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perf uretprobe ppc64le: Fix probe location 

Perf uretprobe probes on GEP(Global Entry Point) which fails to record
all function calls via LEP(Local Entry Point). Fix that by probing on LEP.

Objdump:

  00000000100005f0 <doit>:
      100005f0:   02 10 40 3c     lis     r2,4098
      100005f4:   00 7f 42 38     addi    r2,r2,32512
      100005f8:   a6 02 08 7c     mflr    r0
      100005fc:   10 00 01 f8     std     r0,16(r1)
      10000600:   f8 ff e1 fb     std     r31,-8(r1)

Before applying patch:

  $ cat /sys/kernel/debug/tracing/uprobe_events
    r:probe_uprobe_test/doit /home/ravi/uprobe_test:0x00000000000005f0

After applying patch:

  $ cat /sys/kernel/debug/tracing/uprobe_events
    r:probe_uprobe_test/doit /home/ravi/uprobe_test:0x00000000000005f8

This is not the case with kretprobes because the kernel itself finds LEP
and probes on it.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1475576865-6562-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ravi Bangoria 2016-10-04 15:57:45 +05:30 committed by Arnaldo Carvalho de Melo
parent 8657355f5b
commit a1d9972e59
1 changed files with 2 additions and 1 deletions
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3
tools/perf/arch/powerpc/util/sym-handling.c
View File

@ -82,7 +82,8 @@ void arch__fix_tev_from_maps(struct perf_probe_event *pev,
*
* In addition, we shouldn't specify an offset for kretprobes.
*/
if (pev->point.offset || pev->point.retprobe || !map || !sym)
if (pev->point.offset || (!pev->uprobes && pev->point.retprobe) ||
!map || !sym)
return;
lep_offset = PPC64_LOCAL_ENTRY_OFFSET(sym->arch_sym);