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, 355 insertions, 0 deletions

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
new file mode 100644
index 000000000..75b11dc85
--- /dev/null
+++ b/tools/objtool/builtin-check.c
@@ -0,0 +1,355 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#include <subcmd/parse-options.h>
+#include <string.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/sendfile.h>
+#include <objtool/builtin.h>
+#include <objtool/objtool.h>
+#include <objtool/warn.h>
+
+#define ORIG_SUFFIX ".orig"
+
+int orig_argc;
+static char **orig_argv;
+const char *objname;
+struct opts opts;
+
+static const char * const check_usage[] = {
+	"objtool <actions> [<options>] file.o",
+	NULL,
+};
+
+static const char * const env_usage[] = {
+	"OBJTOOL_ARGS=\"<options>\"",
+	NULL,
+};
+
+static int parse_dump(const struct option *opt, const char *str, int unset)
+{
+	if (!str || !strcmp(str, "orc")) {
+		opts.dump_orc = true;
+		return 0;
+	}
+
+	return -1;
+}
+
+static int parse_hacks(const struct option *opt, const char *str, int unset)
+{
+	bool found = false;
+
+	/*
+	 * Use strstr() as a lazy method of checking for comma-separated
+	 * options.
+	 *
+	 * No string provided == enable all options.
+	 */
+
+	if (!str || strstr(str, "jump_label")) {
+		opts.hack_jump_label = true;
+		found = true;
+	}
+
+	if (!str || strstr(str, "noinstr")) {
+		opts.hack_noinstr = true;
+		found = true;
+	}
+
+	if (!str || strstr(str, "skylake")) {
+		opts.hack_skylake = true;
+		found = true;
+	}
+
+	return found ? 0 : -1;
+}
+
+static const struct option check_options[] = {
+	OPT_GROUP("Actions:"),
+	OPT_STRING_OPTARG('d',	 "disas", &opts.disas, "function-pattern", "disassemble functions", "*"),
+	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
+	OPT_BOOLEAN('i',	 "ibt", &opts.ibt, "validate and annotate IBT"),
+	OPT_BOOLEAN(0,		 "klp-symids", &opts.klp_symids, "generate .klp.symids for duplicate symbol disambiguation"),
+	OPT_BOOLEAN('m',	 "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
+	OPT_BOOLEAN(0,		 "noabs", &opts.noabs, "reject absolute references in allocatable sections"),
+	OPT_BOOLEAN('n',	 "noinstr", &opts.noinstr, "validate noinstr rules"),
+	OPT_BOOLEAN(0,		 "orc", &opts.orc, "generate ORC metadata"),
+	OPT_BOOLEAN('r',	 "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
+	OPT_BOOLEAN(0,		 "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
+	OPT_BOOLEAN(0,		 "unret", &opts.unret, "validate entry unret placement"),
+	OPT_INTEGER(0,		 "prefix", &opts.prefix, "generate or grow prefix symbols for N-byte function padding"),
+	OPT_BOOLEAN('l',	 "sls", &opts.sls, "validate straight-line-speculation mitigations"),
+	OPT_BOOLEAN('s',	 "stackval", &opts.stackval, "validate frame pointer rules"),
+	OPT_BOOLEAN('t',	 "static-call", &opts.static_call, "annotate static calls"),
+	OPT_BOOLEAN('u',	 "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
+	OPT_CALLBACK_OPTARG(0,	 "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
+
+	OPT_GROUP("Options:"),
+	OPT_BOOLEAN(0,		 "cfi", &opts.cfi, "grow kCFI preamble symbols (use with --prefix)"),
+	OPT_BOOLEAN(0,		 "fineibt", &opts.fineibt, "create .cfi_sites section for FineIBT"),
+	OPT_BOOLEAN(0,		 "backtrace", &opts.backtrace, "unwind on error"),
+	OPT_BOOLEAN(0,		 "backup", &opts.backup, "create backup (.orig) file on warning/error"),
+	OPT_BOOLEAN(0,		 "dry-run", &opts.dryrun, "don't write modifications"),
+	OPT_BOOLEAN(0,		 "link", &opts.link, "object is a linked object"),
+	OPT_BOOLEAN(0,		 "module", &opts.module, "object is part of a kernel module"),
+	OPT_BOOLEAN(0,		 "mnop", &opts.mnop, "nop out mcount call sites"),
+	OPT_BOOLEAN(0,		 "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
+	OPT_STRING('o',		 "output", &opts.output, "file", "output file name"),
+	OPT_BOOLEAN(0,		 "sec-address", &opts.sec_address, "print section addresses in warnings"),
+	OPT_BOOLEAN(0,		 "stats", &opts.stats, "print statistics"),
+	OPT_STRING(0,		 "trace", &opts.trace, "func", "trace function validation"),
+	OPT_BOOLEAN('v',	 "verbose", &opts.verbose, "verbose warnings"),
+	OPT_BOOLEAN(0,		 "werror", &opts.werror, "return error on warnings"),
+	OPT_BOOLEAN(0,		 "wide", &opts.wide, "wide output"),
+
+	OPT_END(),
+};
+
+int cmd_parse_options(int argc, const char **argv, const char * const usage[])
+{
+	const char *envv[16] = { };
+	char *env;
+	int envc;
+
+	env = getenv("OBJTOOL_ARGS");
+	if (env) {
+		envv[0] = "OBJTOOL_ARGS";
+		for (envc = 1; envc < ARRAY_SIZE(envv); ) {
+			envv[envc++] = env;
+			env = strchr(env, ' ');
+			if (!env)
+				break;
+			*env = '\0';
+			env++;
+		}
+
+		parse_options(envc, envv, check_options, env_usage, 0);
+	}
+
+	env = getenv("OBJTOOL_VERBOSE");
+	if (env && !strcmp(env, "1"))
+		opts.verbose = true;
+
+	argc = parse_options(argc, argv, check_options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, check_options);
+	return argc;
+}
+
+static bool opts_valid(void)
+{
+	if (opts.mnop && !opts.mcount) {
+		ERROR("--mnop requires --mcount");
+		return false;
+	}
+
+	if (opts.noinstr && !opts.link) {
+		ERROR("--noinstr requires --link");
+		return false;
+	}
+
+	if (opts.ibt && !opts.link) {
+		ERROR("--ibt requires --link");
+		return false;
+	}
+
+	if (opts.unret && !opts.link) {
+		ERROR("--unret requires --link");
+		return false;
+	}
+
+	if (opts.cfi && !opts.prefix) {
+		ERROR("--cfi requires --prefix");
+		return false;
+	}
+
+	if (opts.fineibt && !opts.cfi) {
+		ERROR("--fineibt requires --cfi");
+		return false;
+	}
+
+	if (opts.klp_symids && !opts.link) {
+		ERROR("--klp-symids requires --link");
+		return false;
+	}
+
+	if (opts.disas			||
+	    opts.hack_jump_label	||
+	    opts.hack_noinstr		||
+	    opts.ibt			||
+	    opts.klp_symids		||
+	    opts.mcount			||
+	    opts.noabs			||
+	    opts.noinstr		||
+	    opts.orc			||
+	    opts.retpoline		||
+	    opts.rethunk		||
+	    opts.sls			||
+	    opts.stackval		||
+	    opts.static_call		||
+	    opts.uaccess) {
+		if (opts.dump_orc) {
+			ERROR("--dump can't be combined with other actions");
+			return false;
+		}
+
+		return true;
+	}
+
+	if (opts.dump_orc)
+		return true;
+
+	ERROR("At least one action required");
+	return false;
+}
+
+static int copy_file(const char *src, const char *dst)
+{
+	size_t to_copy, copied;
+	int dst_fd, src_fd;
+	struct stat stat;
+	off_t offset = 0;
+
+	src_fd = open(src, O_RDONLY);
+	if (src_fd == -1) {
+		ERROR("can't open %s for reading: %s", src, strerror(errno));
+		return 1;
+	}
+
+	dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC, 0400);
+	if (dst_fd == -1) {
+		ERROR("can't open %s for writing: %s", dst, strerror(errno));
+		return 1;
+	}
+
+	if (fstat(src_fd, &stat) == -1) {
+		ERROR_GLIBC("fstat");
+		return 1;
+	}
+
+	if (fchmod(dst_fd, stat.st_mode) == -1) {
+		ERROR_GLIBC("fchmod");
+		return 1;
+	}
+
+	for (to_copy = stat.st_size; to_copy > 0; to_copy -= copied) {
+		copied = sendfile(dst_fd, src_fd, &offset, to_copy);
+		if (copied == -1) {
+			ERROR_GLIBC("sendfile");
+			return 1;
+		}
+	}
+
+	close(dst_fd);
+	close(src_fd);
+	return 0;
+}
+
+static void save_argv(int argc, const char **argv)
+{
+	orig_argv = calloc(argc, sizeof(char *));
+	if (!orig_argv) {
+		ERROR_GLIBC("calloc");
+		exit(1);
+	}
+
+	for (int i = 0; i < argc; i++) {
+		orig_argv[i] = strdup(argv[i]);
+		if (!orig_argv[i]) {
+			ERROR_GLIBC("strdup(%s)", argv[i]);
+			exit(1);
+		}
+	}
+}
+
+int make_backup(void)
+{
+	char *backup;
+
+	/*
+	 * Make a backup before kbuild deletes the file so the error
+	 * can be recreated without recompiling or relinking.
+	 */
+	backup = malloc(strlen(objname) + strlen(ORIG_SUFFIX) + 1);
+	if (!backup) {
+		ERROR_GLIBC("malloc");
+		return 1;
+	}
+
+	strcpy(backup, objname);
+	strcat(backup, ORIG_SUFFIX);
+	if (copy_file(objname, backup))
+		return 1;
+
+	/*
+	 * Print the cmdline args to make it easier to recreate.
+	 */
+
+	fprintf(stderr, "%s", orig_argv[0]);
+
+	for (int i = 1; i < orig_argc; i++) {
+		char *arg = orig_argv[i];
+
+		/* Modify the printed args to use the backup */
+		if (!opts.output && !strcmp(arg, objname))
+			fprintf(stderr, " %s -o %s", backup, objname);
+		else
+			fprintf(stderr, " %s", arg);
+	}
+
+	fprintf(stderr, "\n");
+	return 0;
+}
+
+int objtool_run(int argc, const char **argv)
+{
+	struct objtool_file *file;
+	int ret = 0;
+
+	orig_argc = argc;
+	save_argv(argc, argv);
+
+	cmd_parse_options(argc, argv, check_usage);
+
+	if (!opts_valid())
+		return 1;
+
+	objname = argv[0];
+
+	if (opts.dump_orc)
+		return orc_dump(objname);
+
+	if (!opts.dryrun && opts.output) {
+		/* copy original .o file to output file */
+		if (copy_file(objname, opts.output))
+			return 1;
+
+		/* from here on, work directly on the output file */
+		objname = opts.output;
+	}
+
+	file = objtool_open_read(objname);
+	if (!file)
+		return 1;
+
+	if (!opts.link && has_multiple_files(file->elf)) {
+		ERROR("Linked object requires --link");
+		return 1;
+	}
+
+	ret = check(file);
+	if (ret)
+		return ret;
+
+	if (!opts.dryrun && file->elf->changed && elf_write(file->elf))
+		return 1;
+
+	return elf_close(file->elf);
+}