arch/x86/mm/highmem_32.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/highmem.h>
   3 #include <linux/export.h>
   4 #include <linux/swap.h> /* for totalram_pages */
   5 #include <linux/memblock.h>
   6
   7 void *kmap(struct page *page)
   8 {
   9         might_sleep();
  10         if (!PageHighMem(page))
  11                 return page_address(page);
  12         return kmap_high(page);
  13 }
  14 EXPORT_SYMBOL(kmap);
  15
  16 void kunmap(struct page *page)
  17 {
  18         if (in_interrupt())
  19                 BUG();
  20         if (!PageHighMem(page))
  21                 return;
  22         kunmap_high(page);
  23 }
  24 EXPORT_SYMBOL(kunmap);
  25
  26 /*
  27  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  28  * no global lock is needed and because the kmap code must perform a global TLB
  29  * invalidation when the kmap pool wraps.
  30  *
  31  * However when holding an atomic kmap it is not legal to sleep, so atomic
  32  * kmaps are appropriate for short, tight code paths only.
  33  */
  34 void *kmap_atomic_prot(struct page *page, pgprot_t prot)
  35 {
  36         unsigned long vaddr;
  37         int idx, type;
  38
  39         preempt_disable();
  40         pagefault_disable();
  41
  42         if (!PageHighMem(page))
  43                 return page_address(page);
  44
  45         type = kmap_atomic_idx_push();
  46         idx = type + KM_TYPE_NR*smp_processor_id();
  47         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  48         BUG_ON(!pte_none(*(kmap_pte-idx)));
  49         set_pte(kmap_pte-idx, mk_pte(page, prot));
  50         arch_flush_lazy_mmu_mode();
  51
  52         return (void *)vaddr;
  53 }
  54 EXPORT_SYMBOL(kmap_atomic_prot);
  55
  56 void *kmap_atomic(struct page *page)
  57 {
  58         return kmap_atomic_prot(page, kmap_prot);
  59 }
  60 EXPORT_SYMBOL(kmap_atomic);
  61
  62 /*
  63  * This is the same as kmap_atomic() but can map memory that doesn't
  64  * have a struct page associated with it.
  65  */
  66 void *kmap_atomic_pfn(unsigned long pfn)
  67 {
  68         return kmap_atomic_prot_pfn(pfn, kmap_prot);
  69 }
  70 EXPORT_SYMBOL_GPL(kmap_atomic_pfn);
  71
  72 void __kunmap_atomic(void *kvaddr)
  73 {
  74         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  75
  76         if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
  77             vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
  78                 int idx, type;
  79
  80                 type = kmap_atomic_idx();
  81                 idx = type + KM_TYPE_NR * smp_processor_id();
  82
  83 #ifdef CONFIG_DEBUG_HIGHMEM
  84                 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  85 #endif
  86                 /*
  87                  * Force other mappings to Oops if they'll try to access this
  88                  * pte without first remap it.  Keeping stale mappings around
  89                  * is a bad idea also, in case the page changes cacheability
  90                  * attributes or becomes a protected page in a hypervisor.
  91                  */
  92                 kpte_clear_flush(kmap_pte-idx, vaddr);
  93                 kmap_atomic_idx_pop();
  94                 arch_flush_lazy_mmu_mode();
  95         }
  96 #ifdef CONFIG_DEBUG_HIGHMEM
  97         else {
  98                 BUG_ON(vaddr < PAGE_OFFSET);
  99                 BUG_ON(vaddr >= (unsigned long)high_memory);
 100         }
 101 #endif
 102
 103         pagefault_enable();
 104         preempt_enable();
 105 }
 106 EXPORT_SYMBOL(__kunmap_atomic);
 107
 108 void __init set_highmem_pages_init(void)
 109 {
 110         struct zone *zone;
 111         int nid;
 112
 113         /*
 114          * Explicitly reset zone->managed_pages because set_highmem_pages_init()
 115          * is invoked before memblock_free_all()
 116          */
 117         reset_all_zones_managed_pages();
 118         for_each_zone(zone) {
 119                 unsigned long zone_start_pfn, zone_end_pfn;
 120
 121                 if (!is_highmem(zone))
 122                         continue;
 123
 124                 zone_start_pfn = zone->zone_start_pfn;
 125                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 126
 127                 nid = zone_to_nid(zone);
 128                 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
 129                                 zone->name, nid, zone_start_pfn, zone_end_pfn);
 130
 131                 add_highpages_with_active_regions(nid, zone_start_pfn,
 132                                  zone_end_pfn);
 133         }
 134 }