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