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         preempt_disable();
  63         pagefault_disable();
  64         if (!PageHighMem(page))
  65                 return page_address(page);
  66
  67 #ifdef CONFIG_DEBUG_HIGHMEM
  68         /*
  69          * There is no cache coherency issue when non VIVT, so force the
  70          * dedicated kmap usage for better debugging purposes in that case.
  71          */
  72         if (!cache_is_vivt())
  73                 kmap = NULL;
  74         else
  75 #endif
  76                 kmap = kmap_high_get(page);
  77         if (kmap)
  78                 return kmap;
  79
  80         type = kmap_atomic_idx_push();
  81
  82         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
  83         vaddr = __fix_to_virt(idx);
  84 #ifdef CONFIG_DEBUG_HIGHMEM
  85         /*
  86          * With debugging enabled, kunmap_atomic forces that entry to 0.
  87          * Make sure it was indeed properly unmapped.
  88          */
  89         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
  90 #endif
  91         /*
  92          * When debugging is off, kunmap_atomic leaves the previous mapping
  93          * in place, so the contained TLB flush ensures the TLB is updated
  94          * with the new mapping.
  95          */
  96         set_fixmap_pte(idx, mk_pte(page, kmap_prot));
  97
  98         return (void *)vaddr;
  99 }
 100 EXPORT_SYMBOL(kmap_atomic);
 101
 102 void __kunmap_atomic(void *kvaddr)
 103 {
 104         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 105         int idx, type;
 106
 107         if (kvaddr >= (void *)FIXADDR_START) {
 108                 type = kmap_atomic_idx();
 109                 idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 110
 111                 if (cache_is_vivt())
 112                         __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 113 #ifdef CONFIG_DEBUG_HIGHMEM
 114                 BUG_ON(vaddr != __fix_to_virt(idx));
 115                 set_fixmap_pte(idx, __pte(0));
 116 #else
 117                 (void) idx;  /* to kill a warning */
 118 #endif
 119                 kmap_atomic_idx_pop();
 120         } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
 121                 /* this address was obtained through kmap_high_get() */
 122                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
 123         }
 124         pagefault_enable();
 125         preempt_enable();
 126 }
 127 EXPORT_SYMBOL(__kunmap_atomic);
 128
 129 void *kmap_atomic_pfn(unsigned long pfn)
 130 {
 131         unsigned long vaddr;
 132         int idx, type;
 133         struct page *page = pfn_to_page(pfn);
 134
 135         preempt_disable();
 136         pagefault_disable();
 137         if (!PageHighMem(page))
 138                 return page_address(page);
 139
 140         type = kmap_atomic_idx_push();
 141         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 142         vaddr = __fix_to_virt(idx);
 143 #ifdef CONFIG_DEBUG_HIGHMEM
 144         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 145 #endif
 146         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 147
 148         return (void *)vaddr;
 149 }
 150
 151 struct page *kmap_atomic_to_page(const void *ptr)
 152 {
 153         unsigned long vaddr = (unsigned long)ptr;
 154
 155         if (vaddr < FIXADDR_START)
 156                 return virt_to_page(ptr);
 157
 158         return pte_page(get_fixmap_pte(vaddr));
 159 }