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, 198 insertions, 0 deletions

diff --git a/arch/m68k/coldfire/entry.S b/arch/m68k/coldfire/entry.S
new file mode 100644
index 000000000..4ea08336e
--- /dev/null
+++ b/arch/m68k/coldfire/entry.S
@@ -0,0 +1,198 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ *  entry.S  -- interrupt and exception processing for ColdFire
+ *
+ *  Copyright (C) 1999-2007, Greg Ungerer (gerg@snapgear.com)
+ *  Copyright (C) 1998  D. Jeff Dionne <jeff@lineo.ca>,
+ *                      Kenneth Albanowski <kjahds@kjahds.com>,
+ *  Copyright (C) 2000  Lineo Inc. (www.lineo.com)
+ *  Copyright (C) 2004-2006  Macq Electronique SA. (www.macqel.com)
+ *
+ * Based on:
+ *
+ *  linux/arch/m68k/kernel/entry.S
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ * Linux/m68k support by Hamish Macdonald
+ *
+ * 68060 fixes by Jesper Skov
+ * ColdFire support by Greg Ungerer (gerg@snapgear.com)
+ * 5307 fixes by David W. Miller
+ * linux 2.4 support David McCullough <davidm@snapgear.com>
+ * Bug, speed and maintainability fixes by Philippe De Muyter <phdm@macqel.be>
+ */
+
+#include <linux/linkage.h>
+#include <asm/unistd.h>
+#include <asm/thread_info.h>
+#include <asm/errno.h>
+#include <asm/setup.h>
+#include <asm/asm-offsets.h>
+#include <asm/entry.h>
+
+#ifdef CONFIG_COLDFIRE_SW_A7
+/*
+ *	Define software copies of the supervisor and user stack pointers.
+ */
+.bss
+sw_ksp:
+.long	0
+sw_usp:
+.long	0
+#endif /* CONFIG_COLDFIRE_SW_A7 */
+
+.text
+
+.globl system_call
+.globl resume
+.globl ret_from_exception
+.globl sys_call_table
+.globl inthandler
+
+enosys:
+	mov.l	#sys_ni_syscall,%d3
+	bra	1f
+
+ENTRY(system_call)
+	SAVE_ALL_SYS
+	move	#0x2000,%sr		/* enable intrs again */
+	GET_CURRENT(%d2)
+
+	cmpl	#NR_syscalls,%d0
+	jcc	enosys
+	lea	sys_call_table,%a0
+	lsll	#2,%d0			/* movel %a0@(%d0:l:4),%d3 */
+	movel	%a0@(%d0),%d3
+	jeq	enosys
+
+1:
+	movel	%sp,%d2			/* get thread_info pointer */
+	andl	#-THREAD_SIZE,%d2	/* at start of kernel stack */
+	movel	%d2,%a0
+	movel	%a0@,%a1		/* save top of frame */
+	movel	%sp,%a1@(TASK_THREAD+THREAD_ESP0)
+	btst	#(TIF_SYSCALL_TRACE%8),%a0@(TINFO_FLAGS+(31-TIF_SYSCALL_TRACE)/8)
+	bnes	1f
+
+	movel	%d3,%a0
+	jbsr	%a0@
+	movel	%d0,%sp@(PT_OFF_D0)	/* save the return value */
+	jra	ret_from_exception
+1:
+	movel	#-ENOSYS,%d2		/* strace needs -ENOSYS in PT_OFF_D0 */
+	movel	%d2,PT_OFF_D0(%sp)	/* on syscall entry */
+	subql	#4,%sp
+	SAVE_SWITCH_STACK
+	jbsr	syscall_trace_enter
+	RESTORE_SWITCH_STACK
+	addql	#4,%sp
+	addql	#1,%d0
+	jeq	ret_from_exception
+	movel	%d3,%a0
+	jbsr	%a0@
+	movel	%d0,%sp@(PT_OFF_D0)		/* save the return value */
+	subql	#4,%sp			/* dummy return address */
+	SAVE_SWITCH_STACK
+	jbsr	syscall_trace_leave
+	RESTORE_SWITCH_STACK
+	addql	#4,%sp
+
+ret_from_exception:
+	move	#0x2700,%sr		/* disable intrs */
+	btst	#5,%sp@(PT_OFF_SR)	/* check if returning to kernel */
+	jeq	Luser_return		/* if so, skip resched, signals */
+
+#ifdef CONFIG_PREEMPTION
+	movel	%sp,%d1			/* get thread_info pointer */
+	andl	#-THREAD_SIZE,%d1	/* at base of kernel stack */
+	movel	%d1,%a0
+	movel	%a0@(TINFO_FLAGS),%d1	/* get thread_info->flags */
+	andl	#(1<<TIF_NEED_RESCHED),%d1
+	jeq	Lkernel_return
+
+	movel	%a0@(TINFO_PREEMPT),%d1
+	cmpl	#0,%d1
+	jne	Lkernel_return
+
+	pea	Lkernel_return
+	jmp	preempt_schedule_irq	/* preempt the kernel */
+#endif
+
+Lkernel_return:
+	moveml	%sp@,%d1-%d5/%a0-%a2
+	lea	%sp@(32),%sp		/* space for 8 regs */
+	movel	%sp@+,%d0
+	addql	#4,%sp			/* orig d0 */
+	addl	%sp@+,%sp		/* stk adj */
+	rte
+
+Luser_return:
+	movel	%sp,%d1			/* get thread_info pointer */
+	andl	#-THREAD_SIZE,%d1	/* at base of kernel stack */
+	movel	%d1,%a0
+	moveb	%a0@(TINFO_FLAGS+3),%d1	/* thread_info->flags (low 8 bits) */
+	jne	Lwork_to_do		/* still work to do */
+
+Lreturn:
+	RESTORE_USER
+
+Lwork_to_do:
+	movel	%a0@(TINFO_FLAGS),%d1	/* get thread_info->flags */
+	move	#0x2000,%sr		/* enable intrs again */
+	btst	#TIF_NEED_RESCHED,%d1
+	jne	reschedule
+
+Lsignal_return:
+	subql	#4,%sp			/* dummy return address */
+	SAVE_SWITCH_STACK
+	pea	%sp@(SWITCH_STACK_SIZE)
+	jsr	do_notify_resume
+	addql	#4,%sp
+	RESTORE_SWITCH_STACK
+	addql	#4,%sp
+	jmp	Luser_return
+
+/*
+ * This is the generic interrupt handler (for all hardware interrupt
+ * sources). Calls up to high level code to do all the work.
+ */
+ENTRY(inthandler)
+	SAVE_ALL_INT
+	GET_CURRENT(%d2)
+
+	movew	%sp@(PT_OFF_FORMATVEC),%d0 /* put exception # in d0 */
+	andl	#0x03fc,%d0		/* mask out vector only */
+
+	movel	%sp,%sp@-		/* push regs arg */
+	lsrl	#2,%d0			/* calculate real vector # */
+	movel	%d0,%sp@-		/* push vector number */
+	jbsr	do_IRQ			/* call high level irq handler */
+	lea	%sp@(8),%sp		/* pop args off stack */
+
+	bra	ret_from_exception
+
+/*
+ * Beware - when entering resume, prev (the current task) is
+ * in a0, next (the new task) is in a1, so don't change these
+ * registers until their contents are no longer needed.
+ */
+ENTRY(resume)
+	movew	%sr,%d1				 /* save current status */
+	movew	%d1,%a0@(TASK_THREAD+THREAD_SR)
+	movel	%a0,%d1				 /* get prev thread in d1 */
+	SAVE_SWITCH_STACK
+	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP) /* save kernel stack pointer */
+	RDUSP					 /* movel %usp,%a3 */
+	movel	%a3,%a0@(TASK_THREAD+THREAD_USP) /* save thread user stack */
+#ifdef CONFIG_MMU
+	movel	%a1,%a2				 /* set new current */
+#endif
+	movel	%a1@(TASK_THREAD+THREAD_USP),%a3 /* restore thread user stack */
+	WRUSP					 /* movel %a3,%usp */
+	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp /* restore new kernel stack */
+	movew	%a1@(TASK_THREAD+THREAD_SR),%d7	 /* restore new status */
+	movew	%d7,%sr
+	RESTORE_SWITCH_STACK
+	rts
+