diff options
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/core.c | 211 | ||||
| -rw-r--r-- | kernel/events/ring_buffer.c | 15 | ||||
| -rw-r--r-- | kernel/events/uprobes.c | 5 |
3 files changed, 169 insertions, 62 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index a19550d80ab1..a54f2c2cdb20 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -242,18 +242,6 @@ unlock: return ret; } -static void event_function_local(struct perf_event *event, event_f func, void *data) -{ - struct event_function_struct efs = { - .event = event, - .func = func, - .data = data, - }; - - int ret = event_function(&efs); - WARN_ON_ONCE(ret); -} - static void event_function_call(struct perf_event *event, event_f func, void *data) { struct perf_event_context *ctx = event->ctx; @@ -303,6 +291,54 @@ again: raw_spin_unlock_irq(&ctx->lock); } +/* + * Similar to event_function_call() + event_function(), but hard assumes IRQs + * are already disabled and we're on the right CPU. + */ +static void event_function_local(struct perf_event *event, event_f func, void *data) +{ + struct perf_event_context *ctx = event->ctx; + struct perf_cpu_context *cpuctx = __get_cpu_context(ctx); + struct task_struct *task = READ_ONCE(ctx->task); + struct perf_event_context *task_ctx = NULL; + + WARN_ON_ONCE(!irqs_disabled()); + + if (task) { + if (task == TASK_TOMBSTONE) + return; + + task_ctx = ctx; + } + + perf_ctx_lock(cpuctx, task_ctx); + + task = ctx->task; + if (task == TASK_TOMBSTONE) + goto unlock; + + if (task) { + /* + * We must be either inactive or active and the right task, + * otherwise we're screwed, since we cannot IPI to somewhere + * else. + */ + if (ctx->is_active) { + if (WARN_ON_ONCE(task != current)) + goto unlock; + + if (WARN_ON_ONCE(cpuctx->task_ctx != ctx)) + goto unlock; + } + } else { + WARN_ON_ONCE(&cpuctx->ctx != ctx); + } + + func(event, cpuctx, ctx, data); +unlock: + perf_ctx_unlock(cpuctx, task_ctx); +} + #define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\ PERF_FLAG_FD_OUTPUT |\ PERF_FLAG_PID_CGROUP |\ @@ -843,6 +879,32 @@ perf_cgroup_mark_enabled(struct perf_event *event, } } } + +/* + * Update cpuctx->cgrp so that it is set when first cgroup event is added and + * cleared when last cgroup event is removed. + */ +static inline void +list_update_cgroup_event(struct perf_event *event, + struct perf_event_context *ctx, bool add) +{ + struct perf_cpu_context *cpuctx; + + if (!is_cgroup_event(event)) + return; + + if (add && ctx->nr_cgroups++) + return; + else if (!add && --ctx->nr_cgroups) + return; + /* + * Because cgroup events are always per-cpu events, + * this will always be called from the right CPU. + */ + cpuctx = __get_cpu_context(ctx); + cpuctx->cgrp = add ? event->cgrp : NULL; +} + #else /* !CONFIG_CGROUP_PERF */ static inline bool @@ -920,6 +982,13 @@ perf_cgroup_mark_enabled(struct perf_event *event, struct perf_event_context *ctx) { } + +static inline void +list_update_cgroup_event(struct perf_event *event, + struct perf_event_context *ctx, bool add) +{ +} + #endif /* @@ -1392,6 +1461,7 @@ ctx_group_list(struct perf_event *event, struct perf_event_context *ctx) static void list_add_event(struct perf_event *event, struct perf_event_context *ctx) { + lockdep_assert_held(&ctx->lock); WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT); @@ -1412,8 +1482,7 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx) list_add_tail(&event->group_entry, list); } - if (is_cgroup_event(event)) - ctx->nr_cgroups++; + list_update_cgroup_event(event, ctx, true); list_add_rcu(&event->event_entry, &ctx->event_list); ctx->nr_events++; @@ -1581,8 +1650,6 @@ static void perf_group_attach(struct perf_event *event) static void list_del_event(struct perf_event *event, struct perf_event_context *ctx) { - struct perf_cpu_context *cpuctx; - WARN_ON_ONCE(event->ctx != ctx); lockdep_assert_held(&ctx->lock); @@ -1594,20 +1661,7 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) event->attach_state &= ~PERF_ATTACH_CONTEXT; - if (is_cgroup_event(event)) { - ctx->nr_cgroups--; - /* - * Because cgroup events are always per-cpu events, this will - * always be called from the right CPU. - */ - cpuctx = __get_cpu_context(ctx); - /* - * If there are no more cgroup events then clear cgrp to avoid - * stale pointer in update_cgrp_time_from_cpuctx(). - */ - if (!ctx->nr_cgroups) - cpuctx->cgrp = NULL; - } + list_update_cgroup_event(event, ctx, false); ctx->nr_events--; if (event->attr.inherit_stat) @@ -1716,8 +1770,8 @@ static inline int pmu_filter_match(struct perf_event *event) static inline int event_filter_match(struct perf_event *event) { - return (event->cpu == -1 || event->cpu == smp_processor_id()) - && perf_cgroup_match(event) && pmu_filter_match(event); + return (event->cpu == -1 || event->cpu == smp_processor_id()) && + perf_cgroup_match(event) && pmu_filter_match(event); } static void @@ -1737,8 +1791,8 @@ event_sched_out(struct perf_event *event, * maintained, otherwise bogus information is return * via read() for time_enabled, time_running: */ - if (event->state == PERF_EVENT_STATE_INACTIVE - && !event_filter_match(event)) { + if (event->state == PERF_EVENT_STATE_INACTIVE && + !event_filter_match(event)) { delta = tstamp - event->tstamp_stopped; event->tstamp_running += delta; event->tstamp_stopped = tstamp; @@ -2236,10 +2290,15 @@ perf_install_in_context(struct perf_event_context *ctx, lockdep_assert_held(&ctx->mutex); - event->ctx = ctx; if (event->cpu != -1) event->cpu = cpu; + /* + * Ensures that if we can observe event->ctx, both the event and ctx + * will be 'complete'. See perf_iterate_sb_cpu(). + */ + smp_store_release(&event->ctx, ctx); + if (!task) { cpu_function_call(cpu, __perf_install_in_context, event); return; @@ -2437,11 +2496,11 @@ static int __perf_event_stop(void *info) return 0; } -static int perf_event_restart(struct perf_event *event) +static int perf_event_stop(struct perf_event *event, int restart) { struct stop_event_data sd = { .event = event, - .restart = 1, + .restart = restart, }; int ret = 0; @@ -3490,8 +3549,17 @@ static int perf_event_read(struct perf_event *event, bool group) .group = group, .ret = 0, }; - smp_call_function_single(event->oncpu, - __perf_event_read, &data, 1); + /* + * Purposely ignore the smp_call_function_single() return + * value. + * + * If event->oncpu isn't a valid CPU it means the event got + * scheduled out and that will have updated the event count. + * + * Therefore, either way, we'll have an up-to-date event count + * after this. + */ + (void)smp_call_function_single(event->oncpu, __perf_event_read, &data, 1); ret = data.ret; } else if (event->state == PERF_EVENT_STATE_INACTIVE) { struct perf_event_context *ctx = event->ctx; @@ -4777,6 +4845,19 @@ static void ring_buffer_attach(struct perf_event *event, spin_unlock_irqrestore(&rb->event_lock, flags); } + /* + * Avoid racing with perf_mmap_close(AUX): stop the event + * before swizzling the event::rb pointer; if it's getting + * unmapped, its aux_mmap_count will be 0 and it won't + * restart. See the comment in __perf_pmu_output_stop(). + * + * Data will inevitably be lost when set_output is done in + * mid-air, but then again, whoever does it like this is + * not in for the data anyway. + */ + if (has_aux(event)) + perf_event_stop(event, 0); + rcu_assign_pointer(event->rb, rb); if (old_rb) { @@ -5969,6 +6050,14 @@ static void perf_iterate_sb_cpu(perf_iterate_f output, void *data) struct perf_event *event; list_for_each_entry_rcu(event, &pel->list, sb_list) { + /* + * Skip events that are not fully formed yet; ensure that + * if we observe event->ctx, both event and ctx will be + * complete enough. See perf_install_in_context(). + */ + if (!smp_load_acquire(&event->ctx)) + continue; + if (event->state < PERF_EVENT_STATE_INACTIVE) continue; if (!event_filter_match(event)) @@ -6044,7 +6133,7 @@ static void perf_event_addr_filters_exec(struct perf_event *event, void *data) raw_spin_unlock_irqrestore(&ifh->lock, flags); if (restart) - perf_event_restart(event); + perf_event_stop(event, 1); } void perf_event_exec(void) @@ -6088,7 +6177,13 @@ static void __perf_event_output_stop(struct perf_event *event, void *data) /* * In case of inheritance, it will be the parent that links to the - * ring-buffer, but it will be the child that's actually using it: + * ring-buffer, but it will be the child that's actually using it. + * + * We are using event::rb to determine if the event should be stopped, + * however this may race with ring_buffer_attach() (through set_output), + * which will make us skip the event that actually needs to be stopped. + * So ring_buffer_attach() has to stop an aux event before re-assigning + * its rb pointer. */ if (rcu_dereference(parent->rb) == rb) ro->err = __perf_event_stop(&sd); @@ -6098,7 +6193,7 @@ static int __perf_pmu_output_stop(void *info) { struct perf_event *event = info; struct pmu *pmu = event->pmu; - struct perf_cpu_context *cpuctx = get_cpu_ptr(pmu->pmu_cpu_context); + struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); struct remote_output ro = { .rb = event->rb, }; @@ -6553,15 +6648,6 @@ got_name: } /* - * Whether this @filter depends on a dynamic object which is not loaded - * yet or its load addresses are not known. - */ -static bool perf_addr_filter_needs_mmap(struct perf_addr_filter *filter) -{ - return filter->filter && filter->inode; -} - -/* * Check whether inode and address range match filter criteria. */ static bool perf_addr_filter_match(struct perf_addr_filter *filter, @@ -6611,7 +6697,7 @@ static void __perf_addr_filters_adjust(struct perf_event *event, void *data) raw_spin_unlock_irqrestore(&ifh->lock, flags); if (restart) - perf_event_restart(event); + perf_event_stop(event, 1); } /* @@ -6622,6 +6708,13 @@ static void perf_addr_filters_adjust(struct vm_area_struct *vma) struct perf_event_context *ctx; int ctxn; + /* + * Data tracing isn't supported yet and as such there is no need + * to keep track of anything that isn't related to executable code: + */ + if (!(vma->vm_flags & VM_EXEC)) + return; + rcu_read_lock(); for_each_task_context_nr(ctxn) { ctx = rcu_dereference(current->perf_event_ctxp[ctxn]); @@ -7774,7 +7867,11 @@ static void perf_event_addr_filters_apply(struct perf_event *event) list_for_each_entry(filter, &ifh->list, entry) { event->addr_filters_offs[count] = 0; - if (perf_addr_filter_needs_mmap(filter)) + /* + * Adjust base offset if the filter is associated to a binary + * that needs to be mapped: + */ + if (filter->inode) event->addr_filters_offs[count] = perf_addr_filter_apply(filter, mm); @@ -7789,7 +7886,7 @@ static void perf_event_addr_filters_apply(struct perf_event *event) mmput(mm); restart: - perf_event_restart(event); + perf_event_stop(event, 1); } /* @@ -7905,8 +8002,10 @@ perf_event_parse_addr_filter(struct perf_event *event, char *fstr, goto fail; } - if (token == IF_SRC_FILE) { - filename = match_strdup(&args[2]); + if (token == IF_SRC_FILE || token == IF_SRC_FILEADDR) { + int fpos = filter->range ? 2 : 1; + + filename = match_strdup(&args[fpos]); if (!filename) { ret = -ENOMEM; goto fail; diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index ae9b90dc9a5a..257fa460b846 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -330,15 +330,22 @@ void *perf_aux_output_begin(struct perf_output_handle *handle, if (!rb) return NULL; - if (!rb_has_aux(rb) || !atomic_inc_not_zero(&rb->aux_refcount)) + if (!rb_has_aux(rb)) goto err; /* - * If rb::aux_mmap_count is zero (and rb_has_aux() above went through), - * the aux buffer is in perf_mmap_close(), about to get freed. + * If aux_mmap_count is zero, the aux buffer is in perf_mmap_close(), + * about to get freed, so we leave immediately. + * + * Checking rb::aux_mmap_count and rb::refcount has to be done in + * the same order, see perf_mmap_close. Otherwise we end up freeing + * aux pages in this path, which is a bug, because in_atomic(). */ if (!atomic_read(&rb->aux_mmap_count)) - goto err_put; + goto err; + + if (!atomic_inc_not_zero(&rb->aux_refcount)) + goto err; /* * Nesting is not supported for AUX area, make sure nested diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index b7a525ab2083..8c50276b60d1 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -172,8 +172,10 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); err = -EAGAIN; ptep = page_check_address(page, mm, addr, &ptl, 0); - if (!ptep) + if (!ptep) { + mem_cgroup_cancel_charge(kpage, memcg, false); goto unlock; + } get_page(kpage); page_add_new_anon_rmap(kpage, vma, addr, false); @@ -200,7 +202,6 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, err = 0; unlock: - mem_cgroup_cancel_charge(kpage, memcg, false); mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); unlock_page(page); return err; |