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1 | /* |
2 | * highmem.c: virtual kernel memory mappings for high memory |
3 | * |
4 | * Provides kernel-static versions of atomic kmap functions originally |
5 | * found as inlines in include/asm-sparc/highmem.h. These became |
6 | * needed as kmap_atomic() and kunmap_atomic() started getting |
7 | * called from within modules. |
8 | * -- Tomas Szepe <szepe@pinerecords.com>, September 2002 |
9 | * |
10 | * But kmap_atomic() and kunmap_atomic() cannot be inlined in |
11 | * modules because they are loaded with btfixup-ped functions. |
12 | */ |
13 | |
14 | /* |
15 | * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap |
16 | * gives a more generic (and caching) interface. But kmap_atomic can |
17 | * be used in IRQ contexts, so in some (very limited) cases we need it. |
18 | * |
19 | * XXX This is an old text. Actually, it's good to use atomic kmaps, |
20 | * provided you remember that they are atomic and not try to sleep |
21 | * with a kmap taken, much like a spinlock. Non-atomic kmaps are |
22 | * shared by CPUs, and so precious, and establishing them requires IPI. |
23 | * Atomic kmaps are lightweight and we may have NCPUS more of them. |
24 | */ |
25 | #include <linux/mm.h> |
26 | #include <linux/highmem.h> |
27 | #include <asm/pgalloc.h> |
28 | #include <asm/cacheflush.h> |
29 | #include <asm/tlbflush.h> |
30 | #include <asm/fixmap.h> |
31 | |
32 | void *__kmap_atomic(struct page *page) |
33 | { |
34 | unsigned long vaddr; |
35 | long idx, type; |
36 | |
37 | /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ |
38 | pagefault_disable(); |
39 | if (!PageHighMem(page)) |
40 | return page_address(page); |
41 | |
42 | type = kmap_atomic_idx_push(); |
43 | idx = type + KM_TYPE_NR*smp_processor_id(); |
44 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
45 | |
46 | /* XXX Fix - Anton */ |
47 | #if 0 |
48 | __flush_cache_one(vaddr); |
49 | #else |
50 | flush_cache_all(); |
51 | #endif |
52 | |
53 | #ifdef CONFIG_DEBUG_HIGHMEM |
54 | BUG_ON(!pte_none(*(kmap_pte-idx))); |
55 | #endif |
56 | set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); |
57 | /* XXX Fix - Anton */ |
58 | #if 0 |
59 | __flush_tlb_one(vaddr); |
60 | #else |
61 | flush_tlb_all(); |
62 | #endif |
63 | |
64 | return (void*) vaddr; |
65 | } |
66 | EXPORT_SYMBOL(__kmap_atomic); |
67 | |
68 | void __kunmap_atomic(void *kvaddr) |
69 | { |
70 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
71 | int type; |
72 | |
73 | if (vaddr < FIXADDR_START) { // FIXME |
74 | pagefault_enable(); |
75 | return; |
76 | } |
77 | |
78 | type = kmap_atomic_idx(); |
79 | |
80 | #ifdef CONFIG_DEBUG_HIGHMEM |
81 | { |
82 | unsigned long idx; |
83 | |
84 | idx = type + KM_TYPE_NR * smp_processor_id(); |
85 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); |
86 | |
87 | /* XXX Fix - Anton */ |
88 | #if 0 |
89 | __flush_cache_one(vaddr); |
90 | #else |
91 | flush_cache_all(); |
92 | #endif |
93 | |
94 | /* |
95 | * force other mappings to Oops if they'll try to access |
96 | * this pte without first remap it |
97 | */ |
98 | pte_clear(&init_mm, vaddr, kmap_pte-idx); |
99 | /* XXX Fix - Anton */ |
100 | #if 0 |
101 | __flush_tlb_one(vaddr); |
102 | #else |
103 | flush_tlb_all(); |
104 | #endif |
105 | } |
106 | #endif |
107 | |
108 | kmap_atomic_idx_pop(); |
109 | pagefault_enable(); |
110 | } |
111 | EXPORT_SYMBOL(__kunmap_atomic); |
112 | |
113 | /* We may be fed a pagetable here by ptep_to_xxx and others. */ |
114 | struct page *kmap_atomic_to_page(void *ptr) |
115 | { |
116 | unsigned long idx, vaddr = (unsigned long)ptr; |
117 | pte_t *pte; |
118 | |
119 | if (vaddr < SRMMU_NOCACHE_VADDR) |
120 | return virt_to_page(ptr); |
121 | if (vaddr < PKMAP_BASE) |
122 | return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT); |
123 | BUG_ON(vaddr < FIXADDR_START); |
124 | BUG_ON(vaddr > FIXADDR_TOP); |
125 | |
126 | idx = virt_to_fix(vaddr); |
127 | pte = kmap_pte - (idx - FIX_KMAP_BEGIN); |
128 | return pte_page(*pte); |
129 | } |
130 |
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