copypage-v4wt.c

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/*
 *  linux/arch/arm/mm/copypage-v4wt.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.
 *
 *  This is for CPUs with a writethrough cache and 'flush ID cache' is
 *  the only supported cache operation.
 */
#include <linux/init.h>
#include <linux/highmem.h>

/*
 * ARMv4 optimised copy_user_highpage
 *
 * 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.
 */
static void __naked
v4wt_copy_user_page(void *kto, const void *kfrom)
{
    asm("\
    stmfd   sp!, {r4, lr}           @ 2\n\
    mov r2, %2              @ 1\n\
    ldmia   r1!, {r3, r4, ip, lr}       @ 4\n\
1:  stmia   r0!, {r3, r4, ip, lr}       @ 4\n\
    ldmia   r1!, {r3, r4, ip, lr}       @ 4+1\n\
    stmia   r0!, {r3, r4, ip, lr}       @ 4\n\
    ldmia   r1!, {r3, r4, ip, lr}       @ 4\n\
    stmia   r0!, {r3, r4, ip, lr}       @ 4\n\
    ldmia   r1!, {r3, r4, ip, lr}       @ 4\n\
    subs    r2, r2, #1          @ 1\n\
    stmia   r0!, {r3, r4, ip, lr}       @ 4\n\
    ldmneia r1!, {r3, r4, ip, lr}       @ 4\n\
    bne 1b              @ 1\n\
    mcr p15, 0, r2, c7, c7, 0       @ flush ID cache\n\
    ldmfd   sp!, {r4, pc}           @ 3"
    :
    : "r" (kto), "r" (kfrom), "I" (PAGE_SIZE / 64));
}

void v4wt_copy_user_highpage(struct page *to, struct page *from,
    unsigned long vaddr, struct vm_area_struct *vma)
{
    void *kto, *kfrom;

    kto = kmap_atomic(to);
    kfrom = kmap_atomic(from);
    v4wt_copy_user_page(kto, kfrom);
    kunmap_atomic(kfrom);
    kunmap_atomic(kto);
}

/*
 * ARMv4 optimised clear_user_page
 *
 * Same story as above.
 */
void v4wt_clear_user_highpage(struct page *page, unsigned long vaddr)
{
    void *ptr, *kaddr = kmap_atomic(page);
    asm volatile("\
    mov r1, %2              @ 1\n\
    mov r2, #0              @ 1\n\
    mov r3, #0              @ 1\n\
    mov ip, #0              @ 1\n\
    mov lr, #0              @ 1\n\
1:  stmia   %0!, {r2, r3, ip, lr}       @ 4\n\
    stmia   %0!, {r2, r3, ip, lr}       @ 4\n\
    stmia   %0!, {r2, r3, ip, lr}       @ 4\n\
    stmia   %0!, {r2, r3, ip, lr}       @ 4\n\
    subs    r1, r1, #1          @ 1\n\
    bne 1b              @ 1\n\
    mcr p15, 0, r2, c7, c7, 0       @ flush ID cache"
    : "=r" (ptr)
    : "0" (kaddr), "I" (PAGE_SIZE / 64)
    : "r1", "r2", "r3", "ip", "lr");
    kunmap_atomic(kaddr);
}

struct cpu_user_fns v4wt_user_fns __initdata = {
    .cpu_clear_user_highpage = v4wt_clear_user_highpage,
    .cpu_copy_user_highpage = v4wt_copy_user_highpage,
};