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Subject[PATCH 2/2] perf_counter: add support to the 'perf' tool for tracepoints
Add support to 'perf list' and 'perf stat' for kernel tracepoints. The
implementation creates a 'for_each_subsystem' and 'for_each_event' for
easy iteration over the tracepoints. The debugfs filesystem must be mounted
at '/sys/kernel/debug'. We can add an optional search path in the future.


Signed-off-by: Jason Baron <jbaron@redhat.com>

---
tools/perf/util/parse-events.c | 195 +++++++++++++++++++++++++++++++++++++++-
tools/perf/util/util.h | 2 +
2 files changed, 196 insertions(+), 1 deletions(-)
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 5184959..d454eac 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -12,6 +12,8 @@ int nr_counters;

struct perf_counter_attr attrs[MAX_COUNTERS];

+static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";
+
struct event_symbol {
u8 type;
u64 config;
@@ -110,6 +112,86 @@ static unsigned long hw_cache_stat[C(MAX)] = {
[C(BPU)] = (CACHE_READ),
};

+#define for_each_subsystem(sys_dir, sys_dirent, sys_next, file, st) \
+ while (!readdir_r(sys_dir, &sys_dirent, &sys_next) && sys_next) \
+ if (sprintf(file, "%s/%s", default_debugfs_path, sys_dirent.d_name) && \
+ (stat(file, &st) == 0) && (S_ISDIR(st.st_mode)) && \
+ (strcmp(sys_dirent.d_name, ".") != 0) && \
+ (strcmp(sys_dirent.d_name, "..") != 0))
+
+#define for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next, file, st) \
+ while (!readdir_r(evt_dir, &evt_dirent, &evt_next) && evt_next) \
+ if (sprintf(file, "%s/%s/%s", default_debugfs_path, sys_dirent.d_name, \
+ evt_dirent.d_name) && \
+ (stat(file, &st) == 0) && (S_ISDIR(st.st_mode)) && \
+ (strcmp(evt_dirent.d_name, ".") != 0) && \
+ (strcmp(evt_dirent.d_name, "..") != 0))
+
+#define MAX_PATH_LENGTH (strlen(default_debugfs_path) + 3 + \
+ (3 * (strlen(sys_dirent.d_name))) + 1)
+#define MAX_EVENT_LENGTH 30
+
+static int valid_debugfs_mount(void)
+{
+ struct statfs st_fs;
+
+ if (statfs(default_debugfs_path, &st_fs) < 0)
+ return -ENOENT;
+ else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
+ return -ENOENT;
+ return 0;
+}
+
+static char *tracepoint_id_to_name(u64 config)
+{
+ static char tracepoint_name[2 * MAX_EVENT_LENGTH];
+ DIR *sys_dir, *evt_dir;
+ struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+ struct stat st;
+ char id_buf[4];
+ int fd;
+ long long id;
+ char evt_path[MAX_PATH_LENGTH];
+
+ if (valid_debugfs_mount())
+ return "unkown";
+
+ sys_dir = opendir(default_debugfs_path);
+ if (!sys_dir)
+ goto cleanup;
+ for_each_subsystem(sys_dir, sys_dirent, sys_next, evt_path, st) {
+ evt_dir = opendir(evt_path);
+ if (!evt_dir)
+ goto cleanup;
+ for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
+ evt_path, st) {
+ sprintf(evt_path, "%s/%s/%s/id", default_debugfs_path,
+ sys_dirent.d_name, evt_dirent.d_name);
+ fd = open(evt_path, O_RDONLY);
+ if (fd < 0)
+ continue;
+ if (read(fd, id_buf, sizeof(id_buf)) < 0) {
+ close(fd);
+ continue;
+ }
+ close(fd);
+ id = atoll(id_buf);
+ if ((u64)id == config) {
+ closedir(evt_dir);
+ closedir(sys_dir);
+ snprintf(tracepoint_name, 2 * MAX_EVENT_LENGTH,
+ "%s:%s", sys_dirent.d_name,
+ evt_dirent.d_name);
+ return tracepoint_name;
+ }
+ }
+ closedir(evt_dir);
+ }
+cleanup:
+ closedir(sys_dir);
+ return "unkown";
+}
+
static int is_cache_op_valid(u8 cache_type, u8 cache_op)
{
if (hw_cache_stat[cache_type] & COP(cache_op))
@@ -177,6 +259,9 @@ char *event_name(int counter)
return sw_event_names[config];
return "unknown-software";

+ case PERF_TYPE_TRACEPOINT:
+ return tracepoint_id_to_name(config);
+
default:
break;
}
@@ -265,6 +350,78 @@ parse_generic_hw_event(const char **str, struct perf_counter_attr *attr)
return 1;
}

+static int parse_tracepoint_event(const char **strp,
+ struct perf_counter_attr *attr)
+{
+ const char *evt_name;
+ char sys_name[MAX_EVENT_LENGTH];
+ DIR *sys_dir, *evt_dir;
+ struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+ struct stat st;
+ char id_buf[4];
+ int fd;
+ unsigned int sys_length, evt_length;
+ u64 id;
+ char evt_path[MAX_PATH_LENGTH];
+
+ if (valid_debugfs_mount())
+ return 0;
+
+ evt_name = strchr(*strp, ':');
+ if (evt_name) {
+ sys_length = evt_name - *strp;
+ if (sys_length >= MAX_EVENT_LENGTH)
+ return 0;
+ strncpy(sys_name, *strp, sys_length);
+ sys_name[sys_length] = '\0';
+ evt_name = evt_name + 1;
+ evt_length = strlen(evt_name);
+ if (evt_length >= MAX_EVENT_LENGTH)
+ return 0;
+ } else
+ return 0;
+
+ sys_dir = opendir(default_debugfs_path);
+ if (!sys_dir)
+ goto cleanup;
+ for_each_subsystem(sys_dir, sys_dirent, sys_next, evt_path, st) {
+ if (strcmp(sys_dirent.d_name, sys_name) == 0) {
+ evt_dir = opendir(evt_path);
+ if (!evt_dir)
+ goto cleanup;
+ for_each_event(sys_dirent, evt_dir, evt_dirent,
+ evt_next, evt_path, st) {
+ if (strcmp(evt_dirent.d_name, evt_name) == 0) {
+ sprintf(evt_path, "%s/%s/%s/id",
+ default_debugfs_path,
+ sys_dirent.d_name,
+ evt_dirent.d_name);
+ fd = open(evt_path, O_RDONLY);
+ if (fd < 0)
+ continue;
+ if (read(fd, id_buf,
+ sizeof(id_buf)) < 0) {
+ close(fd);
+ continue;
+ }
+ close(fd);
+ id = atoll(id_buf);
+ attr->config = id;
+ attr->type = PERF_TYPE_TRACEPOINT;
+ closedir(evt_dir);
+ closedir(sys_dir);
+ *strp = evt_name + evt_length;
+ return 1;
+ }
+ }
+ closedir(evt_dir);
+ }
+ }
+cleanup:
+ closedir(sys_dir);
+ return 0;
+}
+
static int check_events(const char *str, unsigned int i)
{
int n;
@@ -374,7 +531,8 @@ parse_event_modifier(const char **strp, struct perf_counter_attr *attr)
*/
static int parse_event_symbols(const char **str, struct perf_counter_attr *attr)
{
- if (!(parse_raw_event(str, attr) ||
+ if (!(parse_tracepoint_event(str, attr) ||
+ parse_raw_event(str, attr) ||
parse_numeric_event(str, attr) ||
parse_symbolic_event(str, attr) ||
parse_generic_hw_event(str, attr)))
@@ -423,6 +581,39 @@ static const char * const event_type_descriptors[] = {
};

/*
+ * Print the events from <debugfs_mount_point>/tracing/events
+ */
+
+static void print_tracepoint_events(void)
+{
+ DIR *sys_dir, *evt_dir;
+ struct dirent *sys_next, *evt_next, sys_dirent, evt_dirent;
+ struct stat st;
+ char evt_path[MAX_PATH_LENGTH];
+
+ if (valid_debugfs_mount())
+ return;
+
+ sys_dir = opendir(default_debugfs_path);
+ if (!sys_dir)
+ goto cleanup;
+ for_each_subsystem(sys_dir, sys_dirent, sys_next, evt_path, st) {
+ evt_dir = opendir(evt_path);
+ if (!evt_dir)
+ goto cleanup;
+ for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
+ evt_path, st) {
+ fprintf(stderr, " %s:%-40s [%s]\n", sys_dirent.d_name,
+ evt_dirent.d_name,
+ event_type_descriptors[PERF_TYPE_TRACEPOINT+1]);
+ }
+ closedir(evt_dir);
+ }
+cleanup:
+ closedir(sys_dir);
+}
+
+/*
* Print the help text for the event symbols:
*/
void print_events(void)
@@ -472,5 +663,7 @@ void print_events(void)
"rNNN");
fprintf(stderr, "\n");

+ print_tracepoint_events();
+
exit(129);
}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index b4be607..68fe157 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -50,6 +50,7 @@
#include <unistd.h>
#include <stdio.h>
#include <sys/stat.h>
+#include <sys/statfs.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdlib.h>
@@ -80,6 +81,7 @@
#include <netdb.h>
#include <pwd.h>
#include <inttypes.h>
+#include "../../../include/linux/magic.h"

#ifndef NO_ICONV
#include <iconv.h>
--
1.6.0.6


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