perf intel-pt: Add support for PERF_RECORD_SWITCH
Add support for selecting and processing PERF_RECORD_SWITCH events for use by Intel PT. If they are available, they will be used in preference to sched_switch events. This enables an unprivileged user to trace multi-threaded or multi-process workloads with any level of perf_event_paranoid. However it depends on kernel support for PERF_RECORD_SWITCH. Without this patch, tracing a multi-threaded workload will decode without error but all the data will be attributed to the main thread. Without this patch, tracing a multi-process workload will result in decoder errors because the decoder will not know which executable is executing. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lkml.kernel.org/r/1439458857-30636-3-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter
Arnaldo Carvalho de Melo
parent
1b29ac59b1
commit
86c2786994
2 changed files with 151 additions and 33 deletions
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@ -624,13 +624,49 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
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* threads.
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*/
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if (have_timing_info && !cpu_map__empty(cpus)) {
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err = intel_pt_track_switches(evlist);
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if (err == -EPERM)
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pr_debug2("Unable to select sched:sched_switch\n");
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else if (err)
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return err;
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else
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ptr->have_sched_switch = 1;
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if (perf_can_record_switch_events()) {
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bool cpu_wide = !target__none(&opts->target) &&
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!target__has_task(&opts->target);
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if (!cpu_wide && perf_can_record_cpu_wide()) {
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struct perf_evsel *switch_evsel;
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err = parse_events(evlist, "dummy:u", NULL);
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if (err)
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return err;
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switch_evsel = perf_evlist__last(evlist);
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switch_evsel->attr.freq = 0;
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switch_evsel->attr.sample_period = 1;
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switch_evsel->attr.context_switch = 1;
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switch_evsel->system_wide = true;
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switch_evsel->no_aux_samples = true;
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switch_evsel->immediate = true;
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perf_evsel__set_sample_bit(switch_evsel, TID);
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perf_evsel__set_sample_bit(switch_evsel, TIME);
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perf_evsel__set_sample_bit(switch_evsel, CPU);
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opts->record_switch_events = false;
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ptr->have_sched_switch = 3;
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} else {
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opts->record_switch_events = true;
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if (cpu_wide)
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ptr->have_sched_switch = 3;
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else
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ptr->have_sched_switch = 2;
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}
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} else {
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err = intel_pt_track_switches(evlist);
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if (err == -EPERM)
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pr_debug2("Unable to select sched:sched_switch\n");
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else if (err)
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return err;
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else
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ptr->have_sched_switch = 1;
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}
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}
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if (intel_pt_evsel) {
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@ -663,8 +699,11 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
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tracking_evsel->attr.sample_period = 1;
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/* In per-cpu case, always need the time of mmap events etc */
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if (!cpu_map__empty(cpus))
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if (!cpu_map__empty(cpus)) {
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perf_evsel__set_sample_bit(tracking_evsel, TIME);
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/* And the CPU for switch events */
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perf_evsel__set_sample_bit(tracking_evsel, CPU);
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}
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}
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/*
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@ -1145,11 +1145,13 @@ static int intel_pt_sample(struct intel_pt_queue *ptq)
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return 0;
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}
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static u64 intel_pt_switch_ip(struct machine *machine, u64 *ptss_ip)
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static u64 intel_pt_switch_ip(struct intel_pt *pt, u64 *ptss_ip)
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{
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struct machine *machine = pt->machine;
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struct map *map;
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struct symbol *sym, *start;
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u64 ip, switch_ip = 0;
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const char *ptss;
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if (ptss_ip)
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*ptss_ip = 0;
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@ -1177,8 +1179,13 @@ static u64 intel_pt_switch_ip(struct machine *machine, u64 *ptss_ip)
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if (!switch_ip || !ptss_ip)
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return 0;
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if (pt->have_sched_switch == 1)
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ptss = "perf_trace_sched_switch";
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else
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ptss = "__perf_event_task_sched_out";
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for (sym = start; sym; sym = dso__next_symbol(sym)) {
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if (!strcmp(sym->name, "perf_trace_sched_switch")) {
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if (!strcmp(sym->name, ptss)) {
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ip = map->unmap_ip(map, sym->start);
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if (ip >= map->start && ip < map->end) {
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*ptss_ip = ip;
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@ -1198,11 +1205,11 @@ static int intel_pt_run_decoder(struct intel_pt_queue *ptq, u64 *timestamp)
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if (!pt->kernel_start) {
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pt->kernel_start = machine__kernel_start(pt->machine);
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if (pt->per_cpu_mmaps && pt->have_sched_switch &&
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if (pt->per_cpu_mmaps &&
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(pt->have_sched_switch == 1 || pt->have_sched_switch == 3) &&
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!pt->timeless_decoding && intel_pt_tracing_kernel(pt) &&
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!pt->sampling_mode) {
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pt->switch_ip = intel_pt_switch_ip(pt->machine,
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&pt->ptss_ip);
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pt->switch_ip = intel_pt_switch_ip(pt, &pt->ptss_ip);
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if (pt->switch_ip) {
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intel_pt_log("switch_ip: %"PRIx64" ptss_ip: %"PRIx64"\n",
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pt->switch_ip, pt->ptss_ip);
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@ -1387,31 +1394,18 @@ static struct intel_pt_queue *intel_pt_cpu_to_ptq(struct intel_pt *pt, int cpu)
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return NULL;
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}
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static int intel_pt_process_switch(struct intel_pt *pt,
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struct perf_sample *sample)
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static int intel_pt_sync_switch(struct intel_pt *pt, int cpu, pid_t tid,
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u64 timestamp)
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{
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struct intel_pt_queue *ptq;
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struct perf_evsel *evsel;
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pid_t tid;
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int cpu, err;
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evsel = perf_evlist__id2evsel(pt->session->evlist, sample->id);
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if (evsel != pt->switch_evsel)
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return 0;
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tid = perf_evsel__intval(evsel, sample, "next_pid");
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cpu = sample->cpu;
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intel_pt_log("sched_switch: cpu %d tid %d time %"PRIu64" tsc %#"PRIx64"\n",
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cpu, tid, sample->time, perf_time_to_tsc(sample->time,
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&pt->tc));
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int err;
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if (!pt->sync_switch)
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goto out;
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return 1;
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ptq = intel_pt_cpu_to_ptq(pt, cpu);
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if (!ptq)
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goto out;
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return 1;
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switch (ptq->switch_state) {
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case INTEL_PT_SS_NOT_TRACING:
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@ -1424,7 +1418,7 @@ static int intel_pt_process_switch(struct intel_pt *pt,
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return 0;
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case INTEL_PT_SS_EXPECTING_SWITCH_EVENT:
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if (!ptq->on_heap) {
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ptq->timestamp = perf_time_to_tsc(sample->time,
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ptq->timestamp = perf_time_to_tsc(timestamp,
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&pt->tc);
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err = auxtrace_heap__add(&pt->heap, ptq->queue_nr,
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ptq->timestamp);
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@ -1441,10 +1435,76 @@ static int intel_pt_process_switch(struct intel_pt *pt,
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default:
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break;
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}
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out:
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return 1;
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}
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static int intel_pt_process_switch(struct intel_pt *pt,
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struct perf_sample *sample)
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{
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struct perf_evsel *evsel;
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pid_t tid;
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int cpu, ret;
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evsel = perf_evlist__id2evsel(pt->session->evlist, sample->id);
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if (evsel != pt->switch_evsel)
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return 0;
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tid = perf_evsel__intval(evsel, sample, "next_pid");
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cpu = sample->cpu;
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intel_pt_log("sched_switch: cpu %d tid %d time %"PRIu64" tsc %#"PRIx64"\n",
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cpu, tid, sample->time, perf_time_to_tsc(sample->time,
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&pt->tc));
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ret = intel_pt_sync_switch(pt, cpu, tid, sample->time);
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if (ret <= 0)
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return ret;
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return machine__set_current_tid(pt->machine, cpu, -1, tid);
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}
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static int intel_pt_context_switch(struct intel_pt *pt, union perf_event *event,
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struct perf_sample *sample)
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{
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bool out = event->header.misc & PERF_RECORD_MISC_SWITCH_OUT;
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pid_t pid, tid;
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int cpu, ret;
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cpu = sample->cpu;
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if (pt->have_sched_switch == 3) {
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if (!out)
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return 0;
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if (event->header.type != PERF_RECORD_SWITCH_CPU_WIDE) {
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pr_err("Expecting CPU-wide context switch event\n");
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return -EINVAL;
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}
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pid = event->context_switch.next_prev_pid;
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tid = event->context_switch.next_prev_tid;
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} else {
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if (out)
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return 0;
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pid = sample->pid;
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tid = sample->tid;
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}
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if (tid == -1) {
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pr_err("context_switch event has no tid\n");
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return -EINVAL;
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}
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intel_pt_log("context_switch: cpu %d pid %d tid %d time %"PRIu64" tsc %#"PRIx64"\n",
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cpu, pid, tid, sample->time, perf_time_to_tsc(sample->time,
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&pt->tc));
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ret = intel_pt_sync_switch(pt, cpu, tid, sample->time);
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if (ret <= 0)
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return ret;
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return machine__set_current_tid(pt->machine, cpu, pid, tid);
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}
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static int intel_pt_process_itrace_start(struct intel_pt *pt,
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union perf_event *event,
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struct perf_sample *sample)
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@ -1515,6 +1575,9 @@ static int intel_pt_process_event(struct perf_session *session,
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err = intel_pt_process_switch(pt, sample);
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else if (event->header.type == PERF_RECORD_ITRACE_START)
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err = intel_pt_process_itrace_start(pt, event, sample);
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else if (event->header.type == PERF_RECORD_SWITCH ||
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event->header.type == PERF_RECORD_SWITCH_CPU_WIDE)
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err = intel_pt_context_switch(pt, event, sample);
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intel_pt_log("event %s (%u): cpu %d time %"PRIu64" tsc %#"PRIx64"\n",
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perf_event__name(event->header.type), event->header.type,
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@ -1777,6 +1840,18 @@ static struct perf_evsel *intel_pt_find_sched_switch(struct perf_evlist *evlist)
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return NULL;
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}
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static bool intel_pt_find_switch(struct perf_evlist *evlist)
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{
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struct perf_evsel *evsel;
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evlist__for_each(evlist, evsel) {
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if (evsel->attr.context_switch)
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return true;
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}
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return false;
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}
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static const char * const intel_pt_info_fmts[] = {
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[INTEL_PT_PMU_TYPE] = " PMU Type %"PRId64"\n",
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[INTEL_PT_TIME_SHIFT] = " Time Shift %"PRIu64"\n",
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@ -1888,6 +1963,10 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
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pr_err("%s: missing sched_switch event\n", __func__);
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goto err_delete_thread;
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}
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} else if (pt->have_sched_switch == 2 &&
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!intel_pt_find_switch(session->evlist)) {
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pr_err("%s: missing context_switch attribute flag\n", __func__);
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goto err_delete_thread;
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}
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if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
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