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 <linux/highmem.h> 28 #include <asm/kmap_types.h> 29 #include <asm/tlbflush.h> 30 #include <asm/page.h> 31 #include <asm/fixmap.h> 32 33 extern pte_t *kmap_pte; 34 extern pgprot_t kmap_prot; 35 extern pte_t *pkmap_page_table; 36 37 /* 38 * Right now we initialize only a single pte table. It can be extended 39 * easily, subsequent pte tables have to be allocated in one physical 40 * chunk of RAM. 41 */ 42 /* 43 * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte 44 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP 45 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP 46 * in case of 16K/64K/256K page sizes. 47 */ 48 #ifdef CONFIG_PPC_4K_PAGES 49 #define PKMAP_ORDER PTE_SHIFT 50 #else 51 #define PKMAP_ORDER 9 52 #endif 53 #define LAST_PKMAP (1 << PKMAP_ORDER) 54 #ifndef CONFIG_PPC_4K_PAGES 55 #define PKMAP_BASE (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) 56 #else 57 #define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK) 58 #endif 59 #define LAST_PKMAP_MASK (LAST_PKMAP-1) 60 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT) 61 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 62 63 extern void *kmap_high(struct page *page); 64 extern void kunmap_high(struct page *page); 65 66 static inline void *kmap(struct page *page) 67 { 68 might_sleep(); 69 if (!PageHighMem(page)) 70 return page_address(page); 71 return kmap_high(page); 72 } 73 74 static inline void kunmap(struct page *page) 75 { 76 BUG_ON(in_interrupt()); 77 if (!PageHighMem(page)) 78 return; 79 kunmap_high(page); 80 } 81 82 /* 83 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap 84 * gives a more generic (and caching) interface. But kmap_atomic can 85 * be used in IRQ contexts, so in some (very limited) cases we need 86 * it. 87 */ 88 static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot) 89 { 90 unsigned int idx; 91 unsigned long vaddr; 92 93 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ 94 pagefault_disable(); 95 if (!PageHighMem(page)) 96 return page_address(page); 97 98 debug_kmap_atomic(type); 99 idx = type + KM_TYPE_NR*smp_processor_id(); 100 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 101 #ifdef CONFIG_DEBUG_HIGHMEM 102 BUG_ON(!pte_none(*(kmap_pte-idx))); 103 #endif 104 __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1); 105 local_flush_tlb_page(NULL, vaddr); 106 107 return (void*) vaddr; 108 } 109 110 static inline void *kmap_atomic(struct page *page, enum km_type type) 111 { 112 return kmap_atomic_prot(page, type, kmap_prot); 113 } 114 115 static inline void kunmap_atomic(void *kvaddr, enum km_type type) 116 { 117 #ifdef CONFIG_DEBUG_HIGHMEM 118 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; 119 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); 120 121 if (vaddr < __fix_to_virt(FIX_KMAP_END)) { 122 pagefault_enable(); 123 return; 124 } 125 126 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); 127 128 /* 129 * force other mappings to Oops if they'll try to access 130 * this pte without first remap it 131 */ 132 pte_clear(&init_mm, vaddr, kmap_pte-idx); 133 local_flush_tlb_page(NULL, vaddr); 134 #endif 135 pagefault_enable(); 136 } 137 138 static inline struct page *kmap_atomic_to_page(void *ptr) 139 { 140 unsigned long idx, vaddr = (unsigned long) ptr; 141 pte_t *pte; 142 143 if (vaddr < FIXADDR_START) 144 return virt_to_page(ptr); 145 146 idx = virt_to_fix(vaddr); 147 pte = kmap_pte - (idx - FIX_KMAP_BEGIN); 148 return pte_page(*pte); 149 } 150 151 #define flush_cache_kmaps() flush_cache_all() 152 153 #endif /* __KERNEL__ */ 154 155 #endif /* _ASM_HIGHMEM_H */ 156