Merge git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc
[linux-2.6] / arch / mips / mm / highmem.c
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 /*
87  * This is the same as kmap_atomic() but can map memory that doesn't
88  * have a struct page associated with it.
89  */
90 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
91 {
92         enum fixed_addresses idx;
93         unsigned long vaddr;
94
95         inc_preempt_count();
96
97         idx = type + KM_TYPE_NR*smp_processor_id();
98         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
99         set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
100         flush_tlb_one(vaddr);
101
102         return (void*) vaddr;
103 }
104
105 struct page *__kmap_atomic_to_page(void *ptr)
106 {
107         unsigned long idx, vaddr = (unsigned long)ptr;
108         pte_t *pte;
109
110         if (vaddr < FIXADDR_START)
111                 return virt_to_page(ptr);
112
113         idx = virt_to_fix(vaddr);
114         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
115         return pte_page(*pte);
116 }
117
118 EXPORT_SYMBOL(__kmap);
119 EXPORT_SYMBOL(__kunmap);
120 EXPORT_SYMBOL(__kmap_atomic);
121 EXPORT_SYMBOL(__kunmap_atomic);
122 EXPORT_SYMBOL(__kmap_atomic_to_page);