linux-kernel - Re: [PATCH] Correctly handle symbols in VDSO

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Date:	Wed, 9 Apr 2014 17:35:47 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Vladimir Nikulichev <nvs@...icks.com>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	linux-perf-users@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Correctly handle symbols in VDSO

On Wed, Apr 09, 2014 at 10:46:13AM +0400, Vladimir Nikulichev wrote:
> Hi,
> 
> On Apr 8, 2014, at 7:41 PM, Jiri Olsa <jolsa@...hat.com> wrote:
> 
> > hi,
> > could you please put explanation from first email
> > into the patch changelog?
> > 
> > cc-ing lkml
> > 
> > thanks,
> > jirka
> 
> 
> OK, pasting it together:

ook

hum, your email's encoding kills my 'git am' :-\
also 'perf tools: Adjust symbols in VDSO' should go into the
email subject

I processed this patch by hand this time

thanks,
jirka

> 
> ---------------------------------------------------------------------------------------------------------------------------
> 
> perf tools: Adjust symbols in VDSO
> 
> pert-report doesn't resolve function names in VDSO:
> 
> $ perf report --stdio -g flat,0.0,15,callee --sort pid
> ...
>             8.76%
>                0x7fff6b1fe861
>                __gettimeofday
>                ACE_OS::gettimeofday()
> ...
> 
> In this case symbol values should be adjusted the same way as for executables, relocatable objects and prelinked libraries.
> 
> After fix:
> 
> $ perf report --stdio -g flat,0.0,15,callee --sort pid
> ...
>             8.76%
>                __vdso_gettimeofday
>                __gettimeofday
>                ACE_OS::gettimeofday()
> …
> 
> Signed-off-by: Vladimir Nikulichev <nvs@...icks.com>
> 
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index 3b7dbf5..6864661 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -6,6 +6,7 @@
> #include <inttypes.h>
> 
> #include "symbol.h"
> +#include "vdso.h"
> #include <symbol/kallsyms.h>
> #include "debug.h"
> 
> @@ -618,6 +619,7 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
> 		GElf_Shdr shdr;
> 		ss->adjust_symbols = (ehdr.e_type == ET_EXEC ||
> 				ehdr.e_type == ET_REL ||
> +				is_vdso_map(dso->short_name) ||
> 				elf_section_by_name(elf, &ehdr, &shdr,
> 						     ".gnu.prelink_undo",
> 						     NULL) != NULL);
--
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