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 #include <asm/fixmap.h> 31 32 extern pte_t *kmap_pte; 33 extern pgprot_t kmap_prot; 34 extern pte_t *pkmap_page_table; 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. 40 */ 41 #define LAST_PKMAP (1 << PTE_SHIFT) 42 #define LAST_PKMAP_MASK (LAST_PKMAP-1) 43 #define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK) 44 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT) 45 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 46 47 extern void *kmap_high(struct page *page); 48 extern void kunmap_high(struct page *page); 49 50 static inline void *kmap(struct page *page) 51 { 52 might_sleep(); 53 if (!PageHighMem(page)) 54 return page_address(page); 55 return kmap_high(page); 56 } 57 58 static inline void kunmap(struct page *page) 59 { 60 BUG_ON(in_interrupt()); 61 if (!PageHighMem(page)) 62 return; 63 kunmap_high(page); 64 } 65 66 /* 67 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap 68 * gives a more generic (and caching) interface. But kmap_atomic can 69 * be used in IRQ contexts, so in some (very limited) cases we need 70 * it. 71 */ 72 static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot) 73 { 74 unsigned int idx; 75 unsigned long vaddr; 76 77 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ 78 pagefault_disable(); 79 if (!PageHighMem(page)) 80 return page_address(page); 81 82 idx = type + KM_TYPE_NR*smp_processor_id(); 83 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 84 #ifdef CONFIG_DEBUG_HIGHMEM 85 BUG_ON(!pte_none(*(kmap_pte-idx))); 86 #endif 87 __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot)); 88 local_flush_tlb_page(NULL, vaddr); 89 90 return (void*) vaddr; 91 } 92 93 static inline void *kmap_atomic(struct page *page, enum km_type type) 94 { 95 return kmap_atomic_prot(page, type, kmap_prot); 96 } 97 98 static inline void kunmap_atomic(void *kvaddr, enum km_type type) 99 { 100 #ifdef CONFIG_DEBUG_HIGHMEM 101 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; 102 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); 103 104 if (vaddr < __fix_to_virt(FIX_KMAP_END)) { 105 pagefault_enable(); 106 return; 107 } 108 109 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); 110 111 /* 112 * force other mappings to Oops if they'll try to access 113 * this pte without first remap it 114 */ 115 pte_clear(&init_mm, vaddr, kmap_pte-idx); 116 local_flush_tlb_page(NULL, vaddr); 117 #endif 118 pagefault_enable(); 119 } 120 121 static inline struct page *kmap_atomic_to_page(void *ptr) 122 { 123 unsigned long idx, vaddr = (unsigned long) ptr; 124 pte_t *pte; 125 126 if (vaddr < FIXADDR_START) 127 return virt_to_page(ptr); 128 129 idx = virt_to_fix(vaddr); 130 pte = kmap_pte - (idx - FIX_KMAP_BEGIN); 131 return pte_page(*pte); 132 } 133 134 #define flush_cache_kmaps() flush_cache_all() 135 136 #endif /* __KERNEL__ */ 137 138 #endif /* _ASM_HIGHMEM_H */ 139