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, 48 insertions, 0 deletions

diff --git a/arch/powerpc/sysdev/6xx-suspend.S b/arch/powerpc/sysdev/6xx-suspend.S
new file mode 100644
index 000000000..e882524ff
--- /dev/null
+++ b/arch/powerpc/sysdev/6xx-suspend.S
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Enter and leave sleep state on chips with 6xx-style HID0
+ * power management bits, which don't leave sleep state via reset.
+ *
+ * Author: Scott Wood <scottwood@freescale.com>
+ *
+ * Copyright (c) 2006-2007 Freescale Semiconductor, Inc.
+ */
+
+#include <asm/ppc_asm.h>
+#include <asm/reg.h>
+#include <asm/thread_info.h>
+#include <asm/asm-offsets.h>
+
+_GLOBAL(mpc6xx_enter_standby)
+	mflr	r4
+
+	mfspr	r5, SPRN_HID0
+	rlwinm	r5, r5, 0, ~(HID0_DOZE | HID0_NAP)
+	oris	r5, r5, HID0_SLEEP@h
+	mtspr	SPRN_HID0, r5
+	isync
+
+	lis	r5, ret_from_standby@h
+	ori	r5, r5, ret_from_standby@l
+	mtlr	r5
+
+	lwz	r6, TI_LOCAL_FLAGS(r2)
+	ori	r6, r6, _TLF_SLEEPING
+	stw	r6, TI_LOCAL_FLAGS(r2)
+
+	mfmsr	r5
+	ori	r5, r5, MSR_EE
+	oris	r5, r5, MSR_POW@h
+	sync
+	mtmsr	r5
+	isync
+
+1:	b	1b
+
+ret_from_standby:
+	mfspr	r5, SPRN_HID0
+	rlwinm	r5, r5, 0, ~HID0_SLEEP
+	mtspr	SPRN_HID0, r5
+
+	mtlr	r4
+	blr