arch/arm/mm/copypage-v4wt.c

   1 /*
   2  *  linux/arch/arm/mm/copypage-v4wt.S
   3  *
   4  *  Copyright (C) 1995-1999 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  This is for CPUs with a writethrough cache and 'flush ID cache' is
  11  *  the only supported cache operation.
  12  */
  13 #include <linux/init.h>
  14 #include <linux/highmem.h>
  15
  16 /*
  17  * ARMv4 optimised copy_user_highpage
  18  *
  19  * Since we have writethrough caches, we don't have to worry about
  20  * dirty data in the cache.  However, we do have to ensure that
  21  * subsequent reads are up to date.
  22  */
  23 static void __naked
  24 v4wt_copy_user_page(void *kto, const void *kfrom)
  25 {
  26         asm("\
  27         stmfd   sp!, {r4, lr}                   @ 2\n\
  28         mov     r2, %2                          @ 1\n\
  29         ldmia   r1!, {r3, r4, ip, lr}           @ 4\n\
  30 1:      stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  31         ldmia   r1!, {r3, r4, ip, lr}           @ 4+1\n\
  32         stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  33         ldmia   r1!, {r3, r4, ip, lr}           @ 4\n\
  34         stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  35         ldmia   r1!, {r3, r4, ip, lr}           @ 4\n\
  36         subs    r2, r2, #1                      @ 1\n\
  37         stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  38         ldmneia r1!, {r3, r4, ip, lr}           @ 4\n\
  39         bne     1b                              @ 1\n\
  40         mcr     p15, 0, r2, c7, c7, 0           @ flush ID cache\n\
  41         ldmfd   sp!, {r4, pc}                   @ 3"
  42         :
  43         : "r" (kto), "r" (kfrom), "I" (PAGE_SIZE / 64));
  44 }
  45
  46 void v4wt_copy_user_highpage(struct page *to, struct page *from,
  47         unsigned long vaddr, struct vm_area_struct *vma)
  48 {
  49         void *kto, *kfrom;
  50
  51         kto = kmap_atomic(to, KM_USER0);
  52         kfrom = kmap_atomic(from, KM_USER1);
  53         v4wt_copy_user_page(kto, kfrom);
  54         kunmap_atomic(kfrom, KM_USER1);
  55         kunmap_atomic(kto, KM_USER0);
  56 }
  57
  58 /*
  59  * ARMv4 optimised clear_user_page
  60  *
  61  * Same story as above.
  62  */
  63 void v4wt_clear_user_highpage(struct page *page, unsigned long vaddr)
  64 {
  65         void *ptr, *kaddr = kmap_atomic(page, KM_USER0);
  66         asm volatile("\
  67         mov     r1, %2                          @ 1\n\
  68         mov     r2, #0                          @ 1\n\
  69         mov     r3, #0                          @ 1\n\
  70         mov     ip, #0                          @ 1\n\
  71         mov     lr, #0                          @ 1\n\
  72 1:      stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  73         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  74         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  75         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  76         subs    r1, r1, #1                      @ 1\n\
  77         bne     1b                              @ 1\n\
  78         mcr     p15, 0, r2, c7, c7, 0           @ flush ID cache"
  79         : "=r" (ptr)
  80         : "0" (kaddr), "I" (PAGE_SIZE / 64)
  81         : "r1", "r2", "r3", "ip", "lr");
  82         kunmap_atomic(kaddr, KM_USER0);
  83 }
  84
  85 struct cpu_user_fns v4wt_user_fns __initdata = {
  86         .cpu_clear_user_highpage = v4wt_clear_user_highpage,
  87         .cpu_copy_user_highpage = v4wt_copy_user_highpage,
  88 };