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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 | */ | |
1da177e4 | 25 | #include <linux/highmem.h> |
7b64db60 | 26 | #include <linux/export.h> |
1b6d06d8 SR |
27 | #include <linux/mm.h> |
28 | ||
1da177e4 LT |
29 | #include <asm/cacheflush.h> |
30 | #include <asm/tlbflush.h> | |
1b6d06d8 SR |
31 | #include <asm/pgalloc.h> |
32 | #include <asm/vaddrs.h> | |
1da177e4 | 33 | |
9a4d5b93 SR |
34 | pgprot_t kmap_prot; |
35 | ||
36 | static pte_t *kmap_pte; | |
37 | ||
38 | void __init kmap_init(void) | |
39 | { | |
40 | unsigned long address; | |
41 | pmd_t *dir; | |
42 | ||
43 | address = __fix_to_virt(FIX_KMAP_BEGIN); | |
44 | dir = pmd_offset(pgd_offset_k(address), address); | |
45 | ||
46 | /* cache the first kmap pte */ | |
47 | kmap_pte = pte_offset_kernel(dir, address); | |
48 | kmap_prot = __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE); | |
49 | } | |
50 | ||
a24401bc | 51 | void *kmap_atomic(struct page *page) |
1da177e4 | 52 | { |
1da177e4 | 53 | unsigned long vaddr; |
3e4d3af5 | 54 | long idx, type; |
1da177e4 LT |
55 | |
56 | /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ | |
a866374a | 57 | pagefault_disable(); |
1da177e4 LT |
58 | if (!PageHighMem(page)) |
59 | return page_address(page); | |
60 | ||
3e4d3af5 | 61 | type = kmap_atomic_idx_push(); |
1da177e4 LT |
62 | idx = type + KM_TYPE_NR*smp_processor_id(); |
63 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
64 | ||
65 | /* XXX Fix - Anton */ | |
66 | #if 0 | |
67 | __flush_cache_one(vaddr); | |
68 | #else | |
69 | flush_cache_all(); | |
70 | #endif | |
71 | ||
72 | #ifdef CONFIG_DEBUG_HIGHMEM | |
73 | BUG_ON(!pte_none(*(kmap_pte-idx))); | |
74 | #endif | |
75 | set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); | |
76 | /* XXX Fix - Anton */ | |
77 | #if 0 | |
78 | __flush_tlb_one(vaddr); | |
79 | #else | |
80 | flush_tlb_all(); | |
81 | #endif | |
82 | ||
83 | return (void*) vaddr; | |
84 | } | |
a24401bc | 85 | EXPORT_SYMBOL(kmap_atomic); |
1da177e4 | 86 | |
3e4d3af5 | 87 | void __kunmap_atomic(void *kvaddr) |
1da177e4 | 88 | { |
1da177e4 | 89 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
3e4d3af5 | 90 | int type; |
1da177e4 LT |
91 | |
92 | if (vaddr < FIXADDR_START) { // FIXME | |
a866374a | 93 | pagefault_enable(); |
1da177e4 LT |
94 | return; |
95 | } | |
96 | ||
20273941 | 97 | type = kmap_atomic_idx(); |
1da177e4 | 98 | |
3e4d3af5 PZ |
99 | #ifdef CONFIG_DEBUG_HIGHMEM |
100 | { | |
101 | unsigned long idx; | |
102 | ||
103 | idx = type + KM_TYPE_NR * smp_processor_id(); | |
104 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); | |
105 | ||
106 | /* XXX Fix - Anton */ | |
1da177e4 | 107 | #if 0 |
3e4d3af5 | 108 | __flush_cache_one(vaddr); |
1da177e4 | 109 | #else |
3e4d3af5 | 110 | flush_cache_all(); |
1da177e4 LT |
111 | #endif |
112 | ||
3e4d3af5 PZ |
113 | /* |
114 | * force other mappings to Oops if they'll try to access | |
115 | * this pte without first remap it | |
116 | */ | |
117 | pte_clear(&init_mm, vaddr, kmap_pte-idx); | |
118 | /* XXX Fix - Anton */ | |
1da177e4 | 119 | #if 0 |
3e4d3af5 | 120 | __flush_tlb_one(vaddr); |
1da177e4 | 121 | #else |
3e4d3af5 | 122 | flush_tlb_all(); |
1da177e4 | 123 | #endif |
3e4d3af5 | 124 | } |
1da177e4 | 125 | #endif |
20273941 PZ |
126 | |
127 | kmap_atomic_idx_pop(); | |
a866374a | 128 | pagefault_enable(); |
1da177e4 | 129 | } |
3e4d3af5 | 130 | EXPORT_SYMBOL(__kunmap_atomic); |