copypage-v4wt.s

linux 内核源代码

/*
 *  linux/arch/arm/lib/copypage-v4.S
 *
 *  Copyright (C) 1995-1999 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  ASM optimised string functions
 *
 *  This is for CPUs with a writethrough cache and 'flush ID cache' is
 *  the only supported cache operation.
 */
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/asm-offsets.h>

	.text
	.align	5
/*
 * ARMv4 optimised copy_user_page
 *
 * Since we have writethrough caches, we don't have to worry about
 * dirty data in the cache.  However, we do have to ensure that
 * subsequent reads are up to date.
 */
ENTRY(v4wt_copy_user_page)
	stmfd	sp!, {r4, lr}			@ 2
	mov	r2, #PAGE_SZ/64			@ 1
	ldmia	r1!, {r3, r4, ip, lr}		@ 4
1:	stmia	r0!, {r3, r4, ip, lr}		@ 4
	ldmia	r1!, {r3, r4, ip, lr}		@ 4+1
	stmia	r0!, {r3, r4, ip, lr}		@ 4
	ldmia	r1!, {r3, r4, ip, lr}		@ 4
	stmia	r0!, {r3, r4, ip, lr}		@ 4
	ldmia	r1!, {r3, r4, ip, lr}		@ 4
	subs	r2, r2, #1			@ 1
	stmia	r0!, {r3, r4, ip, lr}		@ 4
	ldmneia	r1!, {r3, r4, ip, lr}		@ 4
	bne	1b				@ 1
	mcr	p15, 0, r2, c7, c7, 0		@ flush ID cache
	ldmfd	sp!, {r4, pc}			@ 3

	.align	5
/*
 * ARMv4 optimised clear_user_page
 *
 * Same story as above.
 */
ENTRY(v4wt_clear_user_page)
	str	lr, [sp, #-4]!
	mov	r1, #PAGE_SZ/64			@ 1
	mov	r2, #0				@ 1
	mov	r3, #0				@ 1
	mov	ip, #0				@ 1
	mov	lr, #0				@ 1
1:	stmia	r0!, {r2, r3, ip, lr}		@ 4
	stmia	r0!, {r2, r3, ip, lr}		@ 4
	stmia	r0!, {r2, r3, ip, lr}		@ 4
	stmia	r0!, {r2, r3, ip, lr}		@ 4
	subs	r1, r1, #1			@ 1
	bne	1b				@ 1
	mcr	p15, 0, r2, c7, c7, 0		@ flush ID cache
	ldr	pc, [sp], #4

	__INITDATA

	.type	v4wt_user_fns, #object
ENTRY(v4wt_user_fns)
	.long	v4wt_clear_user_page
	.long	v4wt_copy_user_page
	.size	v4wt_user_fns, . - v4wt_user_fns