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, 43 insertions, 0 deletions

diff --git a/include/asm-generic/seccomp.h b/include/asm-generic/seccomp.h
new file mode 100644
index 000000000..6b6f42bc5
--- /dev/null
+++ b/include/asm-generic/seccomp.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * include/asm-generic/seccomp.h
+ *
+ * Copyright (C) 2014 Linaro Limited
+ * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
+ */
+#ifndef _ASM_GENERIC_SECCOMP_H
+#define _ASM_GENERIC_SECCOMP_H
+
+#include <linux/unistd.h>
+
+#if defined(CONFIG_COMPAT) && !defined(__NR_seccomp_read_32)
+#define __NR_seccomp_read_32		__NR_read
+#define __NR_seccomp_write_32		__NR_write
+#define __NR_seccomp_exit_32		__NR_exit
+#ifndef __NR_seccomp_sigreturn_32
+#define __NR_seccomp_sigreturn_32	__NR_rt_sigreturn
+#endif
+#endif /* CONFIG_COMPAT && ! already defined */
+
+#define __NR_seccomp_read		__NR_read
+#define __NR_seccomp_write		__NR_write
+#define __NR_seccomp_exit		__NR_exit
+#ifndef __NR_seccomp_sigreturn
+#define __NR_seccomp_sigreturn		__NR_rt_sigreturn
+#endif
+
+#ifdef CONFIG_COMPAT
+#ifndef get_compat_mode1_syscalls
+static inline const int *get_compat_mode1_syscalls(void)
+{
+	static const int mode1_syscalls_32[] = {
+		__NR_seccomp_read_32, __NR_seccomp_write_32,
+		__NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
+		-1, /* negative terminated */
+	};
+	return mode1_syscalls_32;
+}
+#endif
+#endif /* CONFIG_COMPAT */
+
+#endif /* _ASM_GENERIC_SECCOMP_H */