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[PW_SID:1081352] drivers/perf: riscv: do not restart throttled events after overflow #1770

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[PW_SID:1081352] drivers/perf: riscv: do not restart throttled events after overflow #1770

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45 changes: 43 additions & 2 deletions drivers/perf/riscv_pmu_sbi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,33 @@ asm volatile(ALTERNATIVE( \
#define PERF_EVENT_FLAG_LEGACY BIT(SYSCTL_LEGACY)

PMU_FORMAT_ATTR(event, "config:0-55");
static inline bool rvpmu_perf_event_is_throttled(struct perf_event *event)
{
return event->hw.interrupts == MAX_INTERRUPTS;
}

/*
* Return a mask of counters that must not be restarted.
* `base` is the starting bit index to limit the mask to this long word.
*/
static inline unsigned long rvpmu_get_throttled_mask(struct perf_event **events,
unsigned long mask,
int base)
{
unsigned long tmp = mask, throttled = 0;
int bit = -1;
int nr_bits = min_t(int, BITS_PER_LONG, RISCV_MAX_COUNTERS - base);

for_each_set_bit(bit, &tmp, nr_bits) {
struct perf_event *event = events[bit];

if (!event || rvpmu_perf_event_is_throttled(event))
throttled |= BIT(bit);
}

return throttled;
}

PMU_FORMAT_ATTR(firmware, "config:62-63");

static bool sbi_v2_available;
Expand Down Expand Up @@ -1005,6 +1032,8 @@ static inline void pmu_sbi_start_ovf_ctrs_snapshot(struct cpu_hw_events *cpu_hw_
for_each_set_bit(idx, cpu_hw_evt->used_hw_ctrs, RISCV_MAX_COUNTERS) {
if (ctr_ovf_mask & BIT(idx)) {
event = cpu_hw_evt->events[idx];
if (!event || rvpmu_perf_event_is_throttled(event))
continue;
hwc = &event->hw;
max_period = riscv_pmu_ctr_get_width_mask(event);
init_val = local64_read(&hwc->prev_count) & max_period;
Expand All @@ -1017,13 +1046,25 @@ static inline void pmu_sbi_start_ovf_ctrs_snapshot(struct cpu_hw_events *cpu_hw_
}

for (i = 0; i < BITS_TO_LONGS(RISCV_MAX_COUNTERS); i++) {
int base = i * BITS_PER_LONG;
unsigned long throttled;
unsigned long used;
unsigned long start_mask;

used = cpu_hw_evt->used_hw_ctrs[i];
throttled = rvpmu_get_throttled_mask(cpu_hw_evt->events + base,
used, base);
start_mask = used & ~throttled;
if (!start_mask)
continue;

/* Restore the counter values to relative indices for used hw counters */
for_each_set_bit(idx, &cpu_hw_evt->used_hw_ctrs[i], BITS_PER_LONG)
sdata->ctr_values[idx] =
cpu_hw_evt->snapshot_cval_shcopy[idx + i * BITS_PER_LONG];
/* Start all the counters in a single shot */
sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, idx * BITS_PER_LONG,
cpu_hw_evt->used_hw_ctrs[i], flag, 0, 0, 0);
sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, i * BITS_PER_LONG,
start_mask, flag, 0, 0, 0);
}
}

Expand Down
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