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1 | /* |
2 | * highmem.c: virtual kernel memory mappings for high memory | |
3 | * | |
4 | * PowerPC version, stolen from the i386 version. | |
5 | * | |
6 | * Used in CONFIG_HIGHMEM systems for memory pages which | |
7 | * are not addressable by direct kernel virtual addresses. | |
8 | * | |
9 | * Copyright (C) 1999 Gerhard Wichert, Siemens AG | |
10 | * Gerhard.Wichert@pdb.siemens.de | |
11 | * | |
12 | * | |
13 | * Redesigned the x86 32-bit VM architecture to deal with | |
14 | * up to 16 Terrabyte physical memory. With current x86 CPUs | |
15 | * we now support up to 64 Gigabytes physical RAM. | |
16 | * | |
17 | * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> | |
18 | * | |
19 | * Reworked for PowerPC by various contributors. Moved from | |
20 | * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp. | |
21 | */ | |
22 | ||
23 | #include <linux/highmem.h> | |
24 | #include <linux/module.h> | |
25 | ||
26 | /* | |
27 | * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap | |
28 | * gives a more generic (and caching) interface. But kmap_atomic can | |
29 | * be used in IRQ contexts, so in some (very limited) cases we need | |
30 | * it. | |
31 | */ | |
32 | void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot) | |
33 | { | |
34 | unsigned int idx; | |
35 | unsigned long vaddr; | |
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 | debug_kmap_atomic(type); | |
43 | idx = type + KM_TYPE_NR*smp_processor_id(); | |
44 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); | |
45 | #ifdef CONFIG_DEBUG_HIGHMEM | |
46 | BUG_ON(!pte_none(*(kmap_pte-idx))); | |
47 | #endif | |
48 | __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1); | |
49 | local_flush_tlb_page(NULL, vaddr); | |
50 | ||
51 | return (void*) vaddr; | |
52 | } | |
53 | EXPORT_SYMBOL(kmap_atomic_prot); | |
54 | ||
55 | void kunmap_atomic(void *kvaddr, enum km_type type) | |
56 | { | |
57 | #ifdef CONFIG_DEBUG_HIGHMEM | |
58 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; | |
59 | enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); | |
60 | ||
61 | if (vaddr < __fix_to_virt(FIX_KMAP_END)) { | |
62 | pagefault_enable(); | |
63 | return; | |
64 | } | |
65 | ||
66 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); | |
67 | ||
68 | /* | |
69 | * force other mappings to Oops if they'll try to access | |
70 | * this pte without first remap it | |
71 | */ | |
72 | pte_clear(&init_mm, vaddr, kmap_pte-idx); | |
73 | local_flush_tlb_page(NULL, vaddr); | |
74 | #endif | |
75 | pagefault_enable(); | |
76 | } | |
77 | EXPORT_SYMBOL(kunmap_atomic); |