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, 72 insertions, 0 deletions

diff --git a/arch/powerpc/boot/ps3-head.S b/arch/powerpc/boot/ps3-head.S
new file mode 100644
index 000000000..0a4ebfcc3
--- /dev/null
+++ b/arch/powerpc/boot/ps3-head.S
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *  PS3 bootwrapper entry.
+ *
+ *  Copyright (C) 2007 Sony Computer Entertainment Inc.
+ *  Copyright 2007 Sony Corp.
+ */
+
+#include "ppc_asm.h"
+
+	.machine "ppc64"
+
+	.text
+
+/*
+ * __system_reset_overlay - The PS3 first stage entry.
+ *
+ * The bootwraper build script copies the 512 bytes at symbol
+ * __system_reset_overlay to offset 0x100 of the rom image.  This symbol
+ * must occupy 512 or less bytes.
+ *
+ * The PS3 has a single processor with two threads.
+ */
+
+	.globl __system_reset_overlay
+__system_reset_overlay:
+
+	/* Switch to 32-bit mode. */
+
+	mfmsr	r9
+	clrldi	r9,r9,1
+	mtmsrd	r9
+	nop
+
+	/* Get thread number in r3 and branch. */
+
+	mfspr	r3, 0x88
+	cntlzw.	r3, r3
+	beq	1f
+
+	/* Secondary goes to __secondary_hold in kernel. */
+
+	li	r4, 0x60
+	mtctr	r4
+	bctr
+
+1:
+	/* Primary delays then goes to _zimage_start in wrapper. */
+
+	or	31, 31, 31 /* db16cyc */
+	or	31, 31, 31 /* db16cyc */
+
+	lis	r4, _zimage_start@ha
+	addi	r4, r4, _zimage_start@l
+	mtctr	r4
+	bctr
+
+	. = __system_reset_overlay + 512
+
+/*
+ * __system_reset_kernel - Place holder for the kernel reset vector.
+ *
+ * The bootwrapper build script copies 512 bytes from offset 0x100
+ * of the rom image to the symbol __system_reset_kernel.  At runtime
+ * the bootwrapper program copies the 512 bytes at __system_reset_kernel
+ * to ram address 0x100.  This symbol must occupy 512 bytes.
+ */
+
+	.globl __system_reset_kernel
+__system_reset_kernel:
+
+	. = __system_reset_kernel + 512