From cf3beb7c90a8efa16a06b26634cddddc92bb819c Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Thu, 21 Apr 2016 02:30:10 -0700 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Link: http://lkml.kernel.org/r/1461231010-4399-1-git-send-email-kan.liang@intel.com Signed-off-by: Ingo Molnar --- 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 6c3b7c1780c9..1ca5d1e7d4f2 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) && -- 2.39.2