Linux/Unix编程

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Unix_Linux

thunk.S：源码内容

								/*
	 * Save registers before calling assembly functions. This avoids
	 * disturbance of register allocation in some inline assembly constructs.
	 * Copyright 2001,2002 by Andi Kleen, SuSE Labs.
	 * Subject to the GNU public license, v.2. No warranty of any kind.
	 * $Id: thunk.S,v 1.2 2002/03/13 20:06:58 ak Exp $
	 */
	#include <linux/config.h>
	#include <linux/linkage.h>
	#include <asm/calling.h>			
	#include <asm/rwlock.h>
		
	/* rdi:	arg1 ... normal C conventions. rax is saved/restored. */ 	
	.macro thunk name,func
	.globl name
name:	
	SAVE_ARGS
	call func
	jmp  restore
	.endm
	/* rdi:	arg1 ... normal C conventions. rax is passed from C. */ 	
	.macro thunk_retrax name,func
	.globl name
name:	
	SAVE_ARGS
	call func
	jmp  restore_norax
	.endm
	
#ifdef CONFIG_RWSEM_XCHGADD_ALGORITHM
	thunk rwsem_down_read_failed_thunk,rwsem_down_read_failed
	thunk rwsem_down_write_failed_thunk,rwsem_down_write_failed
	thunk rwsem_wake_thunk,rwsem_wake
#endif	
	thunk do_softirq_thunk,do_softirq
	
	thunk __down_failed,__down
	thunk_retrax __down_failed_interruptible,__down_interruptible
	thunk_retrax __down_failed_trylock,__down_trylock
	thunk __up_wakeup,__up
	
restore:
	RESTORE_ARGS
	ret	
	
restore_norax:	
	RESTORE_ARGS 1
	ret
#ifdef CONFIG_SMP
/* Support for read/write spinlocks. */
	
/* rax:	pointer to rwlock_t */	
ENTRY(__write_lock_failed)
	lock
	addl $RW_LOCK_BIAS,(%rax)
1:	rep
	nop
	cmpl $RW_LOCK_BIAS,(%rax)
	jne 1b
	lock 
	subl $RW_LOCK_BIAS,(%rax)
	jnz  __write_lock_failed
	ret
/* rax:	pointer to rwlock_t */	
ENTRY(__read_lock_failed)
	lock
	incl (%rax)
1:	rep
	nop
	cmpl $1,(%rax)
	js 1b
	lock
	decl (%rax)
	js __read_lock_failed
	ret
#endif

						