ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 597 insertions, 0 deletions

diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
new file mode 100644
index 000000000..33fd1b820
--- /dev/null
+++ b/tools/perf/util/data.c
@@ -0,0 +1,597 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/zalloc.h>
+#include <linux/err.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <asm/bug.h>
+#include <dirent.h>
+
+#include "data.h"
+#include "util.h" // rm_rf_perf_data()
+#include "debug.h"
+#include "header.h"
+#include "rlimit.h"
+#include <internal/lib.h>
+
+static void perf_data_file__close(struct perf_data_file *file)
+{
+	if (file->use_stdio) {
+		if (file->fptr) {
+			fclose(file->fptr);
+			file->fptr = NULL;
+		}
+	} else {
+		close(file->fd);
+		file->fd = -1;
+	}
+	zfree(&file->path);
+}
+
+static void close_dir(struct perf_data_file *files, int nr)
+{
+	while (--nr >= 0)
+		perf_data_file__close(&files[nr]);
+
+	free(files);
+}
+
+void perf_data__close_dir(struct perf_data *data)
+{
+	close_dir(data->dir.files, data->dir.nr);
+	data->dir.files = NULL;
+	data->dir.nr = 0;
+}
+
+int perf_data__create_dir(struct perf_data *data, int nr)
+{
+	enum rlimit_action set_rlimit = NO_CHANGE;
+	struct perf_data_file *files = NULL;
+	int i, ret;
+
+	if (WARN_ON(!data->is_dir))
+		return -EINVAL;
+
+	files = calloc(nr, sizeof(*files));
+	if (!files)
+		return -ENOMEM;
+
+	for (i = 0; i < nr; i++) {
+		struct perf_data_file *file = &files[i];
+
+		ret = asprintf(&file->path, "%s/data.%d", data->path, i);
+		if (ret < 0) {
+			ret = -ENOMEM;
+			goto out_err;
+		}
+
+retry_open:
+		ret = open(file->path, O_RDWR|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
+		if (ret < 0) {
+			/*
+			 * If using parallel threads to collect data,
+			 * perf record needs at least 6 fds per CPU.
+			 * When we run out of them try to increase the limits.
+			 */
+			if (errno == EMFILE && rlimit__increase_nofile(&set_rlimit))
+				goto retry_open;
+
+			ret = -errno;
+			goto out_err;
+		}
+		set_rlimit = NO_CHANGE;
+
+		file->fd = ret;
+	}
+
+	data->dir.version = PERF_DIR_VERSION;
+	data->dir.files   = files;
+	data->dir.nr      = nr;
+	return 0;
+
+out_err:
+	close_dir(files, i);
+	return ret;
+}
+
+int perf_data__open_dir(struct perf_data *data)
+{
+	struct perf_data_file *files = NULL;
+	struct dirent *dent;
+	int ret = -1;
+	DIR *dir;
+	int nr = 0;
+
+	/*
+	 * Directory containing a single regular perf data file which is already
+	 * open, means there is nothing more to do here.
+	 */
+	if (perf_data__is_single_file(data))
+		return 0;
+
+	if (WARN_ON(!data->is_dir))
+		return -EINVAL;
+
+	/* The version is provided by DIR_FORMAT feature. */
+	if (WARN_ON(data->dir.version != PERF_DIR_VERSION))
+		return -1;
+
+	dir = opendir(data->path);
+	if (!dir)
+		return -EINVAL;
+
+	while ((dent = readdir(dir)) != NULL) {
+		struct perf_data_file *file;
+		char path[PATH_MAX];
+		struct stat st;
+
+		snprintf(path, sizeof(path), "%s/%s", data->path, dent->d_name);
+		if (stat(path, &st))
+			continue;
+
+		if (!S_ISREG(st.st_mode) || strncmp(dent->d_name, "data.", 5))
+			continue;
+
+		ret = -ENOMEM;
+
+		file = realloc(files, (nr + 1) * sizeof(*files));
+		if (!file)
+			goto out_err;
+
+		files = file;
+		file = &files[nr++];
+
+		*file = (struct perf_data_file){
+			.path = strdup(path),
+			.fd = -1,
+			.size = st.st_size,
+			.use_stdio = false,
+		};
+		if (!file->path)
+			goto out_err;
+
+		ret = open(file->path, O_RDONLY);
+		if (ret < 0) {
+			ret = -errno;
+			goto out_err;
+		}
+		file->fd = ret;
+	}
+
+	closedir(dir);
+	if (!files)
+		return -EINVAL;
+
+	data->dir.files = files;
+	data->dir.nr    = nr;
+	return 0;
+
+out_err:
+	closedir(dir);
+	close_dir(files, nr);
+	return ret;
+}
+
+static bool check_pipe(struct perf_data *data)
+{
+	struct stat st;
+	bool is_pipe = false;
+	int fd = perf_data__is_read(data) ?
+		 STDIN_FILENO : STDOUT_FILENO;
+
+	if (!data->path) {
+		if (!fstat(fd, &st) && S_ISFIFO(st.st_mode))
+			is_pipe = true;
+	} else {
+		if (!strcmp(data->path, "-"))
+			is_pipe = true;
+	}
+
+	if (is_pipe) {
+		if (data->file.use_stdio) {
+			const char *mode;
+
+			mode = perf_data__is_read(data) ? "r" : "w";
+			data->file.fptr = fdopen(fd, mode);
+
+			if (data->file.fptr == NULL) {
+				data->file.fd = fd;
+				data->file.use_stdio = false;
+			}
+
+		/*
+		 * When is_pipe and data->file.fd is given, use given fd
+		 * instead of STDIN_FILENO or STDOUT_FILENO
+		 */
+		} else if (data->file.fd <= 0) {
+			data->file.fd = fd;
+		}
+	}
+
+	return data->is_pipe = is_pipe;
+}
+
+static int check_backup(struct perf_data *data)
+{
+	struct stat st;
+
+	if (perf_data__is_read(data))
+		return 0;
+
+	if (!stat(data->path, &st) && st.st_size) {
+		char oldname[PATH_MAX];
+		int ret;
+
+		snprintf(oldname, sizeof(oldname), "%s.old",
+			 data->path);
+
+		ret = rm_rf_perf_data(oldname);
+		if (ret) {
+			if (ret == -2)
+				pr_err("Can't remove old data: Unknown file found (%s)\n", oldname);
+			else
+				pr_err("Can't remove old data: %m (%s)\n", oldname);
+			return -1;
+		}
+
+		if (rename(data->path, oldname)) {
+			pr_err("Can't move data: %m (%s to %s)\n", data->path, oldname);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static bool is_dir(struct perf_data *data)
+{
+	struct stat st;
+
+	if (stat(data->path, &st))
+		return false;
+
+	return (st.st_mode & S_IFMT) == S_IFDIR;
+}
+
+static int open_file_read(struct perf_data *data)
+{
+	int flags = data->in_place_update ? O_RDWR : O_RDONLY;
+	struct stat st;
+	int fd;
+
+	fd = open(data->file.path, flags);
+	if (fd < 0) {
+		int err = errno;
+
+		pr_err("failed to open %s: %m", data->file.path);
+		if (err == ENOENT && !strcmp(data->file.path, "perf.data"))
+			pr_err("  (try 'perf record' first)");
+		pr_err("\n");
+		return -err;
+	}
+
+	if (fstat(fd, &st) < 0)
+		goto out_close;
+
+	if (!data->force && st.st_uid && (st.st_uid != geteuid())) {
+		pr_err("File %s not owned by current user or root (use -f to override)\n",
+		       data->file.path);
+		goto out_close;
+	}
+
+	if (!st.st_size) {
+		pr_info("zero-sized data (%s), nothing to do!\n",
+			data->file.path);
+		goto out_close;
+	}
+
+	data->file.size = st.st_size;
+	return fd;
+
+ out_close:
+	close(fd);
+	return -1;
+}
+
+static int open_file_write(struct perf_data *data)
+{
+	int fd = open(data->file.path, O_CREAT|O_RDWR|O_TRUNC|O_CLOEXEC, S_IRUSR|S_IWUSR);
+
+	if (fd < 0)
+		pr_err("failed to open %s : %m\n", data->file.path);
+
+	return fd;
+}
+
+static int open_file(struct perf_data *data)
+{
+	int fd;
+
+	fd = perf_data__is_read(data) ?
+	     open_file_read(data) : open_file_write(data);
+
+	if (fd < 0) {
+		zfree(&data->file.path);
+		return -1;
+	}
+
+	data->file.fd = fd;
+	return 0;
+}
+
+static int open_file_dup(struct perf_data *data)
+{
+	data->file.path = strdup(data->path);
+	if (!data->file.path)
+		return -ENOMEM;
+
+	return open_file(data);
+}
+
+static int open_dir(struct perf_data *data)
+{
+	int ret;
+
+	/*
+	 * So far we open only the header, so we can read the data version and
+	 * layout.
+	 */
+	if (asprintf(&data->file.path, "%s/data", data->path) < 0)
+		return -1;
+
+	if (perf_data__is_write(data) && mkdir(data->path, 0700) < 0) {
+		zfree(&data->file.path);
+		return -1;
+	}
+
+	ret = open_file(data);
+
+	/* Cleanup whatever we managed to create so far. */
+	if (ret && perf_data__is_write(data))
+		rm_rf_perf_data(data->path);
+
+	return ret;
+}
+
+int perf_data__open(struct perf_data *data)
+{
+	int ret;
+
+	if (data->open)
+		return 0;
+
+	if (check_pipe(data)) {
+		data->open = true;
+		return 0;
+	}
+
+	/* currently it allows stdio for pipe only */
+	data->file.use_stdio = false;
+
+	if (!data->path)
+		data->path = "perf.data";
+
+	if (check_backup(data))
+		return -1;
+
+	if (perf_data__is_read(data))
+		data->is_dir = is_dir(data);
+
+	ret = perf_data__is_dir(data) ? open_dir(data) : open_file_dup(data);
+
+	if (!ret)
+		data->open = true;
+
+	return ret;
+}
+
+void perf_data__close(struct perf_data *data)
+{
+	if (!data->open)
+		return;
+
+	if (perf_data__is_dir(data))
+		perf_data__close_dir(data);
+
+	perf_data_file__close(&data->file);
+	data->open = false;
+}
+
+static ssize_t perf_data_file__read(struct perf_data_file *file, void *buf, size_t size)
+{
+	if (file->use_stdio) {
+		if (fread(buf, size, 1, file->fptr) == 1)
+			return size;
+		return feof(file->fptr) ? 0 : -1;
+	}
+	return readn(file->fd, buf, size);
+}
+
+ssize_t perf_data__read(struct perf_data *data, void *buf, size_t size)
+{
+	return perf_data_file__read(&data->file, buf, size);
+}
+
+ssize_t perf_data_file__write(struct perf_data_file *file,
+			      void *buf, size_t size)
+{
+	if (file->use_stdio) {
+		if (fwrite(buf, size, /*nmemb=*/1, file->fptr) == 1)
+			return size;
+		return -1;
+	}
+	return writen(file->fd, buf, size);
+}
+
+ssize_t perf_data__write(struct perf_data *data,
+			 void *buf, size_t size)
+{
+	return perf_data_file__write(&data->file, buf, size);
+}
+
+off_t perf_data_file__seek(struct perf_data_file *file, off_t offset, int whence)
+{
+	if (file->use_stdio) {
+		off_t res = fseeko(file->fptr, offset, whence);
+
+		return res < 0 ? -1 : ftello(file->fptr);
+	}
+	return lseek(file->fd, offset, whence);
+}
+
+off_t perf_data__seek(struct perf_data *data, off_t offset, int whence)
+{
+	/* Note, a pipe fd will fail with -1 with errno of ESPIPE. */
+	return perf_data_file__seek(&data->file, offset, whence);
+}
+
+int perf_data__switch(struct perf_data *data,
+		      const char *postfix,
+		      size_t pos, bool at_exit,
+		      char **new_filepath)
+{
+	int ret;
+
+	if (perf_data__is_read(data))
+		return -EINVAL;
+
+	if (asprintf(new_filepath, "%s.%s", data->path, postfix) < 0)
+		return -ENOMEM;
+
+	/*
+	 * Only fire a warning, don't return error, continue fill
+	 * original file.
+	 */
+	if (rename(data->path, *new_filepath))
+		pr_warning("Failed to rename %s to %s\n", data->path, *new_filepath);
+
+	if (!at_exit) {
+		perf_data_file__close(&data->file);
+		data->open = false;
+		ret = perf_data__open(data);
+		if (ret < 0)
+			goto out;
+
+		if (perf_data__seek(data, pos, SEEK_SET) == (off_t)-1) {
+			ret = -errno;
+			pr_debug("Failed to seek to %zu: %m", pos);
+			goto out;
+		}
+	}
+	ret = perf_data__fd(data);
+out:
+	return ret;
+}
+
+unsigned long perf_data__size(struct perf_data *data)
+{
+	u64 size = data->file.size;
+	int i;
+
+	if (perf_data__is_single_file(data))
+		return size;
+
+	for (i = 0; i < data->dir.nr; i++) {
+		struct perf_data_file *file = &data->dir.files[i];
+
+		size += file->size;
+	}
+
+	return size;
+}
+
+int perf_data__make_kcore_dir(struct perf_data *data, char *buf, size_t buf_sz)
+{
+	int ret;
+
+	if (!data->is_dir)
+		return -1;
+
+	ret = snprintf(buf, buf_sz, "%s/kcore_dir", data->path);
+	if (ret < 0 || (size_t)ret >= buf_sz)
+		return -1;
+
+	return mkdir(buf, S_IRWXU);
+}
+
+bool has_kcore_dir(const char *path)
+{
+	struct dirent *d = ERR_PTR(-EINVAL);
+	const char *name = "kcore_dir";
+	DIR *dir = opendir(path);
+	size_t n = strlen(name);
+	bool result = false;
+
+	if (dir) {
+		while (d && !result) {
+			d = readdir(dir);
+			result = d ? strncmp(d->d_name, name, n) : false;
+		}
+		closedir(dir);
+	}
+
+	return result;
+}
+
+char *perf_data__kallsyms_name(struct perf_data *data)
+{
+	char *kallsyms_name;
+	struct stat st;
+
+	if (!data->is_dir)
+		return NULL;
+
+	if (asprintf(&kallsyms_name, "%s/kcore_dir/kallsyms", data->path) < 0)
+		return NULL;
+
+	if (stat(kallsyms_name, &st)) {
+		free(kallsyms_name);
+		return NULL;
+	}
+
+	return kallsyms_name;
+}
+
+char *perf_data__guest_kallsyms_name(struct perf_data *data, pid_t machine_pid)
+{
+	char *kallsyms_name;
+	struct stat st;
+
+	if (!data->is_dir)
+		return NULL;
+
+	if (asprintf(&kallsyms_name, "%s/kcore_dir__%d/kallsyms", data->path, machine_pid) < 0)
+		return NULL;
+
+	if (stat(kallsyms_name, &st)) {
+		free(kallsyms_name);
+		return NULL;
+	}
+
+	return kallsyms_name;
+}
+
+bool is_perf_data(const char *path)
+{
+	bool ret = false;
+	FILE *file;
+	u64 magic;
+
+	file = fopen(path, "r");
+	if (!file)
+		return false;
+
+	if (fread(&magic, 1, 8, file) < 8)
+		goto out;
+
+	ret = is_perf_magic(magic);
+out:
+	fclose(file);
+	return ret;
+}