diff options
Diffstat (limited to 'drivers/hwtracing/coresight/coresight-etm-perf.c')
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-etm-perf.c | 119 |
1 files changed, 106 insertions, 13 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index c1bec2ad3911..6f398377fec9 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -24,7 +24,26 @@ static struct pmu etm_pmu; static bool etm_perf_up; -static DEFINE_PER_CPU(struct perf_output_handle, ctx_handle); +/* + * An ETM context for a running event includes the perf aux handle + * and aux_data. For ETM, the aux_data (etm_event_data), consists of + * the trace path and the sink configuration. The event data is accessible + * via perf_get_aux(handle). However, a sink could "end" a perf output + * handle via the IRQ handler. And if the "sink" encounters a failure + * to "begin" another session (e.g due to lack of space in the buffer), + * the handle will be cleared. Thus, the event_data may not be accessible + * from the handle when we get to the etm_event_stop(), which is required + * for stopping the trace path. The event_data is guaranteed to stay alive + * until "free_aux()", which cannot happen as long as the event is active on + * the ETM. Thus the event_data for the session must be part of the ETM context + * to make sure we can disable the trace path. + */ +struct etm_ctxt { + struct perf_output_handle handle; + struct etm_event_data *event_data; +}; + +static DEFINE_PER_CPU(struct etm_ctxt, etm_ctxt); static DEFINE_PER_CPU(struct coresight_device *, csdev_src); /* @@ -232,6 +251,25 @@ static void etm_free_aux(void *data) schedule_work(&event_data->work); } +/* + * Check if two given sinks are compatible with each other, + * so that they can use the same sink buffers, when an event + * moves around. + */ +static bool sinks_compatible(struct coresight_device *a, + struct coresight_device *b) +{ + if (!a || !b) + return false; + /* + * If the sinks are of the same subtype and driven + * by the same driver, we can use the same buffer + * on these sinks. + */ + return (a->subtype.sink_subtype == b->subtype.sink_subtype) && + (sink_ops(a) == sink_ops(b)); +} + static void *etm_setup_aux(struct perf_event *event, void **pages, int nr_pages, bool overwrite) { @@ -239,6 +277,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, int cpu = event->cpu; cpumask_t *mask; struct coresight_device *sink = NULL; + struct coresight_device *user_sink = NULL, *last_sink = NULL; struct etm_event_data *event_data = NULL; event_data = alloc_event_data(cpu); @@ -249,7 +288,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, /* First get the selected sink from user space. */ if (event->attr.config2) { id = (u32)event->attr.config2; - sink = coresight_get_sink_by_id(id); + sink = user_sink = coresight_get_sink_by_id(id); } mask = &event_data->mask; @@ -277,14 +316,33 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, } /* - * No sink provided - look for a default sink for one of the - * devices. At present we only support topology where all CPUs - * use the same sink [N:1], so only need to find one sink. The - * coresight_build_path later will remove any CPU that does not - * attach to the sink, or if we have not found a sink. + * No sink provided - look for a default sink for all the ETMs, + * where this event can be scheduled. + * We allocate the sink specific buffers only once for this + * event. If the ETMs have different default sink devices, we + * can only use a single "type" of sink as the event can carry + * only one sink specific buffer. Thus we have to make sure + * that the sinks are of the same type and driven by the same + * driver, as the one we allocate the buffer for. As such + * we choose the first sink and check if the remaining ETMs + * have a compatible default sink. We don't trace on a CPU + * if the sink is not compatible. */ - if (!sink) + if (!user_sink) { + /* Find the default sink for this ETM */ sink = coresight_find_default_sink(csdev); + if (!sink) { + cpumask_clear_cpu(cpu, mask); + continue; + } + + /* Check if this sink compatible with the last sink */ + if (last_sink && !sinks_compatible(last_sink, sink)) { + cpumask_clear_cpu(cpu, mask); + continue; + } + last_sink = sink; + } /* * Building a path doesn't enable it, it simply builds a @@ -312,7 +370,12 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, if (!sink_ops(sink)->alloc_buffer || !sink_ops(sink)->free_buffer) goto err; - /* Allocate the sink buffer for this session */ + /* + * Allocate the sink buffer for this session. All the sinks + * where this event can be scheduled are ensured to be of the + * same type. Thus the same sink configuration is used by the + * sinks. + */ event_data->snk_config = sink_ops(sink)->alloc_buffer(sink, event, pages, nr_pages, overwrite); @@ -332,13 +395,18 @@ static void etm_event_start(struct perf_event *event, int flags) { int cpu = smp_processor_id(); struct etm_event_data *event_data; - struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle); + struct etm_ctxt *ctxt = this_cpu_ptr(&etm_ctxt); + struct perf_output_handle *handle = &ctxt->handle; struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu); struct list_head *path; if (!csdev) goto fail; + /* Have we messed up our tracking ? */ + if (WARN_ON(ctxt->event_data)) + goto fail; + /* * Deal with the ring buffer API and get a handle on the * session's information. @@ -374,6 +442,8 @@ static void etm_event_start(struct perf_event *event, int flags) if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF)) goto fail_disable_path; + /* Save the event_data for this ETM */ + ctxt->event_data = event_data; out: return; @@ -392,13 +462,30 @@ static void etm_event_stop(struct perf_event *event, int mode) int cpu = smp_processor_id(); unsigned long size; struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu); - struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle); - struct etm_event_data *event_data = perf_get_aux(handle); + struct etm_ctxt *ctxt = this_cpu_ptr(&etm_ctxt); + struct perf_output_handle *handle = &ctxt->handle; + struct etm_event_data *event_data; struct list_head *path; + /* + * If we still have access to the event_data via handle, + * confirm that we haven't messed up the tracking. + */ + if (handle->event && + WARN_ON(perf_get_aux(handle) != ctxt->event_data)) + return; + + event_data = ctxt->event_data; + /* Clear the event_data as this ETM is stopping the trace. */ + ctxt->event_data = NULL; + if (event->hw.state == PERF_HES_STOPPED) return; + /* We must have a valid event_data for a running event */ + if (WARN_ON(!event_data)) + return; + if (!csdev) return; @@ -416,7 +503,13 @@ static void etm_event_stop(struct perf_event *event, int mode) /* tell the core */ event->hw.state = PERF_HES_STOPPED; - if (mode & PERF_EF_UPDATE) { + /* + * If the handle is not bound to an event anymore + * (e.g, the sink driver was unable to restart the + * handle due to lack of buffer space), we don't + * have to do anything here. + */ + if (handle->event && (mode & PERF_EF_UPDATE)) { if (WARN_ON_ONCE(handle->event != event)) return; |