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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 | ||
32 | void *kmap_atomic(struct page *page, enum km_type type) | |
33 | { | |
34 | unsigned long idx; | |
35 | unsigned long vaddr; | |
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 | ||
42 | idx = type + KM_TYPE_NR*smp_processor_id(); | |
43 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
44 | ||
45 | /* XXX Fix - Anton */ | |
46 | #if 0 | |
47 | __flush_cache_one(vaddr); | |
48 | #else | |
49 | flush_cache_all(); | |
50 | #endif | |
51 | ||
52 | #ifdef CONFIG_DEBUG_HIGHMEM | |
53 | BUG_ON(!pte_none(*(kmap_pte-idx))); | |
54 | #endif | |
55 | set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); | |
56 | /* XXX Fix - Anton */ | |
57 | #if 0 | |
58 | __flush_tlb_one(vaddr); | |
59 | #else | |
60 | flush_tlb_all(); | |
61 | #endif | |
62 | ||
63 | return (void*) vaddr; | |
64 | } | |
65 | ||
66 | void kunmap_atomic(void *kvaddr, enum km_type type) | |
67 | { | |
68 | #ifdef CONFIG_DEBUG_HIGHMEM | |
69 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; | |
70 | unsigned long idx = type + KM_TYPE_NR*smp_processor_id(); | |
71 | ||
72 | if (vaddr < FIXADDR_START) { // FIXME | |
a866374a | 73 | pagefault_enable(); |
1da177e4 LT |
74 | return; |
75 | } | |
76 | ||
77 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); | |
78 | ||
79 | /* XXX Fix - Anton */ | |
80 | #if 0 | |
81 | __flush_cache_one(vaddr); | |
82 | #else | |
83 | flush_cache_all(); | |
84 | #endif | |
85 | ||
86 | /* | |
87 | * force other mappings to Oops if they'll try to access | |
88 | * this pte without first remap it | |
89 | */ | |
90 | pte_clear(&init_mm, vaddr, kmap_pte-idx); | |
91 | /* XXX Fix - Anton */ | |
92 | #if 0 | |
93 | __flush_tlb_one(vaddr); | |
94 | #else | |
95 | flush_tlb_all(); | |
96 | #endif | |
97 | #endif | |
98 | ||
a866374a | 99 | pagefault_enable(); |
1da177e4 LT |
100 | } |
101 | ||
102 | /* We may be fed a pagetable here by ptep_to_xxx and others. */ | |
103 | struct page *kmap_atomic_to_page(void *ptr) | |
104 | { | |
105 | unsigned long idx, vaddr = (unsigned long)ptr; | |
106 | pte_t *pte; | |
107 | ||
108 | if (vaddr < SRMMU_NOCACHE_VADDR) | |
109 | return virt_to_page(ptr); | |
110 | if (vaddr < PKMAP_BASE) | |
111 | return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT); | |
112 | BUG_ON(vaddr < FIXADDR_START); | |
113 | BUG_ON(vaddr > FIXADDR_TOP); | |
114 | ||
115 | idx = virt_to_fix(vaddr); | |
116 | pte = kmap_pte - (idx - FIX_KMAP_BEGIN); | |
117 | return pte_page(*pte); | |
118 | } |