diff options
| -rw-r--r-- | arch/arm64/kernel/perf_event.c | 30 | ||||
| -rw-r--r-- | kernel/events/core.c | 4 |
2 files changed, 32 insertions, 2 deletions
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index dfff5ed5c625..8e38d5267f22 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -25,6 +25,7 @@ #include <asm/virt.h> #include <linux/acpi.h> +#include <linux/clocksource.h> #include <linux/of.h> #include <linux/perf/arm_pmu.h> #include <linux/platform_device.h> @@ -1278,3 +1279,32 @@ static int __init armv8_pmu_driver_init(void) return arm_pmu_acpi_probe(armv8_pmuv3_init); } device_initcall(armv8_pmu_driver_init) + +void arch_perf_update_userpage(struct perf_event *event, + struct perf_event_mmap_page *userpg, u64 now) +{ + u32 freq; + u32 shift; + + /* + * Internal timekeeping for enabled/running/stopped times + * is always computed with the sched_clock. + */ + freq = arch_timer_get_rate(); + userpg->cap_user_time = 1; + + clocks_calc_mult_shift(&userpg->time_mult, &shift, freq, + NSEC_PER_SEC, 0); + /* + * time_shift is not expected to be greater than 31 due to + * the original published conversion algorithm shifting a + * 32-bit value (now specifies a 64-bit value) - refer + * perf_event_mmap_page documentation in perf_event.h. + */ + if (shift == 32) { + shift = 31; + userpg->time_mult >>= 1; + } + userpg->time_shift = (u16)shift; + userpg->time_offset = -now; +} diff --git a/kernel/events/core.c b/kernel/events/core.c index 8f0434a9951a..1a16dcca0da2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5246,8 +5246,8 @@ void perf_event_update_userpage(struct perf_event *event) userpg = rb->user_page; /* - * Disable preemption so as to not let the corresponding user-space - * spin too long if we get preempted. + * Disable preemption to guarantee consistent time stamps are stored to + * the user page. */ preempt_disable(); ++userpg->lock; |