v4.19.13 snapshot.
diff --git a/tools/lib/api/Build b/tools/lib/api/Build
new file mode 100644
index 0000000..6e2373d
--- /dev/null
+++ b/tools/lib/api/Build
@@ -0,0 +1,9 @@
+libapi-y += fd/
+libapi-y += fs/
+libapi-y += cpu.o
+libapi-y += debug.o
+libapi-y += str_error_r.o
+
+$(OUTPUT)str_error_r.o: ../str_error_r.c FORCE
+ $(call rule_mkdir)
+ $(call if_changed_dep,cc_o_c)
diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
new file mode 100644
index 0000000..a13e9c7
--- /dev/null
+++ b/tools/lib/api/Makefile
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: GPL-2.0
+include ../../scripts/Makefile.include
+include ../../scripts/utilities.mak # QUIET_CLEAN
+
+ifeq ($(srctree),)
+srctree := $(patsubst %/,%,$(dir $(CURDIR)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+#$(info Determined 'srctree' to be $(srctree))
+endif
+
+CC ?= $(CROSS_COMPILE)gcc
+AR ?= $(CROSS_COMPILE)ar
+LD ?= $(CROSS_COMPILE)ld
+
+MAKEFLAGS += --no-print-directory
+
+LIBFILE = $(OUTPUT)libapi.a
+
+CFLAGS := $(EXTRA_WARNINGS) $(EXTRA_CFLAGS)
+CFLAGS += -ggdb3 -Wall -Wextra -std=gnu99 -U_FORTIFY_SOURCE -fPIC
+
+ifeq ($(DEBUG),0)
+ifeq ($(CC_NO_CLANG), 0)
+ CFLAGS += -O3
+else
+ CFLAGS += -O6
+endif
+endif
+
+ifeq ($(DEBUG),0)
+ CFLAGS += -D_FORTIFY_SOURCE
+endif
+
+# Treat warnings as errors unless directed not to
+ifneq ($(WERROR),0)
+ CFLAGS += -Werror
+endif
+
+CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
+CFLAGS += -I$(srctree)/tools/lib/api
+CFLAGS += -I$(srctree)/tools/include
+
+RM = rm -f
+
+API_IN := $(OUTPUT)libapi-in.o
+
+all:
+
+export srctree OUTPUT CC LD CFLAGS V
+include $(srctree)/tools/build/Makefile.include
+
+all: fixdep $(LIBFILE)
+
+$(API_IN): FORCE
+ @$(MAKE) $(build)=libapi
+
+$(LIBFILE): $(API_IN)
+ $(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(API_IN)
+
+clean:
+ $(call QUIET_CLEAN, libapi) $(RM) $(LIBFILE); \
+ find $(if $(OUTPUT),$(OUTPUT),.) -name \*.o -or -name \*.o.cmd -or -name \*.o.d | xargs $(RM)
+
+FORCE:
+
+.PHONY: clean FORCE
diff --git a/tools/lib/api/cpu.c b/tools/lib/api/cpu.c
new file mode 100644
index 0000000..4af6d4b
--- /dev/null
+++ b/tools/lib/api/cpu.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+#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 0000000..90a102f
--- /dev/null
+++ b/tools/lib/api/cpu.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_CPU__
+#define __API_CPU__
+
+int cpu__get_max_freq(unsigned long long *freq);
+
+#endif /* __API_CPU__ */
diff --git a/tools/lib/api/debug-internal.h b/tools/lib/api/debug-internal.h
new file mode 100644
index 0000000..80c7834
--- /dev/null
+++ b/tools/lib/api/debug-internal.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_DEBUG_INTERNAL_H__
+#define __API_DEBUG_INTERNAL_H__
+
+#include "debug.h"
+
+#define __pr(func, fmt, ...) \
+do { \
+ if ((func)) \
+ (func)("libapi: " fmt, ##__VA_ARGS__); \
+} while (0)
+
+extern libapi_print_fn_t __pr_warning;
+extern libapi_print_fn_t __pr_info;
+extern libapi_print_fn_t __pr_debug;
+
+#define pr_warning(fmt, ...) __pr(__pr_warning, fmt, ##__VA_ARGS__)
+#define pr_info(fmt, ...) __pr(__pr_info, fmt, ##__VA_ARGS__)
+#define pr_debug(fmt, ...) __pr(__pr_debug, fmt, ##__VA_ARGS__)
+
+#endif /* __API_DEBUG_INTERNAL_H__ */
diff --git a/tools/lib/api/debug.c b/tools/lib/api/debug.c
new file mode 100644
index 0000000..69b1ba3
--- /dev/null
+++ b/tools/lib/api/debug.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <stdarg.h>
+#include "debug.h"
+#include "debug-internal.h"
+
+static int __base_pr(const char *format, ...)
+{
+ va_list args;
+ int err;
+
+ va_start(args, format);
+ err = vfprintf(stderr, format, args);
+ va_end(args);
+ return err;
+}
+
+libapi_print_fn_t __pr_warning = __base_pr;
+libapi_print_fn_t __pr_info = __base_pr;
+libapi_print_fn_t __pr_debug;
+
+void libapi_set_print(libapi_print_fn_t warn,
+ libapi_print_fn_t info,
+ libapi_print_fn_t debug)
+{
+ __pr_warning = warn;
+ __pr_info = info;
+ __pr_debug = debug;
+}
diff --git a/tools/lib/api/debug.h b/tools/lib/api/debug.h
new file mode 100644
index 0000000..3684dd6
--- /dev/null
+++ b/tools/lib/api/debug.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_DEBUG_H__
+#define __API_DEBUG_H__
+
+typedef int (*libapi_print_fn_t)(const char *, ...);
+
+void libapi_set_print(libapi_print_fn_t warn,
+ libapi_print_fn_t info,
+ libapi_print_fn_t debug);
+
+#endif /* __API_DEBUG_H__ */
diff --git a/tools/lib/api/fd/Build b/tools/lib/api/fd/Build
new file mode 100644
index 0000000..605d99f
--- /dev/null
+++ b/tools/lib/api/fd/Build
@@ -0,0 +1 @@
+libapi-y += array.o
diff --git a/tools/lib/api/fd/array.c b/tools/lib/api/fd/array.c
new file mode 100644
index 0000000..b0a035f
--- /dev/null
+++ b/tools/lib/api/fd/array.c
@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2014, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
+ *
+ * Released under the GPL v2. (and only v2, not any later version)
+ */
+#include "array.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+void fdarray__init(struct fdarray *fda, int nr_autogrow)
+{
+ fda->entries = NULL;
+ fda->priv = NULL;
+ fda->nr = fda->nr_alloc = 0;
+ fda->nr_autogrow = nr_autogrow;
+}
+
+int fdarray__grow(struct fdarray *fda, int nr)
+{
+ void *priv;
+ int nr_alloc = fda->nr_alloc + nr;
+ size_t psize = sizeof(fda->priv[0]) * nr_alloc;
+ size_t size = sizeof(struct pollfd) * nr_alloc;
+ struct pollfd *entries = realloc(fda->entries, size);
+
+ if (entries == NULL)
+ return -ENOMEM;
+
+ priv = realloc(fda->priv, psize);
+ if (priv == NULL) {
+ free(entries);
+ return -ENOMEM;
+ }
+
+ fda->nr_alloc = nr_alloc;
+ fda->entries = entries;
+ fda->priv = priv;
+ return 0;
+}
+
+struct fdarray *fdarray__new(int nr_alloc, int nr_autogrow)
+{
+ struct fdarray *fda = calloc(1, sizeof(*fda));
+
+ if (fda != NULL) {
+ if (fdarray__grow(fda, nr_alloc)) {
+ free(fda);
+ fda = NULL;
+ } else {
+ fda->nr_autogrow = nr_autogrow;
+ }
+ }
+
+ return fda;
+}
+
+void fdarray__exit(struct fdarray *fda)
+{
+ free(fda->entries);
+ free(fda->priv);
+ fdarray__init(fda, 0);
+}
+
+void fdarray__delete(struct fdarray *fda)
+{
+ fdarray__exit(fda);
+ free(fda);
+}
+
+int fdarray__add(struct fdarray *fda, int fd, short revents)
+{
+ int pos = fda->nr;
+
+ if (fda->nr == fda->nr_alloc &&
+ fdarray__grow(fda, fda->nr_autogrow) < 0)
+ return -ENOMEM;
+
+ fda->entries[fda->nr].fd = fd;
+ fda->entries[fda->nr].events = revents;
+ fda->nr++;
+ return pos;
+}
+
+int fdarray__filter(struct fdarray *fda, short revents,
+ void (*entry_destructor)(struct fdarray *fda, int fd, void *arg),
+ void *arg)
+{
+ int fd, nr = 0;
+
+ if (fda->nr == 0)
+ return 0;
+
+ for (fd = 0; fd < fda->nr; ++fd) {
+ if (fda->entries[fd].revents & revents) {
+ if (entry_destructor)
+ entry_destructor(fda, fd, arg);
+
+ continue;
+ }
+
+ if (fd != nr) {
+ fda->entries[nr] = fda->entries[fd];
+ fda->priv[nr] = fda->priv[fd];
+ }
+
+ ++nr;
+ }
+
+ return fda->nr = nr;
+}
+
+int fdarray__poll(struct fdarray *fda, int timeout)
+{
+ return poll(fda->entries, fda->nr, timeout);
+}
+
+int fdarray__fprintf(struct fdarray *fda, FILE *fp)
+{
+ int fd, printed = fprintf(fp, "%d [ ", fda->nr);
+
+ for (fd = 0; fd < fda->nr; ++fd)
+ printed += fprintf(fp, "%s%d", fd ? ", " : "", fda->entries[fd].fd);
+
+ return printed + fprintf(fp, " ]");
+}
diff --git a/tools/lib/api/fd/array.h b/tools/lib/api/fd/array.h
new file mode 100644
index 0000000..b39557d
--- /dev/null
+++ b/tools/lib/api/fd/array.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_FD_ARRAY__
+#define __API_FD_ARRAY__
+
+#include <stdio.h>
+
+struct pollfd;
+
+/**
+ * struct fdarray: Array of file descriptors
+ *
+ * @priv: Per array entry priv area, users should access just its contents,
+ * not set it to anything, as it is kept in synch with @entries, being
+ * realloc'ed, * for instance, in fdarray__{grow,filter}.
+ *
+ * I.e. using 'fda->priv[N].idx = * value' where N < fda->nr is ok,
+ * but doing 'fda->priv = malloc(M)' is not allowed.
+ */
+struct fdarray {
+ int nr;
+ int nr_alloc;
+ int nr_autogrow;
+ struct pollfd *entries;
+ union {
+ int idx;
+ void *ptr;
+ } *priv;
+};
+
+void fdarray__init(struct fdarray *fda, int nr_autogrow);
+void fdarray__exit(struct fdarray *fda);
+
+struct fdarray *fdarray__new(int nr_alloc, int nr_autogrow);
+void fdarray__delete(struct fdarray *fda);
+
+int fdarray__add(struct fdarray *fda, int fd, short revents);
+int fdarray__poll(struct fdarray *fda, int timeout);
+int fdarray__filter(struct fdarray *fda, short revents,
+ void (*entry_destructor)(struct fdarray *fda, int fd, void *arg),
+ void *arg);
+int fdarray__grow(struct fdarray *fda, int extra);
+int fdarray__fprintf(struct fdarray *fda, FILE *fp);
+
+static inline int fdarray__available_entries(struct fdarray *fda)
+{
+ return fda->nr_alloc - fda->nr;
+}
+
+#endif /* __API_FD_ARRAY__ */
diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
new file mode 100644
index 0000000..f4ed962
--- /dev/null
+++ b/tools/lib/api/fs/Build
@@ -0,0 +1,2 @@
+libapi-y += fs.o
+libapi-y += tracing_path.o
diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
new file mode 100644
index 0000000..7aba824
--- /dev/null
+++ b/tools/lib/api/fs/fs.c
@@ -0,0 +1,539 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/vfs.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mount.h>
+
+#include "fs.h"
+#include "debug-internal.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
+
+#ifndef HUGETLBFS_MAGIC
+#define HUGETLBFS_MAGIC 0x958458f6
+#endif
+
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC 0xcafe4a11
+#endif
+
+static const char * const sysfs__fs_known_mountpoints[] = {
+ "/sys",
+ 0,
+};
+
+static const char * const procfs__known_mountpoints[] = {
+ "/proc",
+ 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,
+};
+
+static const char * const hugetlbfs__known_mountpoints[] = {
+ 0,
+};
+
+static const char * const bpf_fs__known_mountpoints[] = {
+ "/sys/fs/bpf",
+ 0,
+};
+
+struct fs {
+ const char *name;
+ const char * const *mounts;
+ char path[PATH_MAX];
+ bool found;
+ long magic;
+};
+
+enum {
+ FS__SYSFS = 0,
+ FS__PROCFS = 1,
+ FS__DEBUGFS = 2,
+ FS__TRACEFS = 3,
+ FS__HUGETLBFS = 4,
+ FS__BPF_FS = 5,
+};
+
+#ifndef TRACEFS_MAGIC
+#define TRACEFS_MAGIC 0x74726163
+#endif
+
+static struct fs fs__entries[] = {
+ [FS__SYSFS] = {
+ .name = "sysfs",
+ .mounts = sysfs__fs_known_mountpoints,
+ .magic = SYSFS_MAGIC,
+ },
+ [FS__PROCFS] = {
+ .name = "proc",
+ .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,
+ },
+ [FS__HUGETLBFS] = {
+ .name = "hugetlbfs",
+ .mounts = hugetlbfs__known_mountpoints,
+ .magic = HUGETLBFS_MAGIC,
+ },
+ [FS__BPF_FS] = {
+ .name = "bpf",
+ .mounts = bpf_fs__known_mountpoints,
+ .magic = BPF_FS_MAGIC,
+ },
+};
+
+static bool fs__read_mounts(struct fs *fs)
+{
+ bool found = false;
+ char type[100];
+ FILE *fp;
+
+ fp = fopen("/proc/mounts", "r");
+ if (fp == NULL)
+ return NULL;
+
+ while (!found &&
+ fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
+ fs->path, type) == 2) {
+
+ if (strcmp(type, fs->name) == 0)
+ found = true;
+ }
+
+ fclose(fp);
+ return fs->found = found;
+}
+
+static int fs__valid_mount(const char *fs, long magic)
+{
+ struct statfs st_fs;
+
+ if (statfs(fs, &st_fs) < 0)
+ return -ENOENT;
+ else if ((long)st_fs.f_type != magic)
+ return -ENOENT;
+
+ return 0;
+}
+
+static bool fs__check_mounts(struct fs *fs)
+{
+ const char * const *ptr;
+
+ ptr = fs->mounts;
+ while (*ptr) {
+ if (fs__valid_mount(*ptr, fs->magic) == 0) {
+ fs->found = true;
+ strcpy(fs->path, *ptr);
+ return true;
+ }
+ ptr++;
+ }
+
+ return false;
+}
+
+static void mem_toupper(char *f, size_t len)
+{
+ while (len) {
+ *f = toupper(*f);
+ f++;
+ len--;
+ }
+}
+
+/*
+ * Check for "NAME_PATH" environment variable to override fs location (for
+ * testing). This matches the recommendation in Documentation/admin-guide/sysfs-rules.rst
+ * for SYSFS_PATH.
+ */
+static bool fs__env_override(struct fs *fs)
+{
+ char *override_path;
+ size_t name_len = strlen(fs->name);
+ /* name + "_PATH" + '\0' */
+ char upper_name[name_len + 5 + 1];
+ memcpy(upper_name, fs->name, name_len);
+ mem_toupper(upper_name, name_len);
+ strcpy(&upper_name[name_len], "_PATH");
+
+ override_path = getenv(upper_name);
+ if (!override_path)
+ return false;
+
+ fs->found = true;
+ strncpy(fs->path, override_path, sizeof(fs->path));
+ return true;
+}
+
+static const char *fs__get_mountpoint(struct fs *fs)
+{
+ if (fs__env_override(fs))
+ return fs->path;
+
+ if (fs__check_mounts(fs))
+ return fs->path;
+
+ if (fs__read_mounts(fs))
+ return fs->path;
+
+ return NULL;
+}
+
+static const char *fs__mountpoint(int idx)
+{
+ struct fs *fs = &fs__entries[idx];
+
+ if (fs->found)
+ return (const char *)fs->path;
+
+ return fs__get_mountpoint(fs);
+}
+
+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(sysfs, FS__SYSFS);
+FS(procfs, FS__PROCFS);
+FS(debugfs, FS__DEBUGFS);
+FS(tracefs, FS__TRACEFS);
+FS(hugetlbfs, FS__HUGETLBFS);
+FS(bpf_fs, FS__BPF_FS);
+
+int filename__read_int(const char *filename, int *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 = atoi(line);
+ err = 0;
+ }
+
+ close(fd);
+ return err;
+}
+
+static int filename__read_ull_base(const char *filename,
+ unsigned long long *value, int base)
+{
+ 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, base);
+ if (*value != ULLONG_MAX)
+ err = 0;
+ }
+
+ close(fd);
+ return err;
+}
+
+/*
+ * Parses @value out of @filename with strtoull.
+ * By using 16 for base to treat the number as hex.
+ */
+int filename__read_xll(const char *filename, unsigned long long *value)
+{
+ return filename__read_ull_base(filename, value, 16);
+}
+
+/*
+ * Parses @value out of @filename with strtoull.
+ * By using 0 for base, the strtoull detects the
+ * base automatically (see man strtoull).
+ */
+int filename__read_ull(const char *filename, unsigned long long *value)
+{
+ return filename__read_ull_base(filename, value, 0);
+}
+
+#define STRERR_BUFSIZE 128 /* For the buffer size of strerror_r */
+
+int filename__read_str(const char *filename, char **buf, size_t *sizep)
+{
+ size_t size = 0, alloc_size = 0;
+ void *bf = NULL, *nbf;
+ int fd, n, err = 0;
+ char sbuf[STRERR_BUFSIZE];
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return -errno;
+
+ do {
+ if (size == alloc_size) {
+ alloc_size += BUFSIZ;
+ nbf = realloc(bf, alloc_size);
+ if (!nbf) {
+ err = -ENOMEM;
+ break;
+ }
+
+ bf = nbf;
+ }
+
+ n = read(fd, bf + size, alloc_size - size);
+ if (n < 0) {
+ if (size) {
+ pr_warning("read failed %d: %s\n", errno,
+ strerror_r(errno, sbuf, sizeof(sbuf)));
+ err = 0;
+ } else
+ err = -errno;
+
+ break;
+ }
+
+ size += n;
+ } while (n > 0);
+
+ if (!err) {
+ *sizep = size;
+ *buf = bf;
+ } else
+ free(bf);
+
+ close(fd);
+ return err;
+}
+
+int filename__write_int(const char *filename, int value)
+{
+ int fd = open(filename, O_WRONLY), err = -1;
+ char buf[64];
+
+ if (fd < 0)
+ return err;
+
+ sprintf(buf, "%d", value);
+ if (write(fd, buf, sizeof(buf)) == sizeof(buf))
+ err = 0;
+
+ close(fd);
+ return err;
+}
+
+int procfs__read_str(const char *entry, char **buf, size_t *sizep)
+{
+ char path[PATH_MAX];
+ const char *procfs = procfs__mountpoint();
+
+ if (!procfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/%s", procfs, entry);
+
+ return filename__read_str(path, buf, sizep);
+}
+
+static int sysfs__read_ull_base(const char *entry,
+ unsigned long long *value, int base)
+{
+ 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_base(path, value, base);
+}
+
+int sysfs__read_xll(const char *entry, unsigned long long *value)
+{
+ return sysfs__read_ull_base(entry, value, 16);
+}
+
+int sysfs__read_ull(const char *entry, unsigned long long *value)
+{
+ return sysfs__read_ull_base(entry, value, 0);
+}
+
+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 sysfs__read_str(const char *entry, char **buf, size_t *sizep)
+{
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+ return filename__read_str(path, buf, sizep);
+}
+
+int sysfs__read_bool(const char *entry, bool *value)
+{
+ char *buf;
+ size_t size;
+ int ret;
+
+ ret = sysfs__read_str(entry, &buf, &size);
+ if (ret < 0)
+ return ret;
+
+ switch (buf[0]) {
+ case '1':
+ case 'y':
+ case 'Y':
+ *value = true;
+ break;
+ case '0':
+ case 'n':
+ case 'N':
+ *value = false;
+ break;
+ default:
+ ret = -1;
+ }
+
+ free(buf);
+
+ return ret;
+}
+int sysctl__read_int(const char *sysctl, int *value)
+{
+ char path[PATH_MAX];
+ const char *procfs = procfs__mountpoint();
+
+ if (!procfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
+
+ return filename__read_int(path, value);
+}
+
+int sysfs__write_int(const char *entry, int value)
+{
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return -1;
+
+ if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
+ return -1;
+
+ return filename__write_int(path, value);
+}
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
new file mode 100644
index 0000000..92d03b8
--- /dev/null
+++ b/tools/lib/api/fs/fs.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_FS__
+#define __API_FS__
+
+#include <stdbool.h>
+#include <unistd.h>
+
+/*
+ * 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
+
+#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)
+FS(hugetlbfs)
+FS(bpf_fs)
+
+#undef FS
+
+
+int filename__read_int(const char *filename, int *value);
+int filename__read_ull(const char *filename, unsigned long long *value);
+int filename__read_xll(const char *filename, unsigned long long *value);
+int filename__read_str(const char *filename, char **buf, size_t *sizep);
+
+int filename__write_int(const char *filename, int value);
+
+int procfs__read_str(const char *entry, char **buf, size_t *sizep);
+
+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);
+int sysfs__read_xll(const char *entry, unsigned long long *value);
+int sysfs__read_str(const char *entry, char **buf, size_t *sizep);
+int sysfs__read_bool(const char *entry, bool *value);
+
+int sysfs__write_int(const char *entry, int value);
+#endif /* __API_FS__ */
diff --git a/tools/lib/api/fs/tracing_path.c b/tools/lib/api/fs/tracing_path.c
new file mode 100644
index 0000000..5afb11b
--- /dev/null
+++ b/tools/lib/api/fs/tracing_path.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <linux/string.h>
+#include <errno.h>
+#include <unistd.h>
+#include "fs.h"
+
+#include "tracing_path.h"
+
+static char tracing_mnt[PATH_MAX] = "/sys/kernel/debug";
+static char tracing_path[PATH_MAX] = "/sys/kernel/debug/tracing";
+static 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 tracing_path;
+}
+
+static const char *tracing_path_debugfs_mount(void)
+{
+ const char *mnt;
+
+ mnt = debugfs__mount();
+ if (!mnt)
+ return NULL;
+
+ __tracing_path_set("tracing/", mnt);
+
+ return tracing_path;
+}
+
+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_mount(), name) < 0)
+ return NULL;
+
+ return file;
+}
+
+void put_tracing_file(char *file)
+{
+ free(file);
+}
+
+char *get_events_file(const char *name)
+{
+ char *file;
+
+ if (asprintf(&file, "%s/events/%s", tracing_path_mount(), name) < 0)
+ return NULL;
+
+ return file;
+}
+
+void put_events_file(char *file)
+{
+ free(file);
+}
+
+DIR *tracing_events__opendir(void)
+{
+ DIR *dir = NULL;
+ char *path = get_tracing_file("events");
+
+ if (path) {
+ dir = opendir(path);
+ put_events_file(path);
+ }
+
+ return dir;
+}
+
+int tracing_path__strerror_open_tp(int err, char *buf, size_t size,
+ const char *sys, const char *name)
+{
+ char sbuf[128];
+ char filename[PATH_MAX];
+
+ snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*");
+
+ 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()) {
+ /* sdt markers */
+ if (!strncmp(filename, "sdt_", 4)) {
+ snprintf(buf, size,
+ "Error:\tFile %s/%s not found.\n"
+ "Hint:\tSDT event cannot be directly recorded on.\n"
+ "\tPlease first use 'perf probe %s:%s' before recording it.\n",
+ tracing_events_path, filename, sys, name);
+ } else {
+ 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_path_mount());
+ }
+ break;
+ default:
+ snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
+ break;
+ }
+
+ return 0;
+}
diff --git a/tools/lib/api/fs/tracing_path.h b/tools/lib/api/fs/tracing_path.h
new file mode 100644
index 0000000..a19136b
--- /dev/null
+++ b/tools/lib/api/fs/tracing_path.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __API_FS_TRACING_PATH_H
+#define __API_FS_TRACING_PATH_H
+
+#include <linux/types.h>
+#include <dirent.h>
+
+DIR *tracing_events__opendir(void);
+
+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);
+
+char *get_events_file(const char *name);
+void put_events_file(char *file);
+
+#define zput_events_file(ptr) ({ free(*ptr); *ptr = NULL; })
+
+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 */