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, 210 insertions, 0 deletions

diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c
new file mode 100644
index 000000000..c08f34b9d
--- /dev/null
+++ b/tools/bpf/bpftool/token.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/* Copyright (C) 2025 Didi Technology Co., Tao Chen */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <mntent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "json_writer.h"
+#include "main.h"
+
+#define MOUNTS_FILE "/proc/mounts"
+
+static struct {
+	const char *header;
+	const char *key;
+} sets[] = {
+	{"allowed_cmds", "delegate_cmds"},
+	{"allowed_maps", "delegate_maps"},
+	{"allowed_progs", "delegate_progs"},
+	{"allowed_attachs", "delegate_attachs"},
+};
+
+static bool has_delegate_options(const char *mnt_ops)
+{
+	return strstr(mnt_ops, "delegate_cmds") ||
+	       strstr(mnt_ops, "delegate_maps") ||
+	       strstr(mnt_ops, "delegate_progs") ||
+	       strstr(mnt_ops, "delegate_attachs");
+}
+
+static char *get_delegate_value(char *opts, const char *key)
+{
+	char *token, *rest, *ret = NULL;
+
+	if (!opts)
+		return NULL;
+
+	for (token = strtok_r(opts, ",", &rest); token;
+			token = strtok_r(NULL, ",", &rest)) {
+		if (strncmp(token, key, strlen(key)) == 0 &&
+		    token[strlen(key)] == '=') {
+			ret = token + strlen(key) + 1;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void print_items_per_line(char *input, int items_per_line)
+{
+	char *str, *rest;
+	int cnt = 0;
+
+	if (!input)
+		return;
+
+	for (str = strtok_r(input, ":", &rest); str;
+			str = strtok_r(NULL, ":", &rest)) {
+		if (cnt % items_per_line == 0)
+			printf("\n\t  ");
+
+		printf("%-20s", str);
+		cnt++;
+	}
+}
+
+#define ITEMS_PER_LINE 4
+static void show_token_info_plain(struct mntent *mntent)
+{
+	size_t i;
+
+	printf("token_info  %s", mntent->mnt_dir);
+
+	for (i = 0; i < ARRAY_SIZE(sets); i++) {
+		char *opts, *value;
+
+		printf("\n\t%s:", sets[i].header);
+		opts = strdup(mntent->mnt_opts);
+		value = get_delegate_value(opts, sets[i].key);
+		print_items_per_line(value, ITEMS_PER_LINE);
+		free(opts);
+	}
+
+	printf("\n");
+}
+
+static void split_json_array_str(char *input)
+{
+	char *str, *rest;
+
+	if (!input) {
+		jsonw_start_array(json_wtr);
+		jsonw_end_array(json_wtr);
+		return;
+	}
+
+	jsonw_start_array(json_wtr);
+	for (str = strtok_r(input, ":", &rest); str;
+			str = strtok_r(NULL, ":", &rest)) {
+		jsonw_string(json_wtr, str);
+	}
+	jsonw_end_array(json_wtr);
+}
+
+static void show_token_info_json(struct mntent *mntent)
+{
+	size_t i;
+
+	jsonw_start_object(json_wtr);
+	jsonw_string_field(json_wtr, "token_info", mntent->mnt_dir);
+
+	for (i = 0; i < ARRAY_SIZE(sets); i++) {
+		char *opts, *value;
+
+		jsonw_name(json_wtr, sets[i].header);
+		opts = strdup(mntent->mnt_opts);
+		value = get_delegate_value(opts, sets[i].key);
+		split_json_array_str(value);
+		free(opts);
+	}
+
+	jsonw_end_object(json_wtr);
+}
+
+static int __show_token_info(struct mntent *mntent)
+{
+	if (json_output)
+		show_token_info_json(mntent);
+	else
+		show_token_info_plain(mntent);
+
+	return 0;
+}
+
+static int show_token_info(void)
+{
+	FILE *fp;
+	struct mntent *ent;
+
+	fp = setmntent(MOUNTS_FILE, "r");
+	if (!fp) {
+		p_err("Failed to open: %s", MOUNTS_FILE);
+		return -1;
+	}
+
+	if (json_output)
+		jsonw_start_array(json_wtr);
+
+	while ((ent = getmntent(fp)) != NULL) {
+		if (strncmp(ent->mnt_type, "bpf", 3) == 0) {
+			if (has_delegate_options(ent->mnt_opts))
+				__show_token_info(ent);
+		}
+	}
+
+	if (json_output)
+		jsonw_end_array(json_wtr);
+
+	endmntent(fp);
+
+	return 0;
+}
+
+static int do_show(int argc, char **argv)
+{
+	if (argc)
+		return BAD_ARG();
+
+	return show_token_info();
+}
+
+static int do_help(int argc, char **argv)
+{
+	if (json_output) {
+		jsonw_null(json_wtr);
+		return 0;
+	}
+
+	fprintf(stderr,
+		"Usage: %1$s %2$s { show | list }\n"
+		"       %1$s %2$s help\n"
+		"       " HELP_SPEC_OPTIONS " }\n"
+		"\n"
+		"",
+		bin_name, argv[-2]);
+	return 0;
+}
+
+static const struct cmd cmds[] = {
+	{ "show",	do_show },
+	{ "list",	do_show },
+	{ "help",	do_help },
+	{ 0 }
+};
+
+int do_token(int argc, char **argv)
+{
+	return cmd_select(cmds, argc, argv, do_help);
+}