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Subject[PATCH 1/5] perf, x86: Add PEBSv2 record support v2
Date
From: Andi Kleen <ak@linux.intel.com>

Add support for the v2 PEBS format. It has a superset of the v1 PEBS
fields, but has a longer record so we need to adjust the code paths.

The main advantage is the new "EventingRip" support which directly
gives the instruction, not off-by-one instruction. So with precise == 2
we use that directly and don't try to use LBRs and walking basic blocks.
This lowers the overhead significantly.

Some other features are added in later patches.

Reviewed-by: Stephane Eranian <eranian@google.com>
v2: Rename various identifiers. Add more comments. Get rid of a cast.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/kernel/cpu/perf_event.c | 2 +-
arch/x86/kernel/cpu/perf_event_intel_ds.c | 113 +++++++++++++++++++++++------
2 files changed, 91 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 6774c17..c95290a 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -397,7 +397,7 @@ int x86_pmu_hw_config(struct perf_event *event)
* check that PEBS LBR correction does not conflict with
* whatever the user is asking with attr->branch_sample_type
*/
- if (event->attr.precise_ip > 1) {
+ if (event->attr.precise_ip > 1 && x86_pmu.intel_cap.pebs_format < 2) {
u64 *br_type = &event->attr.branch_sample_type;

if (has_branch_stack(event)) {
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 826054a..3a828ed 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -41,6 +41,22 @@ struct pebs_record_nhm {
u64 status, dla, dse, lat;
};

+/*
+ * Same as pebs_record_nhm, with two additional fields.
+ */
+struct pebs_record_fmt2 {
+ struct pebs_record_nhm nhm;
+ /*
+ * Real IP of the event. In the Intel documentation this
+ * is called eventingrip.
+ */
+ u64 ip_of_the_event;
+ /*
+ * TSX tuning information field: abort cycles and abort flags.
+ */
+ u64 tsx_tuning;
+};
+
void init_debug_store_on_cpu(int cpu)
{
struct debug_store *ds = per_cpu(cpu_hw_events, cpu).ds;
@@ -559,11 +575,11 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
{
/*
* We cast to pebs_record_core since that is a subset of
- * both formats and we don't use the other fields in this
- * routine.
+ * all formats.
*/
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
struct pebs_record_core *pebs = __pebs;
+ struct pebs_record_fmt2 *pebs_fmt2 = __pebs;
struct perf_sample_data data;
struct pt_regs regs;

@@ -588,7 +604,10 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
regs.bp = pebs->bp;
regs.sp = pebs->sp;

- if (event->attr.precise_ip > 1 && intel_pmu_pebs_fixup_ip(&regs))
+ if (event->attr.precise_ip > 1 && x86_pmu.intel_cap.pebs_format >= 2) {
+ regs.ip = pebs_fmt2->ip_of_the_event;
+ regs.flags |= PERF_EFLAGS_EXACT;
+ } else if (event->attr.precise_ip > 1 && intel_pmu_pebs_fixup_ip(&regs))
regs.flags |= PERF_EFLAGS_EXACT;
else
regs.flags &= ~PERF_EFLAGS_EXACT;
@@ -641,35 +660,21 @@ static void intel_pmu_drain_pebs_core(struct pt_regs *iregs)
__intel_pmu_pebs_event(event, iregs, at);
}

-static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
+static void __intel_pmu_drain_pebs_nhm(struct pt_regs *iregs, void *at,
+ void *top)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
struct debug_store *ds = cpuc->ds;
- struct pebs_record_nhm *at, *top;
struct perf_event *event = NULL;
u64 status = 0;
- int bit, n;
-
- if (!x86_pmu.pebs_active)
- return;
-
- at = (struct pebs_record_nhm *)(unsigned long)ds->pebs_buffer_base;
- top = (struct pebs_record_nhm *)(unsigned long)ds->pebs_index;
+ int bit;

ds->pebs_index = ds->pebs_buffer_base;

- n = top - at;
- if (n <= 0)
- return;
+ for ( ; at < top; at += x86_pmu.pebs_record_size) {
+ struct pebs_record_nhm *p = at;

- /*
- * Should not happen, we program the threshold at 1 and do not
- * set a reset value.
- */
- WARN_ONCE(n > x86_pmu.max_pebs_events, "Unexpected number of pebs records %d\n", n);
-
- for ( ; at < top; at++) {
- for_each_set_bit(bit, (unsigned long *)&at->status, x86_pmu.max_pebs_events) {
+ for_each_set_bit(bit, (unsigned long *)&p->status, x86_pmu.max_pebs_events) {
event = cpuc->events[bit];
if (!test_bit(bit, cpuc->active_mask))
continue;
@@ -692,6 +697,61 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
}
}

+static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct debug_store *ds = cpuc->ds;
+ struct pebs_record_nhm *at, *top;
+ int n;
+
+ if (!x86_pmu.pebs_active)
+ return;
+
+ at = (struct pebs_record_nhm *)(unsigned long)ds->pebs_buffer_base;
+ top = (struct pebs_record_nhm *)(unsigned long)ds->pebs_index;
+
+ ds->pebs_index = ds->pebs_buffer_base;
+
+ n = top - at;
+ if (n <= 0)
+ return;
+
+ /*
+ * Should not happen, we program the threshold at 1 and do not
+ * set a reset value.
+ */
+ WARN_ONCE(n > x86_pmu.max_pebs_events,
+ "Unexpected number of pebs records %d\n", n);
+
+ return __intel_pmu_drain_pebs_nhm(iregs, at, top);
+}
+
+static void intel_pmu_drain_pebs_fmt2(struct pt_regs *iregs)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct debug_store *ds = cpuc->ds;
+ struct pebs_record_fmt2 *at, *top;
+ int n;
+
+ if (!x86_pmu.pebs_active)
+ return;
+
+ at = (struct pebs_record_fmt2 *)(unsigned long)ds->pebs_buffer_base;
+ top = (struct pebs_record_fmt2 *)(unsigned long)ds->pebs_index;
+
+ n = top - at;
+ if (n <= 0)
+ return;
+ /*
+ * Should not happen, we program the threshold at 1 and do not
+ * set a reset value.
+ */
+ WARN_ONCE(n > x86_pmu.max_pebs_events,
+ "Unexpected number of pebs records %d\n", n);
+
+ return __intel_pmu_drain_pebs_nhm(iregs, at, top);
+}
+
/*
* BTS, PEBS probe and setup
*/
@@ -723,6 +783,13 @@ void intel_ds_init(void)
x86_pmu.drain_pebs = intel_pmu_drain_pebs_nhm;
break;

+ case 2:
+ printk(KERN_CONT "PEBS fmt2%c, ", pebs_type);
+ x86_pmu.pebs_record_size =
+ sizeof(struct pebs_record_fmt2);
+ x86_pmu.drain_pebs = intel_pmu_drain_pebs_fmt2;
+ break;
+
default:
printk(KERN_CONT "no PEBS fmt%d%c, ", format, pebs_type);
x86_pmu.pebs = 0;
--
1.7.7.6


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