perf tools: Make perf aware of tracefs

As tracefs may be mounted instead of debugfs to get to the event
directories, have perf know about tracefs, and use that file system over
debugfs if it is present.

Signed-off-by: Steven Rostedt <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
[ Fixed up error messages about tracefs pointed out by Namhyung ]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/open-syscall-all-cpus.c

···
 
 	evsel = perf_evsel__newtp("syscalls", "sys_enter_open");
 	if (evsel == NULL) {
-		pr_debug("is debugfs mounted on /sys/kernel/debug?\n");
+		if (tracefs_configured())
+			pr_debug("is tracefs mounted on /sys/kernel/tracing?\n");
+		else if (debugfs_configured())
+			pr_debug("is debugfs mounted on /sys/kernel/debug?\n");
+		else
+			pr_debug("Neither tracefs or debugfs is enabled in this kernel\n");
 		goto out_thread_map_delete;
 	}
 

tools/perf/tests/open-syscall.c

···
 
 	evsel = perf_evsel__newtp("syscalls", "sys_enter_open");
 	if (evsel == NULL) {
-		pr_debug("is debugfs mounted on /sys/kernel/debug?\n");
+		if (tracefs_configured())
+			pr_debug("is tracefs mounted on /sys/kernel/tracing?\n");
+		else if (debugfs_configured())
+			pr_debug("is debugfs mounted on /sys/kernel/debug?\n");
+		else
+			pr_debug("Neither tracefs or debugfs is enabled in this kernel\n");
 		goto out_thread_map_delete;
 	}
 

tools/perf/tests/parse-events.c

···
 #include "evsel.h"
 #include "evlist.h"
 #include <api/fs/fs.h>
+#include <api/fs/tracefs.h>
 #include <api/fs/debugfs.h>
 #include "tests.h"
 #include "debug.h"
···
 {
 	char events_path[PATH_MAX];
 	struct dirent *events_ent;
+	const char *mountpoint;
 	DIR *events_dir;
 	int cnt = 0;
 
-	scnprintf(events_path, PATH_MAX, "%s/tracing/events",
-		  debugfs_find_mountpoint());
+	mountpoint = tracefs_find_mountpoint();
+	if (mountpoint) {
+		scnprintf(events_path, PATH_MAX, "%s/events",
+			  mountpoint);
+	} else {
+		mountpoint = debugfs_find_mountpoint();
+		scnprintf(events_path, PATH_MAX, "%s/tracing/events",
+			  mountpoint);
+	}
 
 	events_dir = opendir(events_path);
 

tools/perf/util/cache.h

···
 #define EXEC_PATH_ENVIRONMENT "PERF_EXEC_PATH"
 #define DEFAULT_PERF_DIR_ENVIRONMENT ".perf"
 #define PERF_DEBUGFS_ENVIRONMENT "PERF_DEBUGFS_DIR"
+#define PERF_TRACEFS_ENVIRONMENT "PERF_TRACEFS_DIR"
 
 typedef int (*config_fn_t)(const char *, const char *, void *);
 extern int perf_default_config(const char *, const char *, void *);

tools/perf/util/evlist.c

···
  * Released under the GPL v2. (and only v2, not any later version)
  */
 #include "util.h"
-#include <api/fs/debugfs.h>
 #include <api/fs/fs.h>
 #include <poll.h>
 #include "cpumap.h"

tools/perf/util/parse-events.h

···
 int print_hwcache_events(const char *event_glob, bool name_only);
 extern int is_valid_tracepoint(const char *event_string);
 
-extern int valid_debugfs_mount(const char *debugfs);
+int valid_event_mount(const char *eventfs);
 
 #endif /* __PERF_PARSE_EVENTS_H */

tools/perf/util/probe-event.c

···
 #include "symbol.h"
 #include "thread.h"
 #include <api/fs/debugfs.h>
+#include <api/fs/tracefs.h>
 #include "trace-event.h"	/* For __maybe_unused */
 #include "probe-event.h"
 #include "probe-finder.h"
···
 			   " - please rebuild kernel with %s.\n",
 			   is_kprobe ? 'k' : 'u', config);
 	} else if (err == -ENOTSUP)
-		pr_warning("Debugfs is not mounted.\n");
+		pr_warning("Tracefs or debugfs is not mounted.\n");
 	else
 		pr_warning("Failed to open %cprobe_events: %s\n",
 			   is_kprobe ? 'k' : 'u',
···
 {
 	/* Both kprobes and uprobes are disabled, warn it. */
 	if (kerr == -ENOTSUP && uerr == -ENOTSUP)
-		pr_warning("Debugfs is not mounted.\n");
+		pr_warning("Tracefs or debugfs is not mounted.\n");
 	else if (kerr == -ENOENT && uerr == -ENOENT)
 		pr_warning("Please rebuild kernel with CONFIG_KPROBE_EVENTS "
 			   "or/and CONFIG_UPROBE_EVENTS.\n");
···
 {
 	char buf[PATH_MAX];
 	const char *__debugfs;
+	const char *tracing_dir = "";
 	int ret;
 
-	__debugfs = debugfs_find_mountpoint();
-	if (__debugfs == NULL)
-		return -ENOTSUP;
+	__debugfs = tracefs_find_mountpoint();
+	if (__debugfs == NULL) {
+		tracing_dir = "tracing/";
 
-	ret = e_snprintf(buf, PATH_MAX, "%s/%s", __debugfs, trace_file);
+		__debugfs = debugfs_find_mountpoint();
+		if (__debugfs == NULL)
+			return -ENOTSUP;
+	}
+
+	ret = e_snprintf(buf, PATH_MAX, "%s/%s%s",
+			 __debugfs, tracing_dir, trace_file);
 	if (ret >= 0) {
 		pr_debug("Opening %s write=%d\n", buf, readwrite);
 		if (readwrite && !probe_event_dry_run)
···
 
 static int open_kprobe_events(bool readwrite)
 {
-	return open_probe_events("tracing/kprobe_events", readwrite);
+	return open_probe_events("kprobe_events", readwrite);
 }
 
 static int open_uprobe_events(bool readwrite)
 {
-	return open_probe_events("tracing/uprobe_events", readwrite);
+	return open_probe_events("uprobe_events", readwrite);
 }
 
 /* Get raw string list of current kprobe_events  or uprobe_events */

tools/perf/util/util.c

···
 	tcsetattr(0, TCSANOW, &tc);
 }
 
-static void set_tracing_events_path(const char *mountpoint)
+static void set_tracing_events_path(const char *tracing, const char *mountpoint)
 {
-	snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s",
-		 mountpoint, "tracing/events");
+	snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
+		 mountpoint, tracing, "events");
 }
 
-const char *perf_debugfs_mount(const char *mountpoint)
+static const char *__perf_tracefs_mount(const char *mountpoint)
+{
+	const char *mnt;
+
+	mnt = tracefs_mount(mountpoint);
+	if (!mnt)
+		return NULL;
+
+	set_tracing_events_path("", mnt);
+
+	return mnt;
+}
+
+static const char *__perf_debugfs_mount(const char *mountpoint)
 {
 	const char *mnt;
 
···
 	if (!mnt)
 		return NULL;
 
-	set_tracing_events_path(mnt);
+	set_tracing_events_path("tracing/", mnt);
+
+	return mnt;
+}
+
+const char *perf_debugfs_mount(const char *mountpoint)
+{
+	const char *mnt;
+
+	mnt = __perf_tracefs_mount(mountpoint);
+	if (mnt)
+		return mnt;
+
+	mnt = __perf_debugfs_mount(mountpoint);
 
 	return mnt;
 }
···
 void perf_debugfs_set_path(const char *mntpt)
 {
 	snprintf(debugfs_mountpoint, strlen(debugfs_mountpoint), "%s", mntpt);
-	set_tracing_events_path(mntpt);
+	set_tracing_events_path("tracing/", mntpt);
+}
+
+static const char *find_tracefs(void)
+{
+	const char *path = __perf_tracefs_mount(NULL);
+
+	return path;
 }
 
 static const char *find_debugfs(void)
 {
-	const char *path = perf_debugfs_mount(NULL);
+	const char *path = __perf_debugfs_mount(NULL);
 
 	if (!path)
 		fprintf(stderr, "Your kernel does not support the debugfs filesystem");
···
  */
 const char *find_tracing_dir(void)
 {
+	const char *tracing_dir = "";
 	static char *tracing;
 	static int tracing_found;
 	const char *debugfs;
···
 	if (tracing_found)
 		return tracing;
 
-	debugfs = find_debugfs();
-	if (!debugfs)
-		return NULL;
+	debugfs = find_tracefs();
+	if (!debugfs) {
+		tracing_dir = "/tracing";
+		debugfs = find_debugfs();
+		if (!debugfs)
+			return NULL;
+	}
 
-	if (asprintf(&tracing, "%s/tracing", debugfs) < 0)
+	if (asprintf(&tracing, "%s%s", debugfs, tracing_dir) < 0)
 		return NULL;
 
 	tracing_found = 1;

tools/perf/util/util.h

···
 #include <linux/types.h>
 #include <sys/ttydefaults.h>
 #include <api/fs/debugfs.h>
+#include <api/fs/tracefs.h>
 #include <termios.h>
 #include <linux/bitops.h>
 #include <termios.h>