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1da177e4 LT |
1 | #include <linux/config.h> |
2 | #include <linux/module.h> | |
3 | #include <linux/highmem.h> | |
4 | #include <asm/tlbflush.h> | |
5 | ||
6 | void *__kmap(struct page *page) | |
7 | { | |
8 | void *addr; | |
9 | ||
10 | might_sleep(); | |
11 | if (!PageHighMem(page)) | |
12 | return page_address(page); | |
13 | addr = kmap_high(page); | |
14 | flush_tlb_one((unsigned long)addr); | |
15 | ||
16 | return addr; | |
17 | } | |
18 | ||
19 | void __kunmap(struct page *page) | |
20 | { | |
21 | if (in_interrupt()) | |
22 | BUG(); | |
23 | if (!PageHighMem(page)) | |
24 | return; | |
25 | kunmap_high(page); | |
26 | } | |
27 | ||
28 | /* | |
29 | * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because | |
30 | * no global lock is needed and because the kmap code must perform a global TLB | |
31 | * invalidation when the kmap pool wraps. | |
32 | * | |
33 | * However when holding an atomic kmap is is not legal to sleep, so atomic | |
34 | * kmaps are appropriate for short, tight code paths only. | |
35 | */ | |
36 | ||
37 | void *__kmap_atomic(struct page *page, enum km_type type) | |
38 | { | |
39 | enum fixed_addresses idx; | |
40 | unsigned long vaddr; | |
41 | ||
42 | /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ | |
43 | inc_preempt_count(); | |
44 | if (!PageHighMem(page)) | |
45 | return page_address(page); | |
46 | ||
47 | idx = type + KM_TYPE_NR*smp_processor_id(); | |
48 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
49 | #ifdef CONFIG_DEBUG_HIGHMEM | |
50 | if (!pte_none(*(kmap_pte-idx))) | |
51 | BUG(); | |
52 | #endif | |
53 | set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); | |
54 | local_flush_tlb_one((unsigned long)vaddr); | |
55 | ||
56 | return (void*) vaddr; | |
57 | } | |
58 | ||
59 | void __kunmap_atomic(void *kvaddr, enum km_type type) | |
60 | { | |
61 | #ifdef CONFIG_DEBUG_HIGHMEM | |
62 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; | |
63 | enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); | |
64 | ||
65 | if (vaddr < FIXADDR_START) { // FIXME | |
66 | dec_preempt_count(); | |
67 | preempt_check_resched(); | |
68 | return; | |
69 | } | |
70 | ||
71 | if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)) | |
72 | BUG(); | |
73 | ||
74 | /* | |
75 | * force other mappings to Oops if they'll try to access | |
76 | * this pte without first remap it | |
77 | */ | |
78 | pte_clear(&init_mm, vaddr, kmap_pte-idx); | |
79 | local_flush_tlb_one(vaddr); | |
80 | #endif | |
81 | ||
82 | dec_preempt_count(); | |
83 | preempt_check_resched(); | |
84 | } | |
85 | ||
86 | struct page *__kmap_atomic_to_page(void *ptr) | |
87 | { | |
88 | unsigned long idx, vaddr = (unsigned long)ptr; | |
89 | pte_t *pte; | |
90 | ||
91 | if (vaddr < FIXADDR_START) | |
92 | return virt_to_page(ptr); | |
93 | ||
94 | idx = virt_to_fix(vaddr); | |
95 | pte = kmap_pte - (idx - FIX_KMAP_BEGIN); | |
96 | return pte_page(*pte); | |
97 | } | |
98 | ||
99 | EXPORT_SYMBOL(__kmap); | |
100 | EXPORT_SYMBOL(__kunmap); | |
101 | EXPORT_SYMBOL(__kmap_atomic); | |
102 | EXPORT_SYMBOL(__kunmap_atomic); | |
103 | EXPORT_SYMBOL(__kmap_atomic_to_page); |