@@ -369,6 +369,22 @@ enum perf_event_read_format {
PERF_FORMAT_MAX = 1U << 5, /* non-ABI */
};
+enum {
+ PERF_AUX_ACTION_START_PAUSED = 1U << 0,
+ PERF_AUX_ACTION_PAUSE = 1U << 1,
+ PERF_AUX_ACTION_RESUME = 1U << 2,
+ PERF_AUX_ACTION_EMIT = 1U << 3,
+ PERF_AUX_ACTION_NR = 0x1f << 4,
+ PERF_AUX_ACTION_NO_IP = 1U << 9,
+ PERF_AUX_ACTION_PAUSE_ON_EVT = 1U << 10,
+ PERF_AUX_ACTION_RESUME_ON_EVT = 1U << 11,
+ PERF_AUX_ACTION_EMIT_ON_EVT = 1U << 12,
+ PERF_AUX_ACTION_NR_ON_EVT = 0x1f << 13,
+ PERF_AUX_ACTION_NO_IP_ON_EVT = 1U << 18,
+ PERF_AUX_ACTION_MASK = ~PERF_AUX_ACTION_START_PAUSED,
+ PERF_AUX_PAUSE_RESUME_MASK = PERF_AUX_ACTION_PAUSE | PERF_AUX_ACTION_RESUME,
+};
+
#define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */
#define PERF_ATTR_SIZE_VER1 72 /* add: config2 */
#define PERF_ATTR_SIZE_VER2 80 /* add: branch_sample_type */
@@ -515,10 +531,19 @@ struct perf_event_attr {
union {
__u32 aux_action;
struct {
- __u32 aux_start_paused : 1, /* start AUX area tracing paused */
- aux_pause : 1, /* on overflow, pause AUX area tracing */
- aux_resume : 1, /* on overflow, resume AUX area tracing */
- __reserved_3 : 29;
+ __u32 aux_start_paused : 1, /* start AUX area tracing paused */
+ aux_pause : 1, /* on overflow, pause AUX area tracing */
+ aux_resume : 1, /* on overflow, resume AUX area tracing */
+ aux_emit : 1, /* generate AUX records instead of events */
+ aux_nr : 5, /* AUX area tracing reference number */
+ aux_no_ip : 1, /* suppress IP in AUX records */
+ /* Following apply to event occurrence not overflows */
+ aux_pause_on_evt : 1, /* on event, pause AUX area tracing */
+ aux_resume_on_evt : 1, /* on event, resume AUX area tracing */
+ aux_emit_on_evt : 1, /* generate AUX records instead of events */
+ aux_nr_on_evt : 5, /* AUX area tracing reference number */
+ aux_no_ip_on_evt : 1, /* suppress IP in AUX records */
+ __reserved_3 : 13;
};
};
Hi Hardware traces, such as instruction traces, can produce a vast amount of trace data, so being able to reduce tracing to more specific circumstances can be useful. The ability to pause or resume tracing when another event happens, can do that. These patches add such a facilty and show how it would work for Intel Processor Trace. Maintainers of other AUX area tracing implementations are requested to consider if this is something they might employ and then whether or not the ABI would work for them. Note, thank you to James Clark (ARM) for evaluating the API for Coresight. Suzuki K Poulose (ARM) also responded positively to the RFC. Changes to perf tools are now (since V4) fleshed out. Please note, Intel® Architecture Instruction Set Extensions and Future Features Programming Reference March 2024 319433-052, currently: https://cdrdv2.intel.com/v1/dl/getContent/671368 introduces hardware pause / resume for Intel PT in a feature named Intel PT Trigger Tracing. For that more fields in perf_event_attr will be necessary. The main differences are: - it can be applied not just to overflows, but optionally to every event - a packet is emitted into the trace, optionally with IP information - no PMI - works with PMC and DR (breakpoint) events only Here are the proposed additions to perf_event_attr, please comment: Changes in V9: perf/x86/intel/pt: Fix sampling synchronization New patch perf/core: Add aux_pause, aux_resume, aux_start_paused Move aux_paused to struct hw_perf_event perf/x86/intel/pt: Add support for pause / resume Add more comments and barriers for resume_allowed and pause_allowed Always use WRITE_ONCE with resume_allowed Changes in V8: perf tools: Parse aux-action Fix clang warning: util/auxtrace.c:821:7: error: missing field 'aux_action' initializer [-Werror,-Wmissing-field-initializers] 821 | {NULL}, | ^ Changes in V7: Add Andi's Reviewed-by for patches 2-12 Re-base Changes in V6: perf/core: Add aux_pause, aux_resume, aux_start_paused Removed READ/WRITE_ONCE from __perf_event_aux_pause() Expanded comment about guarding against NMI Changes in V5: perf/core: Add aux_pause, aux_resume, aux_start_paused Added James' Ack perf/x86/intel: Do not enable large PEBS for events with aux actions or aux sampling New patch perf tools Added Ian's Ack Changes in V4: perf/core: Add aux_pause, aux_resume, aux_start_paused Rename aux_output_cfg -> aux_action Reorder aux_action bits from: aux_pause, aux_resume, aux_start_paused to: aux_start_paused, aux_pause, aux_resume Fix aux_action bits __u64 -> __u32 coresight: Have a stab at support for pause / resume Dropped perf tools All new patches Changes in RFC V3: coresight: Have a stab at support for pause / resume 'mode' -> 'flags' so it at least compiles Changes in RFC V2: Use ->stop() / ->start() instead of ->pause_resume() Move aux_start_paused bit into aux_output_cfg Tighten up when Intel PT pause / resume is allowed Add an example of how it might work for CoreSight Adrian Hunter (13): perf/x86/intel/pt: Fix sampling synchronization perf/core: Add aux_pause, aux_resume, aux_start_paused perf/x86/intel/pt: Add support for pause / resume perf/x86/intel: Do not enable large PEBS for events with aux actions or aux sampling perf tools: Enable evsel__is_aux_event() to work for ARM/ARM64 perf tools: Enable evsel__is_aux_event() to work for S390_CPUMSF perf tools: Add aux_start_paused, aux_pause and aux_resume perf tools: Add aux-action config term perf tools: Parse aux-action perf tools: Add missing_features for aux_start_paused, aux_pause, aux_resume perf intel-pt: Improve man page format perf intel-pt: Add documentation for pause / resume perf intel-pt: Add a test for pause / resume arch/x86/events/intel/core.c | 10 +- arch/x86/events/intel/pt.c | 82 +++- arch/x86/events/intel/pt.h | 4 + include/linux/perf_event.h | 18 + include/uapi/linux/perf_event.h | 11 +- kernel/events/core.c | 76 +++- kernel/events/internal.h | 1 + tools/include/uapi/linux/perf_event.h | 11 +- tools/perf/Documentation/perf-intel-pt.txt | 596 ++++++++++++++++++----------- tools/perf/Documentation/perf-record.txt | 4 + tools/perf/arch/arm/util/pmu.c | 3 + tools/perf/builtin-record.c | 4 +- tools/perf/tests/shell/test_intel_pt.sh | 28 ++ tools/perf/util/auxtrace.c | 67 +++- tools/perf/util/auxtrace.h | 6 +- tools/perf/util/evsel.c | 13 +- tools/perf/util/evsel.h | 1 + tools/perf/util/evsel_config.h | 1 + tools/perf/util/parse-events.c | 10 + tools/perf/util/parse-events.h | 1 + tools/perf/util/parse-events.l | 1 + tools/perf/util/perf_event_attr_fprintf.c | 3 + tools/perf/util/pmu.c | 7 +- 23 files changed, 712 insertions(+), 246 deletions(-) Regards Adrian