arch/arm/include/asm/highmem.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_HIGHMEM_H
   3 #define _ASM_HIGHMEM_H
   4
   5 #include <asm/kmap_types.h>
   6
   7 #define PKMAP_BASE              (PAGE_OFFSET - PMD_SIZE)
   8 #define LAST_PKMAP              PTRS_PER_PTE
   9 #define LAST_PKMAP_MASK         (LAST_PKMAP - 1)
  10 #define PKMAP_NR(virt)          (((virt) - PKMAP_BASE) >> PAGE_SHIFT)
  11 #define PKMAP_ADDR(nr)          (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  12
  13 #define kmap_prot               PAGE_KERNEL
  14
  15 #define flush_cache_kmaps() \
  16         do { \
  17                 if (cache_is_vivt()) \
  18                         flush_cache_all(); \
  19         } while (0)
  20
  21 extern pte_t *pkmap_page_table;
  22 extern pte_t *fixmap_page_table;
  23
  24 extern void *kmap_high(struct page *page);
  25 extern void kunmap_high(struct page *page);
  26
  27 /*
  28  * The reason for kmap_high_get() is to ensure that the currently kmap'd
  29  * page usage count does not decrease to zero while we're using its
  30  * existing virtual mapping in an atomic context.  With a VIVT cache this
  31  * is essential to do, but with a VIPT cache this is only an optimization
  32  * so not to pay the price of establishing a second mapping if an existing
  33  * one can be used.  However, on platforms without hardware TLB maintenance
  34  * broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since
  35  * the locking involved must also disable IRQs which is incompatible with
  36  * the IPI mechanism used by global TLB operations.
  37  */
  38 #define ARCH_NEEDS_KMAP_HIGH_GET
  39 #if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6)
  40 #undef ARCH_NEEDS_KMAP_HIGH_GET
  41 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT)
  42 #error "The sum of features in your kernel config cannot be supported together"
  43 #endif
  44 #endif
  45
  46 /*
  47  * Needed to be able to broadcast the TLB invalidation for kmap.
  48  */
  49 #ifdef CONFIG_ARM_ERRATA_798181
  50 #undef ARCH_NEEDS_KMAP_HIGH_GET
  51 #endif
  52
  53 #ifdef ARCH_NEEDS_KMAP_HIGH_GET
  54 extern void *kmap_high_get(struct page *page);
  55 #else
  56 static inline void *kmap_high_get(struct page *page)
  57 {
  58         return NULL;
  59 }
  60 #endif
  61
  62 /*
  63  * The following functions are already defined by <linux/highmem.h>
  64  * when CONFIG_HIGHMEM is not set.
  65  */
  66 #ifdef CONFIG_HIGHMEM
  67 extern void *kmap(struct page *page);
  68 extern void kunmap(struct page *page);
  69 extern void *kmap_atomic(struct page *page);
  70 extern void __kunmap_atomic(void *kvaddr);
  71 extern void *kmap_atomic_pfn(unsigned long pfn);
  72 #endif
  73
  74 #endif