[PATCH 1/1] perf/x86: filter branches for PEBS event

kan.liang
2015-03-26T18:48:36Z

From: Kan Liang <kan.liang@intel.com>

For supporting Intel LBR branches filtering, Intel LBR sharing logic
mechanism is introduced from commit b36817e88630 ("perf/x86: Add Intel
LBR sharing logic"). It modifies __intel_shared_reg_get_constraints to
config lbr_sel, which is finally used to set LBR_SELECT.
However, the intel_shared_regs_constraints is called after
intel_pebs_constraints. The PEBS event will return immediately after
intel_pebs_constraints. So it's impossible to filter branches for PEBS
event.

This patch move intel_shared_regs_constraints for branch_reg ahead of
intel_pebs_constraints.
intel_shared_regs_constraints for branch_reg doesn't modify event->hw,
so it's safe to be called before intel_pebs_constraints.
intel_shared_regs_constraints for branch_reg also special case when it
returns &emptyconstraint. It put constraints for extra_reg. This patch
remove it. Because it will never get constraints for extra_reg if return
is &emptyconstraint.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
arch/x86/kernel/cpu/perf_event_intel.c | 34 ++++++++++++----------------------
1 file changed, 12 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 9f1dd18..247780a 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1587,25 +1587,14 @@ __intel_shared_reg_put_constraints(struct cpu_hw_events *cpuc,

static struct event_constraint *
intel_shared_regs_constraints(struct cpu_hw_events *cpuc,
- struct perf_event *event)
+ struct perf_event *event,
+ struct hw_perf_event_extra *reg)
{
- struct event_constraint *c = NULL, *d;
- struct hw_perf_event_extra *xreg, *breg;
+ struct event_constraint *c = NULL;
+
+ if (reg->idx != EXTRA_REG_NONE)
+ c = __intel_shared_reg_get_constraints(cpuc, event, reg);

- xreg = &event->hw.extra_reg;
- if (xreg->idx != EXTRA_REG_NONE) {
- c = __intel_shared_reg_get_constraints(cpuc, event, xreg);
- if (c == &emptyconstraint)
- return c;
- }
- breg = &event->hw.branch_reg;
- if (breg->idx != EXTRA_REG_NONE) {
- d = __intel_shared_reg_get_constraints(cpuc, event, breg);
- if (d == &emptyconstraint) {
- __intel_shared_reg_put_constraints(cpuc, xreg);
- c = d;
- }
- }
return c;
}

@@ -1629,17 +1618,18 @@ x86_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
static struct event_constraint *
intel_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
{
- struct event_constraint *c;
+ struct event_constraint *c, *d;

c = intel_bts_constraints(event);
if (c)
return c;

- c = intel_pebs_constraints(event);
- if (c)
- return c;
+ c = intel_shared_regs_constraints(cpuc, event, &event->hw.branch_reg);
+ d = intel_pebs_constraints(event);
+ if (d || c)
+ return (d) ? (d) : (c);

- c = intel_shared_regs_constraints(cpuc, event);
+ c = intel_shared_regs_constraints(cpuc, event, &event->hw.extra_reg);
if (c)
return c;

--
1.8.3.2