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, 47 insertions, 0 deletions

diff --git a/arch/powerpc/boot/of.h b/arch/powerpc/boot/of.h
new file mode 100644
index 000000000..31b2f5dfd
--- /dev/null
+++ b/arch/powerpc/boot/of.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PPC_BOOT_OF_H_
+#define _PPC_BOOT_OF_H_
+
+#include "swab.h"
+
+typedef void *phandle;
+typedef u32 ihandle;
+
+void of_init(void *promptr);
+int of_call_prom(const char *service, int nargs, int nret, ...);
+unsigned int of_claim(unsigned long virt, unsigned long size,
+	unsigned long align);
+void *of_vmlinux_alloc(unsigned long size);
+void of_exit(void);
+void *of_finddevice(const char *name);
+int of_getprop(const void *phandle, const char *name, void *buf,
+	       const int buflen);
+int of_setprop(const void *phandle, const char *name, const void *buf,
+	       const int buflen);
+
+/* Console functions */
+void of_console_init(void);
+
+typedef u16			__be16;
+typedef u32			__be32;
+typedef u64			__be64;
+
+#ifdef __LITTLE_ENDIAN__
+#define cpu_to_be16(x) swab16(x)
+#define be16_to_cpu(x) swab16(x)
+#define cpu_to_be32(x) swab32(x)
+#define be32_to_cpu(x) swab32(x)
+#define cpu_to_be64(x) swab64(x)
+#define be64_to_cpu(x) swab64(x)
+#else
+#define cpu_to_be16(x) (x)
+#define be16_to_cpu(x) (x)
+#define cpu_to_be32(x) (x)
+#define be32_to_cpu(x) (x)
+#define cpu_to_be64(x) (x)
+#define be64_to_cpu(x) (x)
+#endif
+
+#define PROM_ERROR (-1u)
+
+#endif /* _PPC_BOOT_OF_H_ */