lkml.org 
[lkml]   [2012]   [Oct]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 6/6] perf, x86: Discard zero length call entries in LBR call stack
Date
From: "Yan, Zheng" <zheng.z.yan@intel.com>

Zero length calls may confuse the hardware and make the recorded
call stack incorrect. Try fixing the call stack by discarding
zero length call entries.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
arch/x86/kernel/cpu/perf_event_intel_lbr.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index c6efec1..9eee5d9 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -90,7 +90,8 @@ enum {
X86_BR_ABORT = 1 << 12,/* transaction abort */
X86_BR_INTX = 1 << 13,/* in transaction */
X86_BR_NOTX = 1 << 14,/* not in transaction */
- X86_BR_CALL_STACK = 1 << 15,/* call stack */
+ X86_BR_ZERO_CALL = 1 << 15,/* zero length call */
+ X86_BR_CALL_STACK = 1 << 16,/* call stack */
};

#define X86_BR_PLM (X86_BR_USER | X86_BR_KERNEL)
@@ -107,13 +108,15 @@ enum {
X86_BR_JMP |\
X86_BR_IRQ |\
X86_BR_ABORT |\
- X86_BR_IND_CALL)
+ X86_BR_IND_CALL |\
+ X86_BR_ZERO_CALL)

#define X86_BR_ALL (X86_BR_PLM | X86_BR_ANY)

#define X86_BR_ANY_CALL \
(X86_BR_CALL |\
X86_BR_IND_CALL |\
+ X86_BR_ZERO_CALL |\
X86_BR_SYSCALL |\
X86_BR_IRQ |\
X86_BR_INT)
@@ -636,6 +639,12 @@ static int branch_type(unsigned long from, unsigned long to, int abort)
ret = X86_BR_INT;
break;
case 0xe8: /* call near rel */
+ insn_get_immediate(&insn);
+ if (insn.immediate1.value == 0) {
+ /* zero length call */
+ ret = X86_BR_ZERO_CALL;
+ break;
+ }
case 0x9a: /* call far absolute */
ret = X86_BR_CALL;
break;
--
1.7.11.7


\
 
 \ /
  Last update: 2012-10-22 08:41    [W:0.176 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site