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850f6ac3 BH |
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 | */ | |
3e4d3af5 | 32 | void *kmap_atomic_prot(struct page *page, pgprot_t prot) |
850f6ac3 | 33 | { |
850f6ac3 | 34 | unsigned long vaddr; |
3e4d3af5 | 35 | int idx, type; |
850f6ac3 | 36 | |
2cb7c9cb | 37 | preempt_disable(); |
850f6ac3 BH |
38 | pagefault_disable(); |
39 | if (!PageHighMem(page)) | |
40 | return page_address(page); | |
41 | ||
3e4d3af5 | 42 | type = kmap_atomic_idx_push(); |
850f6ac3 BH |
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 | ||
3e4d3af5 | 55 | void __kunmap_atomic(void *kvaddr) |
850f6ac3 | 56 | { |
850f6ac3 | 57 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
3e4d3af5 | 58 | int type; |
850f6ac3 BH |
59 | |
60 | if (vaddr < __fix_to_virt(FIX_KMAP_END)) { | |
61 | pagefault_enable(); | |
2cb7c9cb | 62 | preempt_enable(); |
850f6ac3 BH |
63 | return; |
64 | } | |
65 | ||
20273941 | 66 | type = kmap_atomic_idx(); |
850f6ac3 | 67 | |
3e4d3af5 PZ |
68 | #ifdef CONFIG_DEBUG_HIGHMEM |
69 | { | |
70 | unsigned int idx; | |
71 | ||
72 | idx = type + KM_TYPE_NR * smp_processor_id(); | |
73 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); | |
74 | ||
75 | /* | |
76 | * force other mappings to Oops if they'll try to access | |
77 | * this pte without first remap it | |
78 | */ | |
79 | pte_clear(&init_mm, vaddr, kmap_pte-idx); | |
80 | local_flush_tlb_page(NULL, vaddr); | |
81 | } | |
850f6ac3 | 82 | #endif |
20273941 PZ |
83 | |
84 | kmap_atomic_idx_pop(); | |
850f6ac3 | 85 | pagefault_enable(); |
2cb7c9cb | 86 | preempt_enable(); |
850f6ac3 | 87 | } |
3e4d3af5 | 88 | EXPORT_SYMBOL(__kunmap_atomic); |