arch/arm/mm/copypage-v4wb.c

   1 /*
   2  *  linux/arch/arm/mm/copypage-v4wb.c
   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 #include <linux/init.h>
  11 #include <linux/highmem.h>
  12
  13 /*
  14  * ARMv4 optimised copy_user_highpage
  15  *
  16  * We flush the destination cache lines just before we write the data into the
  17  * corresponding address.  Since the Dcache is read-allocate, this removes the
  18  * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
  19  * and merged as appropriate.
  20  *
  21  * Note: We rely on all ARMv4 processors implementing the "invalidate D line"
  22  * instruction.  If your processor does not supply this, you have to write your
  23  * own copy_user_highpage that does the right thing.
  24  */
  25 static void __naked
  26 v4wb_copy_user_page(void *kto, const void *kfrom)
  27 {
  28         asm("\
  29         stmfd   sp!, {r4, lr}                   @ 2\n\
  30         mov     r2, %2                          @ 1\n\
  31         ldmia   r1!, {r3, r4, ip, lr}           @ 4\n\
  32 1:      mcr     p15, 0, r0, c7, c6, 1           @ 1   invalidate D line\n\
  33         stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  34         ldmia   r1!, {r3, r4, ip, lr}           @ 4+1\n\
  35         stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  36         ldmia   r1!, {r3, r4, ip, lr}           @ 4\n\
  37         mcr     p15, 0, r0, c7, c6, 1           @ 1   invalidate D line\n\
  38         stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  39         ldmia   r1!, {r3, r4, ip, lr}           @ 4\n\
  40         subs    r2, r2, #1                      @ 1\n\
  41         stmia   r0!, {r3, r4, ip, lr}           @ 4\n\
  42         ldmneia r1!, {r3, r4, ip, lr}           @ 4\n\
  43         bne     1b                              @ 1\n\
  44         mcr     p15, 0, r1, c7, c10, 4          @ 1   drain WB\n\
  45         ldmfd    sp!, {r4, pc}                  @ 3"
  46         :
  47         : "r" (kto), "r" (kfrom), "I" (PAGE_SIZE / 64));
  48 }
  49
  50 void v4wb_copy_user_highpage(struct page *to, struct page *from,
  51         unsigned long vaddr, struct vm_area_struct *vma)
  52 {
  53         void *kto, *kfrom;
  54
  55         kto = kmap_atomic(to);
  56         kfrom = kmap_atomic(from);
  57         flush_cache_page(vma, vaddr, page_to_pfn(from));
  58         v4wb_copy_user_page(kto, kfrom);
  59         kunmap_atomic(kfrom);
  60         kunmap_atomic(kto);
  61 }
  62
  63 /*
  64  * ARMv4 optimised clear_user_page
  65  *
  66  * Same story as above.
  67  */
  68 void v4wb_clear_user_highpage(struct page *page, unsigned long vaddr)
  69 {
  70         void *ptr, *kaddr = kmap_atomic(page);
  71         asm volatile("\
  72         mov     r1, %2                          @ 1\n\
  73         mov     r2, #0                          @ 1\n\
  74         mov     r3, #0                          @ 1\n\
  75         mov     ip, #0                          @ 1\n\
  76         mov     lr, #0                          @ 1\n\
  77 1:      mcr     p15, 0, %0, c7, c6, 1           @ 1   invalidate D line\n\
  78         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  79         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  80         mcr     p15, 0, %0, c7, c6, 1           @ 1   invalidate D line\n\
  81         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  82         stmia   %0!, {r2, r3, ip, lr}           @ 4\n\
  83         subs    r1, r1, #1                      @ 1\n\
  84         bne     1b                              @ 1\n\
  85         mcr     p15, 0, r1, c7, c10, 4          @ 1   drain WB"
  86         : "=r" (ptr)
  87         : "0" (kaddr), "I" (PAGE_SIZE / 64)
  88         : "r1", "r2", "r3", "ip", "lr");
  89         kunmap_atomic(kaddr);
  90 }
  91
  92 struct cpu_user_fns v4wb_user_fns __initdata = {
  93         .cpu_clear_user_highpage = v4wb_clear_user_highpage,
  94         .cpu_copy_user_highpage = v4wb_copy_user_highpage,
  95 };