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
  23 extern void *kmap_high(struct page *page);
  24 extern 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
  53 extern void *kmap_high_get(struct page *page);
  54 #else
  55 static 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
  66 extern void *kmap(struct page *page);
  67 extern void kunmap(struct page *page);
  68 extern void *kmap_atomic(struct page *page);
  69 extern void __kunmap_atomic(void *kvaddr);
  70 extern void *kmap_atomic_pfn(unsigned long pfn);
  71 #endif
  72
  73 #endif