root/arch/arm/mm/highmem.c

DEFINITIONS

1. set_fixmap_pte
2. get_fixmap_pte
3. kmap
4. kunmap
5. kmap_atomic
6. __kunmap_atomic
7. kmap_atomic_pfn

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * arch/arm/mm/highmem.c -- ARM highmem support
   4  *
   5  * Author:      Nicolas Pitre
   6  * Created:     september 8, 2008
   7  * Copyright:   Marvell Semiconductors Inc.
   8  */
   9 
  10 #include <linux/module.h>
  11 #include <linux/highmem.h>
  12 #include <linux/interrupt.h>
  13 #include <asm/fixmap.h>
  14 #include <asm/cacheflush.h>
  15 #include <asm/tlbflush.h>
  16 #include "mm.h"
  17 
  18 static inline void set_fixmap_pte(int idx, pte_t pte)
  19 {
  20         unsigned long vaddr = __fix_to_virt(idx);
  21         pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
  22 
  23         set_pte_ext(ptep, pte, 0);
  24         local_flush_tlb_kernel_page(vaddr);
  25 }
  26 
  27 static inline pte_t get_fixmap_pte(unsigned long vaddr)
  28 {
  29         pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
  30 
  31         return *ptep;
  32 }
  33 
  34 void *kmap(struct page *page)
  35 {
  36         might_sleep();
  37         if (!PageHighMem(page))
  38                 return page_address(page);
  39         return kmap_high(page);
  40 }
  41 EXPORT_SYMBOL(kmap);
  42 
  43 void kunmap(struct page *page)
  44 {
  45         BUG_ON(in_interrupt());
  46         if (!PageHighMem(page))
  47                 return;
  48         kunmap_high(page);
  49 }
  50 EXPORT_SYMBOL(kunmap);
  51 
  52 void *kmap_atomic(struct page *page)
  53 {
  54         unsigned int idx;
  55         unsigned long vaddr;
  56         void *kmap;
  57         int type;
  58 
  59         preempt_disable();
  60         pagefault_disable();
  61         if (!PageHighMem(page))
  62                 return page_address(page);
  63 
  64 #ifdef CONFIG_DEBUG_HIGHMEM
  65         /*
  66          * There is no cache coherency issue when non VIVT, so force the
  67          * dedicated kmap usage for better debugging purposes in that case.
  68          */
  69         if (!cache_is_vivt())
  70                 kmap = NULL;
  71         else
  72 #endif
  73                 kmap = kmap_high_get(page);
  74         if (kmap)
  75                 return kmap;
  76 
  77         type = kmap_atomic_idx_push();
  78 
  79         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
  80         vaddr = __fix_to_virt(idx);
  81 #ifdef CONFIG_DEBUG_HIGHMEM
  82         /*
  83          * With debugging enabled, kunmap_atomic forces that entry to 0.
  84          * Make sure it was indeed properly unmapped.
  85          */
  86         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
  87 #endif
  88         /*
  89          * When debugging is off, kunmap_atomic leaves the previous mapping
  90          * in place, so the contained TLB flush ensures the TLB is updated
  91          * with the new mapping.
  92          */
  93         set_fixmap_pte(idx, mk_pte(page, kmap_prot));
  94 
  95         return (void *)vaddr;
  96 }
  97 EXPORT_SYMBOL(kmap_atomic);
  98 
  99 void __kunmap_atomic(void *kvaddr)
 100 {
 101         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 102         int idx, type;
 103 
 104         if (kvaddr >= (void *)FIXADDR_START) {
 105                 type = kmap_atomic_idx();
 106                 idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 107 
 108                 if (cache_is_vivt())
 109                         __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 110 #ifdef CONFIG_DEBUG_HIGHMEM
 111                 BUG_ON(vaddr != __fix_to_virt(idx));
 112                 set_fixmap_pte(idx, __pte(0));
 113 #else
 114                 (void) idx;  /* to kill a warning */
 115 #endif
 116                 kmap_atomic_idx_pop();
 117         } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
 118                 /* this address was obtained through kmap_high_get() */
 119                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
 120         }
 121         pagefault_enable();
 122         preempt_enable();
 123 }
 124 EXPORT_SYMBOL(__kunmap_atomic);
 125 
 126 void *kmap_atomic_pfn(unsigned long pfn)
 127 {
 128         unsigned long vaddr;
 129         int idx, type;
 130         struct page *page = pfn_to_page(pfn);
 131 
 132         preempt_disable();
 133         pagefault_disable();
 134         if (!PageHighMem(page))
 135                 return page_address(page);
 136 
 137         type = kmap_atomic_idx_push();
 138         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 139         vaddr = __fix_to_virt(idx);
 140 #ifdef CONFIG_DEBUG_HIGHMEM
 141         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 142 #endif
 143         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 144 
 145         return (void *)vaddr;
 146 }