arch/mips/mm/highmem.c

   1 #include <linux/module.h>
   2 #include <linux/highmem.h>
   3 #include <linux/smp.h>
   4 #include <asm/fixmap.h>
   5 #include <asm/tlbflush.h>
   6
   7 static pte_t *kmap_pte;
   8
   9 unsigned long highstart_pfn, highend_pfn;
  10
  11 void *__kmap(struct page *page)
  12 {
  13         void *addr;
  14
  15         might_sleep();
  16         if (!PageHighMem(page))
  17                 return page_address(page);
  18         addr = kmap_high(page);
  19         flush_tlb_one((unsigned long)addr);
  20
  21         return addr;
  22 }
  23 EXPORT_SYMBOL(__kmap);
  24
  25 void __kunmap(struct page *page)
  26 {
  27         BUG_ON(in_interrupt());
  28         if (!PageHighMem(page))
  29                 return;
  30         kunmap_high(page);
  31 }
  32 EXPORT_SYMBOL(__kunmap);
  33
  34 /*
  35  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  36  * no global lock is needed and because the kmap code must perform a global TLB
  37  * invalidation when the kmap pool wraps.
  38  *
  39  * However when holding an atomic kmap is is not legal to sleep, so atomic
  40  * kmaps are appropriate for short, tight code paths only.
  41  */
  42
  43 void *__kmap_atomic(struct page *page, enum km_type type)
  44 {
  45         enum fixed_addresses idx;
  46         unsigned long vaddr;
  47
  48         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  49         pagefault_disable();
  50         if (!PageHighMem(page))
  51                 return page_address(page);
  52
  53         debug_kmap_atomic(type);
  54         idx = type + KM_TYPE_NR*smp_processor_id();
  55         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  56 #ifdef CONFIG_DEBUG_HIGHMEM
  57         BUG_ON(!pte_none(*(kmap_pte - idx)));
  58 #endif
  59         set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
  60         local_flush_tlb_one((unsigned long)vaddr);
  61
  62         return (void*) vaddr;
  63 }
  64 EXPORT_SYMBOL(__kmap_atomic);
  65
  66 void __kunmap_atomic(void *kvaddr, enum km_type type)
  67 {
  68 #ifdef CONFIG_DEBUG_HIGHMEM
  69         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  70         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  71
  72         if (vaddr < FIXADDR_START) { // FIXME
  73                 pagefault_enable();
  74                 return;
  75         }
  76
  77         BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  78
  79         /*
  80          * force other mappings to Oops if they'll try to access
  81          * this pte without first remap it
  82          */
  83         pte_clear(&init_mm, vaddr, kmap_pte-idx);
  84         local_flush_tlb_one(vaddr);
  85 #endif
  86
  87         pagefault_enable();
  88 }
  89 EXPORT_SYMBOL(__kunmap_atomic);
  90
  91 /*
  92  * This is the same as kmap_atomic() but can map memory that doesn't
  93  * have a struct page associated with it.
  94  */
  95 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  96 {
  97         enum fixed_addresses idx;
  98         unsigned long vaddr;
  99
 100         pagefault_disable();
 101
 102         debug_kmap_atomic(type);
 103         idx = type + KM_TYPE_NR*smp_processor_id();
 104         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 105         set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
 106         flush_tlb_one(vaddr);
 107
 108         return (void*) vaddr;
 109 }
 110
 111 struct page *__kmap_atomic_to_page(void *ptr)
 112 {
 113         unsigned long idx, vaddr = (unsigned long)ptr;
 114         pte_t *pte;
 115
 116         if (vaddr < FIXADDR_START)
 117                 return virt_to_page(ptr);
 118
 119         idx = virt_to_fix(vaddr);
 120         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 121         return pte_page(*pte);
 122 }
 123
 124 void __init kmap_init(void)
 125 {
 126         unsigned long kmap_vstart;
 127
 128         /* cache the first kmap pte */
 129         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
 130         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
 131 }