2 * highmem.h: virtual kernel memory mappings for high memory
4 * PowerPC version, stolen from the i386 version.
6 * Used in CONFIG_HIGHMEM systems for memory pages which
7 * are not addressable by direct kernel virtual addresses.
9 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
10 * Gerhard.Wichert@pdb.siemens.de
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.
17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
20 #ifndef _ASM_HIGHMEM_H
21 #define _ASM_HIGHMEM_H
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <asm/kmap_types.h>
28 #include <asm/tlbflush.h>
30 #include <asm/fixmap.h>
32 extern pte_t
*kmap_pte
;
33 extern pgprot_t kmap_prot
;
34 extern pte_t
*pkmap_page_table
;
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
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))
47 extern void *kmap_high(struct page
*page
);
48 extern void kunmap_high(struct page
*page
);
50 static inline void *kmap(struct page
*page
)
53 if (!PageHighMem(page
))
54 return page_address(page
);
55 return kmap_high(page
);
58 static inline void kunmap(struct page
*page
)
60 BUG_ON(in_interrupt());
61 if (!PageHighMem(page
))
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
72 static inline void *kmap_atomic_prot(struct page
*page
, enum km_type type
, pgprot_t prot
)
77 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
79 if (!PageHighMem(page
))
80 return page_address(page
);
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
)));
87 __set_pte_at(&init_mm
, vaddr
, kmap_pte
-idx
, mk_pte(page
, prot
));
88 flush_tlb_page(NULL
, vaddr
);
93 static inline void *kmap_atomic(struct page
*page
, enum km_type type
)
95 return kmap_atomic_prot(page
, type
, kmap_prot
);
98 static inline void kunmap_atomic(void *kvaddr
, enum km_type type
)
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();
104 if (vaddr
< __fix_to_virt(FIX_KMAP_END
)) {
109 BUG_ON(vaddr
!= __fix_to_virt(FIX_KMAP_BEGIN
+ idx
));
112 * force other mappings to Oops if they'll try to access
113 * this pte without first remap it
115 pte_clear(&init_mm
, vaddr
, kmap_pte
-idx
);
116 flush_tlb_page(NULL
, vaddr
);
121 static inline struct page
*kmap_atomic_to_page(void *ptr
)
123 unsigned long idx
, vaddr
= (unsigned long) ptr
;
126 if (vaddr
< FIXADDR_START
)
127 return virt_to_page(ptr
);
129 idx
= virt_to_fix(vaddr
);
130 pte
= kmap_pte
- (idx
- FIX_KMAP_BEGIN
);
131 return pte_page(*pte
);
134 #define flush_cache_kmaps() flush_cache_all()
136 #endif /* __KERNEL__ */
138 #endif /* _ASM_HIGHMEM_H */
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