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, 500 insertions, 0 deletions

diff --git a/tools/perf/util/trace-event-read.c b/tools/perf/util/trace-event-read.c
new file mode 100644
index 000000000..db1622fc9
--- /dev/null
+++ b/tools/perf/util/trace-event-read.c
@@ -0,0 +1,500 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2009, Steven Rostedt <srostedt@redhat.com>
+ */
+#include <dirent.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 <sys/mman.h>
+#include <event-parse.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <limits.h>
+
+#include "trace-event.h"
+#include "debug.h"
+#include "util.h"
+
+static int input_fd;
+
+static ssize_t trace_data_size;
+static bool repipe;
+
+static ssize_t __do_read(int fd, void *buf, size_t size)
+{
+	size_t rsize = size;
+
+	while (size) {
+		ssize_t ret = read(fd, buf, size);
+
+		if (ret <= 0)
+			return -1;
+
+		if (repipe) {
+			ssize_t retw = write(STDOUT_FILENO, buf, ret);
+
+			if (retw <= 0 || retw != ret) {
+				pr_debug("repiping input file");
+				return -1;
+			}
+		}
+
+		size -= ret;
+		buf += ret;
+	}
+
+	return rsize;
+}
+
+static ssize_t do_read(void *data, size_t size)
+{
+	ssize_t r;
+
+	r = __do_read(input_fd, data, size);
+	if (r <= 0) {
+		pr_debug("reading input file (size expected=%zu received=%zd)",
+			 size, r);
+		return -1;
+	}
+
+	trace_data_size += r;
+
+	return r;
+}
+
+/* If it fails, the next read will report it */
+static void skip(size_t size)
+{
+	char buf[BUFSIZ];
+	ssize_t ret;
+
+	while (size) {
+		size_t len = size > BUFSIZ ? BUFSIZ : size;
+
+		ret = do_read(buf, len);
+		if (ret <= 0)
+			break;
+
+		size -= ret;
+	}
+}
+
+static unsigned int read4(struct tep_handle *pevent)
+{
+	unsigned int data;
+
+	if (do_read(&data, 4) < 0)
+		return 0;
+	return tep_read_number(pevent, &data, 4);
+}
+
+static unsigned long long read8(struct tep_handle *pevent)
+{
+	unsigned long long data;
+
+	if (do_read(&data, 8) < 0)
+		return 0;
+	return tep_read_number(pevent, &data, 8);
+}
+
+static char *read_string(void)
+{
+	char buf[BUFSIZ];
+	char *str = NULL;
+	int size = 0;
+	off_t r;
+	char c;
+
+	for (;;) {
+		r = read(input_fd, &c, 1);
+		if (r < 0) {
+			pr_debug("reading input file");
+			goto out;
+		}
+
+		if (!r) {
+			pr_debug("no data");
+			goto out;
+		}
+
+		if (repipe) {
+			int retw = write(STDOUT_FILENO, &c, 1);
+
+			if (retw <= 0 || retw != r) {
+				pr_debug("repiping input file string");
+				goto out;
+			}
+		}
+
+		if (size >= (int)sizeof(buf) - 1) {
+			pr_debug("string too long (max %zu bytes)", sizeof(buf) - 1);
+			goto out;
+		}
+
+		buf[size++] = c;
+
+		if (!c)
+			break;
+	}
+
+	trace_data_size += size;
+
+	str = malloc(size);
+	if (str)
+		memcpy(str, buf, size);
+out:
+	return str;
+}
+
+static int read_proc_kallsyms(struct tep_handle *pevent)
+{
+	unsigned int size;
+
+	size = read4(pevent);
+	if (!size)
+		return 0;
+	/*
+	 * Just skip it, now that we configure libtraceevent to use the
+	 * tools/perf/ symbol resolver.
+	 *
+	 * We need to skip it so that we can continue parsing old perf.data
+	 * files, that contains this /proc/kallsyms payload.
+	 *
+	 * Newer perf.data files will have just the 4-bytes zeros "kallsyms
+	 * payload", so that older tools can continue reading it and interpret
+	 * it as "no kallsyms payload is present".
+	 */
+	lseek(input_fd, size, SEEK_CUR);
+	trace_data_size += size;
+	return 0;
+}
+
+static int read_ftrace_printk(struct tep_handle *pevent)
+{
+	unsigned int size;
+	char *buf;
+
+	/* it can have 0 size */
+	size = read4(pevent);
+	if (!size)
+		return 0;
+
+	if (size == UINT_MAX) {
+		pr_debug("invalid ftrace printk size\n");
+		return -1;
+	}
+
+	buf = malloc(size + 1);
+	if (buf == NULL)
+		return -1;
+
+	if (do_read(buf, size) < 0) {
+		free(buf);
+		return -1;
+	}
+
+	buf[size] = '\0';
+
+	parse_ftrace_printk(pevent, buf, size);
+
+	free(buf);
+	return 0;
+}
+
+static int read_header_files(struct tep_handle *pevent)
+{
+	unsigned long long size;
+	char *header_page;
+	char buf[BUFSIZ];
+	ssize_t ret = 0;
+
+	if (do_read(buf, 12) < 0)
+		return -1;
+
+	if (memcmp(buf, "header_page", 12) != 0) {
+		pr_debug("did not read header page");
+		return -1;
+	}
+
+	size = read8(pevent);
+
+	header_page = malloc(size);
+	if (header_page == NULL)
+		return -1;
+
+	if (do_read(header_page, size) < 0) {
+		pr_debug("did not read header page");
+		free(header_page);
+		return -1;
+	}
+
+	if (!tep_parse_header_page(pevent, header_page, size,
+				   tep_get_long_size(pevent))) {
+		/*
+		 * The commit field in the page is of type long,
+		 * use that instead, since it represents the kernel.
+		 */
+		tep_set_long_size(pevent, tep_get_header_page_size(pevent));
+	}
+	free(header_page);
+
+	if (do_read(buf, 13) < 0)
+		return -1;
+
+	if (memcmp(buf, "header_event", 13) != 0) {
+		pr_debug("did not read header event");
+		return -1;
+	}
+
+	size = read8(pevent);
+	skip(size);
+
+	return ret;
+}
+
+static int read_ftrace_file(struct tep_handle *pevent, unsigned long long size)
+{
+	ssize_t ret;
+	char *buf;
+
+	buf = malloc(size);
+	if (buf == NULL) {
+		pr_debug("memory allocation failure\n");
+		return -1;
+	}
+
+	ret = do_read(buf, size);
+	if (ret < 0) {
+		pr_debug("error reading ftrace file.\n");
+		goto out;
+	}
+
+	ret = parse_ftrace_file(pevent, buf, size);
+	if (ret < 0)
+		pr_debug("error parsing ftrace file.\n");
+out:
+	free(buf);
+	return ret;
+}
+
+static int read_event_file(struct tep_handle *pevent, char *sys,
+			   unsigned long long size)
+{
+	ssize_t ret;
+	char *buf;
+
+	buf = malloc(size);
+	if (buf == NULL) {
+		pr_debug("memory allocation failure\n");
+		return -1;
+	}
+
+	ret = do_read(buf, size);
+	if (ret < 0)
+		goto out;
+
+	ret = parse_event_file(pevent, buf, size, sys);
+	if (ret < 0)
+		pr_debug("error parsing event file.\n");
+out:
+	free(buf);
+	return ret;
+}
+
+static int read_ftrace_files(struct tep_handle *pevent)
+{
+	unsigned long long size;
+	int count;
+	int i;
+	int ret;
+
+	count = read4(pevent);
+
+	for (i = 0; i < count; i++) {
+		size = read8(pevent);
+		ret = read_ftrace_file(pevent, size);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+static int read_event_files(struct tep_handle *pevent)
+{
+	unsigned long long size;
+	char *sys;
+	int systems;
+	int count;
+	int i,x;
+	ssize_t ret;
+
+	systems = read4(pevent);
+
+	for (i = 0; i < systems; i++) {
+		sys = read_string();
+		if (sys == NULL)
+			return -1;
+
+		count = read4(pevent);
+
+		for (x=0; x < count; x++) {
+			size = read8(pevent);
+			ret = read_event_file(pevent, sys, size);
+			if (ret) {
+				free(sys);
+				return ret;
+			}
+		}
+		free(sys);
+	}
+	return 0;
+}
+
+static int read_saved_cmdline(struct tep_handle *pevent)
+{
+	unsigned long long size;
+	char *buf;
+	ssize_t ret;
+
+	/* it can have 0 size */
+	size = read8(pevent);
+	if (!size)
+		return 0;
+
+	if (size == ULLONG_MAX) {
+		pr_debug("invalid saved cmdline size");
+		return -1;
+	}
+
+	buf = malloc(size + 1);
+	if (buf == NULL) {
+		pr_debug("memory allocation failure\n");
+		return -1;
+	}
+
+	ret = do_read(buf, size);
+	if (ret < 0) {
+		pr_debug("error reading saved cmdlines\n");
+		goto out;
+	}
+	buf[ret] = '\0';
+
+	parse_saved_cmdline(pevent, buf, size);
+	ret = 0;
+out:
+	free(buf);
+	return ret;
+}
+
+ssize_t trace_report(int fd, struct trace_event *tevent, bool __repipe)
+{
+	char buf[BUFSIZ];
+	char test[] = { 23, 8, 68 };
+	char *version;
+	int show_version = 0;
+	int show_funcs = 0;
+	int show_printk = 0;
+	ssize_t size = -1;
+	int file_bigendian;
+	int host_bigendian;
+	int file_long_size;
+	int file_page_size;
+	struct tep_handle *pevent = NULL;
+	int err;
+
+	repipe = __repipe;
+	input_fd = fd;
+
+	if (do_read(buf, 3) < 0)
+		return -1;
+	if (memcmp(buf, test, 3) != 0) {
+		pr_debug("no trace data in the file");
+		return -1;
+	}
+
+	if (do_read(buf, 7) < 0)
+		return -1;
+	if (memcmp(buf, "tracing", 7) != 0) {
+		pr_debug("not a trace file (missing 'tracing' tag)");
+		return -1;
+	}
+
+	version = read_string();
+	if (version == NULL)
+		return -1;
+	if (show_version)
+		printf("version = %s\n", version);
+
+	if (do_read(buf, 1) < 0) {
+		free(version);
+		return -1;
+	}
+	file_bigendian = buf[0];
+	host_bigendian = host_is_bigendian() ? 1 : 0;
+
+	if (trace_event__init(tevent)) {
+		pr_debug("trace_event__init failed");
+		goto out;
+	}
+
+	pevent = tevent->pevent;
+
+	tep_set_flag(pevent, TEP_NSEC_OUTPUT);
+	tep_set_file_bigendian(pevent, file_bigendian);
+	tep_set_local_bigendian(pevent, host_bigendian);
+
+	if (do_read(buf, 1) < 0)
+		goto out;
+	file_long_size = buf[0];
+
+	file_page_size = read4(pevent);
+	if (!file_page_size)
+		goto out;
+
+	tep_set_long_size(pevent, file_long_size);
+	tep_set_page_size(pevent, file_page_size);
+
+	err = read_header_files(pevent);
+	if (err)
+		goto out;
+	err = read_ftrace_files(pevent);
+	if (err)
+		goto out;
+	err = read_event_files(pevent);
+	if (err)
+		goto out;
+	err = read_proc_kallsyms(pevent);
+	if (err)
+		goto out;
+	err = read_ftrace_printk(pevent);
+	if (err)
+		goto out;
+	if (atof(version) >= 0.6) {
+		err = read_saved_cmdline(pevent);
+		if (err)
+			goto out;
+	}
+
+	size = trace_data_size;
+	repipe = false;
+
+	if (show_funcs) {
+		tep_print_funcs(pevent);
+	} else if (show_printk) {
+		tep_print_printk(pevent);
+	}
+
+	pevent = NULL;
+
+out:
+	if (pevent)
+		trace_event__cleanup(tevent);
+	free(version);
+	return size;
+}