From: Kan Liang <[email protected]>
This patch fixes an issue which starts from
'commit b16a5b52eb90 ("perf/x86: Add option to disable reading
branch flags/cycles")'. In this patch, lbr_sel_mask is used to mask
the lbr_select. But LBR_SEL_MASK doesn't include the bit for
LBR_CALL_STACK. So LBR call stack will never be set in lbr_select.
This patch corrects the LBR_SEL_MASK by including all valid bits in
LBR_SELECT. Also, the LBR_CALL_STACK bit is different as other bit in
LBR_SELECT. It does not operate in suppress mode, so it needs to be
specially handled in intel_pmu_setup_hw_lbr_filter.
Signed-off-by: Kan Liang <[email protected]>
---
arch/x86/events/intel/lbr.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 317e29e..551d655 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -64,7 +64,7 @@ static enum {
#define LBR_PLM (LBR_KERNEL | LBR_USER)
-#define LBR_SEL_MASK 0x1ff /* valid bits in LBR_SELECT */
+#define LBR_SEL_MASK 0x3ff /* valid bits in LBR_SELECT */
#define LBR_NOT_SUPP -1 /* LBR filter not supported */
#define LBR_IGN 0 /* ignored */
@@ -621,8 +621,10 @@ static int intel_pmu_setup_hw_lbr_filter(struct perf_event *event)
* The first 9 bits (LBR_SEL_MASK) in LBR_SELECT operate
* in suppress mode. So LBR_SELECT should be set to
* (~mask & LBR_SEL_MASK) | (mask & ~LBR_SEL_MASK)
+ * But the 10th bit LBR_CALL_STACK does not operate
+ * in suppress mode.
*/
- reg->config = mask ^ x86_pmu.lbr_sel_mask;
+ reg->config = mask ^ (x86_pmu.lbr_sel_mask & ~LBR_CALL_STACK);
if ((br_type & PERF_SAMPLE_BRANCH_NO_CYCLES) &&
(br_type & PERF_SAMPLE_BRANCH_NO_FLAGS) &&
--
2.5.0
Commit-ID: cf3beb7c90a8efa16a06b26634cddddc92bb819c
Gitweb: http://git.kernel.org/tip/cf3beb7c90a8efa16a06b26634cddddc92bb819c
Author: Kan Liang <[email protected]>
AuthorDate: Thu, 21 Apr 2016 02:30:10 -0700
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 28 Apr 2016 10:32:43 +0200
perf/x86/intel: Fix incorrect lbr_sel_mask value
This patch fixes a bug which was introduced by:
b16a5b52eb90 ("perf/x86: Add option to disable reading branch flags/cycles")
In this patch, lbr_sel_mask is used to mask the lbr_select. But LBR_SEL_MASK
doesn't include the bit for LBR_CALL_STACK. So LBR call stack will never be
set in lbr_select.
This patch corrects the LBR_SEL_MASK by including all valid bits in
LBR_SELECT. Also, the LBR_CALL_STACK bit is different as other bit in
LBR_SELECT. It does not operate in suppress mode, so it needs to be
specially handled in intel_pmu_setup_hw_lbr_filter.
Signed-off-by: Kan Liang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/events/intel/lbr.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 6c3b7c1..1ca5d1e 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -63,7 +63,7 @@ static enum {
#define LBR_PLM (LBR_KERNEL | LBR_USER)
-#define LBR_SEL_MASK 0x1ff /* valid bits in LBR_SELECT */
+#define LBR_SEL_MASK 0x3ff /* valid bits in LBR_SELECT */
#define LBR_NOT_SUPP -1 /* LBR filter not supported */
#define LBR_IGN 0 /* ignored */
@@ -610,8 +610,10 @@ static int intel_pmu_setup_hw_lbr_filter(struct perf_event *event)
* The first 9 bits (LBR_SEL_MASK) in LBR_SELECT operate
* in suppress mode. So LBR_SELECT should be set to
* (~mask & LBR_SEL_MASK) | (mask & ~LBR_SEL_MASK)
+ * But the 10th bit LBR_CALL_STACK does not operate
+ * in suppress mode.
*/
- reg->config = mask ^ x86_pmu.lbr_sel_mask;
+ reg->config = mask ^ (x86_pmu.lbr_sel_mask & ~LBR_CALL_STACK);
if ((br_type & PERF_SAMPLE_BRANCH_NO_CYCLES) &&
(br_type & PERF_SAMPLE_BRANCH_NO_FLAGS) &&