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Commit 1b290d67 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
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perf tools: Add support for breakpoint events in perf tools 



Add the breakpoint events support with this new sysnopsis:

  mem:addr[:access]

Where addr is a raw addr value in the kernel and access can be
either [r][w][x]

Example to profile tasklist_lock:

	$ grep tasklist_lock /proc/kallsyms
	ffffffff8189c000 D tasklist_lock

	$ perf record -e mem:0xffffffff8189c000:rw -a -f -c 1
	$ perf report

	# Samples: 62
	#
	# Overhead          Command  Shared Object  Symbol
	# ........  ...............  .............  ......
	#
	    29.03%          swapper  [kernel]       [k] _raw_read_trylock
	    29.03%          swapper  [kernel]       [k] _raw_read_unlock
	    19.35%             init  [kernel]       [k] _raw_read_trylock
	    19.35%             init  [kernel]       [k] _raw_read_unlock
	     1.61%         events/0  [kernel]       [k] _raw_read_trylock
	     1.61%         events/0  [kernel]       [k] _raw_read_unlock

Coming soon:

 - Support for symbols in the event definition.

 - Default period to 1 for breakpoint events because these are
   not high frequency events. The same thing is needed for trace
   events.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1258987355-8751-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
parent f5ffe02e

tools/perf/Documentation/perf-record.txt

+12 −4
Original line number Diff line number Diff line
@@ -26,11 +26,19 @@ OPTIONS 


-e::

--event=::

	Select the PMU event. Selection can be a symbolic event name

	(use 'perf list' to list all events) or a raw PMU

	event (eventsel+umask) in the form of rNNN where NNN is a

	Select the PMU event. Selection can be:



        - a symbolic event name	(use 'perf list' to list all events)



        - a raw PMU event (eventsel+umask) in the form of rNNN where NNN is a

	  hexadecimal event descriptor.



        - a hardware breakpoint event in the form of '\mem:addr[:access]'

          where addr is the address in memory you want to break in.

          Access is the memory access type (read, write, execute) it can

          be passed as follows: '\mem:addr[:[r][w][x]]'.

          If you want to profile read-write accesses in 0x1000, just set

          'mem:0x1000:rw'.

-a::

        System-wide collection.

tools/perf/util/parse-events.c

+83 −1
Original line number Diff line number Diff line 


#include "../../../include/linux/hw_breakpoint.h"

#include "util.h"

#include "../perf.h"

#include "parse-options.h"
@@ -540,6 +540,81 @@ static enum event_result parse_tracepoint_event(const char **strp, 
						     attr, strp);

}



static enum event_result

parse_breakpoint_type(const char *type, const char **strp,

		      struct perf_event_attr *attr)

{

	int i;



	for (i = 0; i < 3; i++) {

		if (!type[i])

			break;



		switch (type[i]) {

		case 'r':

			attr->bp_type |= HW_BREAKPOINT_R;

			break;

		case 'w':

			attr->bp_type |= HW_BREAKPOINT_W;

			break;

		case 'x':

			attr->bp_type |= HW_BREAKPOINT_X;

			break;

		default:

			return EVT_FAILED;

		}

	}

	if (!attr->bp_type) /* Default */

		attr->bp_type = HW_BREAKPOINT_R | HW_BREAKPOINT_W;



	*strp = type + i;



	return EVT_HANDLED;

}



static enum event_result

parse_breakpoint_event(const char **strp, struct perf_event_attr *attr)

{

	const char *target;

	const char *type;

	char *endaddr;

	u64 addr;

	enum event_result err;



	target = strchr(*strp, ':');

	if (!target)

		return EVT_FAILED;



	if (strncmp(*strp, "mem", target - *strp) != 0)

		return EVT_FAILED;



	target++;



	addr = strtoull(target, &endaddr, 0);

	if (target == endaddr)

		return EVT_FAILED;



	attr->bp_addr = addr;

	*strp = endaddr;



	type = strchr(target, ':');



	/* If no type is defined, just rw as default */

	if (!type) {

		attr->bp_type = HW_BREAKPOINT_R | HW_BREAKPOINT_W;

	} else {

		err = parse_breakpoint_type(++type, strp, attr);

		if (err == EVT_FAILED)

			return EVT_FAILED;

	}



	/* We should find a nice way to override the access type */

	attr->bp_len = HW_BREAKPOINT_LEN_4;

	attr->type = PERF_TYPE_BREAKPOINT;



	return EVT_HANDLED;

}



static int check_events(const char *str, unsigned int i)

{

	int n;
@@ -673,6 +748,10 @@ parse_event_symbols(const char **str, struct perf_event_attr *attr) 
	if (ret != EVT_FAILED)

		goto modifier;



	ret = parse_breakpoint_event(str, attr);

	if (ret != EVT_FAILED)

		goto modifier;



	fprintf(stderr, "invalid or unsupported event: '%s'\n", *str);

	fprintf(stderr, "Run 'perf list' for a list of valid events\n");

	return EVT_FAILED;
@@ -859,6 +938,9 @@ void print_events(void) 
		"rNNN");

	printf("\n");



	printf("  %-42s [hardware breakpoint]\n", "mem:<addr>[:access]");

	printf("\n");



	print_tracepoint_events();



	exit(129);