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: Frederic 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: Ingo 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>

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 0ff23de..fc46c0b 100644 (file)
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -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
-       hexadecimal event descriptor.
+       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.
 

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 0faf4f2..0700274 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1,4 +1,4 @@
-
+#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);