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 static inline void set_fixmap_pte(int idx, pte_t pte)
  22 {
  23         unsigned long vaddr = __fix_to_virt(idx);
  24         pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
  25
  26         set_pte_ext(ptep, pte, 0);
  27         local_flush_tlb_kernel_page(vaddr);
  28 }
  29
  30 static inline pte_t get_fixmap_pte(unsigned long vaddr)
  31 {
  32         pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
  33
  34         return *ptep;
  35 }
  36
  37 void *kmap(struct page *page)
  38 {
  39         might_sleep();
  40         if (!PageHighMem(page))
  41                 return page_address(page);
  42         return kmap_high(page);
  43 }
  44 EXPORT_SYMBOL(kmap);
  45
  46 void kunmap(struct page *page)
  47 {
  48         BUG_ON(in_interrupt());
  49         if (!PageHighMem(page))
  50                 return;
  51         kunmap_high(page);
  52 }
  53 EXPORT_SYMBOL(kunmap);
  54
  55 void *kmap_atomic(struct page *page)
  56 {
  57         unsigned int idx;
  58         unsigned long vaddr;
  59         void *kmap;
  60         int type;
  61
  62         pagefault_disable();
  63         if (!PageHighMem(page))
  64                 return page_address(page);
  65
  66 #ifdef CONFIG_DEBUG_HIGHMEM
  67         /*
  68          * There is no cache coherency issue when non VIVT, so force the
  69          * dedicated kmap usage for better debugging purposes in that case.
  70          */
  71         if (!cache_is_vivt())
  72                 kmap = NULL;
  73         else
  74 #endif
  75                 kmap = kmap_high_get(page);
  76         if (kmap)
  77                 return kmap;
  78
  79         type = kmap_atomic_idx_push();
  80
  81         idx = type + KM_TYPE_NR * smp_processor_id();
  82         vaddr = __fix_to_virt(idx);
  83 #ifdef CONFIG_DEBUG_HIGHMEM
  84         /*
  85          * With debugging enabled, kunmap_atomic forces that entry to 0.
  86          * Make sure it was indeed properly unmapped.
  87          */
  88         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
  89 #endif
  90         /*
  91          * When debugging is off, kunmap_atomic leaves the previous mapping
  92          * in place, so the contained TLB flush ensures the TLB is updated
  93          * with the new mapping.
  94          */
  95         set_fixmap_pte(idx, mk_pte(page, kmap_prot));
  96
  97         return (void *)vaddr;
  98 }
  99 EXPORT_SYMBOL(kmap_atomic);
 100
 101 void __kunmap_atomic(void *kvaddr)
 102 {
 103         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 104         int idx, type;
 105
 106         if (kvaddr >= (void *)FIXADDR_START) {
 107                 type = kmap_atomic_idx();
 108                 idx = type + KM_TYPE_NR * smp_processor_id();
 109
 110                 if (cache_is_vivt())
 111                         __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 112 #ifdef CONFIG_DEBUG_HIGHMEM
 113                 BUG_ON(vaddr != __fix_to_virt(idx));
 114                 set_fixmap_pte(idx, __pte(0));
 115 #else
 116                 (void) idx;  /* to kill a warning */
 117 #endif
 118                 kmap_atomic_idx_pop();
 119         } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
 120                 /* this address was obtained through kmap_high_get() */
 121                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
 122         }
 123         pagefault_enable();
 124 }
 125 EXPORT_SYMBOL(__kunmap_atomic);
 126
 127 void *kmap_atomic_pfn(unsigned long pfn)
 128 {
 129         unsigned long vaddr;
 130         int idx, type;
 131         struct page *page = pfn_to_page(pfn);
 132
 133         pagefault_disable();
 134         if (!PageHighMem(page))
 135                 return page_address(page);
 136
 137         type = kmap_atomic_idx_push();
 138         idx = type + KM_TYPE_NR * smp_processor_id();
 139         vaddr = __fix_to_virt(idx);
 140 #ifdef CONFIG_DEBUG_HIGHMEM
 141         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 142 #endif
 143         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 144
 145         return (void *)vaddr;
 146 }
 147
 148 struct page *kmap_atomic_to_page(const void *ptr)
 149 {
 150         unsigned long vaddr = (unsigned long)ptr;
 151
 152         if (vaddr < FIXADDR_START)
 153                 return virt_to_page(ptr);
 154
 155         return pte_page(get_fixmap_pte(vaddr));
 156 }