LXR linux/arch/arm/mm/copypage-xscale.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/arch/arm/lib/copypage-xscale.S
   4 *
   5 *  Copyright (C) 1995-2005 Russell King
   6 *
   7 * This handles the mini data cache, as found on SA11x0 and XScale
   8 * processors.  When we copy a user page page, we map it in such a way
   9 * that accesses to this page will not touch the main data cache, but
  10 * will be cached in the mini data cache.  This prevents us thrashing
  11 * the main data cache on page faults.
  12 */
  13#include <linux/init.h>
  14#include <linux/mm.h>
  15#include <linux/highmem.h>
  16
  17#include <asm/pgtable.h>
  18#include <asm/tlbflush.h>
  19#include <asm/cacheflush.h>
  20
  21#include "mm.h"
  22
  23#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
  24                                  L_PTE_MT_MINICACHE)
  25
  26static DEFINE_RAW_SPINLOCK(minicache_lock);
  27
  28/*
  29 * XScale mini-dcache optimised copy_user_highpage
  30 *
  31 * We flush the destination cache lines just before we write the data into the
  32 * corresponding address.  Since the Dcache is read-allocate, this removes the
  33 * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
  34 * and merged as appropriate.
  35 */
  36static void mc_copy_user_page(void *from, void *to)
  37{
  38        int tmp;
  39
  40        /*
  41         * Strangely enough, best performance is achieved
  42         * when prefetching destination as well.  (NP)
  43         */
  44        asm volatile ("\
  45        pld     [%0, #0]                        \n\
  46        pld     [%0, #32]                       \n\
  47        pld     [%1, #0]                        \n\
  48        pld     [%1, #32]                       \n\
  491:      pld     [%0, #64]                       \n\
  50        pld     [%0, #96]                       \n\
  51        pld     [%1, #64]                       \n\
  52        pld     [%1, #96]                       \n\
  532:      ldrd    r2, r3, [%0], #8                \n\
  54        ldrd    r4, r5, [%0], #8                \n\
  55        mov     ip, %1                          \n\
  56        strd    r2, r3, [%1], #8                \n\
  57        ldrd    r2, r3, [%0], #8                \n\
  58        strd    r4, r5, [%1], #8                \n\
  59        ldrd    r4, r5, [%0], #8                \n\
  60        strd    r2, r3, [%1], #8                \n\
  61        strd    r4, r5, [%1], #8                \n\
  62        mcr     p15, 0, ip, c7, c10, 1          @ clean D line\n\
  63        ldrd    r2, r3, [%0], #8                \n\
  64        mcr     p15, 0, ip, c7, c6, 1           @ invalidate D line\n\
  65        ldrd    r4, r5, [%0], #8                \n\
  66        mov     ip, %1                          \n\
  67        strd    r2, r3, [%1], #8                \n\
  68        ldrd    r2, r3, [%0], #8                \n\
  69        strd    r4, r5, [%1], #8                \n\
  70        ldrd    r4, r5, [%0], #8                \n\
  71        strd    r2, r3, [%1], #8                \n\
  72        strd    r4, r5, [%1], #8                \n\
  73        mcr     p15, 0, ip, c7, c10, 1          @ clean D line\n\
  74        subs    %2, %2, #1                      \n\
  75        mcr     p15, 0, ip, c7, c6, 1           @ invalidate D line\n\
  76        bgt     1b                              \n\
  77        beq     2b                              "
  78        : "+&r" (from), "+&r" (to), "=&r" (tmp)
  79        : "2" (PAGE_SIZE / 64 - 1)
  80        : "r2", "r3", "r4", "r5", "ip");
  81}
  82
  83void xscale_mc_copy_user_highpage(struct page *to, struct page *from,
  84        unsigned long vaddr, struct vm_area_struct *vma)
  85{
  86        void *kto = kmap_atomic(to);
  87
  88        if (!test_and_set_bit(PG_dcache_clean, &from->flags))
  89                __flush_dcache_page(page_mapping_file(from), from);
  90
  91        raw_spin_lock(&minicache_lock);
  92
  93        set_top_pte(COPYPAGE_MINICACHE, mk_pte(from, minicache_pgprot));
  94
  95        mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
  96
  97        raw_spin_unlock(&minicache_lock);
  98
  99        kunmap_atomic(kto);
 100}
 101
 102/*
 103 * XScale optimised clear_user_page
 104 */
 105void
 106xscale_mc_clear_user_highpage(struct page *page, unsigned long vaddr)
 107{
 108        void *ptr, *kaddr = kmap_atomic(page);
 109        asm volatile(
 110        "mov    r1, %2                          \n\
 111        mov     r2, #0                          \n\
 112        mov     r3, #0                          \n\
 1131:      mov     ip, %0                          \n\
 114        strd    r2, r3, [%0], #8                \n\
 115        strd    r2, r3, [%0], #8                \n\
 116        strd    r2, r3, [%0], #8                \n\
 117        strd    r2, r3, [%0], #8                \n\
 118        mcr     p15, 0, ip, c7, c10, 1          @ clean D line\n\
 119        subs    r1, r1, #1                      \n\
 120        mcr     p15, 0, ip, c7, c6, 1           @ invalidate D line\n\
 121        bne     1b"
 122        : "=r" (ptr)
 123        : "0" (kaddr), "I" (PAGE_SIZE / 32)
 124        : "r1", "r2", "r3", "ip");
 125        kunmap_atomic(kaddr);
 126}
 127
 128struct cpu_user_fns xscale_mc_user_fns __initdata = {
 129        .cpu_clear_user_highpage = xscale_mc_clear_user_highpage,
 130        .cpu_copy_user_highpage = xscale_mc_copy_user_highpage,
 131};
 132