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1da177e4 LT |
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 | ||
3e4d3af5 | 32 | void *__kmap_atomic(struct page *page) |
1da177e4 | 33 | { |
1da177e4 | 34 | unsigned long vaddr; |
3e4d3af5 | 35 | long idx, type; |
1da177e4 LT |
36 | |
37 | /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ | |
a866374a | 38 | pagefault_disable(); |
1da177e4 LT |
39 | if (!PageHighMem(page)) |
40 | return page_address(page); | |
41 | ||
3e4d3af5 | 42 | type = kmap_atomic_idx_push(); |
1da177e4 LT |
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 | } | |
3e4d3af5 | 66 | EXPORT_SYMBOL(__kmap_atomic); |
1da177e4 | 67 | |
3e4d3af5 | 68 | void __kunmap_atomic(void *kvaddr) |
1da177e4 | 69 | { |
1da177e4 | 70 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
3e4d3af5 | 71 | int type; |
1da177e4 LT |
72 | |
73 | if (vaddr < FIXADDR_START) { // FIXME | |
a866374a | 74 | pagefault_enable(); |
1da177e4 LT |
75 | return; |
76 | } | |
77 | ||
20273941 | 78 | type = kmap_atomic_idx(); |
1da177e4 | 79 | |
3e4d3af5 PZ |
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 */ | |
1da177e4 | 88 | #if 0 |
3e4d3af5 | 89 | __flush_cache_one(vaddr); |
1da177e4 | 90 | #else |
3e4d3af5 | 91 | flush_cache_all(); |
1da177e4 LT |
92 | #endif |
93 | ||
3e4d3af5 PZ |
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 */ | |
1da177e4 | 100 | #if 0 |
3e4d3af5 | 101 | __flush_tlb_one(vaddr); |
1da177e4 | 102 | #else |
3e4d3af5 | 103 | flush_tlb_all(); |
1da177e4 | 104 | #endif |
3e4d3af5 | 105 | } |
1da177e4 | 106 | #endif |
20273941 PZ |
107 | |
108 | kmap_atomic_idx_pop(); | |
a866374a | 109 | pagefault_enable(); |
1da177e4 | 110 | } |
3e4d3af5 | 111 | EXPORT_SYMBOL(__kunmap_atomic); |
1da177e4 LT |
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 | } |