Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1460521

Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF

Show all headers | View raw

On Thursday 11 August 2016 05:20 PM, Arnaldo Carvalho de Melo wrote:
> Em Thu, Aug 11, 2016 at 10:01:04AM +0530, Ravi Bangoria escreveu:
>>
>> On Thursday 11 August 2016 05:24 AM, Anton Blanchard wrote:
>>> Hi,
>>>
>>>> Powerpc has Global Entry Point and Local Entry Point for functions.
>>>> LEP catches call from both the GEP and the LEP. Symbol table of ELF
>>>> contains GEP and Offset from which we can calculate LEP, but debuginfo
>>>> does not have LEP info.
>>>>
>>>> Currently, perf prioritize symbol table over dwarf to probe on LEP
>>>> for ppc64le. But when user tries to probe with function parameter,
>>>> we fall back to using dwarf(i.e. GEP) and when function called via
>>>> LEP, probe will never hit.
>>> This patch causes a build failure for me on ppc64le:
>>>
>>> libperf.a(libperf-in.o): In function `arch__post_process_probe_trace_events':
>>>
>>> tools/perf/arch/powerpc/util/sym-handling.c:109: undefined reference to `get_target_map'
>> Thanks Anton. Sorry, I should have caught that.
>>
>> @Arnaldo, Can you please pick this up. I've prepared this on top of
>> acme/perf/core.
>>
>>
>>  From 89c977ae9c3ae35c78b16cddabcf2b01d3cf5cc8 Mon Sep 17 00:00:00 2001
>> From: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
>> Date: Wed, 10 Aug 2016 23:13:45 -0500
>> Subject: [PATCH] perf ppc64le: Fix build failure when no dwarf support
>>
>> Fix perf build failure on ppc64le because of Commit 99e608b5954c ("perf
>> probe ppc64le: Fix probe location when using DWARF")
> Can you please provide a better explanation? I had to look at the patch
> to understand what it was fixing, and then the patch adds LIBELF_SUPPORT
> ifdefs while the patch description, talks about DWARF.

Yes. Explanation could have been better. Apologies for that.

arch__post_process_probe_trace_events() calls get_target_map() to prepare
symbol table. get_target_map() is defined inside util/probe-event.c.

probe-event.c will only get included in perf binary if CONFIG_LIBELF is set.
Hence arch__post_process_probe_trace_events() needs to be defined inside
#ifdef HAVE_LIBELF_SUPPORT to solve compilation error.

Please let me know if any doubts.

Thanks,
Ravi

> Anyway, Anton, does this fix the problem for you?
>
> - Arnaldo
>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
>> ---
>>   tools/perf/arch/powerpc/util/sym-handling.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/tools/perf/arch/powerpc/util/sym-handling.c
>> b/tools/perf/arch/powerpc/util/sym-handling.c
>> index 8d4dc97..c27a51a 100644
>> --- a/tools/perf/arch/powerpc/util/sym-handling.c
>> +++ b/tools/perf/arch/powerpc/util/sym-handling.c
>> @@ -97,6 +97,7 @@ void arch__fix_tev_from_maps(struct perf_probe_event *pev,
>>          }
>>   }
>>
>> +#ifdef HAVE_LIBELF_SUPPORT
>>   void arch__post_process_probe_trace_events(struct perf_probe_event *pev,
>>                                             int ntevs)
>>   {
>> @@ -118,5 +119,6 @@ void arch__post_process_probe_trace_events(struct
>> perf_probe_event *pev,
>>                  }
>>          }
>>   }
>> +#endif
>>
>>   #endif
>> -- 
>> 2.7.4

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Anton Blanchard <anton@samba.org> - 2016-08-11 02:00 +0200
  Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> - 2016-08-11 06:40 +0200
    Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-08-11 14:00 +0200
      Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> - 2016-08-11 15:30 +0200
        Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-08-11 16:50 +0200
          Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-08-11 19:50 +0200
      Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Anton Blanchard <anton@samba.org> - 2016-08-12 08:10 +0200
        Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-08-12 15:10 +0200
    [tip:perf/urgent] perf ppc64le: Fix build failure when libelf is  not present tip-bot for Ravi Bangoria <tipbot@zytor.com> - 2016-08-16 20:20 +0200
  Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-08-11 17:50 +0200

csiph-web