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

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Date:	Thu, 11 Aug 2016 10:01:04 +0530
From:	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:	Anton Blanchard <anton@...ba.org>, acme@...nel.org
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org,
	mingo@...hat.com, alexander.shishkin@...ux.intel.com,
	bsingharora@...il.com, naveen.n.rao@...ux.vnet.ibm.com,
	ananth@...ibm.com, mhiramat@...nel.org, wangnan0@...wei.com,
	namhyung@...nel.org,
	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Subject: Re: [PATCH 2/2] perf ppc64le: Fix probe location when using DWARF



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@...ux.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")

Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.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