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/*
* i386 semaphore implementation.
*
* (C) Copyright 1999 Linus Torvalds
*
* Portions Copyright 1999 Red Hat, Inc.
*
* 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.
*
* rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org>
*/
#include <linux/config.h>
#include <asm/semaphore.h>
/*
* The semaphore operations have a special calling sequence that
* allow us to do a simpler in-line version of them. These routines
* need to convert that sequence back into the C sequence when
* there is contention on the semaphore.
*
* %eax contains the semaphore pointer on entry. Save the C-clobbered
* registers (%eax, %edx and %ecx) except %eax whish is either a return
* value or just clobbered..
*/
asm(
".section .sched.text\n"
".align 4\n"
".globl __down_failed\n"
"__down_failed:\n\t"
#if defined(CONFIG_FRAME_POINTER)
"pushl %ebp\n\t"
"movl %esp,%ebp\n\t"
#endif
"pushl %edx\n\t"
"pushl %ecx\n\t"
"call __down\n\t"
"popl %ecx\n\t"
"popl %edx\n\t"
#if defined(CONFIG_FRAME_POINTER)
"movl %ebp,%esp\n\t"
"popl %ebp\n\t"
#endif
"ret"
);
asm(
".section .sched.text\n"
".align 4\n"
".globl __down_failed_interruptible\n"
"__down_failed_interruptible:\n\t"
#if defined(CONFIG_FRAME_POINTER)
"pushl %ebp\n\t"
"movl %esp,%ebp\n\t"
#endif
"pushl %edx\n\t"
"pushl %ecx\n\t"
"call __down_interruptible\n\t"
"popl %ecx\n\t"
"popl %edx\n\t"
#if defined(CONFIG_FRAME_POINTER)
"movl %ebp,%esp\n\t"
"popl %ebp\n\t"
#endif
"ret"
);
asm(
".section .sched.text\n"
".align 4\n"
".globl __down_failed_trylock\n"
"__down_failed_trylock:\n\t"
#if defined(CONFIG_FRAME_POINTER)
"pushl %ebp\n\t"
"movl %esp,%ebp\n\t"
#endif
"pushl %edx\n\t"
"pushl %ecx\n\t"
"call __down_trylock\n\t"
"popl %ecx\n\t"
"popl %edx\n\t"
#if defined(CONFIG_FRAME_POINTER)
"movl %ebp,%esp\n\t"
"popl %ebp\n\t"
#endif
"ret"
);
asm(
".section .sched.text\n"
".align 4\n"
".globl __up_wakeup\n"
"__up_wakeup:\n\t"
"pushl %edx\n\t"
"pushl %ecx\n\t"
"call __up\n\t"
"popl %ecx\n\t"
"popl %edx\n\t"
"ret"
);
/*
* rw spinlock fallbacks
*/
#if defined(CONFIG_SMP)
asm(
".section .sched.text\n"
".align 4\n"
".globl __write_lock_failed\n"
"__write_lock_failed:\n\t"
LOCK_PREFIX "addl $" RW_LOCK_BIAS_STR ",(%eax)\n"
"1: rep; nop\n\t"
"cmpl $" RW_LOCK_BIAS_STR ",(%eax)\n\t"
"jne 1b\n\t"
LOCK_PREFIX "subl $" RW_LOCK_BIAS_STR ",(%eax)\n\t"
"jnz __write_lock_failed\n\t"
"ret"
);
asm(
".section .sched.text\n"
".align 4\n"
".globl __read_lock_failed\n"
"__read_lock_failed:\n\t"
LOCK_PREFIX "incl (%eax)\n"
"1: rep; nop\n\t"
"cmpl $1,(%eax)\n\t"
"js 1b\n\t"
LOCK_PREFIX "decl (%eax)\n\t"
"js __read_lock_failed\n\t"
"ret"
);
#endif
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