1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * highmem.h: virtual kernel memory mappings for high memory 4 * 5 * Used in CONFIG_HIGHMEM systems for memory pages which 6 * are not addressable by direct kernel virtual addresses. 7 * 8 * Copyright (C) 1999 Gerhard Wichert, Siemens AG 9 * Gerhard.Wichert@pdb.siemens.de 10 * 11 * 12 * Redesigned the x86 32-bit VM architecture to deal with 13 * up to 16 Terabyte physical memory. With current x86 CPUs 14 * we now support up to 64 Gigabytes physical RAM. 15 * 16 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> 17 */ 18 #ifndef _ASM_HIGHMEM_H 19 #define _ASM_HIGHMEM_H 20 21 #ifdef __KERNEL__ 22 23 #include <linux/bug.h> 24 #include <linux/interrupt.h> 25 #include <linux/uaccess.h> 26 #include <asm/cpu-features.h> 27 #include <asm/kmap_types.h> 28 29 /* declarations for highmem.c */ 30 extern unsigned long highstart_pfn, highend_pfn; 31 32 extern pte_t *pkmap_page_table; 33 34 /* 35 * Right now we initialize only a single pte table. It can be extended 36 * easily, subsequent pte tables have to be allocated in one physical 37 * chunk of RAM. 38 */ 39 #ifdef CONFIG_PHYS_ADDR_T_64BIT 40 #define LAST_PKMAP 512 41 #else 42 #define LAST_PKMAP 1024 43 #endif 44 45 #define LAST_PKMAP_MASK (LAST_PKMAP-1) 46 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT) 47 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 48 49 extern void * kmap_high(struct page *page); 50 extern void kunmap_high(struct page *page); 51 52 extern void *kmap(struct page *page); 53 extern void kunmap(struct page *page); 54 extern void *kmap_atomic(struct page *page); 55 extern void __kunmap_atomic(void *kvaddr); 56 extern void *kmap_atomic_pfn(unsigned long pfn); 57 58 #define flush_cache_kmaps() BUG_ON(cpu_has_dc_aliases) 59 60 extern void kmap_init(void); 61 62 #define kmap_prot PAGE_KERNEL 63 64 #endif /* __KERNEL__ */ 65 66 #endif /* _ASM_HIGHMEM_H */ 67