perf/aux: Allow using AUX data in perf samples

AUX data can be used to annotate perf events such as performance counters or tracepoints/breakpoints by including it in sample records when PERF_SAMPLE_AUX flag is set. Such samples would be instrumental in debugging and profiling by providing, for example, a history of instruction flow leading up to the event's overflow. The implementation makes use of grouping an AUX event with all the events that wish to take samples of the AUX data, such that the former is the group leader. The samplees should also specify the desired size of the AUX sample via attr.aux_sample_size. AUX capable PMUs need to explicitly add support for sampling, because it relies on a new callback to take a snapshot of the buffer without touching the event states.

Alexander Shishkin committed 7 years ago

Commit a4faf001 parent deb0c3c5 files · +234 −5Browse files

Showing the changes to include/uapi/linux (1 of 5 files). Show all

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include/uapi/linux/perf_event.h+8−2

@@ -141,8 +141,9 @@ enum perf_event_sample_format { · 140 unmodified lines
141	141	PERF_SAMPLE_TRANSACTION = 1U << 17,
142	142	PERF_SAMPLE_REGS_INTR = 1U << 18,
143	143	PERF_SAMPLE_PHYS_ADDR = 1U << 19,
	144	+ PERF_SAMPLE_AUX = 1U << 20,
144	145
145		− PERF_SAMPLE_MAX = 1U << 20, /* non-ABI */
	146	+ PERF_SAMPLE_MAX = 1U << 21, /* non-ABI */
146	147
147	148	__PERF_SAMPLE_CALLCHAIN_EARLY = 1ULL << 63, /* non-ABI; internal use */
148	149	};
@@ -300,6 +301,7 @@ enum perf_event_read_format { · 151 unmodified lines
300	301	/* add: sample_stack_user */
301	302	#define PERF_ATTR_SIZE_VER4 104 /* add: sample_regs_intr */
302	303	#define PERF_ATTR_SIZE_VER5 112 /* add: aux_watermark */
	304	+#define PERF_ATTR_SIZE_VER6 120 /* add: aux_sample_size */
303	305
304	306	/*
305	307	* Hardware event_id to monitor via a performance monitoring event:
@@ -424,7 +426,9 @@ struct perf_event_attr { · 118 unmodified lines
424	426	*/
425	427	__u32 aux_watermark;
426	428	__u16 sample_max_stack;
427		− __u16 __reserved_2; /* align to __u64 */
	429	+ __u16 __reserved_2;
	430	+ __u32 aux_sample_size;
	431	+ __u32 __reserved_3;
428	432	};
429	433
430	434	/*
@@ -864,6 +868,8 @@ enum perf_event_type { · 433 unmodified lines
864	868	* { u64 abi; # enum perf_sample_regs_abi
865	869	* u64 regs[weight(mask)]; } && PERF_SAMPLE_REGS_INTR
866	870	* { u64 phys_addr;} && PERF_SAMPLE_PHYS_ADDR
	871	+ * { u64 size;
	872	+ * char data[size]; } && PERF_SAMPLE_AUX
867	873	* };
868	874	*/
869	875	PERF_RECORD_SAMPLE = 9,