1/* 2 * highmem.h: virtual kernel memory mappings for high memory 3 * 4 * PowerPC version, stolen from the i386 version. 5 * 6 * Used in CONFIG_HIGHMEM systems for memory pages which 7 * are not addressable by direct kernel virtual addresses. 8 * 9 * Copyright (C) 1999 Gerhard Wichert, Siemens AG 10 * Gerhard.Wichert@pdb.siemens.de 11 * 12 * 13 * Redesigned the x86 32-bit VM architecture to deal with 14 * up to 16 Terrabyte physical memory. With current x86 CPUs 15 * we now support up to 64 Gigabytes physical RAM. 16 * 17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> 18 */ 19 20#ifndef _ASM_HIGHMEM_H 21#define _ASM_HIGHMEM_H 22 23#ifdef __KERNEL__ 24 25#include <linux/init.h> 26#include <linux/interrupt.h> 27#include <asm/kmap_types.h> 28#include <asm/tlbflush.h> 29#include <asm/page.h> 30 31/* undef for production */ 32#define HIGHMEM_DEBUG 1 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 CONFIG_HIGHMEM_START 44#define LAST_PKMAP (1 << PTE_SHIFT) 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#define KMAP_FIX_BEGIN (PKMAP_BASE + 0x00400000UL) 50 51extern void *kmap_high(struct page *page); 52extern void kunmap_high(struct page *page); 53 54static inline void *kmap(struct page *page) 55{ 56 might_sleep(); 57 if (!PageHighMem(page)) 58 return page_address(page); 59 return kmap_high(page); 60} 61 62static inline void kunmap(struct page *page) 63{ 64 BUG_ON(in_interrupt()); 65 if (!PageHighMem(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 unsigned int idx; 79 unsigned long vaddr; 80 81 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ 82 pagefault_disable(); 83 if (!PageHighMem(page)) 84 return page_address(page); 85 86 idx = type + KM_TYPE_NR*smp_processor_id(); 87 vaddr = KMAP_FIX_BEGIN + idx * PAGE_SIZE; 88#ifdef HIGHMEM_DEBUG 89 BUG_ON(!pte_none(*(kmap_pte+idx))); 90#endif 91 set_pte_at(&init_mm, vaddr, kmap_pte+idx, mk_pte(page, kmap_prot)); 92 flush_tlb_page(NULL, vaddr); 93 94 return (void*) vaddr; 95} 96 97static inline void kunmap_atomic(void *kvaddr, enum km_type type) 98{ 99#ifdef HIGHMEM_DEBUG 100 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; 101 unsigned int idx = type + KM_TYPE_NR*smp_processor_id(); 102 103 if (vaddr < KMAP_FIX_BEGIN) { 104 pagefault_enable(); 105 return; 106 } 107 108 BUG_ON(vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE); 109 110 /* 111 * force other mappings to Oops if they'll try to access 112 * this pte without first remap it 113 */ 114 pte_clear(&init_mm, vaddr, kmap_pte+idx); 115 flush_tlb_page(NULL, vaddr); 116#endif 117 pagefault_enable(); 118} 119 120static inline struct page *kmap_atomic_to_page(void *ptr) 121{ 122 unsigned long idx, vaddr = (unsigned long) ptr; 123 124 if (vaddr < KMAP_FIX_BEGIN) 125 return virt_to_page(ptr); 126 127 idx = (vaddr - KMAP_FIX_BEGIN) >> PAGE_SHIFT; 128 return pte_page(kmap_pte[idx]); 129} 130 131#define flush_cache_kmaps() flush_cache_all() 132 133#endif /* __KERNEL__ */ 134 135#endif /* _ASM_HIGHMEM_H */ 136