diff options
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/callchain.c | 14 | ||||
| -rw-r--r-- | kernel/events/core.c | 100 |
2 files changed, 105 insertions, 9 deletions
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 808c0d7a31fa..b9c7e00725d6 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -218,7 +218,7 @@ static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entr struct perf_callchain_entry * get_perf_callchain(struct pt_regs *regs, bool kernel, bool user, - u32 max_stack, bool crosstask, bool add_mark) + u32 max_stack, bool crosstask, bool add_mark, u64 defer_cookie) { struct perf_callchain_entry *entry; struct perf_callchain_entry_ctx ctx; @@ -251,6 +251,18 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user, regs = task_pt_regs(current); } + if (defer_cookie) { + /* + * Foretell the coming of PERF_RECORD_CALLCHAIN_DEFERRED + * which can be stitched to this one, and add + * the cookie after it (it will be cut off when the + * user stack is copied to the callchain). + */ + perf_callchain_store_context(&ctx, PERF_CONTEXT_USER_DEFERRED); + perf_callchain_store_context(&ctx, defer_cookie); + goto exit_put; + } + if (add_mark) perf_callchain_store_context(&ctx, PERF_CONTEXT_USER); diff --git a/kernel/events/core.c b/kernel/events/core.c index 177e57c1a362..ece716879cbc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -56,6 +56,7 @@ #include <linux/buildid.h> #include <linux/task_work.h> #include <linux/percpu-rwsem.h> +#include <linux/unwind_deferred.h> #include "internal.h" @@ -8200,6 +8201,8 @@ static u64 perf_get_page_size(unsigned long addr) static struct perf_callchain_entry __empty_callchain = { .nr = 0, }; +static struct unwind_work perf_unwind_work; + struct perf_callchain_entry * perf_callchain(struct perf_event *event, struct pt_regs *regs) { @@ -8208,8 +8211,11 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) !(current->flags & (PF_KTHREAD | PF_USER_WORKER)); /* Disallow cross-task user callchains. */ bool crosstask = event->ctx->task && event->ctx->task != current; + bool defer_user = IS_ENABLED(CONFIG_UNWIND_USER) && user && + event->attr.defer_callchain; const u32 max_stack = event->attr.sample_max_stack; struct perf_callchain_entry *callchain; + u64 defer_cookie; if (!current->mm) user = false; @@ -8217,8 +8223,13 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) if (!kernel && !user) return &__empty_callchain; - callchain = get_perf_callchain(regs, kernel, user, - max_stack, crosstask, true); + if (!(user && defer_user && !crosstask && + unwind_deferred_request(&perf_unwind_work, &defer_cookie) >= 0)) + defer_cookie = 0; + + callchain = get_perf_callchain(regs, kernel, user, max_stack, + crosstask, true, defer_cookie); + return callchain ?: &__empty_callchain; } @@ -10003,6 +10014,66 @@ void perf_event_bpf_event(struct bpf_prog *prog, perf_iterate_sb(perf_event_bpf_output, &bpf_event, NULL); } +struct perf_callchain_deferred_event { + struct unwind_stacktrace *trace; + struct { + struct perf_event_header header; + u64 cookie; + u64 nr; + u64 ips[]; + } event; +}; + +static void perf_callchain_deferred_output(struct perf_event *event, void *data) +{ + struct perf_callchain_deferred_event *deferred_event = data; + struct perf_output_handle handle; + struct perf_sample_data sample; + int ret, size = deferred_event->event.header.size; + + if (!event->attr.defer_output) + return; + + /* XXX do we really need sample_id_all for this ??? */ + perf_event_header__init_id(&deferred_event->event.header, &sample, event); + + ret = perf_output_begin(&handle, &sample, event, + deferred_event->event.header.size); + if (ret) + goto out; + + perf_output_put(&handle, deferred_event->event); + for (int i = 0; i < deferred_event->trace->nr; i++) { + u64 entry = deferred_event->trace->entries[i]; + perf_output_put(&handle, entry); + } + perf_event__output_id_sample(event, &handle, &sample); + + perf_output_end(&handle); +out: + deferred_event->event.header.size = size; +} + +static void perf_unwind_deferred_callback(struct unwind_work *work, + struct unwind_stacktrace *trace, u64 cookie) +{ + struct perf_callchain_deferred_event deferred_event = { + .trace = trace, + .event = { + .header = { + .type = PERF_RECORD_CALLCHAIN_DEFERRED, + .misc = PERF_RECORD_MISC_USER, + .size = sizeof(deferred_event.event) + + (trace->nr * sizeof(u64)), + }, + .cookie = cookie, + .nr = trace->nr, + }, + }; + + perf_iterate_sb(perf_callchain_deferred_output, &deferred_event, NULL); +} + struct perf_text_poke_event { const void *old_bytes; const void *new_bytes; @@ -11773,7 +11844,8 @@ static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer) event = container_of(hrtimer, struct perf_event, hw.hrtimer); - if (event->state != PERF_EVENT_STATE_ACTIVE) + if (event->state != PERF_EVENT_STATE_ACTIVE || + event->hw.state & PERF_HES_STOPPED) return HRTIMER_NORESTART; event->pmu->read(event); @@ -11819,15 +11891,20 @@ static void perf_swevent_cancel_hrtimer(struct perf_event *event) struct hw_perf_event *hwc = &event->hw; /* - * The throttle can be triggered in the hrtimer handler. - * The HRTIMER_NORESTART should be used to stop the timer, - * rather than hrtimer_cancel(). See perf_swevent_hrtimer() + * Careful: this function can be triggered in the hrtimer handler, + * for cpu-clock events, so hrtimer_cancel() would cause a + * deadlock. + * + * So use hrtimer_try_to_cancel() to try to stop the hrtimer, + * and the cpu-clock handler also sets the PERF_HES_STOPPED flag, + * which guarantees that perf_swevent_hrtimer() will stop the + * hrtimer once it sees the PERF_HES_STOPPED flag. */ if (is_sampling_event(event) && (hwc->interrupts != MAX_INTERRUPTS)) { ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer); local64_set(&hwc->period_left, ktime_to_ns(remaining)); - hrtimer_cancel(&hwc->hrtimer); + hrtimer_try_to_cancel(&hwc->hrtimer); } } @@ -11871,12 +11948,14 @@ static void cpu_clock_event_update(struct perf_event *event) static void cpu_clock_event_start(struct perf_event *event, int flags) { + event->hw.state = 0; local64_set(&event->hw.prev_count, local_clock()); perf_swevent_start_hrtimer(event); } static void cpu_clock_event_stop(struct perf_event *event, int flags) { + event->hw.state = PERF_HES_STOPPED; perf_swevent_cancel_hrtimer(event); if (flags & PERF_EF_UPDATE) cpu_clock_event_update(event); @@ -11893,7 +11972,7 @@ static int cpu_clock_event_add(struct perf_event *event, int flags) static void cpu_clock_event_del(struct perf_event *event, int flags) { - cpu_clock_event_stop(event, flags); + cpu_clock_event_stop(event, PERF_EF_UPDATE); } static void cpu_clock_event_read(struct perf_event *event) @@ -11950,12 +12029,14 @@ static void task_clock_event_update(struct perf_event *event, u64 now) static void task_clock_event_start(struct perf_event *event, int flags) { + event->hw.state = 0; local64_set(&event->hw.prev_count, event->ctx->time); perf_swevent_start_hrtimer(event); } static void task_clock_event_stop(struct perf_event *event, int flags) { + event->hw.state = PERF_HES_STOPPED; perf_swevent_cancel_hrtimer(event); if (flags & PERF_EF_UPDATE) task_clock_event_update(event, event->ctx->time); @@ -14799,6 +14880,9 @@ void __init perf_event_init(void) idr_init(&pmu_idr); + unwind_deferred_init(&perf_unwind_work, + perf_unwind_deferred_callback); + perf_event_init_all_cpus(); init_srcu_struct(&pmus_srcu); perf_pmu_register(&perf_swevent, "software", PERF_TYPE_SOFTWARE); |