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 Terrabyte 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 19 #ifndef _ASM_HIGHMEM_H 20 #define _ASM_HIGHMEM_H 21 22 #ifdef __KERNEL__ 23 24 #include <linux/interrupt.h> 25 #include <asm/vaddrs.h> 26 #include <asm/kmap_types.h> 27 #include <asm/pgtable.h> 28 29 /* declarations for highmem.c */ 30 extern unsigned long highstart_pfn, highend_pfn; 31 32 extern pgprot_t kmap_prot; 33 extern pte_t *pkmap_page_table; 34 35 void kmap_init(void) __init; 36 37 /* 38 * Right now we initialize only a single pte table. It can be extended 39 * easily, subsequent pte tables have to be allocated in one physical 40 * chunk of RAM. Currently the simplest way to do this is to align the 41 * pkmap region on a pagetable boundary (4MB). 42 */ 43 #define LAST_PKMAP 1024 44 #define PKMAP_SIZE (LAST_PKMAP << PAGE_SHIFT) 45 #define PKMAP_BASE PMD_ALIGN(SRMMU_NOCACHE_VADDR + (SRMMU_MAX_NOCACHE_PAGES << PAGE_SHIFT)) 46 47 #define LAST_PKMAP_MASK (LAST_PKMAP - 1) 48 #define PKMAP_NR(virt) ((virt - PKMAP_BASE) >> PAGE_SHIFT) 49 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 50 51 #define PKMAP_END (PKMAP_ADDR(LAST_PKMAP)) 52 53 void *kmap_high(struct page *page); 54 void kunmap_high(struct page *page); 55 56 static inline void *kmap(struct page *page) 57 { 58 BUG_ON(in_interrupt()); 59 if (!PageHighMem(page)) 60 return page_address(page); 61 return kmap_high(page); 62 } 63 64 static inline void kunmap(struct page *page) 65 { 66 BUG_ON(in_interrupt()); 67 if (!PageHighMem(page)) 68 return; 69 kunmap_high(page); 70 } 71 72 void *kmap_atomic(struct page *page); 73 void __kunmap_atomic(void *kvaddr); 74 75 #define flush_cache_kmaps() flush_cache_all() 76 77 #endif /* __KERNEL__ */ 78 79 #endif /* _ASM_HIGHMEM_H */ 80