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, 73 insertions, 0 deletions

diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
new file mode 100644
index 000000000..da4eeb4a1
--- /dev/null
+++ b/tools/perf/util/bpf-event.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_BPF_EVENT_H
+#define __PERF_BPF_EVENT_H
+
+#include <linux/compiler.h>
+#include <linux/rbtree.h>
+#include <api/fd/array.h>
+#include <stdio.h>
+
+struct bpf_prog_info;
+struct machine;
+union perf_event;
+struct perf_env;
+struct perf_sample;
+struct perf_session;
+struct record_opts;
+struct evlist;
+struct target;
+
+struct bpf_metadata {
+	union perf_event *event;
+	char		 **prog_names;
+	__u64		 nr_prog_names;
+};
+
+struct bpf_prog_info_node {
+	struct perf_bpil		*info_linear;
+	struct bpf_metadata		*metadata;
+	struct rb_node			rb_node;
+};
+
+struct btf_node {
+	struct rb_node	rb_node;
+	u32		id;
+	u32		data_size;
+	char		data[];
+};
+
+#ifdef HAVE_LIBBPF_SUPPORT
+int machine__process_bpf(struct machine *machine, union perf_event *event,
+			 struct perf_sample *sample);
+int evlist__add_bpf_sb_event(struct evlist *evlist, struct perf_env *env);
+void __bpf_event__print_bpf_prog_info(struct perf_bpil *info_linear,
+				      struct perf_env *env,
+				      FILE *fp);
+void bpf_metadata_free(struct bpf_metadata *metadata);
+#else
+static inline int machine__process_bpf(struct machine *machine __maybe_unused,
+				       union perf_event *event __maybe_unused,
+				       struct perf_sample *sample __maybe_unused)
+{
+	return 0;
+}
+
+static inline int evlist__add_bpf_sb_event(struct evlist *evlist __maybe_unused,
+					   struct perf_env *env __maybe_unused)
+{
+	return 0;
+}
+
+static inline void __bpf_event__print_bpf_prog_info(struct perf_bpil *info_linear __maybe_unused,
+						    struct perf_env *env __maybe_unused,
+						    FILE *fp __maybe_unused)
+{
+
+}
+
+static inline void bpf_metadata_free(struct bpf_metadata *metadata __maybe_unused)
+{
+
+}
+#endif // HAVE_LIBBPF_SUPPORT
+#endif