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/interrupt.h> 26 #include <asm/kmap_types.h> 27 #include <asm/tlbflush.h> 28 #include <asm/page.h> 29 #include <asm/fixmap.h> 30 31 extern pte_t *kmap_pte; 32 extern pgprot_t kmap_prot; 33 extern pte_t *pkmap_page_table; 34 35 /* 36 * Right now we initialize only a single pte table. It can be extended 37 * easily, subsequent pte tables have to be allocated in one physical 38 * chunk of RAM. 39 */ 40 /* 41 * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte 42 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP 43 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP 44 * in case of 16K/64K/256K page sizes. 45 */ 46 #ifdef CONFIG_PPC_4K_PAGES 47 #define PKMAP_ORDER PTE_SHIFT 48 #else 49 #define PKMAP_ORDER 9 50 #endif 51 #define LAST_PKMAP (1 << PKMAP_ORDER) 52 #ifndef CONFIG_PPC_4K_PAGES 53 #define PKMAP_BASE (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) 54 #else 55 #define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK) 56 #endif 57 #define LAST_PKMAP_MASK (LAST_PKMAP-1) 58 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT) 59 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 60 61 extern void *kmap_high(struct page *page); 62 extern void kunmap_high(struct page *page); 63 extern void *kmap_atomic_prot(struct page *page, pgprot_t prot); 64 extern void __kunmap_atomic(void *kvaddr); 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 static inline void *__kmap_atomic(struct page *page) 83 { 84 return kmap_atomic_prot(page, kmap_prot); 85 } 86 87 static inline struct page *kmap_atomic_to_page(void *ptr) 88 { 89 unsigned long idx, vaddr = (unsigned long) ptr; 90 pte_t *pte; 91 92 if (vaddr < FIXADDR_START) 93 return virt_to_page(ptr); 94 95 idx = virt_to_fix(vaddr); 96 pte = kmap_pte - (idx - FIX_KMAP_BEGIN); 97 return pte_page(*pte); 98 } 99 100 101 #define flush_cache_kmaps() flush_cache_all() 102 103 #endif /* __KERNEL__ */ 104 105 #endif /* _ASM_HIGHMEM_H */ 106