android_kernel_xiaomi_sm8350/include/asm-x86_64/rwlock.h
Andi Kleen 9a0b26e6bc [PATCH] Clean up read write lock assembly
- Move the slow path fallbacks to their own assembly files
This makes them much easier to read and is needed for the next change.
- Add CFI annotations for unwinding (XXX need review)
- Remove constant case which can never happen with out of line spinlocks
- Use patchable LOCK prefixes
- Don't use lock sections anymore for inline code because they can't
be expressed by the unwinder (this adds one taken jump to the lock
fast path)

Cc: jbeulich@novell.com

Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26 10:52:28 +02:00

39 lines
1.1 KiB
C

/* include/asm-x86_64/rwlock.h
*
* Helpers used by both rw spinlocks and rw semaphores.
*
* Based in part on code from semaphore.h and
* spinlock.h Copyright 1996 Linus Torvalds.
*
* Copyright 1999 Red Hat, Inc.
* Copyright 2001,2002 SuSE labs
*
* Written by Benjamin LaHaise.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _ASM_X86_64_RWLOCK_H
#define _ASM_X86_64_RWLOCK_H
#define RW_LOCK_BIAS 0x01000000
#define RW_LOCK_BIAS_STR "0x01000000"
#define __build_read_lock(rw) \
asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t" \
"jns 1f\n" \
"call __read_lock_failed\n" \
"1:\n" \
::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")
#define __build_write_lock(rw) \
asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t" \
"jz 1f\n" \
"\tcall __write_lock_failed\n\t" \
"1:\n" \
::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")
#endif