arch/arm/mm/highmem.c

   1 /*
   2  * arch/arm/mm/highmem.c -- ARM highmem support
   3  *
   4  * Author:      Nicolas Pitre
   5  * Created:     september 8, 2008
   6  * Copyright:   Marvell Semiconductors Inc.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/highmem.h>
  15 #include <linux/interrupt.h>
  16 #include <asm/fixmap.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/tlbflush.h>
  19 #include "mm.h"
  20
  21 pte_t *fixmap_page_table;
  22
  23 static inline void set_fixmap_pte(int idx, pte_t pte)
  24 {
  25         unsigned long vaddr = __fix_to_virt(idx);
  26         set_pte_ext(fixmap_page_table + idx, pte, 0);
  27         local_flush_tlb_kernel_page(vaddr);
  28 }
  29
  30 static inline pte_t get_fixmap_pte(unsigned long vaddr)
  31 {
  32         unsigned long idx = __virt_to_fix(vaddr);
  33         return *(fixmap_page_table + idx);
  34 }
  35
  36 void *kmap(struct page *page)
  37 {
  38         might_sleep();
  39         if (!PageHighMem(page))
  40                 return page_address(page);
  41         return kmap_high(page);
  42 }
  43 EXPORT_SYMBOL(kmap);
  44
  45 void kunmap(struct page *page)
  46 {
  47         BUG_ON(in_interrupt());
  48         if (!PageHighMem(page))
  49                 return;
  50         kunmap_high(page);
  51 }
  52 EXPORT_SYMBOL(kunmap);
  53
  54 void *kmap_atomic(struct page *page)
  55 {
  56         unsigned int idx;
  57         unsigned long vaddr;
  58         void *kmap;
  59         int type;
  60
  61         pagefault_disable();
  62         if (!PageHighMem(page))
  63                 return page_address(page);
  64
  65 #ifdef CONFIG_DEBUG_HIGHMEM
  66         /*
  67          * There is no cache coherency issue when non VIVT, so force the
  68          * dedicated kmap usage for better debugging purposes in that case.
  69          */
  70         if (!cache_is_vivt())
  71                 kmap = NULL;
  72         else
  73 #endif
  74                 kmap = kmap_high_get(page);
  75         if (kmap)
  76                 return kmap;
  77
  78         type = kmap_atomic_idx_push();
  79
  80         idx = type + KM_TYPE_NR * smp_processor_id();
  81         vaddr = __fix_to_virt(idx);
  82 #ifdef CONFIG_DEBUG_HIGHMEM
  83         /*
  84          * With debugging enabled, kunmap_atomic forces that entry to 0.
  85          * Make sure it was indeed properly unmapped.
  86          */
  87         BUG_ON(!pte_none(*(fixmap_page_table + idx)));
  88 #endif
  89         /*
  90          * When debugging is off, kunmap_atomic leaves the previous mapping
  91          * in place, so the contained TLB flush ensures the TLB is updated
  92          * with the new mapping.
  93          */
  94         set_fixmap_pte(idx, mk_pte(page, kmap_prot));
  95
  96         return (void *)vaddr;
  97 }
  98 EXPORT_SYMBOL(kmap_atomic);
  99
 100 void __kunmap_atomic(void *kvaddr)
 101 {
 102         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 103         int idx, type;
 104
 105         if (kvaddr >= (void *)FIXADDR_START) {
 106                 type = kmap_atomic_idx();
 107                 idx = type + KM_TYPE_NR * smp_processor_id();
 108
 109                 if (cache_is_vivt())
 110                         __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 111 #ifdef CONFIG_DEBUG_HIGHMEM
 112                 BUG_ON(vaddr != __fix_to_virt(idx));
 113                 set_fixmap_pte(idx, __pte(0));
 114 #else
 115                 (void) idx;  /* to kill a warning */
 116 #endif
 117                 kmap_atomic_idx_pop();
 118         } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
 119                 /* this address was obtained through kmap_high_get() */
 120                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
 121         }
 122         pagefault_enable();
 123 }
 124 EXPORT_SYMBOL(__kunmap_atomic);
 125
 126 void *kmap_atomic_pfn(unsigned long pfn)
 127 {
 128         unsigned long vaddr;
 129         int idx, type;
 130
 131         pagefault_disable();
 132
 133         type = kmap_atomic_idx_push();
 134         idx = type + KM_TYPE_NR * smp_processor_id();
 135         vaddr = __fix_to_virt(idx);
 136 #ifdef CONFIG_DEBUG_HIGHMEM
 137         BUG_ON(!pte_none(*(fixmap_page_table + idx)));
 138 #endif
 139         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 140
 141         return (void *)vaddr;
 142 }
 143
 144 struct page *kmap_atomic_to_page(const void *ptr)
 145 {
 146         unsigned long vaddr = (unsigned long)ptr;
 147
 148         if (vaddr < FIXADDR_START)
 149                 return virt_to_page(ptr);
 150
 151         return pte_page(get_fixmap_pte(vaddr));
 152 }