arch/xtensa/mm/highmem.c

   1 /*
   2  * High memory support for Xtensa architecture
   3  *
   4  * This file is subject to the terms and conditions of the GNU General
   5  * Public License.  See the file "COPYING" in the main directory of
   6  * this archive for more details.
   7  *
   8  * Copyright (C) 2014 Cadence Design Systems Inc.
   9  */
  10
  11 #include <linux/export.h>
  12 #include <linux/highmem.h>
  13 #include <asm/tlbflush.h>
  14
  15 static pte_t *kmap_pte;
  16
  17 #if DCACHE_WAY_SIZE > PAGE_SIZE
  18 unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
  19 wait_queue_head_t pkmap_map_wait_arr[DCACHE_N_COLORS];
  20
  21 static void __init kmap_waitqueues_init(void)
  22 {
  23         unsigned int i;
  24
  25         for (i = 0; i < ARRAY_SIZE(pkmap_map_wait_arr); ++i)
  26                 init_waitqueue_head(pkmap_map_wait_arr + i);
  27 }
  28 #else
  29 static inline void kmap_waitqueues_init(void)
  30 {
  31 }
  32 #endif
  33
  34 static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
  35 {
  36         return (type + KM_TYPE_NR * smp_processor_id()) * DCACHE_N_COLORS +
  37                 color;
  38 }
  39
  40 void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
  41 {
  42         enum fixed_addresses idx;
  43         unsigned long vaddr;
  44
  45         idx = kmap_idx(kmap_atomic_idx_push(),
  46                        DCACHE_ALIAS(page_to_phys(page)));
  47         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  48 #ifdef CONFIG_DEBUG_HIGHMEM
  49         BUG_ON(!pte_none(*(kmap_pte + idx)));
  50 #endif
  51         set_pte(kmap_pte + idx, mk_pte(page, prot));
  52
  53         return (void *)vaddr;
  54 }
  55 EXPORT_SYMBOL(kmap_atomic_high_prot);
  56
  57 void kunmap_atomic_high(void *kvaddr)
  58 {
  59         if (kvaddr >= (void *)FIXADDR_START &&
  60             kvaddr < (void *)FIXADDR_TOP) {
  61                 int idx = kmap_idx(kmap_atomic_idx(),
  62                                    DCACHE_ALIAS((unsigned long)kvaddr));
  63
  64                 /*
  65                  * Force other mappings to Oops if they'll try to access this
  66                  * pte without first remap it.  Keeping stale mappings around
  67                  * is a bad idea also, in case the page changes cacheability
  68                  * attributes or becomes a protected page in a hypervisor.
  69                  */
  70                 pte_clear(&init_mm, kvaddr, kmap_pte + idx);
  71                 local_flush_tlb_kernel_range((unsigned long)kvaddr,
  72                                              (unsigned long)kvaddr + PAGE_SIZE);
  73
  74                 kmap_atomic_idx_pop();
  75         }
  76 }
  77 EXPORT_SYMBOL(kunmap_atomic_high);
  78
  79 void __init kmap_init(void)
  80 {
  81         unsigned long kmap_vstart;
  82
  83         /* Check if this memory layout is broken because PKMAP overlaps
  84          * page table.
  85          */
  86         BUILD_BUG_ON(PKMAP_BASE < TLBTEMP_BASE_1 + TLBTEMP_SIZE);
  87         /* cache the first kmap pte */
  88         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
  89         kmap_pte = virt_to_kpte(kmap_vstart);
  90         kmap_waitqueues_init();
  91 }