diff options
| -rw-r--r-- | arch/x86/events/amd/uncore.c | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c index 70e0af36c378..d328de166481 100644 --- a/arch/x86/events/amd/uncore.c +++ b/arch/x86/events/amd/uncore.c @@ -956,6 +956,39 @@ static void amd_uncore_umc_start(struct perf_event *event, int flags) perf_event_update_userpage(event); } +static void amd_uncore_umc_read(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + u64 prev, new, shift; + s64 delta; + + shift = COUNTER_SHIFT + 1; + prev = local64_read(&hwc->prev_count); + + /* + * UMC counters do not have RDPMC assignments. Read counts directly + * from the corresponding PERF_CTR. + */ + rdmsrl(hwc->event_base, new); + + /* + * Unlike the other uncore counters, UMC counters saturate and set the + * Overflow bit (bit 48) on overflow. Since they do not roll over, + * proactively reset the corresponding PERF_CTR when bit 47 is set so + * that the counter never gets a chance to saturate. + */ + if (new & BIT_ULL(63 - COUNTER_SHIFT)) { + wrmsrl(hwc->event_base, 0); + local64_set(&hwc->prev_count, 0); + } else { + local64_set(&hwc->prev_count, new); + } + + delta = (new << shift) - (prev << shift); + delta >>= shift; + local64_add(delta, &event->count); +} + static void amd_uncore_umc_ctx_scan(struct amd_uncore *uncore, unsigned int cpu) { @@ -1034,7 +1067,7 @@ int amd_uncore_umc_ctx_init(struct amd_uncore *uncore, unsigned int cpu) .del = amd_uncore_del, .start = amd_uncore_umc_start, .stop = amd_uncore_stop, - .read = amd_uncore_read, + .read = amd_uncore_umc_read, .capabilities = PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_NO_INTERRUPT, .module = THIS_MODULE, }; |