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, 79 insertions, 0 deletions

diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
new file mode 100644
index 000000000..73bad90b0
--- /dev/null
+++ b/tools/perf/util/build-id.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef PERF_BUILD_ID_H_
+#define PERF_BUILD_ID_H_ 1
+
+#define BUILD_ID_SIZE	20 /* SHA-1 length in bytes */
+#define BUILD_ID_MIN_SIZE	16 /* MD5/UUID/GUID length in bytes */
+#define SBUILD_ID_SIZE	(BUILD_ID_SIZE * 2 + 1)
+#define SBUILD_ID_MIN_SIZE	(BUILD_ID_MIN_SIZE * 2 + 1)
+
+#include "machine.h"
+#include "tool.h"
+#include <linux/types.h>
+
+struct build_id {
+	u8	data[BUILD_ID_SIZE];
+	u8	size;
+};
+
+struct dso;
+struct feat_fd;
+struct nsinfo;
+
+void build_id__init(struct build_id *bid, const u8 *data, size_t size);
+int build_id__snprintf(const struct build_id *build_id, char *bf, size_t bf_size);
+bool build_id__is_defined(const struct build_id *bid);
+int sysfs__snprintf_build_id(const char *root_dir, char *sbuild_id, size_t sbuild_id_size);
+int filename__snprintf_build_id(const char *pathname, char *sbuild_id, size_t sbuild_id_size);
+char *build_id_cache__kallsyms_path(const char *sbuild_id, char *bf,
+				    size_t size);
+
+char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
+			     bool is_debug);
+char *__dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
+			       bool is_debug, bool is_kallsyms);
+
+int build_id__mark_dso_hit(const struct perf_tool *tool, union perf_event *event,
+			   struct perf_sample *sample, struct machine *machine);
+
+bool perf_session__read_build_ids(struct perf_session *session, bool with_hits);
+int perf_session__write_buildid_table(struct perf_session *session,
+				      struct feat_fd *fd);
+int perf_session__cache_build_ids(struct perf_session *session);
+int __perf_session__cache_build_ids(struct perf_session *session,
+				    machine__dso_t fn, void *priv);
+
+char *build_id_cache__origname(const char *sbuild_id);
+char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size);
+char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
+			       struct nsinfo *nsi, bool is_kallsyms,
+			       bool is_vdso);
+
+struct strlist;
+
+struct strlist *build_id_cache__list_all(bool validonly);
+char *build_id_cache__complement(const char *incomplete_sbuild_id);
+int build_id_cache__list_build_ids(const char *pathname, struct nsinfo *nsi,
+				   struct strlist **result);
+bool build_id_cache__cached(const char *sbuild_id);
+int build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
+			struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
+			const char *proper_name, const char *root_dir);
+int __build_id_cache__add_s(const char *sbuild_id,
+			    const char *name, struct nsinfo *nsi,
+			    bool is_kallsyms, bool is_vdso,
+			    const char *proper_name, const char *root_dir);
+static inline int build_id_cache__add_s(const char *sbuild_id,
+					const char *name, struct nsinfo *nsi,
+					bool is_kallsyms, bool is_vdso)
+{
+	return __build_id_cache__add_s(sbuild_id, name, nsi, is_kallsyms, is_vdso, NULL, NULL);
+}
+int build_id_cache__remove_s(const char *sbuild_id);
+
+extern char buildid_dir[];
+
+void set_buildid_dir(const char *dir);
+void disable_buildid_cache(void);
+
+#endif