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author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2019-10-25 16:08:35 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2019-11-13 11:06:16 +0100 |
commit | 25e8920b301c133aeaa9f57d81295bf4ac78e17b (patch) | |
tree | 46f7dea6e4e34e272035bf8a20081aa58ce6cde0 /arch/x86/events/intel | |
parent | perf/x86/intel/pt: Factor out pt_config_start() (diff) | |
download | linux-25e8920b301c133aeaa9f57d81295bf4ac78e17b.tar.xz linux-25e8920b301c133aeaa9f57d81295bf4ac78e17b.zip |
perf/x86/intel/pt: Add sampling support
Add AUX sampling support to the PT PMU: implement an NMI-safe callback
that takes a snapshot of the buffer without touching the event states.
This is done for PT events that don't use PMIs, that is, snapshot mode
(RO mapping of the AUX area).
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: adrian.hunter@intel.com
Cc: mathieu.poirier@linaro.org
Link: https://lkml.kernel.org/r/20191025140835.53665-4-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/events/intel')
-rw-r--r-- | arch/x86/events/intel/pt.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index 170f3b402274..2f20d5a333c1 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -1208,6 +1208,13 @@ pt_buffer_setup_aux(struct perf_event *event, void **pages, if (!nr_pages) return NULL; + /* + * Only support AUX sampling in snapshot mode, where we don't + * generate NMIs. + */ + if (event->attr.aux_sample_size && !snapshot) + return NULL; + if (cpu == -1) cpu = raw_smp_processor_id(); node = cpu_to_node(cpu); @@ -1506,6 +1513,52 @@ static void pt_event_stop(struct perf_event *event, int mode) } } +static long pt_event_snapshot_aux(struct perf_event *event, + struct perf_output_handle *handle, + unsigned long size) +{ + struct pt *pt = this_cpu_ptr(&pt_ctx); + struct pt_buffer *buf = perf_get_aux(&pt->handle); + unsigned long from = 0, to; + long ret; + + if (WARN_ON_ONCE(!buf)) + return 0; + + /* + * Sampling is only allowed on snapshot events; + * see pt_buffer_setup_aux(). + */ + if (WARN_ON_ONCE(!buf->snapshot)) + return 0; + + /* + * Here, handle_nmi tells us if the tracing is on + */ + if (READ_ONCE(pt->handle_nmi)) + pt_config_stop(event); + + pt_read_offset(buf); + pt_update_head(pt); + + to = local_read(&buf->data_size); + if (to < size) + from = buf->nr_pages << PAGE_SHIFT; + from += to - size; + + ret = perf_output_copy_aux(&pt->handle, handle, from, to); + + /* + * If the tracing was on when we turned up, restart it. + * Compiler barrier not needed as we couldn't have been + * preempted by anything that touches pt->handle_nmi. + */ + if (pt->handle_nmi) + pt_config_start(event); + + return ret; +} + static void pt_event_del(struct perf_event *event, int mode) { pt_event_stop(event, PERF_EF_UPDATE); @@ -1625,6 +1678,7 @@ static __init int pt_init(void) pt_pmu.pmu.del = pt_event_del; pt_pmu.pmu.start = pt_event_start; pt_pmu.pmu.stop = pt_event_stop; + pt_pmu.pmu.snapshot_aux = pt_event_snapshot_aux; pt_pmu.pmu.read = pt_event_read; pt_pmu.pmu.setup_aux = pt_buffer_setup_aux; pt_pmu.pmu.free_aux = pt_buffer_free_aux; |