2 * BK Id: SCCS/s.highmem.h 1.14 05/29/02 13:02:56 mporter
5 * highmem.h: virtual kernel memory mappings for high memory
7 * PowerPC version, stolen from the i386 version.
9 * Used in CONFIG_HIGHMEM systems for memory pages which
10 * are not addressable by direct kernel virtual addresses.
12 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
13 * Gerhard.Wichert@pdb.siemens.de
16 * Redesigned the x86 32-bit VM architecture to deal with
17 * up to 16 Terrabyte physical memory. With current x86 CPUs
18 * we now support up to 64 Gigabytes physical RAM.
20 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
23 #ifndef _ASM_HIGHMEM_H
24 #define _ASM_HIGHMEM_H
28 #include <linux/init.h>
29 #include <linux/interrupt.h>
30 #include <asm/kmap_types.h>
31 #include <asm/pgtable.h>
33 /* undef for production */
34 #define HIGHMEM_DEBUG 1
36 extern pte_t *kmap_pte;
37 extern pgprot_t kmap_prot;
38 extern pte_t *pkmap_page_table;
40 extern void kmap_init(void) __init;
43 * Right now we initialize only a single pte table. It can be extended
44 * easily, subsequent pte tables have to be allocated in one physical
47 #ifdef CONFIG_HIGHMEM_START_BOOL
48 #define PKMAP_BASE CONFIG_HIGHMEM_START
50 #define PKMAP_BASE (0xfe000000UL)
51 #endif /* CONFIG_HIGHMEM_START_BOOL */
53 #define LAST_PKMAP 512
55 #define LAST_PKMAP 1024
56 #endif /* CONFIG_440 */
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))
61 #define KMAP_FIX_BEGIN (PKMAP_BASE + 0x00400000UL)
63 extern void *kmap_high(struct page *page);
64 extern void kunmap_high(struct page *page);
66 static inline void *kmap(struct page *page)
70 if (page < highmem_start_page)
71 return page_address(page);
72 return kmap_high(page);
75 static inline void kunmap(struct page *page)
79 if (page < highmem_start_page)
85 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
86 * gives a more generic (and caching) interface. But kmap_atomic can
87 * be used in IRQ contexts, so in some (very limited) cases we need
90 static inline void *kmap_atomic(struct page *page, enum km_type type)
95 if (page < highmem_start_page)
96 return page_address(page);
98 idx = type + KM_TYPE_NR*smp_processor_id();
99 vaddr = KMAP_FIX_BEGIN + idx * PAGE_SIZE;
101 if (!pte_none(*(kmap_pte+idx)))
104 set_pte(kmap_pte+idx, mk_pte(page, kmap_prot));
105 flush_tlb_page(0, vaddr);
107 return (void*) vaddr;
110 static inline void kunmap_atomic(void *kvaddr, enum km_type type)
113 unsigned long vaddr = (unsigned long) kvaddr;
114 unsigned int idx = type + KM_TYPE_NR*smp_processor_id();
116 if (vaddr < KMAP_FIX_BEGIN) // FIXME
119 if (vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE)
123 * force other mappings to Oops if they'll try to access
124 * this pte without first remap it
126 pte_clear(kmap_pte+idx);
127 flush_tlb_page(0, vaddr);
131 #endif /* __KERNEL__ */
133 #endif /* _ASM_HIGHMEM_H */