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 Terabyte 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/init.h> 24#include <linux/interrupt.h> 25#include <asm/kmap_types.h> 26#include <asm/pgtable.h> 27 28/* undef for production */ 29#define HIGHMEM_DEBUG 1 30 31/* declarations for highmem.c */ 32extern unsigned long highstart_pfn, highend_pfn; 33 34extern pte_t *kmap_pte; 35extern pgprot_t kmap_prot; 36extern pte_t *pkmap_page_table; 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. 42 */ 43#define PKMAP_BASE (0xfe000000UL) 44#define LAST_PKMAP 1024 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 49extern void * kmap_high(struct page *page); 50extern void kunmap_high(struct page *page); 51 52static inline void *kmap(struct page *page) 53{ 54 if (in_interrupt()) 55 out_of_line_bug(); 56 if (page < highmem_start_page) 57 return page_address(page); 58 return kmap_high(page); 59} 60 61static inline void kunmap(struct page *page) 62{ 63 if (in_interrupt()) 64 out_of_line_bug(); 65 if (page < highmem_start_page) 66 return; 67 kunmap_high(page); 68} 69 70/* 71 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap 72 * gives a more generic (and caching) interface. But kmap_atomic can 73 * be used in IRQ contexts, so in some (very limited) cases we need 74 * it. 75 */ 76static inline void *kmap_atomic(struct page *page, enum km_type type) 77{ 78 enum fixed_addresses idx; 79 unsigned long vaddr; 80 81 if (page < highmem_start_page) 82 return page_address(page); 83 84 idx = type + KM_TYPE_NR*smp_processor_id(); 85 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 86 set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); 87 //local_flush_tlb_page(NULL, vaddr); 88 local_flush_tlb_all(); 89 90 return (void*) vaddr; 91} 92 93static inline void kunmap_atomic(void *kvaddr, enum km_type type) 94{ 95} 96 97#endif /* __KERNEL__ */ 98 99#endif /* _ASM_HIGHMEM_H */ 100