[Patch v1 06/10] perf/x86: add support for PEBS Precise Store

Stephane Eranian
2012-10-29T15:18:51Z

This patch adds support for PEBS Precise Store
which is available on Intel Sandy Bridge and
Ivy Bridge processors.

To use Precise store, the proper PEBS event
must be used: mem_trans_retired:precise_stores.
For the perf tool, the generic mem-stores event
exported via sysfs can be used directly.

Signed-off-by: Stephane Eranian <eranian@google.com>
---
arch/x86/kernel/cpu/perf_event.h | 5 +++
arch/x86/kernel/cpu/perf_event_intel.c | 2 ++
arch/x86/kernel/cpu/perf_event_intel_ds.c | 49 +++++++++++++++++++++++++++--
3 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 3c5aa72..4e95c90 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -66,6 +66,7 @@ struct event_constraint {
* struct event_constraint flags
*/
#define PERF_X86_EVENT_PEBS_LDLAT 0x1 /* ld+ldlat data address sampling */
+#define PERF_X86_EVENT_PEBS_ST 0x2 /* st data address sampling */

struct amd_nb {
int nb_id; /* NorthBridge id */
@@ -242,6 +243,10 @@ struct cpu_hw_events {
__EVENT_CONSTRAINT(c, n, INTEL_ARCH_EVENT_MASK, \
HWEIGHT(n), 0, PERF_X86_EVENT_PEBS_LDLAT)

+#define INTEL_PST_CONSTRAINT(c, n) \
+ __EVENT_CONSTRAINT(c, n, INTEL_ARCH_EVENT_MASK, \
+ HWEIGHT(n), 0, PERF_X86_EVENT_PEBS_ST)
+
#define EVENT_CONSTRAINT_END \
EVENT_CONSTRAINT(0, 0, 0)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index c37b7f8..bf25b7b 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -150,6 +150,7 @@ EVENT_ATTR(ref-cycles, REF_CPU_CYCLES );

EVENT_ATTR_STR(mem-loads, mem_ld_nhm, "event=0x100b,umask=0x1,ldlat=3");
EVENT_ATTR_STR(mem-loads, mem_ld_snb, "event=0xcd,umask=0x1,ldlat=3");
+EVENT_ATTR_STR(mem-stores, mem_st_snb, "event=0xcd,umask=0x2");

struct attribute *nhm_events_attrs[] = {
EVENT_PTR(CPU_CYCLES),
@@ -178,6 +179,7 @@ struct attribute *snb_events_attrs[] = {
EVENT_PTR(STALLED_CYCLES_BACKEND),
EVENT_PTR(REF_CPU_CYCLES),
EVENT_PTR(mem_ld_snb),
+ EVENT_PTR(mem_st_snb),
NULL,
};

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 3ee6e83..4c5f639 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -69,6 +69,44 @@ static const u64 pebs_data_source[] = {
OP_LH | P(LVL,UNC) | P(SNOOP, NONE), /* 0x0f: uncached */
};

+static u64 precise_store_data(u64 status)
+{
+ union intel_x86_pebs_dse dse;
+ u64 val = P(OP, STORE) | P(SNOOP, NA) | P(LVL, L1) | P(TLB, L2);
+
+ dse.val = status;
+
+ /*
+ * bit 4: TLB access
+ * 1 = stored missed 2nd level TLB
+ *
+ * so it either hit the walker or the OS
+ * otherwise hit 2nd level TLB
+ */
+ if (dse.st_stlb_miss)
+ val |= P(TLB, MISS);
+ else
+ val |= P(TLB, HIT);
+
+ /*
+ * bit 0: hit L1 data cache
+ * if not set, then all we know is that
+ * it missed L1D
+ */
+ if (dse.st_l1d_hit)
+ val |= P(LVL, HIT);
+ else
+ val |= P(LVL, MISS);
+
+ /*
+ * bit 5: Locked prefix
+ */
+ if (dse.st_locked)
+ val |= P(LOCK, LOCKED);
+
+ return val;
+}
+
static u64 load_latency_data(u64 status)
{
union intel_x86_pebs_dse dse;
@@ -486,6 +524,7 @@ struct event_constraint intel_snb_pebs_event_constraints[] = {
INTEL_EVENT_CONSTRAINT(0xc4, 0xf), /* BR_INST_RETIRED.* */
INTEL_EVENT_CONSTRAINT(0xc5, 0xf), /* BR_MISP_RETIRED.* */
INTEL_PLD_CONSTRAINT(0x01cd, 0x8), /* MEM_TRANS_RETIRED.LAT_ABOVE_THR */
+ INTEL_PST_CONSTRAINT(0x02cd, 0x8), /* MEM_TRANS_RETIRED.PRECISE_STORES */
INTEL_EVENT_CONSTRAINT(0xd0, 0xf), /* MEM_UOP_RETIRED.* */
INTEL_EVENT_CONSTRAINT(0xd1, 0xf), /* MEM_LOAD_UOPS_RETIRED.* */
INTEL_EVENT_CONSTRAINT(0xd2, 0xf), /* MEM_LOAD_UOPS_LLC_HIT_RETIRED.* */
@@ -500,6 +539,7 @@ struct event_constraint intel_ivb_pebs_event_constraints[] = {
INTEL_EVENT_CONSTRAINT(0xc4, 0xf), /* BR_INST_RETIRED.* */
INTEL_EVENT_CONSTRAINT(0xc5, 0xf), /* BR_MISP_RETIRED.* */
INTEL_PLD_CONSTRAINT(0x01cd, 0x8), /* MEM_TRANS_RETIRED.LAT_ABOVE_THR */
+ INTEL_PST_CONSTRAINT(0x02cd, 0x8), /* MEM_TRANS_RETIRED.PRECISE_STORES */
INTEL_EVENT_CONSTRAINT(0xd0, 0xf), /* MEM_UOP_RETIRED.* */
INTEL_EVENT_CONSTRAINT(0xd1, 0xf), /* MEM_LOAD_UOPS_RETIRED.* */
INTEL_EVENT_CONSTRAINT(0xd2, 0xf), /* MEM_LOAD_UOPS_LLC_HIT_RETIRED.* */
@@ -537,6 +577,8 @@ void intel_pmu_pebs_enable(struct perf_event *event)

if (event->hw.flags & PERF_X86_EVENT_PEBS_LDLAT)
cpuc->pebs_enabled |= 1ULL << (hwc->idx + 32);
+ else if (event->hw.flags & PERF_X86_EVENT_PEBS_ST)
+ cpuc->pebs_enabled |= 1ULL << 63;
}

void intel_pmu_pebs_disable(struct perf_event *event)
@@ -657,12 +699,13 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
struct perf_sample_data data;
struct pt_regs regs;
u64 sample_type;
- int fll;
+ int fll, fst;

if (!intel_pmu_save_and_restart(event))
return;

fll = event->hw.flags & PERF_X86_EVENT_PEBS_LDLAT;
+ fst = event->hw.flags & PERF_X86_EVENT_PEBS_ST;

perf_sample_data_init(&data, 0, event->hw.last_period);

@@ -672,7 +715,7 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
/*
* if PEBS-LL or PreciseStore
*/
- if (fll) {
+ if (fll || fst) {
if (sample_type & PERF_SAMPLE_ADDR)
data.addr = pebs->dla;

@@ -688,6 +731,8 @@ static void __intel_pmu_pebs_event(struct perf_event *event,
if (sample_type & PERF_SAMPLE_DSRC) {
if (fll)
data.dsrc.val = load_latency_data(pebs->dse);
+ else if (fst)
+ data.dsrc.val = precise_store_data(pebs->dse);
}
}

--
1.7.9.5