diff options
| -rw-r--r-- | include/linux/perf_event.h | 14 | ||||
| -rw-r--r-- | include/uapi/linux/perf_event.h | 3 | ||||
| -rw-r--r-- | kernel/events/core.c | 93 |
3 files changed, 109 insertions, 1 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index e8ad3c590a23..61448c19a132 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -246,6 +246,7 @@ struct perf_event; #define PERF_PMU_CAP_ITRACE 0x20 #define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x40 #define PERF_PMU_CAP_NO_EXCLUDE 0x80 +#define PERF_PMU_CAP_AUX_OUTPUT 0x100 /** * struct pmu - generic performance monitoring unit @@ -447,6 +448,16 @@ struct pmu { /* optional */ /* + * Check if event can be used for aux_output purposes for + * events of this PMU. + * + * Runs from perf_event_open(). Should return 0 for "no match" + * or non-zero for "match". + */ + int (*aux_output_match) (struct perf_event *event); + /* optional */ + + /* * Filter events for PMU-specific reasons. */ int (*filter_match) (struct perf_event *event); /* optional */ @@ -681,6 +692,9 @@ struct perf_event { struct perf_addr_filter_range *addr_filter_ranges; unsigned long addr_filters_gen; + /* for aux_output events */ + struct perf_event *aux_event; + void (*destroy)(struct perf_event *); struct rcu_head rcu_head; diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 7198ddd0c6b1..bb7b271397a6 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -374,7 +374,8 @@ struct perf_event_attr { namespaces : 1, /* include namespaces data */ ksymbol : 1, /* include ksymbol events */ bpf_event : 1, /* include bpf events */ - __reserved_1 : 33; + aux_output : 1, /* generate AUX records instead of events */ + __reserved_1 : 32; union { __u32 wakeup_events; /* wakeup every n events */ diff --git a/kernel/events/core.c b/kernel/events/core.c index 0463c1151bae..2aad959e6def 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1887,6 +1887,89 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) ctx->generation++; } +static int +perf_aux_output_match(struct perf_event *event, struct perf_event *aux_event) +{ + if (!has_aux(aux_event)) + return 0; + + if (!event->pmu->aux_output_match) + return 0; + + return event->pmu->aux_output_match(aux_event); +} + +static void put_event(struct perf_event *event); +static void event_sched_out(struct perf_event *event, + struct perf_cpu_context *cpuctx, + struct perf_event_context *ctx); + +static void perf_put_aux_event(struct perf_event *event) +{ + struct perf_event_context *ctx = event->ctx; + struct perf_cpu_context *cpuctx = __get_cpu_context(ctx); + struct perf_event *iter; + + /* + * If event uses aux_event tear down the link + */ + if (event->aux_event) { + iter = event->aux_event; + event->aux_event = NULL; + put_event(iter); + return; + } + + /* + * If the event is an aux_event, tear down all links to + * it from other events. + */ + for_each_sibling_event(iter, event->group_leader) { + if (iter->aux_event != event) + continue; + + iter->aux_event = NULL; + put_event(event); + + /* + * If it's ACTIVE, schedule it out and put it into ERROR + * state so that we don't try to schedule it again. Note + * that perf_event_enable() will clear the ERROR status. + */ + event_sched_out(iter, cpuctx, ctx); + perf_event_set_state(event, PERF_EVENT_STATE_ERROR); + } +} + +static int perf_get_aux_event(struct perf_event *event, + struct perf_event *group_leader) +{ + /* + * Our group leader must be an aux event if we want to be + * an aux_output. This way, the aux event will precede its + * aux_output events in the group, and therefore will always + * schedule first. + */ + if (!group_leader) + return 0; + + if (!perf_aux_output_match(event, group_leader)) + return 0; + + if (!atomic_long_inc_not_zero(&group_leader->refcount)) + return 0; + + /* + * Link aux_outputs to their aux event; this is undone in + * perf_group_detach() by perf_put_aux_event(). When the + * group in torn down, the aux_output events loose their + * link to the aux_event and can't schedule any more. + */ + event->aux_event = group_leader; + + return 1; +} + static void perf_group_detach(struct perf_event *event) { struct perf_event *sibling, *tmp; @@ -1902,6 +1985,8 @@ static void perf_group_detach(struct perf_event *event) event->attach_state &= ~PERF_ATTACH_GROUP; + perf_put_aux_event(event); + /* * If this is a sibling, remove it from its group. */ @@ -10426,6 +10511,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, goto err_ns; } + if (event->attr.aux_output && + !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) { + err = -EOPNOTSUPP; + goto err_pmu; + } + err = exclusive_event_init(event); if (err) goto err_pmu; @@ -11082,6 +11173,8 @@ SYSCALL_DEFINE5(perf_event_open, } } + if (event->attr.aux_output && !perf_get_aux_event(event, group_leader)) + goto err_locked; /* * Must be under the same ctx::mutex as perf_install_in_context(), |