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, 243 insertions, 0 deletions

diff --git a/drivers/block/swim_asm.S b/drivers/block/swim_asm.S
new file mode 100644
index 000000000..3d7a2d875
--- /dev/null
+++ b/drivers/block/swim_asm.S
@@ -0,0 +1,243 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * low-level functions for the SWIM floppy controller
+ *
+ * needs assembly language because is very timing dependent
+ * this controller exists only on macintosh 680x0 based
+ *
+ * Copyright (C) 2004,2008 Laurent Vivier <Laurent@lvivier.info>
+ *
+ * based on Alastair Bridgewater SWIM analysis, 2001
+ * based on netBSD IWM driver (c) 1997, 1998 Hauke Fath.
+ *
+ * 2004-08-21 (lv) - Initial implementation
+ * 2008-11-05 (lv) - add get_swim_mode
+ */
+
+	.equ	write_data,	0x0000
+	.equ	write_mark,	0x0200
+	.equ	write_CRC,	0x0400
+	.equ	write_parameter,0x0600
+	.equ	write_phase,	0x0800
+	.equ	write_setup,	0x0a00
+	.equ	write_mode0,	0x0c00
+	.equ	write_mode1,	0x0e00
+	.equ	read_data,	0x1000
+	.equ	read_mark,	0x1200
+	.equ	read_error,	0x1400
+	.equ	read_parameter,	0x1600
+	.equ	read_phase,	0x1800
+	.equ	read_setup,	0x1a00
+	.equ	read_status,	0x1c00
+	.equ	read_handshake,	0x1e00
+
+	.equ	o_side, 0
+	.equ	o_track, 1
+	.equ	o_sector, 2
+	.equ	o_size, 3
+	.equ	o_crc0, 4
+	.equ	o_crc1, 5
+
+	.equ	seek_time, 30000
+	.equ	max_retry, 40
+	.equ	sector_size, 512
+
+	.global swim_read_sector_header
+swim_read_sector_header:
+	link	%a6, #0
+	moveml	%d1-%d5/%a0-%a4,%sp@-
+	movel	%a6@(0x0c), %a4
+	bsr	mfm_read_addrmark
+	moveml	%sp@+, %d1-%d5/%a0-%a4
+	unlk	%a6
+	rts
+
+sector_address_mark:
+	.byte	0xa1, 0xa1, 0xa1, 0xfe
+sector_data_mark:
+	.byte	0xa1, 0xa1, 0xa1, 0xfb
+
+mfm_read_addrmark:
+	movel	%a6@(0x08), %a3
+	lea	%a3@(read_handshake), %a2
+	lea	%a3@(read_mark), %a3
+	moveq	#-1, %d0
+	movew	#seek_time, %d2
+
+wait_header_init:
+	tstb	%a3@(read_error - read_mark)
+	moveb	#0x18, %a3@(write_mode0 - read_mark)
+	moveb	#0x01, %a3@(write_mode1 - read_mark)
+	moveb	#0x01, %a3@(write_mode0 - read_mark)
+	tstb	%a3@(read_error - read_mark)
+	moveb	#0x08, %a3@(write_mode1 - read_mark)
+
+	lea	sector_address_mark, %a0
+	moveq	#3, %d1
+
+wait_addr_mark_byte:
+
+	tstb	%a2@
+	dbmi	%d2, wait_addr_mark_byte
+	bpl	header_exit
+
+	moveb	%a3@, %d3
+	cmpb	%a0@+, %d3
+	dbne	%d1, wait_addr_mark_byte
+	bne	wait_header_init
+
+	moveq	#max_retry, %d2
+
+amark0:	tstb	%a2@
+	dbmi	%d2, amark0
+	bpl	signal_nonyb
+
+	moveb	%a3@, %a4@(o_track)
+
+	moveq	#max_retry, %d2
+
+amark1:	tstb	%a2@
+	dbmi	%d2, amark1
+	bpl	signal_nonyb
+
+	moveb	%a3@, %a4@(o_side)
+
+	moveq	#max_retry, %d2
+
+amark2:	tstb	%a2@
+	dbmi	%d2, amark2
+	bpl	signal_nonyb
+
+	moveb	%a3@, %a4@(o_sector)
+
+	moveq	#max_retry, %d2
+
+amark3:	tstb	%a2@
+	dbmi	%d2, amark3
+	bpl	signal_nonyb
+
+	moveb	%a3@, %a4@(o_size)
+
+	moveq	#max_retry, %d2
+
+crc0:	tstb	%a2@
+	dbmi	%d2, crc0
+	bpl	signal_nonyb
+
+	moveb	%a3@, %a4@(o_crc0)
+
+	moveq	#max_retry, %d2
+
+crc1:	tstb	%a2@
+	dbmi	%d2, crc1
+	bpl	signal_nonyb
+
+	moveb	%a3@, %a4@(o_crc1)
+
+	tstb	%a3@(read_error - read_mark)
+
+header_exit:
+	moveq	#0, %d0
+	moveb	#0x18, %a3@(write_mode0 - read_mark)
+	rts
+signal_nonyb:
+	moveq	#-1, %d0
+	moveb	#0x18, %a3@(write_mode0 - read_mark)
+	rts
+
+	.global swim_read_sector_data
+swim_read_sector_data:
+	link	%a6, #0
+	moveml	%d1-%d5/%a0-%a5,%sp@-
+	movel	%a6@(0x0c), %a4
+	bsr	mfm_read_data
+	moveml	%sp@+, %d1-%d5/%a0-%a5
+	unlk	%a6
+	rts
+
+mfm_read_data:
+	movel	%a6@(0x08), %a3
+	lea	%a3@(read_handshake), %a2
+	lea	%a3@(read_data), %a5
+	lea	%a3@(read_mark), %a3
+	movew	#seek_time, %d2
+
+wait_data_init:
+	tstb	%a3@(read_error - read_mark)
+	moveb	#0x18, %a3@(write_mode0 - read_mark)
+	moveb	#0x01, %a3@(write_mode1 - read_mark)
+	moveb	#0x01, %a3@(write_mode0 - read_mark)
+	tstb	%a3@(read_error - read_mark)
+	moveb	#0x08, %a3@(write_mode1 - read_mark)
+
+	lea	sector_data_mark, %a0
+	moveq	#3, %d1
+
+	/* wait data address mark */
+
+wait_data_mark_byte:
+
+	tstb	%a2@
+	dbmi	%d2, wait_data_mark_byte
+	bpl	data_exit
+
+	moveb	%a3@, %d3
+	cmpb	%a0@+, %d3
+	dbne	%d1, wait_data_mark_byte
+	bne	wait_data_init
+
+	/* read data */
+
+	tstb	%a3@(read_error - read_mark)
+
+	movel	#sector_size-1, %d4		/* sector size */
+read_new_data:
+	movew	#max_retry, %d2
+read_data_loop:
+	moveb	%a2@, %d5
+	andb	#0xc0, %d5
+	dbne	%d2, read_data_loop
+	beq	data_exit
+	moveb	%a5@, %a4@+
+	andb	#0x40, %d5
+	dbne	%d4, read_new_data
+	beq	exit_loop
+	moveb	%a5@, %a4@+
+	dbra	%d4, read_new_data
+exit_loop:
+
+	/* read CRC */
+
+	movew	#max_retry, %d2
+data_crc0:
+
+	tstb	%a2@
+	dbmi	%d2, data_crc0
+	bpl	data_exit
+
+	moveb	%a3@, %d5
+
+	moveq	#max_retry, %d2
+
+data_crc1:
+
+	tstb	%a2@
+	dbmi	%d2, data_crc1
+	bpl	data_exit
+
+	moveb	%a3@, %d5
+
+	tstb	%a3@(read_error - read_mark)
+
+	moveb	#0x18, %a3@(write_mode0 - read_mark)
+
+	/* return number of bytes read */
+
+	movel	#sector_size, %d0
+	addw	#1, %d4
+	subl	%d4, %d0
+	rts
+data_exit:
+	moveb	#0x18, %a3@(write_mode0 - read_mark)
+	moveq	#-1, %d0
+	rts