[PATCH] mm: pagefault_{disable,enable}()
[linux-2.6.git] / arch / i386 / mm / highmem.c
1 #include <linux/highmem.h>
2 #include <linux/module.h>
3
4 void *kmap(struct page *page)
5 {
6         might_sleep();
7         if (!PageHighMem(page))
8                 return page_address(page);
9         return kmap_high(page);
10 }
11
12 void kunmap(struct page *page)
13 {
14         if (in_interrupt())
15                 BUG();
16         if (!PageHighMem(page))
17                 return;
18         kunmap_high(page);
19 }
20
21 /*
22  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
23  * no global lock is needed and because the kmap code must perform a global TLB
24  * invalidation when the kmap pool wraps.
25  *
26  * However when holding an atomic kmap is is not legal to sleep, so atomic
27  * kmaps are appropriate for short, tight code paths only.
28  */
29 void *kmap_atomic(struct page *page, enum km_type type)
30 {
31         enum fixed_addresses idx;
32         unsigned long vaddr;
33
34         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
35         pagefault_disable();
36         if (!PageHighMem(page))
37                 return page_address(page);
38
39         idx = type + KM_TYPE_NR*smp_processor_id();
40         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
41         if (!pte_none(*(kmap_pte-idx)))
42                 BUG();
43         set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
44
45         return (void*) vaddr;
46 }
47
48 void kunmap_atomic(void *kvaddr, enum km_type type)
49 {
50         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
51         enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
52
53 #ifdef CONFIG_DEBUG_HIGHMEM
54         if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
55                 pagefault_enable();
56                 return;
57         }
58
59         if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
60                 BUG();
61 #endif
62         /*
63          * Force other mappings to Oops if they'll try to access this pte
64          * without first remap it.  Keeping stale mappings around is a bad idea
65          * also, in case the page changes cacheability attributes or becomes
66          * a protected page in a hypervisor.
67          */
68         kpte_clear_flush(kmap_pte-idx, vaddr);
69
70         pagefault_enable();
71 }
72
73 /* This is the same as kmap_atomic() but can map memory that doesn't
74  * have a struct page associated with it.
75  */
76 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
77 {
78         enum fixed_addresses idx;
79         unsigned long vaddr;
80
81         pagefault_disable();
82
83         idx = type + KM_TYPE_NR*smp_processor_id();
84         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
85         set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
86
87         return (void*) vaddr;
88 }
89
90 struct page *kmap_atomic_to_page(void *ptr)
91 {
92         unsigned long idx, vaddr = (unsigned long)ptr;
93         pte_t *pte;
94
95         if (vaddr < FIXADDR_START)
96                 return virt_to_page(ptr);
97
98         idx = virt_to_fix(vaddr);
99         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
100         return pte_page(*pte);
101 }
102
103 EXPORT_SYMBOL(kmap);
104 EXPORT_SYMBOL(kunmap);
105 EXPORT_SYMBOL(kmap_atomic);
106 EXPORT_SYMBOL(kunmap_atomic);
107 EXPORT_SYMBOL(kmap_atomic_to_page);