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;
  21extern pte_t *fixmap_page_table;
  22
  23extern void *kmap_high(struct page *page);
  24extern void kunmap_high(struct page *page);
  25
  26/*
  27 * The reason for kmap_high_get() is to ensure that the currently kmap'd
  28 * page usage count does not decrease to zero while we're using its
  29 * existing virtual mapping in an atomic context.  With a VIVT cache this
  30 * is essential to do, but with a VIPT cache this is only an optimization
  31 * so not to pay the price of establishing a second mapping if an existing
  32 * one can be used.  However, on platforms without hardware TLB maintenance
  33 * broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since
  34 * the locking involved must also disable IRQs which is incompatible with
  35 * the IPI mechanism used by global TLB operations.
  36 */
  37#define ARCH_NEEDS_KMAP_HIGH_GET
  38#if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6)
  39#undef ARCH_NEEDS_KMAP_HIGH_GET
  40#if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT)
  41#error "The sum of features in your kernel config cannot be supported together"
  42#endif
  43#endif
  44
  45/*
  46 * Needed to be able to broadcast the TLB invalidation for kmap.
  47 */
  48#ifdef CONFIG_ARM_ERRATA_798181
  49#undef ARCH_NEEDS_KMAP_HIGH_GET
  50#endif
  51
  52#ifdef ARCH_NEEDS_KMAP_HIGH_GET
  53extern void *kmap_high_get(struct page *page);
  54#else
  55static inline void *kmap_high_get(struct page *page)
  56{
  57        return NULL;
  58}
  59#endif
  60
  61/*
  62 * The following functions are already defined by <linux/highmem.h>
  63 * when CONFIG_HIGHMEM is not set.
  64 */
  65#ifdef CONFIG_HIGHMEM
  66extern void *kmap(struct page *page);
  67extern void kunmap(struct page *page);
  68extern void *kmap_atomic(struct page *page);
  69extern void __kunmap_atomic(void *kvaddr);
  70extern void *kmap_atomic_pfn(unsigned long pfn);
  71#endif
  72
  73#endif
  74