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         void *kmap;
  44
  45         pagefault_disable();
  46         if (!PageHighMem(page))
  47                 return page_address(page);
  48
  49         debug_kmap_atomic(type);
  50
  51         kmap = kmap_high_get(page);
  52         if (kmap)
  53                 return kmap;
  54
  55         idx = type + KM_TYPE_NR * smp_processor_id();
  56         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  57 #ifdef CONFIG_DEBUG_HIGHMEM
  58         /*
  59          * With debugging enabled, kunmap_atomic forces that entry to 0.
  60          * Make sure it was indeed properly unmapped.
  61          */
  62         BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
  63 #endif
  64         set_pte_ext(TOP_PTE(vaddr), mk_pte(page, kmap_prot), 0);
  65         /*
  66          * When debugging is off, kunmap_atomic leaves the previous mapping
  67          * in place, so this TLB flush ensures the TLB is updated with the
  68          * new mapping.
  69          */
  70         local_flush_tlb_kernel_page(vaddr);
  71
  72         return (void *)vaddr;
  73 }
  74 EXPORT_SYMBOL(kmap_atomic);
  75
  76 void kunmap_atomic(void *kvaddr, enum km_type type)
  77 {
  78         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  79         unsigned int idx = type + KM_TYPE_NR * smp_processor_id();
  80
  81         if (kvaddr >= (void *)FIXADDR_START) {
  82                 __cpuc_flush_dcache_page((void *)vaddr);
  83 #ifdef CONFIG_DEBUG_HIGHMEM
  84                 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  85                 set_pte_ext(TOP_PTE(vaddr), __pte(0), 0);
  86                 local_flush_tlb_kernel_page(vaddr);
  87 #else
  88                 (void) idx;  /* to kill a warning */
  89 #endif
  90         } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
  91                 /* this address was obtained through kmap_high_get() */
  92                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
  93         }
  94         pagefault_enable();
  95 }
  96 EXPORT_SYMBOL(kunmap_atomic);
  97
  98 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  99 {
 100         unsigned int idx;
 101         unsigned long vaddr;
 102
 103         pagefault_disable();
 104
 105         idx = type + KM_TYPE_NR * smp_processor_id();
 106         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 107 #ifdef CONFIG_DEBUG_HIGHMEM
 108         BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
 109 #endif
 110         set_pte_ext(TOP_PTE(vaddr), pfn_pte(pfn, kmap_prot), 0);
 111         local_flush_tlb_kernel_page(vaddr);
 112
 113         return (void *)vaddr;
 114 }
 115
 116 struct page *kmap_atomic_to_page(const void *ptr)
 117 {
 118         unsigned long vaddr = (unsigned long)ptr;
 119         pte_t *pte;
 120
 121         if (vaddr < FIXADDR_START)
 122                 return virt_to_page(ptr);
 123
 124         pte = TOP_PTE(vaddr);
 125         return pte_page(*pte);
 126 }