Linux-libre 4.4-gnupck-4.4-gnu

15 files changed, 357 insertions, 361 deletions

diff --git a/tools/lib/api/Build b/tools/lib/api/Build
index 3653965cf..e8b8a23b9 100644
--- a/tools/lib/api/Build
+++ b/tools/lib/api/Build
@@ -1,2 +1,3 @@
 libapi-y += fd/
 libapi-y += fs/
+libapi-y += cpu.o
diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
index fe1b02c2c..d85904dc9 100644
--- a/tools/lib/api/Makefile
+++ b/tools/lib/api/Makefile
@@ -21,12 +21,14 @@ CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
 
 RM = rm -f
 
-build  := -f $(srctree)/tools/build/Makefile.build dir=. obj
 API_IN := $(OUTPUT)libapi-in.o
 
+all:
+
 export srctree OUTPUT CC LD CFLAGS V
+include $(srctree)/tools/build/Makefile.include
 
-all: $(LIBFILE)
+all: fixdep $(LIBFILE)
 
 $(API_IN): FORCE
 	@$(MAKE) $(build)=libapi
diff --git a/tools/lib/api/cpu.c b/tools/lib/api/cpu.c
new file mode 100644
index 000000000..8c6489356
--- /dev/null
+++ b/tools/lib/api/cpu.c
@@ -0,0 +1,18 @@
+#include <stdio.h>
+
+#include "cpu.h"
+#include "fs/fs.h"
+
+int cpu__get_max_freq(unsigned long long *freq)
+{
+	char entry[PATH_MAX];
+	int cpu;
+
+	if (sysfs__read_int("devices/system/cpu/online", &cpu) < 0)
+		return -1;
+
+	snprintf(entry, sizeof(entry),
+		 "devices/system/cpu/cpu%d/cpufreq/cpuinfo_max_freq", cpu);
+
+	return sysfs__read_ull(entry, freq);
+}
diff --git a/tools/lib/api/cpu.h b/tools/lib/api/cpu.h
new file mode 100644
index 000000000..81e9d3955
--- /dev/null
+++ b/tools/lib/api/cpu.h
@@ -0,0 +1,6 @@
+#ifndef __API_CPU__
+#define __API_CPU__
+
+int cpu__get_max_freq(unsigned long long *freq);
+
+#endif /* __API_CPU__ */
diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
index 6de5a4f0b..f4ed9629a 100644
--- a/tools/lib/api/fs/Build
+++ b/tools/lib/api/fs/Build
@@ -1,4 +1,2 @@
 libapi-y += fs.o
-libapi-y += debugfs.o
-libapi-y += findfs.o
-libapi-y += tracefs.o
+libapi-y += tracing_path.o
diff --git a/tools/lib/api/fs/debugfs.c b/tools/lib/api/fs/debugfs.c
deleted file mode 100644
index eb7cf4d18..000000000
--- a/tools/lib/api/fs/debugfs.c
+++ /dev/null
@@ -1,129 +0,0 @@
-#define _GNU_SOURCE
-#include <errno.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <stdbool.h>
-#include <sys/vfs.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/mount.h>
-#include <linux/kernel.h>
-
-#include "debugfs.h"
-#include "tracefs.h"
-
-#ifndef DEBUGFS_DEFAULT_PATH
-#define DEBUGFS_DEFAULT_PATH		"/sys/kernel/debug"
-#endif
-
-char debugfs_mountpoint[PATH_MAX + 1] = DEBUGFS_DEFAULT_PATH;
-
-static const char * const debugfs_known_mountpoints[] = {
-	DEBUGFS_DEFAULT_PATH,
-	"/debug",
-	0,
-};
-
-static bool debugfs_found;
-
-bool debugfs_configured(void)
-{
-	return debugfs_find_mountpoint() != NULL;
-}
-
-/* find the path to the mounted debugfs */
-const char *debugfs_find_mountpoint(void)
-{
-	const char *ret;
-
-	if (debugfs_found)
-		return (const char *)debugfs_mountpoint;
-
-	ret = find_mountpoint("debugfs", (long) DEBUGFS_MAGIC,
-			      debugfs_mountpoint, PATH_MAX + 1,
-			      debugfs_known_mountpoints);
-	if (ret)
-		debugfs_found = true;
-
-	return ret;
-}
-
-/* mount the debugfs somewhere if it's not mounted */
-char *debugfs_mount(const char *mountpoint)
-{
-	/* see if it's already mounted */
-	if (debugfs_find_mountpoint())
-		goto out;
-
-	/* if not mounted and no argument */
-	if (mountpoint == NULL) {
-		/* see if environment variable set */
-		mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
-		/* if no environment variable, use default */
-		if (mountpoint == NULL)
-			mountpoint = DEBUGFS_DEFAULT_PATH;
-	}
-
-	if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
-		return NULL;
-
-	/* save the mountpoint */
-	debugfs_found = true;
-	strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
-out:
-	return debugfs_mountpoint;
-}
-
-int debugfs__strerror_open(int err, char *buf, size_t size, const char *filename)
-{
-	char sbuf[128];
-
-	switch (err) {
-	case ENOENT:
-		if (debugfs_found) {
-			snprintf(buf, size,
-				 "Error:\tFile %s/%s not found.\n"
-				 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
-				 debugfs_mountpoint, filename);
-			break;
-		}
-		snprintf(buf, size, "%s",
-			 "Error:\tUnable to find debugfs\n"
-			 "Hint:\tWas your kernel compiled with debugfs support?\n"
-			 "Hint:\tIs the debugfs filesystem mounted?\n"
-			 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
-		break;
-	case EACCES: {
-		const char *mountpoint = debugfs_mountpoint;
-
-		if (!access(debugfs_mountpoint, R_OK) && strncmp(filename, "tracing/", 8) == 0) {
-			const char *tracefs_mntpoint = tracefs_find_mountpoint();
-
-			if (tracefs_mntpoint)
-				mountpoint = tracefs_mntpoint;
-		}
-
-		snprintf(buf, size,
-			 "Error:\tNo permissions to read %s/%s\n"
-			 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
-			 debugfs_mountpoint, filename, mountpoint);
-	}
-		break;
-	default:
-		snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
-		break;
-	}
-
-	return 0;
-}
-
-int debugfs__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
-{
-	char path[PATH_MAX];
-
-	snprintf(path, PATH_MAX, "tracing/events/%s/%s", sys, name ?: "*");
-
-	return debugfs__strerror_open(err, buf, size, path);
-}
diff --git a/tools/lib/api/fs/debugfs.h b/tools/lib/api/fs/debugfs.h
deleted file mode 100644
index 455023698..000000000
--- a/tools/lib/api/fs/debugfs.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef __API_DEBUGFS_H__
-#define __API_DEBUGFS_H__
-
-#include "findfs.h"
-
-#ifndef DEBUGFS_MAGIC
-#define DEBUGFS_MAGIC          0x64626720
-#endif
-
-#ifndef PERF_DEBUGFS_ENVIRONMENT
-#define PERF_DEBUGFS_ENVIRONMENT "PERF_DEBUGFS_DIR"
-#endif
-
-bool debugfs_configured(void);
-const char *debugfs_find_mountpoint(void);
-char *debugfs_mount(const char *mountpoint);
-
-extern char debugfs_mountpoint[];
-
-int debugfs__strerror_open(int err, char *buf, size_t size, const char *filename);
-int debugfs__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name);
-
-#endif /* __API_DEBUGFS_H__ */
diff --git a/tools/lib/api/fs/findfs.c b/tools/lib/api/fs/findfs.c
deleted file mode 100644
index 49946cb6d..000000000
--- a/tools/lib/api/fs/findfs.c
+++ /dev/null
@@ -1,63 +0,0 @@
-#include <errno.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdbool.h>
-#include <sys/vfs.h>
-
-#include "findfs.h"
-
-/* verify that a mountpoint is actually the type we want */
-
-int valid_mountpoint(const char *mount, long magic)
-{
-	struct statfs st_fs;
-
-	if (statfs(mount, &st_fs) < 0)
-		return -ENOENT;
-	else if ((long)st_fs.f_type != magic)
-		return -ENOENT;
-
-	return 0;
-}
-
-/* find the path to a mounted file system */
-const char *find_mountpoint(const char *fstype, long magic,
-			    char *mountpoint, int len,
-			    const char * const *known_mountpoints)
-{
-	const char * const *ptr;
-	char format[128];
-	char type[100];
-	FILE *fp;
-
-	if (known_mountpoints) {
-		ptr = known_mountpoints;
-		while (*ptr) {
-			if (valid_mountpoint(*ptr, magic) == 0) {
-				strncpy(mountpoint, *ptr, len - 1);
-				mountpoint[len-1] = 0;
-				return mountpoint;
-			}
-			ptr++;
-		}
-	}
-
-	/* give up and parse /proc/mounts */
-	fp = fopen("/proc/mounts", "r");
-	if (fp == NULL)
-		return NULL;
-
-	snprintf(format, 128, "%%*s %%%ds %%99s %%*s %%*d %%*d\n", len);
-
-	while (fscanf(fp, format, mountpoint, type) == 2) {
-		if (strcmp(type, fstype) == 0)
-			break;
-	}
-	fclose(fp);
-
-	if (strcmp(type, fstype) != 0)
-		return NULL;
-
-	return mountpoint;
-}
diff --git a/tools/lib/api/fs/findfs.h b/tools/lib/api/fs/findfs.h
deleted file mode 100644
index b6f5d05ac..000000000
--- a/tools/lib/api/fs/findfs.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef __API_FINDFS_H__
-#define __API_FINDFS_H__
-
-#include <stdbool.h>
-
-#define _STR(x) #x
-#define STR(x) _STR(x)
-
-/*
- * On most systems <limits.h> would have given us this, but  not on some systems
- * (e.g. GNU/Hurd).
- */
-#ifndef PATH_MAX
-#define PATH_MAX 4096
-#endif
-
-const char *find_mountpoint(const char *fstype, long magic,
-			    char *mountpoint, int len,
-			    const char * const *known_mountpoints);
-
-int valid_mountpoint(const char *mount, long magic);
-
-#endif /* __API_FINDFS_H__ */
diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
index 128ef6332..459599d1b 100644
--- a/tools/lib/api/fs/fs.c
+++ b/tools/lib/api/fs/fs.c
@@ -1,7 +1,6 @@
-/* TODO merge/factor in debugfs.c here */
-
 #include <ctype.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -11,10 +10,29 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <sys/mount.h>
 
-#include "debugfs.h"
 #include "fs.h"
 
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
+#ifndef SYSFS_MAGIC
+#define SYSFS_MAGIC            0x62656572
+#endif
+
+#ifndef PROC_SUPER_MAGIC
+#define PROC_SUPER_MAGIC       0x9fa0
+#endif
+
+#ifndef DEBUGFS_MAGIC
+#define DEBUGFS_MAGIC          0x64626720
+#endif
+
+#ifndef TRACEFS_MAGIC
+#define TRACEFS_MAGIC          0x74726163
+#endif
+
 static const char * const sysfs__fs_known_mountpoints[] = {
 	"/sys",
 	0,
@@ -25,19 +43,48 @@ static const char * const procfs__known_mountpoints[] = {
 	0,
 };
 
+#ifndef DEBUGFS_DEFAULT_PATH
+#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
+#endif
+
+static const char * const debugfs__known_mountpoints[] = {
+	DEBUGFS_DEFAULT_PATH,
+	"/debug",
+	0,
+};
+
+
+#ifndef TRACEFS_DEFAULT_PATH
+#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
+#endif
+
+static const char * const tracefs__known_mountpoints[] = {
+	TRACEFS_DEFAULT_PATH,
+	"/sys/kernel/debug/tracing",
+	"/tracing",
+	"/trace",
+	0,
+};
+
 struct fs {
 	const char		*name;
 	const char * const	*mounts;
-	char			 path[PATH_MAX + 1];
+	char			 path[PATH_MAX];
 	bool			 found;
 	long			 magic;
 };
 
 enum {
-	FS__SYSFS  = 0,
-	FS__PROCFS = 1,
+	FS__SYSFS   = 0,
+	FS__PROCFS  = 1,
+	FS__DEBUGFS = 2,
+	FS__TRACEFS = 3,
 };
 
+#ifndef TRACEFS_MAGIC
+#define TRACEFS_MAGIC 0x74726163
+#endif
+
 static struct fs fs__entries[] = {
 	[FS__SYSFS] = {
 		.name	= "sysfs",
@@ -49,6 +96,16 @@ static struct fs fs__entries[] = {
 		.mounts	= procfs__known_mountpoints,
 		.magic	= PROC_SUPER_MAGIC,
 	},
+	[FS__DEBUGFS] = {
+		.name	= "debugfs",
+		.mounts	= debugfs__known_mountpoints,
+		.magic	= DEBUGFS_MAGIC,
+	},
+	[FS__TRACEFS] = {
+		.name	= "tracefs",
+		.mounts	= tracefs__known_mountpoints,
+		.magic	= TRACEFS_MAGIC,
+	},
 };
 
 static bool fs__read_mounts(struct fs *fs)
@@ -159,14 +216,54 @@ static const char *fs__mountpoint(int idx)
 	return fs__get_mountpoint(fs);
 }
 
-#define FS__MOUNTPOINT(name, idx)	\
-const char *name##__mountpoint(void)	\
-{					\
-	return fs__mountpoint(idx);	\
+static const char *mount_overload(struct fs *fs)
+{
+	size_t name_len = strlen(fs->name);
+	/* "PERF_" + name + "_ENVIRONMENT" + '\0' */
+	char upper_name[5 + name_len + 12 + 1];
+
+	snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
+	mem_toupper(upper_name, name_len);
+
+	return getenv(upper_name) ?: *fs->mounts;
+}
+
+static const char *fs__mount(int idx)
+{
+	struct fs *fs = &fs__entries[idx];
+	const char *mountpoint;
+
+	if (fs__mountpoint(idx))
+		return (const char *)fs->path;
+
+	mountpoint = mount_overload(fs);
+
+	if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
+		return NULL;
+
+	return fs__check_mounts(fs) ? fs->path : NULL;
+}
+
+#define FS(name, idx)				\
+const char *name##__mountpoint(void)		\
+{						\
+	return fs__mountpoint(idx);		\
+}						\
+						\
+const char *name##__mount(void)			\
+{						\
+	return fs__mount(idx);			\
+}						\
+						\
+bool name##__configured(void)			\
+{						\
+	return name##__mountpoint() != NULL;	\
 }
 
-FS__MOUNTPOINT(sysfs,  FS__SYSFS);
-FS__MOUNTPOINT(procfs, FS__PROCFS);
+FS(sysfs,   FS__SYSFS);
+FS(procfs,  FS__PROCFS);
+FS(debugfs, FS__DEBUGFS);
+FS(tracefs, FS__TRACEFS);
 
 int filename__read_int(const char *filename, int *value)
 {
@@ -185,6 +282,50 @@ int filename__read_int(const char *filename, int *value)
 	return err;
 }
 
+int filename__read_ull(const char *filename, unsigned long long *value)
+{
+	char line[64];
+	int fd = open(filename, O_RDONLY), err = -1;
+
+	if (fd < 0)
+		return -1;
+
+	if (read(fd, line, sizeof(line)) > 0) {
+		*value = strtoull(line, NULL, 10);
+		if (*value != ULLONG_MAX)
+			err = 0;
+	}
+
+	close(fd);
+	return err;
+}
+
+int sysfs__read_ull(const char *entry, unsigned long long *value)
+{
+	char path[PATH_MAX];
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+	return filename__read_ull(path, value);
+}
+
+int sysfs__read_int(const char *entry, int *value)
+{
+	char path[PATH_MAX];
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return -1;
+
+	snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+	return filename__read_int(path, value);
+}
+
 int sysctl__read_int(const char *sysctl, int *value)
 {
 	char path[PATH_MAX];
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 6caa2bbc6..d024a7f68 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -1,17 +1,33 @@
 #ifndef __API_FS__
 #define __API_FS__
 
-#ifndef SYSFS_MAGIC
-#define SYSFS_MAGIC            0x62656572
-#endif
+#include <stdbool.h>
 
-#ifndef PROC_SUPER_MAGIC
-#define PROC_SUPER_MAGIC       0x9fa0
+/*
+ * On most systems <limits.h> would have given us this, but  not on some systems
+ * (e.g. GNU/Hurd).
+ */
+#ifndef PATH_MAX
+#define PATH_MAX 4096
 #endif
 
-const char *sysfs__mountpoint(void);
-const char *procfs__mountpoint(void);
+#define FS(name)				\
+	const char *name##__mountpoint(void);	\
+	const char *name##__mount(void);	\
+	bool name##__configured(void);		\
+
+FS(sysfs)
+FS(procfs)
+FS(debugfs)
+FS(tracefs)
+
+#undef FS
+
 
 int filename__read_int(const char *filename, int *value);
+int filename__read_ull(const char *filename, unsigned long long *value);
+
 int sysctl__read_int(const char *sysctl, int *value);
+int sysfs__read_int(const char *entry, int *value);
+int sysfs__read_ull(const char *entry, unsigned long long *value);
 #endif /* __API_FS__ */
diff --git a/tools/lib/api/fs/tracefs.c b/tools/lib/api/fs/tracefs.c
deleted file mode 100644
index e4aa9688b..000000000
--- a/tools/lib/api/fs/tracefs.c
+++ /dev/null
@@ -1,78 +0,0 @@
-#include <errno.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <stdbool.h>
-#include <sys/vfs.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/mount.h>
-#include <linux/kernel.h>
-
-#include "tracefs.h"
-
-#ifndef TRACEFS_DEFAULT_PATH
-#define TRACEFS_DEFAULT_PATH		"/sys/kernel/tracing"
-#endif
-
-char tracefs_mountpoint[PATH_MAX + 1] = TRACEFS_DEFAULT_PATH;
-
-static const char * const tracefs_known_mountpoints[] = {
-	TRACEFS_DEFAULT_PATH,
-	"/sys/kernel/debug/tracing",
-	"/tracing",
-	"/trace",
-	0,
-};
-
-static bool tracefs_found;
-
-bool tracefs_configured(void)
-{
-	return tracefs_find_mountpoint() != NULL;
-}
-
-/* find the path to the mounted tracefs */
-const char *tracefs_find_mountpoint(void)
-{
-	const char *ret;
-
-	if (tracefs_found)
-		return (const char *)tracefs_mountpoint;
-
-	ret = find_mountpoint("tracefs", (long) TRACEFS_MAGIC,
-			      tracefs_mountpoint, PATH_MAX + 1,
-			      tracefs_known_mountpoints);
-
-	if (ret)
-		tracefs_found = true;
-
-	return ret;
-}
-
-/* mount the tracefs somewhere if it's not mounted */
-char *tracefs_mount(const char *mountpoint)
-{
-	/* see if it's already mounted */
-	if (tracefs_find_mountpoint())
-		goto out;
-
-	/* if not mounted and no argument */
-	if (mountpoint == NULL) {
-		/* see if environment variable set */
-		mountpoint = getenv(PERF_TRACEFS_ENVIRONMENT);
-		/* if no environment variable, use default */
-		if (mountpoint == NULL)
-			mountpoint = TRACEFS_DEFAULT_PATH;
-	}
-
-	if (mount(NULL, mountpoint, "tracefs", 0, NULL) < 0)
-		return NULL;
-
-	/* save the mountpoint */
-	tracefs_found = true;
-	strncpy(tracefs_mountpoint, mountpoint, sizeof(tracefs_mountpoint));
-out:
-	return tracefs_mountpoint;
-}
diff --git a/tools/lib/api/fs/tracefs.h b/tools/lib/api/fs/tracefs.h
deleted file mode 100644
index da780ac49..000000000
--- a/tools/lib/api/fs/tracefs.h
+++ /dev/null
@@ -1,21 +0,0 @@
-#ifndef __API_TRACEFS_H__
-#define __API_TRACEFS_H__
-
-#include "findfs.h"
-
-#ifndef TRACEFS_MAGIC
-#define TRACEFS_MAGIC          0x74726163
-#endif
-
-#ifndef PERF_TRACEFS_ENVIRONMENT
-#define PERF_TRACEFS_ENVIRONMENT "PERF_TRACEFS_DIR"
-#endif
-
-bool tracefs_configured(void);
-const char *tracefs_find_mountpoint(void);
-int tracefs_valid_mountpoint(const char *debugfs);
-char *tracefs_mount(const char *mountpoint);
-
-extern char tracefs_mountpoint[];
-
-#endif /* __API_DEBUGFS_H__ */
diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
new file mode 100644
index 000000000..a26bb5ea8
--- /dev/null
+++ b/tools/lib/api/fs/tracing_path.c
@@ -0,0 +1,135 @@
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include "fs.h"
+
+#include "tracing_path.h"
+
+
+char tracing_mnt[PATH_MAX]         = "/sys/kernel/debug";
+char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
+char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
+
+
+static void __tracing_path_set(const char *tracing, const char *mountpoint)
+{
+	snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
+	snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
+		 mountpoint, tracing);
+	snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
+		 mountpoint, tracing, "events");
+}
+
+static const char *tracing_path_tracefs_mount(void)
+{
+	const char *mnt;
+
+	mnt = tracefs__mount();
+	if (!mnt)
+		return NULL;
+
+	__tracing_path_set("", mnt);
+
+	return mnt;
+}
+
+static const char *tracing_path_debugfs_mount(void)
+{
+	const char *mnt;
+
+	mnt = debugfs__mount();
+	if (!mnt)
+		return NULL;
+
+	__tracing_path_set("tracing/", mnt);
+
+	return mnt;
+}
+
+const char *tracing_path_mount(void)
+{
+	const char *mnt;
+
+	mnt = tracing_path_tracefs_mount();
+	if (mnt)
+		return mnt;
+
+	mnt = tracing_path_debugfs_mount();
+
+	return mnt;
+}
+
+void tracing_path_set(const char *mntpt)
+{
+	__tracing_path_set("tracing/", mntpt);
+}
+
+char *get_tracing_file(const char *name)
+{
+	char *file;
+
+	if (asprintf(&file, "%s/%s", tracing_path, name) < 0)
+		return NULL;
+
+	return file;
+}
+
+void put_tracing_file(char *file)
+{
+	free(file);
+}
+
+static int strerror_open(int err, char *buf, size_t size, const char *filename)
+{
+	char sbuf[128];
+
+	switch (err) {
+	case ENOENT:
+		/*
+		 * We will get here if we can't find the tracepoint, but one of
+		 * debugfs or tracefs is configured, which means you probably
+		 * want some tracepoint which wasn't compiled in your kernel.
+		 * - jirka
+		 */
+		if (debugfs__configured() || tracefs__configured()) {
+			snprintf(buf, size,
+				 "Error:\tFile %s/%s not found.\n"
+				 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
+				 tracing_events_path, filename);
+			break;
+		}
+		snprintf(buf, size, "%s",
+			 "Error:\tUnable to find debugfs/tracefs\n"
+			 "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
+			 "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
+			 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
+		break;
+	case EACCES: {
+		snprintf(buf, size,
+			 "Error:\tNo permissions to read %s/%s\n"
+			 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
+			 tracing_events_path, filename, tracing_mnt);
+	}
+		break;
+	default:
+		snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
+		break;
+	}
+
+	return 0;
+}
+
+int tracing_path__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
+{
+	char path[PATH_MAX];
+
+	snprintf(path, PATH_MAX, "%s/%s", sys, name ?: "*");
+
+	return strerror_open(err, buf, size, path);
+}
diff --git a/tools/lib/api/fs/tracing_path.h b/tools/lib/api/fs/tracing_path.h
new file mode 100644
index 000000000..3f233ac70
--- /dev/null
+++ b/tools/lib/api/fs/tracing_path.h
@@ -0,0 +1,16 @@
+#ifndef __API_FS_TRACING_PATH_H
+#define __API_FS_TRACING_PATH_H
+
+#include <linux/types.h>
+
+extern char tracing_path[];
+extern char tracing_events_path[];
+
+void tracing_path_set(const char *mountpoint);
+const char *tracing_path_mount(void);
+
+char *get_tracing_file(const char *name);
+void put_tracing_file(char *file);
+
+int tracing_path__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name);
+#endif /* __API_FS_TRACING_PATH_H */