LXR linux/arch/arm/include/asm/highmem.h

   1#ifndef _ASM_HIGHMEM_H
   2#define _ASM_HIGHMEM_H
   3
   4#include <asm/kmap_types.h>
   5
   6#define PKMAP_BASE              (PAGE_OFFSET - PMD_SIZE)
   7#define LAST_PKMAP              PTRS_PER_PTE
   8#define LAST_PKMAP_MASK         (LAST_PKMAP - 1)
   9#define PKMAP_NR(virt)          (((virt) - PKMAP_BASE) >> PAGE_SHIFT)
  10#define PKMAP_ADDR(nr)          (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  11
  12#define kmap_prot               PAGE_KERNEL
  13
  14#define flush_cache_kmaps() \
  15        do { \
  16                if (cache_is_vivt()) \
  17                        flush_cache_all(); \
  18        } while (0)
  19
  20extern pte_t *pkmap_page_table;
  21
  22extern void *kmap_high(struct page *page);
  23extern void kunmap_high(struct page *page);
  24
  25/*
  26 * The reason for kmap_high_get() is to ensure that the currently kmap'd
  27 * page usage count does not decrease to zero while we're using its
  28 * existing virtual mapping in an atomic context.  With a VIVT cache this
  29 * is essential to do, but with a VIPT cache this is only an optimization
  30 * so not to pay the price of establishing a second mapping if an existing
  31 * one can be used.  However, on platforms without hardware TLB maintenance
  32 * broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since
  33 * the locking involved must also disable IRQs which is incompatible with
  34 * the IPI mechanism used by global TLB operations.
  35 */
  36#define ARCH_NEEDS_KMAP_HIGH_GET
  37#if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6)
  38#undef ARCH_NEEDS_KMAP_HIGH_GET
  39#if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT)
  40#error "The sum of features in your kernel config cannot be supported together"
  41#endif
  42#endif
  43
  44#ifdef ARCH_NEEDS_KMAP_HIGH_GET
  45extern void *kmap_high_get(struct page *page);
  46#else
  47static inline void *kmap_high_get(struct page *page)
  48{
  49        return NULL;
  50}
  51#endif
  52
  53/*
  54 * The following functions are already defined by <linux/highmem.h>
  55 * when CONFIG_HIGHMEM is not set.
  56 */
  57#ifdef CONFIG_HIGHMEM
  58extern void *kmap(struct page *page);
  59extern void kunmap(struct page *page);
  60extern void *__kmap_atomic(struct page *page);
  61extern void __kunmap_atomic(void *kvaddr);
  62extern void *kmap_atomic_pfn(unsigned long pfn);
  63extern struct page *kmap_atomic_to_page(const void *ptr);
  64#endif
  65
  66#endif
  67