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arm_pmu: Add support for 64bit event counters 

Each PMU has a set of 32bit event counters. But in some
special cases, the events could be counted using counters
which are effectively 64bit wide.

e.g, Arm V8 PMUv3 has a 64 bit cycle counter which can count
only the CPU cycles. Also, the PMU can chain the event counters
to effectively count as a 64bit counter.

Add support for tracking the events that uses 64bit counters.
This only affects the periods set for each counter in the core
driver.

Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Suzuki K Poulose 2018-07-10 09:58:00 +01:00 committed by Will Deacon
parent 3a95200d3f
commit e2da97d328
2 changed files with 16 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/perf/arm_pmu.c
View File

@ -28,9 +28,12 @@
static DEFINE_PER_CPU(struct arm_pmu *, cpu_armpmu);
static DEFINE_PER_CPU(int, cpu_irq);
static inline u64 arm_pmu_max_period(void)
static inline u64 arm_pmu_event_max_period(struct perf_event *event)
{
return (1ULL << 32) - 1;
if (event->hw.flags & ARMPMU_EVT_64BIT)
return GENMASK_ULL(63, 0);
else
return GENMASK_ULL(31, 0);
}
static int
@ -122,7 +125,7 @@ int armpmu_event_set_period(struct perf_event *event)
u64 max_period;
int ret = 0;
max_period = arm_pmu_max_period();
max_period = arm_pmu_event_max_period(event);
if (unlikely(left <= -period)) {
left = period;
local64_set(&hwc->period_left, left);
@ -148,7 +151,7 @@ int armpmu_event_set_period(struct perf_event *event)
local64_set(&hwc->prev_count, (u64)-left);
armpmu->write_counter(event, (u64)(-left) & 0xffffffff);
armpmu->write_counter(event, (u64)(-left) & max_period);
perf_event_update_userpage(event);
@ -160,7 +163,7 @@ u64 armpmu_event_update(struct perf_event *event)
struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
struct hw_perf_event *hwc = &event->hw;
u64 delta, prev_raw_count, new_raw_count;
u64 max_period = arm_pmu_max_period();
u64 max_period = arm_pmu_event_max_period(event);
again:
prev_raw_count = local64_read(&hwc->prev_count);
@ -368,6 +371,7 @@ __hw_perf_event_init(struct perf_event *event)
struct hw_perf_event *hwc = &event->hw;
int mapping;
hwc->flags = 0;
mapping = armpmu->map_event(event);
if (mapping < 0) {
@ -410,7 +414,7 @@ __hw_perf_event_init(struct perf_event *event)
* is far less likely to overtake the previous one unless
* you have some serious IRQ latency issues.
*/
hwc->sample_period = arm_pmu_max_period() >> 1;
hwc->sample_period = arm_pmu_event_max_period(event) >> 1;
hwc->last_period = hwc->sample_period;
local64_set(&hwc->period_left, hwc->sample_period);
}

6
include/linux/perf/arm_pmu.h
View File

@ -25,6 +25,12 @@
*/
#define ARMPMU_MAX_HWEVENTS 32
/*
* ARM PMU hw_event flags
*/
/* Event uses a 64bit counter */
#define ARMPMU_EVT_64BIT 1
#define HW_OP_UNSUPPORTED 0xFFFF
#define C(_x) PERF_COUNT_HW_CACHE_##_x
#define CACHE_OP_UNSUPPORTED 0xFFFF