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 void *kmap(struct page *page)
  22 {
  23         might_sleep();
  24         if (!PageHighMem(page))
  25                 return page_address(page);
  26         return kmap_high(page);
  27 }
  28 EXPORT_SYMBOL(kmap);
  29
  30 void kunmap(struct page *page)
  31 {
  32         BUG_ON(in_interrupt());
  33         if (!PageHighMem(page))
  34                 return;
  35         kunmap_high(page);
  36 }
  37 EXPORT_SYMBOL(kunmap);
  38
  39 void *kmap_atomic(struct page *page, enum km_type type)
  40 {
  41         unsigned int idx;
  42         unsigned long vaddr;
  43
  44         pagefault_disable();
  45         if (!PageHighMem(page))
  46                 return page_address(page);
  47
  48         idx = type + KM_TYPE_NR * smp_processor_id();
  49         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  50 #ifdef CONFIG_DEBUG_HIGHMEM
  51         /*
  52          * With debugging enabled, kunmap_atomic forces that entry to 0.
  53          * Make sure it was indeed properly unmapped.
  54          */
  55         BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
  56 #endif
  57         set_pte_ext(TOP_PTE(vaddr), mk_pte(page, kmap_prot), 0);
  58         /*
  59          * When debugging is off, kunmap_atomic leaves the previous mapping
  60          * in place, so this TLB flush ensures the TLB is updated with the
  61          * new mapping.
  62          */
  63         local_flush_tlb_kernel_page(vaddr);
  64
  65         return (void *)vaddr;
  66 }
  67 EXPORT_SYMBOL(kmap_atomic);
  68
  69 void kunmap_atomic(void *kvaddr, enum km_type type)
  70 {
  71         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  72         unsigned int idx = type + KM_TYPE_NR * smp_processor_id();
  73
  74         if (kvaddr >= (void *)FIXADDR_START) {
  75                 __cpuc_flush_dcache_page((void *)vaddr);
  76 #ifdef CONFIG_DEBUG_HIGHMEM
  77                 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  78                 set_pte_ext(TOP_PTE(vaddr), __pte(0), 0);
  79                 local_flush_tlb_kernel_page(vaddr);
  80 #else
  81                 (void) idx;  /* to kill a warning */
  82 #endif
  83         }
  84         pagefault_enable();
  85 }
  86 EXPORT_SYMBOL(kunmap_atomic);
  87
  88 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  89 {
  90         unsigned int idx;
  91         unsigned long vaddr;
  92
  93         pagefault_disable();
  94
  95         idx = type + KM_TYPE_NR * smp_processor_id();
  96         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  97 #ifdef CONFIG_DEBUG_HIGHMEM
  98         BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
  99 #endif
 100         set_pte_ext(TOP_PTE(vaddr), pfn_pte(pfn, kmap_prot), 0);
 101         local_flush_tlb_kernel_page(vaddr);
 102
 103         return (void *)vaddr;
 104 }
 105
 106 struct page *kmap_atomic_to_page(const void *ptr)
 107 {
 108         unsigned long vaddr = (unsigned long)ptr;
 109         pte_t *pte;
 110
 111         if (vaddr < FIXADDR_START)
 112                 return virt_to_page(ptr);
 113
 114         pte = TOP_PTE(vaddr);
 115         return pte_page(*pte);
 116 }