LXR linux/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
  15static pte_t *kmap_pte;
  16
  17#if DCACHE_WAY_SIZE > PAGE_SIZE
  18unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
  19wait_queue_head_t pkmap_map_wait_arr[DCACHE_N_COLORS];
  20
  21static 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
  29static inline void kmap_waitqueues_init(void)
  30{
  31}
  32#endif
  33
  34static 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
  40void *kmap_atomic(struct page *page)
  41{
  42        enum fixed_addresses idx;
  43        unsigned long vaddr;
  44
  45        preempt_disable();
  46        pagefault_disable();
  47        if (!PageHighMem(page))
  48                return page_address(page);
  49
  50        idx = kmap_idx(kmap_atomic_idx_push(),
  51                       DCACHE_ALIAS(page_to_phys(page)));
  52        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  53#ifdef CONFIG_DEBUG_HIGHMEM
  54        BUG_ON(!pte_none(*(kmap_pte + idx)));
  55#endif
  56        set_pte(kmap_pte + idx, mk_pte(page, PAGE_KERNEL_EXEC));
  57
  58        return (void *)vaddr;
  59}
  60EXPORT_SYMBOL(kmap_atomic);
  61
  62void __kunmap_atomic(void *kvaddr)
  63{
  64        if (kvaddr >= (void *)FIXADDR_START &&
  65            kvaddr < (void *)FIXADDR_TOP) {
  66                int idx = kmap_idx(kmap_atomic_idx(),
  67                                   DCACHE_ALIAS((unsigned long)kvaddr));
  68
  69                /*
  70                 * Force other mappings to Oops if they'll try to access this
  71                 * pte without first remap it.  Keeping stale mappings around
  72                 * is a bad idea also, in case the page changes cacheability
  73                 * attributes or becomes a protected page in a hypervisor.
  74                 */
  75                pte_clear(&init_mm, kvaddr, kmap_pte + idx);
  76                local_flush_tlb_kernel_range((unsigned long)kvaddr,
  77                                             (unsigned long)kvaddr + PAGE_SIZE);
  78
  79                kmap_atomic_idx_pop();
  80        }
  81
  82        pagefault_enable();
  83        preempt_enable();
  84}
  85EXPORT_SYMBOL(__kunmap_atomic);
  86
  87void __init kmap_init(void)
  88{
  89        unsigned long kmap_vstart;
  90
  91        /* cache the first kmap pte */
  92        kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
  93        kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
  94        kmap_waitqueues_init();
  95}
  96