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