Commit 60e2364e authored by Stephane Eranian's avatar Stephane Eranian Committed by Ingo Molnar
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perf: Add ability to sample machine state on interrupt 



Enable capture of interrupted machine state for each sample.

Registers to sample are passed per event in the sample_regs_intr bitmask.

To sample interrupt machine state, the PERF_SAMPLE_INTR_REGS must be passed in
sample_type.

The list of available registers is arch dependent and provided by asm/perf_regs.h

Registers are laid out as u64 in the order of the bit order of sample_intr_regs.

This patch also adds a new ABI version PERF_ATTR_SIZE_VER4 because we extend
the perf_event_attr struct with a new u64 field.

Reviewed-by: default avatarJiri Olsa <jolsa@redhat.com>
Signed-off-by: default avatarStephane Eranian <eranian@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: cebbert.lkml@gmail.com
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/1411559322-16548-2-git-send-email-eranian@google.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent af4bdcf6

include/linux/perf_event.h

+5 −2
Original line number Diff line number Diff line
@@ -79,7 +79,7 @@ struct perf_branch_stack { 
	struct perf_branch_entry	entries[0];

};



struct perf_regs_user {

struct perf_regs {

	__u64		abi;

	struct pt_regs	*regs;

};
@@ -600,7 +600,8 @@ struct perf_sample_data { 
	struct perf_callchain_entry	*callchain;

	struct perf_raw_record		*raw;

	struct perf_branch_stack	*br_stack;

	struct perf_regs_user		regs_user;

	struct perf_regs		regs_user;

	struct perf_regs		regs_intr;

	u64				stack_user_size;

	u64				weight;

	/*
@@ -630,6 +631,8 @@ static inline void perf_sample_data_init(struct perf_sample_data *data, 
	data->weight = 0;

	data->data_src.val = PERF_MEM_NA;

	data->txn = 0;

	data->regs_intr.abi = PERF_SAMPLE_REGS_ABI_NONE;

	data->regs_intr.regs = NULL;

}



extern void perf_output_sample(struct perf_output_handle *handle,

include/uapi/linux/perf_event.h

+14 −1
Original line number Diff line number Diff line
@@ -137,8 +137,9 @@ enum perf_event_sample_format { 
	PERF_SAMPLE_DATA_SRC			= 1U << 15,

	PERF_SAMPLE_IDENTIFIER			= 1U << 16,

	PERF_SAMPLE_TRANSACTION			= 1U << 17,

	PERF_SAMPLE_REGS_INTR			= 1U << 18,



	PERF_SAMPLE_MAX = 1U << 18,		/* non-ABI */

	PERF_SAMPLE_MAX = 1U << 19,		/* non-ABI */

};



/*
@@ -238,6 +239,7 @@ enum perf_event_read_format { 
#define PERF_ATTR_SIZE_VER2	80	/* add: branch_sample_type */

#define PERF_ATTR_SIZE_VER3	96	/* add: sample_regs_user */

					/* add: sample_stack_user */

#define PERF_ATTR_SIZE_VER4	104	/* add: sample_regs_intr */



/*

 * Hardware event_id to monitor via a performance monitoring event:
@@ -334,6 +336,15 @@ struct perf_event_attr { 


	/* Align to u64. */

	__u32	__reserved_2;

	/*

	 * Defines set of regs to dump for each sample

	 * state captured on:

	 *  - precise = 0: PMU interrupt

	 *  - precise > 0: sampled instruction

	 *

	 * See asm/perf_regs.h for details.

	 */

	__u64	sample_regs_intr;

};



#define perf_flags(attr)	(*(&(attr)->read_format + 1))
@@ -686,6 +697,8 @@ enum perf_event_type { 
	 *	{ u64			weight;   } && PERF_SAMPLE_WEIGHT

	 *	{ u64			data_src; } && PERF_SAMPLE_DATA_SRC

	 *	{ u64			transaction; } && PERF_SAMPLE_TRANSACTION

	 *	{ u64			abi; # enum perf_sample_regs_abi

	 *	  u64			regs[weight(mask)]; } && PERF_SAMPLE_REGS_INTR

	 * };

	 */

	PERF_RECORD_SAMPLE			= 9,

kernel/events/core.c

+44 −2
Original line number Diff line number Diff line
@@ -4460,7 +4460,7 @@ perf_output_sample_regs(struct perf_output_handle *handle, 
	}

}



static void perf_sample_regs_user(struct perf_regs_user *regs_user,

static void perf_sample_regs_user(struct perf_regs *regs_user,

				  struct pt_regs *regs)

{

	if (!user_mode(regs)) {
@@ -4476,6 +4476,14 @@ static void perf_sample_regs_user(struct perf_regs_user *regs_user, 
	}

}



static void perf_sample_regs_intr(struct perf_regs *regs_intr,

				  struct pt_regs *regs)

{

	regs_intr->regs = regs;

	regs_intr->abi  = perf_reg_abi(current);

}





/*

 * Get remaining task size from user stack pointer.

 *
@@ -4857,6 +4865,23 @@ void perf_output_sample(struct perf_output_handle *handle, 
	if (sample_type & PERF_SAMPLE_TRANSACTION)

		perf_output_put(handle, data->txn);



	if (sample_type & PERF_SAMPLE_REGS_INTR) {

		u64 abi = data->regs_intr.abi;

		/*

		 * If there are no regs to dump, notice it through

		 * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).

		 */

		perf_output_put(handle, abi);



		if (abi) {

			u64 mask = event->attr.sample_regs_intr;



			perf_output_sample_regs(handle,

						data->regs_intr.regs,

						mask);

		}

	}



	if (!event->attr.watermark) {

		int wakeup_events = event->attr.wakeup_events;
@@ -4943,7 +4968,7 @@ void perf_prepare_sample(struct perf_event_header *header, 
		 * in case new sample type is added, because we could eat

		 * up the rest of the sample size.

		 */

		struct perf_regs_user *uregs = &data->regs_user;

		struct perf_regs *uregs = &data->regs_user;

		u16 stack_size = event->attr.sample_stack_user;

		u16 size = sizeof(u64);
@@ -4964,6 +4989,21 @@ void perf_prepare_sample(struct perf_event_header *header, 
		data->stack_user_size = stack_size;

		header->size += size;

	}



	if (sample_type & PERF_SAMPLE_REGS_INTR) {

		/* regs dump ABI info */

		int size = sizeof(u64);



		perf_sample_regs_intr(&data->regs_intr, regs);



		if (data->regs_intr.regs) {

			u64 mask = event->attr.sample_regs_intr;



			size += hweight64(mask) * sizeof(u64);

		}



		header->size += size;

	}

}



static void perf_event_output(struct perf_event *event,
@@ -7151,6 +7191,8 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr, 
			ret = -EINVAL;

	}



	if (attr->sample_type & PERF_SAMPLE_REGS_INTR)

		ret = perf_reg_validate(attr->sample_regs_intr);

out:

	return ret;

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