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, 57 insertions, 0 deletions

diff --git a/tools/perf/util/capstone.h b/tools/perf/util/capstone.h
new file mode 100644
index 000000000..7c0baaa01
--- /dev/null
+++ b/tools/perf/util/capstone.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_CAPSTONE_H
+#define __PERF_CAPSTONE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+struct annotate_args;
+struct machine;
+struct symbol;
+struct thread;
+
+#ifdef HAVE_LIBCAPSTONE_SUPPORT
+ssize_t capstone__fprintf_insn_asm(struct machine *machine, struct thread *thread, u8 cpumode,
+				   bool is64bit, const uint8_t *code, size_t code_size,
+				   uint64_t ip, int *lenp, int print_opts, FILE *fp);
+int symbol__disassemble_capstone(const char *filename, struct symbol *sym,
+				 struct annotate_args *args);
+int symbol__disassemble_capstone_powerpc(const char *filename, struct symbol *sym,
+					 struct annotate_args *args);
+
+#else /* !HAVE_LIBCAPSTONE_SUPPORT */
+static inline ssize_t capstone__fprintf_insn_asm(struct machine *machine __maybe_unused,
+						 struct thread *thread __maybe_unused,
+						 u8 cpumode __maybe_unused,
+						 bool is64bit __maybe_unused,
+						 const uint8_t *code __maybe_unused,
+						 size_t code_size __maybe_unused,
+						 uint64_t ip __maybe_unused,
+						 int *lenp __maybe_unused,
+						 int print_opts __maybe_unused,
+						 FILE *fp __maybe_unused)
+{
+	return -1;
+}
+
+static inline int symbol__disassemble_capstone(const char *filename __maybe_unused,
+					       struct symbol *sym __maybe_unused,
+					       struct annotate_args *args __maybe_unused)
+{
+	return -1;
+}
+
+static inline int symbol__disassemble_capstone_powerpc(const char *filename __maybe_unused,
+						       struct symbol *sym __maybe_unused,
+						       struct annotate_args *args __maybe_unused)
+{
+	return -1;
+}
+
+#endif /* HAVE_LIBCAPSTONE_SUPPORT */
+
+#endif /* __PERF_CAPSTONE_H */