arch/arm/mm/highmem.c

   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 = virt_to_kpte(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 = virt_to_kpte(vaddr);
  30
  31         return *ptep;
  32 }
  33
  34 void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
  35 {
  36         unsigned int idx;
  37         unsigned long vaddr;
  38         void *kmap;
  39         int type;
  40
  41 #ifdef CONFIG_DEBUG_HIGHMEM
  42         /*
  43          * There is no cache coherency issue when non VIVT, so force the
  44          * dedicated kmap usage for better debugging purposes in that case.
  45          */
  46         if (!cache_is_vivt())
  47                 kmap = NULL;
  48         else
  49 #endif
  50                 kmap = kmap_high_get(page);
  51         if (kmap)
  52                 return kmap;
  53
  54         type = kmap_atomic_idx_push();
  55
  56         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
  57         vaddr = __fix_to_virt(idx);
  58 #ifdef CONFIG_DEBUG_HIGHMEM
  59         /*
  60          * With debugging enabled, kunmap_atomic forces that entry to 0.
  61          * Make sure it was indeed properly unmapped.
  62          */
  63         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
  64 #endif
  65         /*
  66          * When debugging is off, kunmap_atomic leaves the previous mapping
  67          * in place, so the contained TLB flush ensures the TLB is updated
  68          * with the new mapping.
  69          */
  70         set_fixmap_pte(idx, mk_pte(page, prot));
  71
  72         return (void *)vaddr;
  73 }
  74 EXPORT_SYMBOL(kmap_atomic_high_prot);
  75
  76 void kunmap_atomic_high(void *kvaddr)
  77 {
  78         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  79         int idx, type;
  80
  81         if (kvaddr >= (void *)FIXADDR_START) {
  82                 type = kmap_atomic_idx();
  83                 idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
  84
  85                 if (cache_is_vivt())
  86                         __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
  87 #ifdef CONFIG_DEBUG_HIGHMEM
  88                 BUG_ON(vaddr != __fix_to_virt(idx));
  89                 set_fixmap_pte(idx, __pte(0));
  90 #else
  91                 (void) idx;  /* to kill a warning */
  92 #endif
  93                 kmap_atomic_idx_pop();
  94         } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
  95                 /* this address was obtained through kmap_high_get() */
  96                 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
  97         }
  98 }
  99 EXPORT_SYMBOL(kunmap_atomic_high);
 100
 101 void *kmap_atomic_pfn(unsigned long pfn)
 102 {
 103         unsigned long vaddr;
 104         int idx, type;
 105         struct page *page = pfn_to_page(pfn);
 106
 107         preempt_disable();
 108         pagefault_disable();
 109         if (!PageHighMem(page))
 110                 return page_address(page);
 111
 112         type = kmap_atomic_idx_push();
 113         idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 114         vaddr = __fix_to_virt(idx);
 115 #ifdef CONFIG_DEBUG_HIGHMEM
 116         BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 117 #endif
 118         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
 119
 120         return (void *)vaddr;
 121 }