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 /* 42 * We use one full pte table with 4K pages. And with 16K/64K pages pte 43 * table covers enough memory (32MB and 512MB resp.) that both FIXMAP 44 * and PKMAP can be placed in single pte table. We use 1024 pages for 45 * PKMAP in case of 16K/64K pages. 46 */ 47 #ifdef CONFIG_PPC_4K_PAGES 48 #define PKMAP_ORDER PTE_SHIFT 49 #else 50 #define PKMAP_ORDER 10 51 #endif 52 #define LAST_PKMAP (1 << PKMAP_ORDER) 53 #ifndef CONFIG_PPC_4K_PAGES 54 #define PKMAP_BASE (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) 55 #else 56 #define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK) 57 #endif 58 #define LAST_PKMAP_MASK (LAST_PKMAP-1) 59 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT) 60 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 61 62 extern void *kmap_high(struct page *page); 63 extern void kunmap_high(struct page *page); 64 65 static inline void *kmap(struct page *page) 66 { 67 might_sleep(); 68 if (!PageHighMem(page)) 69 return page_address(page); 70 return kmap_high(page); 71 } 72 73 static inline void kunmap(struct page *page) 74 { 75 BUG_ON(in_interrupt()); 76 if (!PageHighMem(page)) 77 return; 78 kunmap_high(page); 79 } 80 81 /* 82 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap 83 * gives a more generic (and caching) interface. But kmap_atomic can 84 * be used in IRQ contexts, so in some (very limited) cases we need 85 * it. 86 */ 87 static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot) 88 { 89 unsigned int idx; 90 unsigned long vaddr; 91 92 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ 93 pagefault_disable(); 94 if (!PageHighMem(page)) 95 return page_address(page); 96 97 idx = type + KM_TYPE_NR*smp_processor_id(); 98 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 99 #ifdef CONFIG_DEBUG_HIGHMEM 100 BUG_ON(!pte_none(*(kmap_pte-idx))); 101 #endif 102 __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot)); 103 local_flush_tlb_page(NULL, vaddr); 104 105 return (void*) vaddr; 106 } 107 108 static inline void *kmap_atomic(struct page *page, enum km_type type) 109 { 110 return kmap_atomic_prot(page, type, kmap_prot); 111 } 112 113 static inline void kunmap_atomic(void *kvaddr, enum km_type type) 114 { 115 #ifdef CONFIG_DEBUG_HIGHMEM 116 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; 117 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); 118 119 if (vaddr < __fix_to_virt(FIX_KMAP_END)) { 120 pagefault_enable(); 121 return; 122 } 123 124 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); 125 126 /* 127 * force other mappings to Oops if they'll try to access 128 * this pte without first remap it 129 */ 130 pte_clear(&init_mm, vaddr, kmap_pte-idx); 131 local_flush_tlb_page(NULL, vaddr); 132 #endif 133 pagefault_enable(); 134 } 135 136 static inline struct page *kmap_atomic_to_page(void *ptr) 137 { 138 unsigned long idx, vaddr = (unsigned long) ptr; 139 pte_t *pte; 140 141 if (vaddr < FIXADDR_START) 142 return virt_to_page(ptr); 143 144 idx = virt_to_fix(vaddr); 145 pte = kmap_pte - (idx - FIX_KMAP_BEGIN); 146 return pte_page(*pte); 147 } 148 149 #define flush_cache_kmaps() flush_cache_all() 150 151 #endif /* __KERNEL__ */ 152 153 #endif /* _ASM_HIGHMEM_H */ 154