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, 703 insertions, 0 deletions

diff --git a/tools/perf/util/trace-event-info.c b/tools/perf/util/trace-event-info.c
new file mode 100644
index 000000000..45774722f
--- /dev/null
+++ b/tools/perf/util/trace-event-info.c
@@ -0,0 +1,703 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2008,2009, Steven Rostedt <srostedt@redhat.com>
+ */
+#include <dirent.h>
+#include <mntent.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/zalloc.h>
+#include <internal/lib.h> // page_size
+#include <sys/param.h>
+
+#include "trace-event.h"
+#include "tracepoint.h"
+#include <api/fs/tracing_path.h>
+#include "evsel.h"
+#include "debug.h"
+#include "util.h"
+
+#define VERSION "0.6"
+#define MAX_EVENT_LENGTH 512
+
+static int output_fd;
+
+struct tracepoint_path {
+	char *system;
+	char *name;
+	struct tracepoint_path *next;
+};
+
+/* unfortunately, you can not stat debugfs or proc files for size */
+static int record_file(const char *file, ssize_t hdr_sz)
+{
+	unsigned long long size = 0;
+	char buf[BUFSIZ], *sizep;
+	off_t hdr_pos = lseek(output_fd, 0, SEEK_CUR);
+	int r, fd;
+	int err = -EIO;
+
+	fd = open(file, O_RDONLY);
+	if (fd < 0) {
+		pr_debug("Can't read '%s'", file);
+		return -errno;
+	}
+
+	/* put in zeros for file size, then fill true size later */
+	if (hdr_sz) {
+		if (write(output_fd, &size, hdr_sz) != hdr_sz)
+			goto out;
+	}
+
+	do {
+		r = read(fd, buf, BUFSIZ);
+		if (r > 0) {
+			size += r;
+			if (write(output_fd, buf, r) != r)
+				goto out;
+		}
+	} while (r > 0);
+
+	/* ugh, handle big-endian hdr_size == 4 */
+	sizep = (char*)&size;
+	if (host_is_bigendian())
+		sizep += sizeof(u64) - hdr_sz;
+
+	if (hdr_sz && pwrite(output_fd, sizep, hdr_sz, hdr_pos) < 0) {
+		pr_debug("writing file size failed\n");
+		goto out;
+	}
+
+	err = 0;
+out:
+	close(fd);
+	return err;
+}
+
+static int record_header_files(void)
+{
+	char *path = get_events_file("header_page");
+	struct stat st;
+	int err = -EIO;
+
+	if (!path) {
+		pr_debug("can't get tracing/events/header_page");
+		return -ENOMEM;
+	}
+
+	if (stat(path, &st) < 0) {
+		pr_debug("can't read '%s'", path);
+		goto out;
+	}
+
+	if (write(output_fd, "header_page", 12) != 12) {
+		pr_debug("can't write header_page\n");
+		goto out;
+	}
+
+	if (record_file(path, 8) < 0) {
+		pr_debug("can't record header_page file\n");
+		goto out;
+	}
+
+	put_events_file(path);
+
+	path = get_events_file("header_event");
+	if (!path) {
+		pr_debug("can't get tracing/events/header_event");
+		err = -ENOMEM;
+		goto out;
+	}
+
+	if (stat(path, &st) < 0) {
+		pr_debug("can't read '%s'", path);
+		goto out;
+	}
+
+	if (write(output_fd, "header_event", 13) != 13) {
+		pr_debug("can't write header_event\n");
+		goto out;
+	}
+
+	if (record_file(path, 8) < 0) {
+		pr_debug("can't record header_event file\n");
+		goto out;
+	}
+
+	err = 0;
+out:
+	put_events_file(path);
+	return err;
+}
+
+static bool name_in_tp_list(char *sys, struct tracepoint_path *tps)
+{
+	while (tps) {
+		if (!strcmp(sys, tps->name))
+			return true;
+		tps = tps->next;
+	}
+
+	return false;
+}
+
+#define for_each_event_tps(dir, dent, tps)			\
+	while ((dent = readdir(dir)))				\
+		if (dent->d_type == DT_DIR &&			\
+		    (strcmp(dent->d_name, ".")) &&		\
+		    (strcmp(dent->d_name, "..")))		\
+
+static int copy_event_system(const char *sys, struct tracepoint_path *tps)
+{
+	struct dirent *dent;
+	struct stat st;
+	char *format;
+	DIR *dir;
+	int count = 0;
+	int ret;
+	int err;
+
+	dir = opendir(sys);
+	if (!dir) {
+		pr_debug("can't read directory '%s'", sys);
+		return -errno;
+	}
+
+	for_each_event_tps(dir, dent, tps) {
+		if (!name_in_tp_list(dent->d_name, tps))
+			continue;
+
+		if (asprintf(&format, "%s/%s/format", sys, dent->d_name) < 0) {
+			err = -ENOMEM;
+			goto out;
+		}
+		ret = stat(format, &st);
+		free(format);
+		if (ret < 0)
+			continue;
+		count++;
+	}
+
+	if (write(output_fd, &count, 4) != 4) {
+		err = -EIO;
+		pr_debug("can't write count\n");
+		goto out;
+	}
+
+	rewinddir(dir);
+	for_each_event_tps(dir, dent, tps) {
+		if (!name_in_tp_list(dent->d_name, tps))
+			continue;
+
+		if (asprintf(&format, "%s/%s/format", sys, dent->d_name) < 0) {
+			err = -ENOMEM;
+			goto out;
+		}
+		ret = stat(format, &st);
+
+		if (ret >= 0) {
+			err = record_file(format, 8);
+			if (err) {
+				free(format);
+				goto out;
+			}
+		}
+		free(format);
+	}
+	err = 0;
+out:
+	closedir(dir);
+	return err;
+}
+
+static int record_ftrace_files(struct tracepoint_path *tps)
+{
+	char *path;
+	int ret;
+
+	path = get_events_file("ftrace");
+	if (!path) {
+		pr_debug("can't get tracing/events/ftrace");
+		return -ENOMEM;
+	}
+
+	ret = copy_event_system(path, tps);
+
+	put_tracing_file(path);
+
+	return ret;
+}
+
+static bool system_in_tp_list(char *sys, struct tracepoint_path *tps)
+{
+	while (tps) {
+		if (!strcmp(sys, tps->system))
+			return true;
+		tps = tps->next;
+	}
+
+	return false;
+}
+
+static int record_event_files(struct tracepoint_path *tps)
+{
+	struct dirent *dent;
+	struct stat st;
+	char *path;
+	char *sys;
+	DIR *dir;
+	int count = 0;
+	int ret;
+	int err;
+
+	path = get_tracing_file("events");
+	if (!path) {
+		pr_debug("can't get tracing/events");
+		return -ENOMEM;
+	}
+
+	dir = opendir(path);
+	if (!dir) {
+		err = -errno;
+		pr_debug("can't read directory '%s'", path);
+		goto out;
+	}
+
+	for_each_event_tps(dir, dent, tps) {
+		if (strcmp(dent->d_name, "ftrace") == 0 ||
+		    !system_in_tp_list(dent->d_name, tps))
+			continue;
+
+		count++;
+	}
+
+	if (write(output_fd, &count, 4) != 4) {
+		err = -EIO;
+		pr_debug("can't write count\n");
+		goto out;
+	}
+
+	rewinddir(dir);
+	for_each_event_tps(dir, dent, tps) {
+		if (strcmp(dent->d_name, "ftrace") == 0 ||
+		    !system_in_tp_list(dent->d_name, tps))
+			continue;
+
+		if (asprintf(&sys, "%s/%s", path, dent->d_name) < 0) {
+			err = -ENOMEM;
+			goto out;
+		}
+		ret = stat(sys, &st);
+		if (ret >= 0) {
+			ssize_t size = strlen(dent->d_name) + 1;
+
+			if (write(output_fd, dent->d_name, size) != size ||
+			    copy_event_system(sys, tps) < 0) {
+				err = -EIO;
+				free(sys);
+				goto out;
+			}
+		}
+		free(sys);
+	}
+	err = 0;
+out:
+	if (dir)
+		closedir(dir);
+	put_tracing_file(path);
+
+	return err;
+}
+
+static int record_proc_kallsyms(void)
+{
+	unsigned long long size = 0;
+	/*
+	 * Just to keep older perf.data file parsers happy, record a zero
+	 * sized kallsyms file, i.e. do the same thing that was done when
+	 * /proc/kallsyms (or something specified via --kallsyms, in a
+	 * different path) couldn't be read.
+	 */
+	return write(output_fd, &size, 4) != 4 ? -EIO : 0;
+}
+
+static int record_ftrace_printk(void)
+{
+	unsigned int size;
+	char *path;
+	struct stat st;
+	int ret, err = 0;
+
+	path = get_tracing_file("printk_formats");
+	if (!path) {
+		pr_debug("can't get tracing/printk_formats");
+		return -ENOMEM;
+	}
+
+	ret = stat(path, &st);
+	if (ret < 0) {
+		/* not found */
+		size = 0;
+		if (write(output_fd, &size, 4) != 4)
+			err = -EIO;
+		goto out;
+	}
+	err = record_file(path, 4);
+
+out:
+	put_tracing_file(path);
+	return err;
+}
+
+static int record_saved_cmdline(void)
+{
+	unsigned long long size;
+	char *path;
+	struct stat st;
+	int ret, err = 0;
+
+	path = get_tracing_file("saved_cmdlines");
+	if (!path) {
+		pr_debug("can't get tracing/saved_cmdline");
+		return -ENOMEM;
+	}
+
+	ret = stat(path, &st);
+	if (ret < 0) {
+		/* not found */
+		size = 0;
+		if (write(output_fd, &size, 8) != 8)
+			err = -EIO;
+		goto out;
+	}
+	err = record_file(path, 8);
+
+out:
+	put_tracing_file(path);
+	return err;
+}
+
+static void
+put_tracepoints_path(struct tracepoint_path *tps)
+{
+	while (tps) {
+		struct tracepoint_path *t = tps;
+
+		tps = tps->next;
+		zfree(&t->name);
+		zfree(&t->system);
+		free(t);
+	}
+}
+
+static struct tracepoint_path *tracepoint_id_to_path(u64 config)
+{
+	struct tracepoint_path *path = NULL;
+	DIR *sys_dir, *evt_dir;
+	struct dirent *sys_dirent, *evt_dirent;
+	char id_buf[24];
+	int fd;
+	u64 id;
+	char evt_path[MAXPATHLEN];
+	char *dir_path;
+
+	sys_dir = tracing_events__opendir();
+	if (!sys_dir)
+		return NULL;
+
+	for_each_subsystem(sys_dir, sys_dirent) {
+		dir_path = get_events_file(sys_dirent->d_name);
+		if (!dir_path)
+			continue;
+		evt_dir = opendir(dir_path);
+		if (!evt_dir)
+			goto next;
+
+		for_each_event(dir_path, evt_dir, evt_dirent) {
+
+			scnprintf(evt_path, MAXPATHLEN, "%s/%s/id", dir_path,
+				  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 (id == config) {
+				put_events_file(dir_path);
+				closedir(evt_dir);
+				closedir(sys_dir);
+				path = zalloc(sizeof(*path));
+				if (!path)
+					return NULL;
+				if (asprintf(&path->system, "%.*s",
+					     MAX_EVENT_LENGTH, sys_dirent->d_name) < 0) {
+					free(path);
+					return NULL;
+				}
+				if (asprintf(&path->name, "%.*s",
+					     MAX_EVENT_LENGTH, evt_dirent->d_name) < 0) {
+					zfree(&path->system);
+					free(path);
+					return NULL;
+				}
+				return path;
+			}
+		}
+		closedir(evt_dir);
+next:
+		put_events_file(dir_path);
+	}
+
+	closedir(sys_dir);
+	return NULL;
+}
+
+char *tracepoint_id_to_name(u64 config)
+{
+	struct tracepoint_path *path = tracepoint_id_to_path(config);
+	char *buf = NULL;
+
+	if (path && asprintf(&buf, "%s:%s", path->system, path->name) < 0)
+		buf = NULL;
+
+	put_tracepoints_path(path);
+	return buf;
+}
+
+static struct tracepoint_path *tracepoint_name_to_path(const char *name)
+{
+	struct tracepoint_path *path = zalloc(sizeof(*path));
+	const char *str = strchr(name, ':');
+
+	if (path == NULL || str == NULL) {
+		free(path);
+		return NULL;
+	}
+
+	path->system = strndup(name, str - name);
+	path->name = strdup(str+1);
+
+	if (path->system == NULL || path->name == NULL) {
+		zfree(&path->system);
+		zfree(&path->name);
+		zfree(&path);
+	}
+
+	return path;
+}
+
+static struct tracepoint_path *
+get_tracepoints_path(struct list_head *pattrs)
+{
+	struct tracepoint_path path, *ppath = &path;
+	struct evsel *pos;
+	int nr_tracepoints = 0;
+
+	list_for_each_entry(pos, pattrs, core.node) {
+		if (pos->core.attr.type != PERF_TYPE_TRACEPOINT)
+			continue;
+		++nr_tracepoints;
+
+		if (pos->name) {
+			ppath->next = tracepoint_name_to_path(pos->name);
+			if (ppath->next)
+				goto next;
+
+			if (strchr(pos->name, ':') == NULL)
+				goto try_id;
+
+			goto error;
+		}
+
+try_id:
+		ppath->next = tracepoint_id_to_path(pos->core.attr.config);
+		if (!ppath->next) {
+error:
+			pr_debug("No memory to alloc tracepoints list\n");
+			put_tracepoints_path(path.next);
+			return NULL;
+		}
+next:
+		ppath = ppath->next;
+	}
+
+	return nr_tracepoints > 0 ? path.next : NULL;
+}
+
+bool have_tracepoints(struct list_head *pattrs)
+{
+	struct evsel *pos;
+
+	list_for_each_entry(pos, pattrs, core.node)
+		if (pos->core.attr.type == PERF_TYPE_TRACEPOINT)
+			return true;
+
+	return false;
+}
+
+static int tracing_data_header(void)
+{
+	char buf[20];
+	ssize_t size;
+
+	/* just guessing this is someone's birthday.. ;) */
+	buf[0] = 23;
+	buf[1] = 8;
+	buf[2] = 68;
+	memcpy(buf + 3, "tracing", 7);
+
+	if (write(output_fd, buf, 10) != 10)
+		return -1;
+
+	size = strlen(VERSION) + 1;
+	if (write(output_fd, VERSION, size) != size)
+		return -1;
+
+	/* save endian */
+	if (host_is_bigendian())
+		buf[0] = 1;
+	else
+		buf[0] = 0;
+
+	if (write(output_fd, buf, 1) != 1)
+		return -1;
+
+	/* save size of long */
+	buf[0] = sizeof(long);
+	if (write(output_fd, buf, 1) != 1)
+		return -1;
+
+	/* save page_size */
+	if (write(output_fd, &page_size, 4) != 4)
+		return -1;
+
+	return 0;
+}
+
+struct tracing_data *tracing_data_get(struct list_head *pattrs,
+				      int fd, bool temp)
+{
+	struct tracepoint_path *tps;
+	struct tracing_data *tdata;
+	int err;
+
+	output_fd = fd;
+
+	tps = get_tracepoints_path(pattrs);
+	if (!tps)
+		return NULL;
+
+	tdata = malloc(sizeof(*tdata));
+	if (!tdata)
+		return NULL;
+
+	tdata->temp = temp;
+	tdata->size = 0;
+
+	if (temp) {
+		int temp_fd;
+
+		snprintf(tdata->temp_file, sizeof(tdata->temp_file),
+			 "/tmp/perf-XXXXXX");
+		if (!mkstemp(tdata->temp_file)) {
+			pr_debug("Can't make temp file");
+			free(tdata);
+			return NULL;
+		}
+
+		temp_fd = open(tdata->temp_file, O_RDWR);
+		if (temp_fd < 0) {
+			pr_debug("Can't read '%s'", tdata->temp_file);
+			free(tdata);
+			return NULL;
+		}
+
+		/*
+		 * Set the temp file the default output, so all the
+		 * tracing data are stored into it.
+		 */
+		output_fd = temp_fd;
+	}
+
+	err = tracing_data_header();
+	if (err)
+		goto out;
+	err = record_header_files();
+	if (err)
+		goto out;
+	err = record_ftrace_files(tps);
+	if (err)
+		goto out;
+	err = record_event_files(tps);
+	if (err)
+		goto out;
+	err = record_proc_kallsyms();
+	if (err)
+		goto out;
+	err = record_ftrace_printk();
+	if (err)
+		goto out;
+	err = record_saved_cmdline();
+
+out:
+	/*
+	 * All tracing data are stored by now, we can restore
+	 * the default output file in case we used temp file.
+	 */
+	if (temp) {
+		tdata->size = lseek(output_fd, 0, SEEK_CUR);
+		close(output_fd);
+		output_fd = fd;
+	}
+
+	if (err)
+		zfree(&tdata);
+
+	put_tracepoints_path(tps);
+	return tdata;
+}
+
+int tracing_data_put(struct tracing_data *tdata)
+{
+	int err = 0;
+
+	if (tdata->temp) {
+		err = record_file(tdata->temp_file, 0);
+		unlink(tdata->temp_file);
+	}
+
+	free(tdata);
+	return err;
+}
+
+int read_tracing_data(int fd, struct list_head *pattrs)
+{
+	int err;
+	struct tracing_data *tdata;
+
+	/*
+	 * We work over the real file, so we can write data
+	 * directly, no temp file is needed.
+	 */
+	tdata = tracing_data_get(pattrs, fd, false);
+	if (!tdata)
+		return -ENOMEM;
+
+	err = tracing_data_put(tdata);
+	return err;
+}