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
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.
47 #ifdef CONFIG_PPC_4K_PAGES
48 #define PKMAP_ORDER PTE_SHIFT
50 #define PKMAP_ORDER 10
52 #define LAST_PKMAP (1 << PKMAP_ORDER)
53 #ifndef CONFIG_PPC_4K_PAGES
54 #define PKMAP_BASE (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1))
56 #define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
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))
62 extern void *kmap_high(struct page
*page
);
63 extern void kunmap_high(struct page
*page
);
65 static inline void *kmap(struct page
*page
)
68 if (!PageHighMem(page
))
69 return page_address(page
);
70 return kmap_high(page
);
73 static inline void kunmap(struct page
*page
)
75 BUG_ON(in_interrupt());
76 if (!PageHighMem(page
))
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
87 static inline void *kmap_atomic_prot(struct page
*page
, enum km_type type
, pgprot_t prot
)
92 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
94 if (!PageHighMem(page
))
95 return page_address(page
);
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
)));
102 __set_pte_at(&init_mm
, vaddr
, kmap_pte
-idx
, mk_pte(page
, prot
));
103 local_flush_tlb_page(NULL
, vaddr
);
105 return (void*) vaddr
;
108 static inline void *kmap_atomic(struct page
*page
, enum km_type type
)
110 return kmap_atomic_prot(page
, type
, kmap_prot
);
113 static inline void kunmap_atomic(void *kvaddr
, enum km_type type
)
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();
119 if (vaddr
< __fix_to_virt(FIX_KMAP_END
)) {
124 BUG_ON(vaddr
!= __fix_to_virt(FIX_KMAP_BEGIN
+ idx
));
127 * force other mappings to Oops if they'll try to access
128 * this pte without first remap it
130 pte_clear(&init_mm
, vaddr
, kmap_pte
-idx
);
131 local_flush_tlb_page(NULL
, vaddr
);
136 static inline struct page
*kmap_atomic_to_page(void *ptr
)
138 unsigned long idx
, vaddr
= (unsigned long) ptr
;
141 if (vaddr
< FIXADDR_START
)
142 return virt_to_page(ptr
);
144 idx
= virt_to_fix(vaddr
);
145 pte
= kmap_pte
- (idx
- FIX_KMAP_BEGIN
);
146 return pte_page(*pte
);
149 #define flush_cache_kmaps() flush_cache_all()
151 #endif /* __KERNEL__ */
153 #endif /* _ASM_HIGHMEM_H */
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