root/arch/mips/mm/highmem.c

DEFINITIONS

1. kmap
2. kunmap
3. kmap_atomic
4. __kunmap_atomic
5. kmap_atomic_pfn
6. kmap_init

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/compiler.h>
   3 #include <linux/init.h>
   4 #include <linux/export.h>
   5 #include <linux/highmem.h>
   6 #include <linux/sched.h>
   7 #include <linux/smp.h>
   8 #include <asm/fixmap.h>
   9 #include <asm/tlbflush.h>
  10 
  11 static pte_t *kmap_pte;
  12 
  13 unsigned long highstart_pfn, highend_pfn;
  14 
  15 void *kmap(struct page *page)
  16 {
  17         void *addr;
  18 
  19         might_sleep();
  20         if (!PageHighMem(page))
  21                 return page_address(page);
  22         addr = kmap_high(page);
  23         flush_tlb_one((unsigned long)addr);
  24 
  25         return addr;
  26 }
  27 EXPORT_SYMBOL(kmap);
  28 
  29 void kunmap(struct page *page)
  30 {
  31         BUG_ON(in_interrupt());
  32         if (!PageHighMem(page))
  33                 return;
  34         kunmap_high(page);
  35 }
  36 EXPORT_SYMBOL(kunmap);
  37 
  38 /*
  39  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
  40  * no global lock is needed and because the kmap code must perform a global TLB
  41  * invalidation when the kmap pool wraps.
  42  *
  43  * However when holding an atomic kmap is is not legal to sleep, so atomic
  44  * kmaps are appropriate for short, tight code paths only.
  45  */
  46 
  47 void *kmap_atomic(struct page *page)
  48 {
  49         unsigned long vaddr;
  50         int idx, type;
  51 
  52         preempt_disable();
  53         pagefault_disable();
  54         if (!PageHighMem(page))
  55                 return page_address(page);
  56 
  57         type = kmap_atomic_idx_push();
  58         idx = type + KM_TYPE_NR*smp_processor_id();
  59         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  60 #ifdef CONFIG_DEBUG_HIGHMEM
  61         BUG_ON(!pte_none(*(kmap_pte - idx)));
  62 #endif
  63         set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
  64         local_flush_tlb_one((unsigned long)vaddr);
  65 
  66         return (void*) vaddr;
  67 }
  68 EXPORT_SYMBOL(kmap_atomic);
  69 
  70 void __kunmap_atomic(void *kvaddr)
  71 {
  72         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  73         int type __maybe_unused;
  74 
  75         if (vaddr < FIXADDR_START) { // FIXME
  76                 pagefault_enable();
  77                 preempt_enable();
  78                 return;
  79         }
  80 
  81         type = kmap_atomic_idx();
  82 #ifdef CONFIG_DEBUG_HIGHMEM
  83         {
  84                 int idx = type + KM_TYPE_NR * smp_processor_id();
  85 
  86                 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  87 
  88                 /*
  89                  * force other mappings to Oops if they'll try to access
  90                  * this pte without first remap it
  91                  */
  92                 pte_clear(&init_mm, vaddr, kmap_pte-idx);
  93                 local_flush_tlb_one(vaddr);
  94         }
  95 #endif
  96         kmap_atomic_idx_pop();
  97         pagefault_enable();
  98         preempt_enable();
  99 }
 100 EXPORT_SYMBOL(__kunmap_atomic);
 101 
 102 /*
 103  * This is the same as kmap_atomic() but can map memory that doesn't
 104  * have a struct page associated with it.
 105  */
 106 void *kmap_atomic_pfn(unsigned long pfn)
 107 {
 108         unsigned long vaddr;
 109         int idx, type;
 110 
 111         preempt_disable();
 112         pagefault_disable();
 113 
 114         type = kmap_atomic_idx_push();
 115         idx = type + KM_TYPE_NR*smp_processor_id();
 116         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 117         set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
 118         flush_tlb_one(vaddr);
 119 
 120         return (void*) vaddr;
 121 }
 122 
 123 void __init kmap_init(void)
 124 {
 125         unsigned long kmap_vstart;
 126 
 127         /* cache the first kmap pte */
 128         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
 129         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
 130 }