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SubjectRe: [PATCH v5 16/16] perf util: use correct IP mapping to find srcline for hist entry
Hi Milian,

On Mon, Oct 09, 2017 at 10:33:10PM +0200, Milian Wolff wrote:
> When inline frame resolution is disabled, a bogus srcline is obtained
> for hist entries:
>
> ~~~~~
> $ perf report -s sym,srcline --no-inline --stdio -g none
> 95.21% 0.00% [.] __libc_start_main __libc_start_main+18446603358170398953
> 95.21% 0.00% [.] _start _start+18446650082411225129
> 46.67% 0.00% [.] main main+18446650082411225208
> 38.75% 0.00% [.] hypot hypot+18446603358164312084
> 23.75% 0.00% [.] main main+18446650082411225151
> 20.83% 20.83% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > random.h:143
> 18.12% 0.00% [.] main main+18446650082411225165
> 13.12% 13.12% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > random.tcc:3330
> 4.17% 4.17% [.] __hypot_finite __hypot_finite+163
> 4.17% 4.17% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > random.tcc:3333
> 4.17% 0.00% [.] __hypot_finite __hypot_finite+18446603358164312227
> 4.17% 0.00% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > std::generate_canonical<double, 53ul, std::line
> 2.92% 0.00% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > std::generate_canonical<double, 53ul, std::line
> 2.50% 2.50% [.] __hypot_finite __hypot_finite+11
> 2.50% 2.50% [.] __hypot_finite __hypot_finite+24
> 2.50% 0.00% [.] __hypot_finite __hypot_finite+18446603358164312075
> 2.50% 0.00% [.] __hypot_finite __hypot_finite+18446603358164312088
> ~~~~~
>
> Note how we get very large offsets to main and cannot see any srcline
> from one of the complex or random headers, even though the instruction
> pointers actually lie in code inlined from there.
>
> This patch fixes the mapping to use map__objdump_2mem instead of
> map__objdump_2mem in hist_entry__get_srcline. This fixes the srcline
> values for me when inline resolution is disabled:
>
> ~~~~~
> $ perf report -s sym,srcline --no-inline --stdio -g none
> 95.21% 0.00% [.] __libc_start_main __libc_start_main+233
> 95.21% 0.00% [.] _start _start+41
> 46.88% 0.00% [.] main complex:589
> 43.96% 0.00% [.] main random.h:185
> 38.75% 0.00% [.] hypot hypot+20
> 20.83% 0.00% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > random.h:143
> 13.12% 0.00% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > random.tcc:3330
> 4.17% 4.17% [.] __hypot_finite __hypot_finite+140715545239715
> 4.17% 4.17% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > std::generate_canonical<double, 53ul, std::line
> 4.17% 0.00% [.] __hypot_finite __hypot_finite+163
> 4.17% 0.00% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > random.tcc:3333
> 2.92% 2.92% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > std::generate_canonical<double, 53ul, std::line
> 2.50% 2.50% [.] __hypot_finite __hypot_finite+140715545239563
> 2.50% 2.50% [.] __hypot_finite __hypot_finite+140715545239576
> 2.50% 2.50% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > std::generate_canonical<double, 53ul, std::line
> 2.50% 2.50% [.] std::generate_canonical<double, 53ul, std::linear_congruential_engine<unsigned long, 16807ul, 0ul, 2147483647ul> > std::generate_canonical<double, 53ul, std::line
> 2.50% 0.00% [.] __hypot_finite __hypot_finite+11
> ~~~~~
>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Yao Jin <yao.jin@linux.intel.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
>
> Note how most of the large offset values are now gone. Most notably,
> we get proper srcline resolution for the random.h and complex headers.
> ---
> tools/perf/util/sort.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
> index 006d10a0dc96..6f3d109078a3 100644
> --- a/tools/perf/util/sort.c
> +++ b/tools/perf/util/sort.c
> @@ -334,7 +334,7 @@ char *hist_entry__get_srcline(struct hist_entry *he)
> if (!map)
> return SRCLINE_UNKNOWN;
>
> - return get_srcline(map->dso, map__rip_2objdump(map, he->ip),
> + return get_srcline(map->dso, map__objdump_2mem(map, he->ip),
> he->ms.sym, true, true);

I'm not sure this is right. IIRC hist_entry->ip is a relative IP so
it needs to be changed for objdump use. Maybe there's some bug on
translating the address but it seems that the original code is
correct. And this change breaks srcline for my test program (which is
a PIE).

Thanks,
Namhyung


> }
>
> --
> 2.14.2
>

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