1 /*
2 * highmem.h: virtual kernel memory mappings for high memory
3 *
4 * Used in CONFIG_HIGHMEM systems for memory pages which
5 * are not addressable by direct kernel virtual addresses.
6 *
7 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
8 * Gerhard.Wichert@pdb.siemens.de
9 *
10 *
11 * Redesigned the x86 32-bit VM architecture to deal with
12 * up to 16 Terabyte physical memory. With current x86 CPUs
13 * we now support up to 64 Gigabytes physical RAM.
14 *
15 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
16 */
17
18 #ifndef _ASM_HIGHMEM_H
19 #define _ASM_HIGHMEM_H
20
21 #ifdef __KERNEL__
22
23 #include <linux/init.h>
24 #include <linux/interrupt.h>
25 #include <asm/kmap_types.h>
26 #include <asm/pgtable.h>
27
28 /* undef for production */
29 #define HIGHMEM_DEBUG 1
30
31 /* declarations for highmem.c */
32 extern unsigned long highstart_pfn, highend_pfn;
33
34 extern pte_t *kmap_pte;
35 extern pgprot_t kmap_prot;
36 extern pte_t *pkmap_page_table;
37
38 /*
39 * Right now we initialize only a single pte table. It can be extended
40 * easily, subsequent pte tables have to be allocated in one physical
41 * chunk of RAM.
42 */
43 #define PKMAP_BASE (0xfe000000UL)
44 #define LAST_PKMAP 1024
45 #define LAST_PKMAP_MASK (LAST_PKMAP-1)
46 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
47 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
48
49 extern void * kmap_high(struct page *page, int nonblocking);
50 extern void kunmap_high(struct page *page);
51
__kmap(struct page * page,int nonblocking)52 static inline void *__kmap(struct page *page, int nonblocking)
53 {
54 if (in_interrupt())
55 out_of_line_bug();
56 if (page < highmem_start_page)
57 return page_address(page);
58 return kmap_high(page, nonblocking);
59 }
60
61 #define kmap(page) __kmap(page, 0)
62 #define kmap_nonblock(page) __kmap(page, 1)
63
kunmap(struct page * page)64 static inline void kunmap(struct page *page)
65 {
66 if (in_interrupt())
67 out_of_line_bug();
68 if (page < highmem_start_page)
69 return;
70 kunmap_high(page);
71 }
72
73 /*
74 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
75 * gives a more generic (and caching) interface. But kmap_atomic can
76 * be used in IRQ contexts, so in some (very limited) cases we need
77 * it.
78 */
kmap_atomic(struct page * page,enum km_type type)79 static inline void *kmap_atomic(struct page *page, enum km_type type)
80 {
81 enum fixed_addresses idx;
82 unsigned long vaddr;
83
84 if (page < highmem_start_page)
85 return page_address(page);
86
87 idx = type + KM_TYPE_NR*smp_processor_id();
88 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
89 set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
90 local_flush_tlb_one(vaddr);
91
92 return (void*) vaddr;
93 }
94
kunmap_atomic(void * kvaddr,enum km_type type)95 static inline void kunmap_atomic(void *kvaddr, enum km_type type)
96 {
97 }
98
99 #endif /* __KERNEL__ */
100
101 #endif /* _ASM_HIGHMEM_H */
102