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 kmap_high_get(struct page * page)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 74