arch/x86/mm/highmem_32.c

   1 #include <linux/highmem.h>
   2 #include <linux/module.h>
   3 #include <linux/swap.h> /* for totalram_pages */
   4
   5 void *kmap(struct page *page)
   6 {
   7         might_sleep();
   8         if (!PageHighMem(page))
   9                 return page_address(page);
  10         return kmap_high(page);
  11 }
  12
  13 void kunmap(struct page *page)
  14 {
  15         if (in_interrupt())
  16                 BUG();
  17         if (!PageHighMem(page))
  18                 return;
  19         kunmap_high(page);
  20 }
  21
  22 static void debug_kmap_atomic_prot(enum km_type type)
  23 {
  24 #ifdef CONFIG_DEBUG_HIGHMEM
  25         static unsigned warn_count = 10;
  26
  27         if (unlikely(warn_count == 0))
  28                 return;
  29
  30         if (unlikely(in_interrupt())) {
  31                 if (in_irq()) {
  32                         if (type != KM_IRQ0 && type != KM_IRQ1 &&
  33                             type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
  34                             type != KM_BOUNCE_READ) {
  35                                 WARN_ON(1);
  36                                 warn_count--;
  37                         }
  38                 } else if (!irqs_disabled()) {  /* softirq */
  39                         if (type != KM_IRQ0 && type != KM_IRQ1 &&
  40                             type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
  41                             type != KM_SKB_SUNRPC_DATA &&
  42                             type != KM_SKB_DATA_SOFTIRQ &&
  43                             type != KM_BOUNCE_READ) {
  44                                 WARN_ON(1);
  45                                 warn_count--;
  46                         }
  47                 }
  48         }
  49
  50         if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
  51                         type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ) {
  52                 if (!irqs_disabled()) {
  53                         WARN_ON(1);
  54                         warn_count--;
  55                 }
  56         } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
  57                 if (irq_count() == 0 && !irqs_disabled()) {
  58                         WARN_ON(1);
  59                         warn_count--;
  60                 }
  61         }
  62 #endif
  63 }
  64
  65 /*
  66  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  67  * no global lock is needed and because the kmap code must perform a global TLB
  68  * invalidation when the kmap pool wraps.
  69  *
  70  * However when holding an atomic kmap is is not legal to sleep, so atomic
  71  * kmaps are appropriate for short, tight code paths only.
  72  */
  73 void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
  74 {
  75         enum fixed_addresses idx;
  76         unsigned long vaddr;
  77
  78         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  79         pagefault_disable();
  80
  81         if (!PageHighMem(page))
  82                 return page_address(page);
  83
  84         debug_kmap_atomic_prot(type);
  85
  86         idx = type + KM_TYPE_NR*smp_processor_id();
  87         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  88         BUG_ON(!pte_none(*(kmap_pte-idx)));
  89         set_pte(kmap_pte-idx, mk_pte(page, prot));
  90
  91         return (void *)vaddr;
  92 }
  93
  94 void *kmap_atomic(struct page *page, enum km_type type)
  95 {
  96         return kmap_atomic_prot(page, type, kmap_prot);
  97 }
  98
  99 void kunmap_atomic(void *kvaddr, enum km_type type)
 100 {
 101         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 102         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
 103
 104         /*
 105          * Force other mappings to Oops if they'll try to access this pte
 106          * without first remap it.  Keeping stale mappings around is a bad idea
 107          * also, in case the page changes cacheability attributes or becomes
 108          * a protected page in a hypervisor.
 109          */
 110         if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
 111                 kpte_clear_flush(kmap_pte-idx, vaddr);
 112         else {
 113 #ifdef CONFIG_DEBUG_HIGHMEM
 114                 BUG_ON(vaddr < PAGE_OFFSET);
 115                 BUG_ON(vaddr >= (unsigned long)high_memory);
 116 #endif
 117         }
 118
 119         pagefault_enable();
 120 }
 121
 122 /* This is the same as kmap_atomic() but can map memory that doesn't
 123  * have a struct page associated with it.
 124  */
 125 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
 126 {
 127         enum fixed_addresses idx;
 128         unsigned long vaddr;
 129
 130         pagefault_disable();
 131
 132         idx = type + KM_TYPE_NR*smp_processor_id();
 133         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 134         set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
 135         arch_flush_lazy_mmu_mode();
 136
 137         return (void*) vaddr;
 138 }
 139 EXPORT_SYMBOL_GPL(kmap_atomic_pfn); /* temporarily in use by i915 GEM until vmap */
 140
 141 struct page *kmap_atomic_to_page(void *ptr)
 142 {
 143         unsigned long idx, vaddr = (unsigned long)ptr;
 144         pte_t *pte;
 145
 146         if (vaddr < FIXADDR_START)
 147                 return virt_to_page(ptr);
 148
 149         idx = virt_to_fix(vaddr);
 150         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
 151         return pte_page(*pte);
 152 }
 153
 154 EXPORT_SYMBOL(kmap);
 155 EXPORT_SYMBOL(kunmap);
 156 EXPORT_SYMBOL(kmap_atomic);
 157 EXPORT_SYMBOL(kunmap_atomic);
 158
 159 #ifdef CONFIG_NUMA
 160 void __init set_highmem_pages_init(void)
 161 {
 162         struct zone *zone;
 163         int nid;
 164
 165         for_each_zone(zone) {
 166                 unsigned long zone_start_pfn, zone_end_pfn;
 167
 168                 if (!is_highmem(zone))
 169                         continue;
 170
 171                 zone_start_pfn = zone->zone_start_pfn;
 172                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 173
 174                 nid = zone_to_nid(zone);
 175                 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 176                                 zone->name, nid, zone_start_pfn, zone_end_pfn);
 177
 178                 add_highpages_with_active_regions(nid, zone_start_pfn,
 179                                  zone_end_pfn);
 180         }
 181         totalram_pages += totalhigh_pages;
 182 }
 183 #else
 184 void __init set_highmem_pages_init(void)
 185 {
 186         add_highpages_with_active_regions(0, highstart_pfn, highend_pfn);
 187
 188         totalram_pages += totalhigh_pages;
 189 }
 190 #endif /* CONFIG_NUMA */