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bbc17704 JH |
1 | #include <linux/export.h> |
2 | #include <linux/highmem.h> | |
3 | #include <linux/sched.h> | |
4 | #include <linux/smp.h> | |
5 | #include <linux/interrupt.h> | |
6 | #include <asm/fixmap.h> | |
7 | #include <asm/tlbflush.h> | |
8 | ||
9 | static pte_t *kmap_pte; | |
10 | ||
11 | unsigned long highstart_pfn, highend_pfn; | |
12 | ||
13 | void *kmap(struct page *page) | |
14 | { | |
15 | might_sleep(); | |
16 | if (!PageHighMem(page)) | |
17 | return page_address(page); | |
18 | return kmap_high(page); | |
19 | } | |
20 | EXPORT_SYMBOL(kmap); | |
21 | ||
22 | void kunmap(struct page *page) | |
23 | { | |
24 | BUG_ON(in_interrupt()); | |
25 | if (!PageHighMem(page)) | |
26 | return; | |
27 | kunmap_high(page); | |
28 | } | |
29 | EXPORT_SYMBOL(kunmap); | |
30 | ||
31 | /* | |
32 | * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because | |
33 | * no global lock is needed and because the kmap code must perform a global TLB | |
34 | * invalidation when the kmap pool wraps. | |
35 | * | |
36 | * However when holding an atomic kmap is is not legal to sleep, so atomic | |
37 | * kmaps are appropriate for short, tight code paths only. | |
38 | */ | |
39 | ||
40 | void *kmap_atomic(struct page *page) | |
41 | { | |
42 | enum fixed_addresses idx; | |
43 | unsigned long vaddr; | |
44 | int type; | |
45 | ||
2cb7c9cb | 46 | preempt_disable(); |
bbc17704 JH |
47 | pagefault_disable(); |
48 | if (!PageHighMem(page)) | |
49 | return page_address(page); | |
50 | ||
51 | type = kmap_atomic_idx_push(); | |
52 | idx = type + KM_TYPE_NR * smp_processor_id(); | |
53 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
54 | #ifdef CONFIG_DEBUG_HIGHMEM | |
55 | BUG_ON(!pte_none(*(kmap_pte - idx))); | |
56 | #endif | |
57 | set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL)); | |
58 | ||
59 | return (void *)vaddr; | |
60 | } | |
61 | EXPORT_SYMBOL(kmap_atomic); | |
62 | ||
63 | void __kunmap_atomic(void *kvaddr) | |
64 | { | |
65 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; | |
66 | int idx, type; | |
67 | ||
68 | if (kvaddr >= (void *)FIXADDR_START) { | |
69 | type = kmap_atomic_idx(); | |
70 | idx = type + KM_TYPE_NR * smp_processor_id(); | |
71 | ||
72 | /* | |
73 | * Force other mappings to Oops if they'll try to access this | |
74 | * pte without first remap it. Keeping stale mappings around | |
75 | * is a bad idea also, in case the page changes cacheability | |
76 | * attributes or becomes a protected page in a hypervisor. | |
77 | */ | |
78 | pte_clear(&init_mm, vaddr, kmap_pte-idx); | |
79 | flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); | |
80 | ||
81 | kmap_atomic_idx_pop(); | |
82 | } | |
83 | ||
84 | pagefault_enable(); | |
2cb7c9cb | 85 | preempt_enable(); |
bbc17704 JH |
86 | } |
87 | EXPORT_SYMBOL(__kunmap_atomic); | |
88 | ||
89 | /* | |
90 | * This is the same as kmap_atomic() but can map memory that doesn't | |
91 | * have a struct page associated with it. | |
92 | */ | |
93 | void *kmap_atomic_pfn(unsigned long pfn) | |
94 | { | |
95 | enum fixed_addresses idx; | |
96 | unsigned long vaddr; | |
97 | int type; | |
98 | ||
2cb7c9cb | 99 | preempt_disable(); |
bbc17704 JH |
100 | pagefault_disable(); |
101 | ||
102 | type = kmap_atomic_idx_push(); | |
103 | idx = type + KM_TYPE_NR * smp_processor_id(); | |
104 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
105 | #ifdef CONFIG_DEBUG_HIGHMEM | |
106 | BUG_ON(!pte_none(*(kmap_pte - idx))); | |
107 | #endif | |
108 | set_pte(kmap_pte - idx, pfn_pte(pfn, PAGE_KERNEL)); | |
109 | flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); | |
110 | ||
111 | return (void *)vaddr; | |
112 | } | |
113 | ||
bbc17704 JH |
114 | void __init kmap_init(void) |
115 | { | |
116 | unsigned long kmap_vstart; | |
117 | ||
118 | /* cache the first kmap pte */ | |
119 | kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN); | |
120 | kmap_pte = kmap_get_fixmap_pte(kmap_vstart); | |
121 | } |