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