> [BZ #22284]
>> * gmon/Makefile [$(have-fpie)$(build-shared) == yesyes] (tests,
>> tests-pie): Add tst-gmon-pie.
>> (CFLAGS-tst-gmon-pie.c): New.
>> (CRT-tst-gmon-pie): Likewise.
>> (tst-gmon-pie-ENV): Likewise.
>> [$(have-fpie)$(build-shared) == yesyes] (tests-special): Likewise.
>> ($(objpfx)tst-gmon-pie.out): Likewise.
>> (clean-tst-gmon-pie-data): Likewise.
>> ($(objpfx)tst-gmon-pie-gprof.out): Likewise.
>> * gmon/gmon.c [PIC]: Include <link.h>.
>> [PIC] (callback): New function.
>> (write_hist): Add an argument for load address. Subtract load
>> address from PCs.
>> (write_call_graph): Likewise.
>> (write_gmon): Call __dl_iterate_phdr to get load address, pass
>> it to write_hist and write_call_graph.
>> ---
>> gmon/Makefile | 21 +++++++++++++++++++++
>> gmon/gmon.c | 44 ++++++++++++++++++++++++++++++++++----------
>> gmon/tst-gmon-pie.c | 1 +
>> 3 files changed, 56 insertions(+), 10 deletions(-)
>> create mode 100644 gmon/tst-gmon-pie.c
>>
>> diff --git a/gmon/Makefile b/gmon/Makefile
>> index 79e29d188f..2cd077dece 100644
>> --- a/gmon/Makefile
>> +++ b/gmon/Makefile
>> @@ -33,6 +33,11 @@ tests-static += tst-profile-static
>> LDFLAGS-tst-profile-static = -profile
>> endif
>>
>> +ifeq (yesyes,$(have-fpie)$(build-shared))
>> +tests += tst-gmon-pie
>> +tests-pie += tst-gmon-pie
>> +endif
>
> OK.
>
>> +
>> # The mcount code won't work without a frame pointer.
>> CFLAGS-mcount.c := -fno-omit-frame-pointer
>>
>> @@ -44,6 +49,14 @@ ifeq ($(run-built-tests),yes)
>> tests-special += $(objpfx)tst-gmon-gprof.out
>> endif
>>
>> +CFLAGS-tst-gmon-pie.c := $(PIE-ccflag) -fno-omit-frame-pointer -pg
>> +CRT-tst-gmon-pie := $(csu-objpfx)gcrt1.o
>> +tst-gmon-pie-ENV := GMON_OUT_PREFIX=$(objpfx)tst-gmon-pie.data
>> +ifeq ($(run-built-tests),yes)
>> +tests-special += $(objpfx)tst-gmon-pie-gprof.out
>> +endif
>
>
> OK.
>
>> +
>> +
>> include ../Rules
>>
>> # We cannot compile mcount.c with -pg because that would
>> @@ -69,3 +82,11 @@ clean-tst-gmon-data:
>> $(objpfx)tst-gmon-gprof.out: tst-gmon-gprof.sh $(objpfx)tst-gmon.out
>> $(SHELL) $< $(GPROF) $(objpfx)tst-gmon $(objpfx)tst-gmon.data.* > $@; \
>> $(evaluate-test)
>> +
>> +$(objpfx)tst-gmon-pie.out: clean-tst-gmon-pie-data
>> +clean-tst-gmon-pie-data:
>> + rm -f $(objpfx)tst-gmon-pie.data.*
>> +
>> +$(objpfx)tst-gmon-pie-gprof.out: tst-gmon-gprof.sh
>> $(objpfx)tst-gmon-pie.out
>> + $(SHELL) $< $(GPROF) $(objpfx)tst-gmon-pie $(objpfx)tst-gmon-pie.data.*
>> > $@; \
>> + $(evaluate-test)
>
> OK.
>
>> diff --git a/gmon/gmon.c b/gmon/gmon.c
>> index f1aa3b776c..5f569cc994 100644
>> --- a/gmon/gmon.c
>> +++ b/gmon/gmon.c
>> @@ -46,6 +46,23 @@
>> #include <libc-internal.h>
>> #include <not-cancel.h>
>>
>> +#ifdef PIC
>> +# include <link.h>
>> +
>> +static int
>> +callback (struct dl_phdr_info *info, size_t size, void *data)
>> +{
>> + u_long *load_address = data;
>> +
>
> Does the dl_iterate_phdr ABI mandate taht the application istelf
> is always an empty string?
>
> You should add a comment to that effect here if you believe that
> to be true.
This is what I checked in.
Thanks.
>> + if (info->dlpi_name[0] == '\0')
>> + {
>> + *load_address = (u_long) info->dlpi_addr;
>> + return 1;
>> + }
>> +
>> + return 0;
>> +}
>> +#endif
>>
>> /* Head of basic-block list or NULL. */
>> struct __bb *__bb_head attribute_hidden;
>> @@ -63,8 +80,8 @@ static int s_scale;
>> void moncontrol (int mode);
>> void __moncontrol (int mode);
>> libc_hidden_proto (__moncontrol)
>> -static void write_hist (int fd);
>> -static void write_call_graph (int fd);
>> +static void write_hist (int fd, u_long load_address);
>> +static void write_call_graph (int fd, u_long load_address);
>
> OK.
>
>> static void write_bb_counts (int fd);
>>
>> /*
>> @@ -173,7 +190,7 @@ weak_alias (__monstartup, monstartup)
>>
>>
>> static void
>> -write_hist (int fd)
>> +write_hist (int fd, u_long load_address)
>> {
>> u_char tag = GMON_TAG_TIME_HIST;
>>
>> @@ -210,8 +227,8 @@ write_hist (int fd)
>> != offsetof (struct gmon_hist_hdr, dimen_abbrev)))
>> abort ();
>>
>> - thdr.low_pc = (char *) _gmonparam.lowpc;
>> - thdr.high_pc = (char *) _gmonparam.highpc;
>> + thdr.low_pc = (char *) _gmonparam.lowpc - load_address;
>> + thdr.high_pc = (char *) _gmonparam.highpc - load_address;
>
> OK.
>
>> thdr.hist_size = _gmonparam.kcountsize / sizeof (HISTCOUNTER);
>> thdr.prof_rate = __profile_frequency ();
>> strncpy (thdr.dimen, "seconds", sizeof (thdr.dimen));
>> @@ -223,7 +240,7 @@ write_hist (int fd)
>>
>>
>> static void
>> -write_call_graph (int fd)
>> +write_call_graph (int fd, u_long load_address)
>> {
>> #define NARCS_PER_WRITEV 32
>> u_char tag = GMON_TAG_CG_ARC;
>> @@ -266,8 +283,9 @@ write_call_graph (int fd)
>> }
>> arc;
>>
>> - arc.frompc = (char *) frompc;
>> - arc.selfpc = (char *) _gmonparam.tos[to_index].selfpc;
>> + arc.frompc = (char *) frompc - load_address;
>> + arc.selfpc = ((char *) _gmonparam.tos[to_index].selfpc
>> + - load_address);
>
> OK.
>
>> arc.count = _gmonparam.tos[to_index].count;
>> memcpy (raw_arc + nfilled, &arc, sizeof (raw_arc [0]));
>>
>> @@ -376,11 +394,17 @@ write_gmon (void)
>> memset (ghdr.spare, '\0', sizeof (ghdr.spare));
>> __write_nocancel (fd, &ghdr, sizeof (struct gmon_hdr));
>>
>> + /* Get load_address to profile PIE. */
>> + u_long load_address = 0;
>> +#ifdef PIC
>> + __dl_iterate_phdr (callback, &load_address);
>> +#endif
>
> OK.
>
>> +
>> /* write PC histogram: */
>> - write_hist (fd);
>> + write_hist (fd, load_address);
>
> OK.
>
>>
>> /* write call-graph: */
>> - write_call_graph (fd);
>> + write_call_graph (fd, load_address);
>
> OK.
>
>
>>
>> /* write basic-block execution counts: */
>> write_bb_counts (fd);
>> diff --git a/gmon/tst-gmon-pie.c b/gmon/tst-gmon-pie.c
>> new file mode 100644
>> index 0000000000..1eef2583b6
>> --- /dev/null
>> +++ b/gmon/tst-gmon-pie.c
>> @@ -0,0 +1 @@
>> +#include "tst-gmon.c"
>> -- 2.13.6
>
>
> --
> Cheers,
> Carlos.
>
--
H.J.
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