9a0b26e6bc
- 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>
39 lines
1.1 KiB
C
39 lines
1.1 KiB
C
/* include/asm-x86_64/rwlock.h
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*
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* Helpers used by both rw spinlocks and rw semaphores.
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*
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* Based in part on code from semaphore.h and
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* spinlock.h Copyright 1996 Linus Torvalds.
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*
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* Copyright 1999 Red Hat, Inc.
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* Copyright 2001,2002 SuSE labs
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*
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* Written by Benjamin LaHaise.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_X86_64_RWLOCK_H
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#define _ASM_X86_64_RWLOCK_H
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#define RW_LOCK_BIAS 0x01000000
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#define RW_LOCK_BIAS_STR "0x01000000"
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#define __build_read_lock(rw) \
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asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t" \
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"jns 1f\n" \
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"call __read_lock_failed\n" \
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"1:\n" \
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::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")
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#define __build_write_lock(rw) \
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asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t" \
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"jz 1f\n" \
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"\tcall __write_lock_failed\n\t" \
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"1:\n" \
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::"D" (rw), "i" (RW_LOCK_BIAS) : "memory")
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#endif
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