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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> | |
7b64db60 | 27 | #include <linux/export.h> |
1da177e4 LT |
28 | #include <asm/pgalloc.h> |
29 | #include <asm/cacheflush.h> | |
30 | #include <asm/tlbflush.h> | |
31 | #include <asm/fixmap.h> | |
32 | ||
a24401bc | 33 | void *kmap_atomic(struct page *page) |
1da177e4 | 34 | { |
1da177e4 | 35 | unsigned long vaddr; |
3e4d3af5 | 36 | long idx, type; |
1da177e4 LT |
37 | |
38 | /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ | |
a866374a | 39 | pagefault_disable(); |
1da177e4 LT |
40 | if (!PageHighMem(page)) |
41 | return page_address(page); | |
42 | ||
3e4d3af5 | 43 | type = kmap_atomic_idx_push(); |
1da177e4 LT |
44 | idx = type + KM_TYPE_NR*smp_processor_id(); |
45 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
46 | ||
47 | /* XXX Fix - Anton */ | |
48 | #if 0 | |
49 | __flush_cache_one(vaddr); | |
50 | #else | |
51 | flush_cache_all(); | |
52 | #endif | |
53 | ||
54 | #ifdef CONFIG_DEBUG_HIGHMEM | |
55 | BUG_ON(!pte_none(*(kmap_pte-idx))); | |
56 | #endif | |
57 | set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); | |
58 | /* XXX Fix - Anton */ | |
59 | #if 0 | |
60 | __flush_tlb_one(vaddr); | |
61 | #else | |
62 | flush_tlb_all(); | |
63 | #endif | |
64 | ||
65 | return (void*) vaddr; | |
66 | } | |
a24401bc | 67 | EXPORT_SYMBOL(kmap_atomic); |
1da177e4 | 68 | |
3e4d3af5 | 69 | void __kunmap_atomic(void *kvaddr) |
1da177e4 | 70 | { |
1da177e4 | 71 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
3e4d3af5 | 72 | int type; |
1da177e4 LT |
73 | |
74 | if (vaddr < FIXADDR_START) { // FIXME | |
a866374a | 75 | pagefault_enable(); |
1da177e4 LT |
76 | return; |
77 | } | |
78 | ||
20273941 | 79 | type = kmap_atomic_idx(); |
1da177e4 | 80 | |
3e4d3af5 PZ |
81 | #ifdef CONFIG_DEBUG_HIGHMEM |
82 | { | |
83 | unsigned long idx; | |
84 | ||
85 | idx = type + KM_TYPE_NR * smp_processor_id(); | |
86 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); | |
87 | ||
88 | /* XXX Fix - Anton */ | |
1da177e4 | 89 | #if 0 |
3e4d3af5 | 90 | __flush_cache_one(vaddr); |
1da177e4 | 91 | #else |
3e4d3af5 | 92 | flush_cache_all(); |
1da177e4 LT |
93 | #endif |
94 | ||
3e4d3af5 PZ |
95 | /* |
96 | * force other mappings to Oops if they'll try to access | |
97 | * this pte without first remap it | |
98 | */ | |
99 | pte_clear(&init_mm, vaddr, kmap_pte-idx); | |
100 | /* XXX Fix - Anton */ | |
1da177e4 | 101 | #if 0 |
3e4d3af5 | 102 | __flush_tlb_one(vaddr); |
1da177e4 | 103 | #else |
3e4d3af5 | 104 | flush_tlb_all(); |
1da177e4 | 105 | #endif |
3e4d3af5 | 106 | } |
1da177e4 | 107 | #endif |
20273941 PZ |
108 | |
109 | kmap_atomic_idx_pop(); | |
a866374a | 110 | pagefault_enable(); |
1da177e4 | 111 | } |
3e4d3af5 | 112 | EXPORT_SYMBOL(__kunmap_atomic); |
1da177e4 LT |
113 | |
114 | /* We may be fed a pagetable here by ptep_to_xxx and others. */ | |
115 | struct page *kmap_atomic_to_page(void *ptr) | |
116 | { | |
117 | unsigned long idx, vaddr = (unsigned long)ptr; | |
118 | pte_t *pte; | |
119 | ||
120 | if (vaddr < SRMMU_NOCACHE_VADDR) | |
121 | return virt_to_page(ptr); | |
122 | if (vaddr < PKMAP_BASE) | |
123 | return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT); | |
124 | BUG_ON(vaddr < FIXADDR_START); | |
125 | BUG_ON(vaddr > FIXADDR_TOP); | |
126 | ||
127 | idx = virt_to_fix(vaddr); | |
128 | pte = kmap_pte - (idx - FIX_KMAP_BEGIN); | |
129 | return pte_page(*pte); | |
130 | } |