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