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/cachetype.h>
   6 #include <asm/fixmap.h>
   7
   8 #define PKMAP_BASE              (PAGE_OFFSET - PMD_SIZE)
   9 #define LAST_PKMAP              PTRS_PER_PTE
  10 #define LAST_PKMAP_MASK         (LAST_PKMAP - 1)
  11 #define PKMAP_NR(virt)          (((virt) - PKMAP_BASE) >> PAGE_SHIFT)
  12 #define PKMAP_ADDR(nr)          (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  13
  14 #define flush_cache_kmaps() \
  15         do { \
  16                 if (cache_is_vivt()) \
  17                         flush_cache_all(); \
  18         } while (0)
  19
  20 extern pte_t *pkmap_page_table;
  21
  22 /*
  23  * The reason for kmap_high_get() is to ensure that the currently kmap'd
  24  * page usage count does not decrease to zero while we're using its
  25  * existing virtual mapping in an atomic context.  With a VIVT cache this
  26  * is essential to do, but with a VIPT cache this is only an optimization
  27  * so not to pay the price of establishing a second mapping if an existing
  28  * one can be used.  However, on platforms without hardware TLB maintenance
  29  * broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since
  30  * the locking involved must also disable IRQs which is incompatible with
  31  * the IPI mechanism used by global TLB operations.
  32  */
  33 #define ARCH_NEEDS_KMAP_HIGH_GET
  34 #if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6)
  35 #undef ARCH_NEEDS_KMAP_HIGH_GET
  36 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT)
  37 #error "The sum of features in your kernel config cannot be supported together"
  38 #endif
  39 #endif
  40
  41 /*
  42  * Needed to be able to broadcast the TLB invalidation for kmap.
  43  */
  44 #ifdef CONFIG_ARM_ERRATA_798181
  45 #undef ARCH_NEEDS_KMAP_HIGH_GET
  46 #endif
  47
  48 #ifdef ARCH_NEEDS_KMAP_HIGH_GET
  49 extern void *kmap_high_get(struct page *page);
  50
  51 static inline void *arch_kmap_local_high_get(struct page *page)
  52 {
  53         if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !cache_is_vivt())
  54                 return NULL;
  55         return kmap_high_get(page);
  56 }
  57 #define arch_kmap_local_high_get arch_kmap_local_high_get
  58
  59 #else /* ARCH_NEEDS_KMAP_HIGH_GET */
  60 static inline void *kmap_high_get(struct page *page)
  61 {
  62         return NULL;
  63 }
  64 #endif /* !ARCH_NEEDS_KMAP_HIGH_GET */
  65
  66 #define arch_kmap_local_post_map(vaddr, pteval)                         \
  67         local_flush_tlb_kernel_page(vaddr)
  68
  69 #define arch_kmap_local_pre_unmap(vaddr)                                \
  70 do {                                                                    \
  71         if (cache_is_vivt())                                            \
  72                 __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);     \
  73 } while (0)
  74
  75 #define arch_kmap_local_post_unmap(vaddr)                               \
  76         local_flush_tlb_kernel_page(vaddr)
  77
  78 #endif