1 /* 2 * highmem.h: virtual kernel memory mappings for high memory 3 * 4 * Used in CONFIG_HIGHMEM systems for memory pages which 5 * are not addressable by direct kernel virtual addresses. 6 * 7 * Copyright (C) 1999 Gerhard Wichert, Siemens AG 8 * Gerhard.Wichert@pdb.siemens.de 9 * 10 * 11 * Redesigned the x86 32-bit VM architecture to deal with 12 * up to 16 Terrabyte physical memory. With current x86 CPUs 13 * we now support up to 64 Gigabytes physical RAM. 14 * 15 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> 16 */ 17 18 #ifndef _ASM_HIGHMEM_H 19 #define _ASM_HIGHMEM_H 20 21 #ifdef __KERNEL__ 22 23 #include <linux/interrupt.h> 24 #include <asm/fixmap.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 pte_t *kmap_pte; 33 extern pgprot_t kmap_prot; 34 extern pte_t *pkmap_page_table; 35 36 extern void kmap_init(void) __init; 37 38 /* 39 * Right now we initialize only a single pte table. It can be extended 40 * easily, subsequent pte tables have to be allocated in one physical 41 * chunk of RAM. Currently the simplest way to do this is to align the 42 * pkmap region on a pagetable boundary (4MB). 43 */ 44 #define LAST_PKMAP 1024 45 #define PKMAP_SIZE (LAST_PKMAP << PAGE_SHIFT) 46 #define PKMAP_BASE PMD_ALIGN(SRMMU_NOCACHE_VADDR + (SRMMU_MAX_NOCACHE_PAGES << PAGE_SHIFT)) 47 48 #define LAST_PKMAP_MASK (LAST_PKMAP - 1) 49 #define PKMAP_NR(virt) ((virt - PKMAP_BASE) >> PAGE_SHIFT) 50 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 51 52 #define PKMAP_END (PKMAP_ADDR(LAST_PKMAP)) 53 54 extern void *kmap_high(struct page *page); 55 extern void kunmap_high(struct page *page); 56 57 static inline void *kmap(struct page *page) 58 { 59 BUG_ON(in_interrupt()); 60 if (!PageHighMem(page)) 61 return page_address(page); 62 return kmap_high(page); 63 } 64 65 static inline void kunmap(struct page *page) 66 { 67 BUG_ON(in_interrupt()); 68 if (!PageHighMem(page)) 69 return; 70 kunmap_high(page); 71 } 72 73 extern void *kmap_atomic(struct page *page, enum km_type type); 74 extern void kunmap_atomic(void *kvaddr, enum km_type type); 75 extern struct page *kmap_atomic_to_page(void *vaddr); 76 77 #define flush_cache_kmaps() flush_cache_all() 78 79 #endif /* __KERNEL__ */ 80 81 #endif /* _ASM_HIGHMEM_H */ 82