perf tools: Introduce 'P' modifier to request max precision

The 'P' will cause the event to get maximum possible detected precise
level.

Following record:
  $ perf record -e cycles:P ...

will detect maximum precise level for 'cycles' event and use it.

Commiter note:

Testing it:

  $ perf record -e cycles:P usleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.013 MB perf.data (9 samples) ]
  $ perf evlist
  cycles:P
  $ perf evlist -v
  cycles:P: size: 112, { sample_period, sample_freq }: 4000, sample_type:
  IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1,
  enable_on_exec: 1, task: 1, precise_ip: 2, sample_id_all: 1, mmap2: 1,
  comm_exec: 1
  $

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1444068369-20978-6-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-list.txt

@@ -30,6 +30,7 @@ counted. The following modifiers exist:
  G - guest counting (in KVM guests)
  H - host counting (not in KVM guests)
  p - precise level
+ P - use maximum detected precise level
  S - read sample value (PERF_SAMPLE_READ)
  D - pin the event to the PMU
 

tools/perf/util/evsel.c

@@ -882,6 +882,9 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts)
 		attr->clockid = opts->clockid;
 	}
 
+	if (evsel->precise_max)
+		perf_event_attr__set_max_precise_ip(attr);
+
 	/*
 	 * Apply event specific term settings,
 	 * it overloads any global configuration.

tools/perf/util/evsel.h

@@ -111,6 +111,7 @@ struct perf_evsel {
 	bool			system_wide;
 	bool			tracking;
 	bool			per_pkg;
+	bool			precise_max;
 	/* parse modifier helper */
 	int			exclude_GH;
 	int			nr_members;

tools/perf/util/parse-events.c

@@ -923,6 +923,7 @@ struct event_modifier {
 	int eG;
 	int eI;
 	int precise;
+	int precise_max;
 	int exclude_GH;
 	int sample_read;
 	int pinned;
@@ -938,6 +939,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
 	int eG = evsel ? evsel->attr.exclude_guest : 0;
 	int eI = evsel ? evsel->attr.exclude_idle : 0;
 	int precise = evsel ? evsel->attr.precise_ip : 0;
+	int precise_max = 0;
 	int sample_read = 0;
 	int pinned = evsel ? evsel->attr.pinned : 0;
 
@@ -974,6 +976,8 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
 			/* use of precise requires exclude_guest */
 			if (!exclude_GH)
 				eG = 1;
+		} else if (*str == 'P') {
+			precise_max = 1;
 		} else if (*str == 'S') {
 			sample_read = 1;
 		} else if (*str == 'D') {
@@ -1004,6 +1008,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
 	mod->eG = eG;
 	mod->eI = eI;
 	mod->precise = precise;
+	mod->precise_max = precise_max;
 	mod->exclude_GH = exclude_GH;
 	mod->sample_read = sample_read;
 	mod->pinned = pinned;
@@ -1020,7 +1025,7 @@ static int check_modifier(char *str)
 	char *p = str;
 
 	/* The sizeof includes 0 byte as well. */
-	if (strlen(str) > (sizeof("ukhGHpppSDI") - 1))
+	if (strlen(str) > (sizeof("ukhGHpppPSDI") - 1))
 		return -1;
 
 	while (*p) {
@@ -1059,6 +1064,7 @@ int parse_events__modifier_event(struct list_head *list, char *str, bool add)
 		evsel->attr.exclude_idle   = mod.eI;
 		evsel->exclude_GH          = mod.exclude_GH;
 		evsel->sample_read         = mod.sample_read;
+		evsel->precise_max         = mod.precise_max;
 
 		if (perf_evsel__is_group_leader(evsel))
 			evsel->attr.pinned = mod.pinned;

tools/perf/util/parse-events.l

@@ -122,7 +122,7 @@ num_raw_hex	[a-fA-F0-9]+
 name		[a-zA-Z_*?][a-zA-Z0-9_*?.]*
 name_minus	[a-zA-Z_*?][a-zA-Z0-9\-_*?.]*
 /* If you add a modifier you need to update check_modifier() */
-modifier_event	[ukhpGHSDI]+
+modifier_event	[ukhpPGHSDI]+
 modifier_bp	[rwx]{1,3}
 
 %%