tree 97f9dcd94f98cf444b2fa498e19e3c5cb20c238c
parent 2c70d0086e4e9e2440f0f78098090f32bde14277
author Yan, Zheng <zheng.z.yan@intel.com> 1415156171 -0500
committer Ingo Molnar <mingo@kernel.org> 1424276174 +0100

perf/x86/intel: Discard zero length call entries in LBR call stack

"Zero length call" uses the attribute of the call instruction to push
the immediate instruction pointer on to the stack and then pops off
that address into a register. This is accomplished without any matching
return instruction. It confuses the hardware and make the recorded call
stack incorrect.

We can partially resolve this issue by: decode call instructions and
discard any zero length call entry in the LBR stack.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: eranian@google.com
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1415156173-10035-16-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>