perf symbols: Ignore stripped vmlinux and fallback to kallsyms
authorAnton Blanchard <anton@samba.org>
Mon, 8 Sep 2014 22:59:29 +0000 (08:59 +1000)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Wed, 17 Sep 2014 20:08:10 +0000 (17:08 -0300)
commitd0b0d0406fe6743e734e1ba780155f8db5f713e6
treebfcfc7526ab33adf7a21ccdc5dc088db29864afa
parent512fe365373b9c95a70b4b6357503ee74d27214f
perf symbols: Ignore stripped vmlinux and fallback to kallsyms

If a vmlinux is stripped, perf will use it and ignore kallsyms. We
end up with useless profiles where everything maps to a few
runtime symbols:

    63.39%       swapper  [kernel.kallsyms]   [k] hcall_real_table
     4.90%      beam.smp  [kernel.kallsyms]   [k] hcall_real_table
     4.44%      beam.smp  [kernel.kallsyms]   [k] __sched_text_start
     3.72%      beam.smp  [kernel.kallsyms]   [k] __run_at_kexec

Detect this case and fallback to using kallsyms. This fixes the issue:

    62.81%       swapper  [kernel.kallsyms]   [k] snooze_loop
     4.44%      beam.smp  [kernel.kallsyms]   [k] __schedule
     0.91%      beam.smp  [kernel.kallsyms]   [k] _switch
     0.73%      beam.smp  [kernel.kallsyms]   [k] put_prev_entity

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20140909085929.4a5a81f0@kryten
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/util/symbol-elf.c