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>

2 files changed, 95 insertions, 5 deletions

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 0ff23de9e453..fc46c0b40f6e 100644
--- 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 0faf4f2bb5ca..070027469270 100644
--- 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);