arch/mips/mm/highmem.c

   1 #include <linux/module.h>
   2 #include <linux/highmem.h>
   3 #include <linux/sched.h>
   4 #include <linux/smp.h>
   5 #include <asm/fixmap.h>
   6 #include <asm/tlbflush.h>
   7
   8 static pte_t *kmap_pte;
   9
  10 unsigned long highstart_pfn, highend_pfn;
  11
  12 void *__kmap(struct page *page)
  13 {
  14         void *addr;
  15
  16         might_sleep();
  17         if (!PageHighMem(page))
  18                 return page_address(page);
  19         addr = kmap_high(page);
  20         flush_tlb_one((unsigned long)addr);
  21
  22         return addr;
  23 }
  24 EXPORT_SYMBOL(__kmap);
  25
  26 void __kunmap(struct page *page)
  27 {
  28         BUG_ON(in_interrupt());
  29         if (!PageHighMem(page))
  30                 return;
  31         kunmap_high(page);
  32 }
  33 EXPORT_SYMBOL(__kunmap);
  34
  35 /*
  36  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  37  * no global lock is needed and because the kmap code must perform a global TLB
  38  * invalidation when the kmap pool wraps.
  39  *
  40  * However when holding an atomic kmap is is not legal to sleep, so atomic
  41  * kmaps are appropriate for short, tight code paths only.
  42  */
  43
  44 void *__kmap_atomic(struct page *page, enum km_type type)
  45 {
  46         enum fixed_addresses idx;
  47         unsigned long vaddr;
  48
  49         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  50         pagefault_disable();
  51         if (!PageHighMem(page))
  52                 return page_address(page);
  53
  54         debug_kmap_atomic(type);
  55         idx = type + KM_TYPE_NR*smp_processor_id();
  56         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  57 #ifdef CONFIG_DEBUG_HIGHMEM
  58         BUG_ON(!pte_none(*(kmap_pte - idx)));
  59 #endif
  60         set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
  61         local_flush_tlb_one((unsigned long)vaddr);
  62
  63         return (void*) vaddr;
  64 }
  65 EXPORT_SYMBOL(__kmap_atomic);
  66
  67 void __kunmap_atomic(void *kvaddr, enum km_type type)
  68 {
  69 #ifdef CONFIG_DEBUG_HIGHMEM
  70         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  71         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
  72
  73         if (vaddr < FIXADDR_START) { // FIXME
  74                 pagefault_enable();
  75                 return;
  76         }
  77
  78         BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  79
  80         /*
  81          * force other mappings to Oops if they'll try to access
  82          * this pte without first remap it
  83          */
  84         pte_clear(&init_mm, vaddr, kmap_pte-idx);
  85         local_flush_tlb_one(vaddr);
  86 #endif
  87
  88         pagefault_enable();
  89 }
  90 EXPORT_SYMBOL(__kunmap_atomic);
  91
  92 /*
  93  * This is the same as kmap_atomic() but can map memory that doesn't
  94  * have a struct page associated with it.
  95  */
  96 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
  97 {
  98         enum fixed_addresses idx;
  99         unsigned long vaddr;
 100
 101         pagefault_disable();
 102
 103         debug_kmap_atomic(type);
 104         idx = type + KM_TYPE_NR*smp_processor_id();
 105         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 106         set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
 107         flush_tlb_one(vaddr);
 108
 109         return (void*) vaddr;
 110 }
 111
 112 struct page *__kmap_atomic_to_page(void *ptr)
 113 {
 114         unsigned long idx, vaddr = (unsigned long)ptr;
 115         pte_t *pte;
 116
 117         if (vaddr < FIXADDR_START)
 118                 return virt_to_page(ptr);
 119
 120         idx = virt_to_fix(vaddr);
 121         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 122         return pte_page(*pte);
 123 }
 124
 125 void __init kmap_init(void)
 126 {
 127         unsigned long kmap_vstart;
 128
 129         /* cache the first kmap pte */
 130         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
 131         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
 132 }