On Wed, Dec 04, 2013 at 04:02:36PM +0530, Anshuman Khandual wrote:
> This patch adds conditional branch filtering support,
> enabling it for PERF_SAMPLE_BRANCH_COND in perf branch
> stack sampling framework by utilizing an available
> software filter X86_BR_JCC.
Newer Intel CPUs a hardware filter too for "not a conditional
branch". I can look at implementing that.
The software option seems fine for now.
-Andi
>
> Signed-off-by: Anshuman Khandual <khand...@linux.vnet.ibm.com>
> Reviewed-by: Stephane Eranian <eran...@google.com>
> ---
> arch/x86/kernel/cpu/perf_event_intel_lbr.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> index d82d155..9dd2459 100644
> --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> @@ -384,6 +384,9 @@ static void intel_pmu_setup_sw_lbr_filter(struct
> perf_event *event)
> if (br_type & PERF_SAMPLE_BRANCH_NO_TX)
> mask |= X86_BR_NO_TX;
>
> + if (br_type & PERF_SAMPLE_BRANCH_COND)
> + mask |= X86_BR_JCC;
> +
> /*
> * stash actual user request into reg, it may
> * be used by fixup code for some CPU
> @@ -678,6 +681,7 @@ static const int nhm_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX]
> = {
> * NHM/WSM erratum: must include IND_JMP to capture IND_CALL
> */
> [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL | LBR_IND_JMP,
> + [PERF_SAMPLE_BRANCH_COND] = LBR_JCC,
> };
>
> static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = {
> @@ -689,6 +693,7 @@ static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX]
> = {
> [PERF_SAMPLE_BRANCH_ANY_CALL] = LBR_REL_CALL | LBR_IND_CALL
> | LBR_FAR,
> [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL,
> + [PERF_SAMPLE_BRANCH_COND] = LBR_JCC,
> };
>
> /* core */
> --
> 1.7.11.7
>
--
a...@linux.intel.com -- Speaking for myself only
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