1 /*
2 * arch/arm/mm/highmem.c -- ARM highmem support
3 *
4 * Author: Nicolas Pitre
5 * Created: september 8, 2008
6 * Copyright: Marvell Semiconductors Inc.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13 #include <linux/module.h>
14 #include <linux/highmem.h>
15 #include <linux/interrupt.h>
16 #include <asm/fixmap.h>
17 #include <asm/cacheflush.h>
18 #include <asm/tlbflush.h>
19 #include "mm.h"
20
kmap(struct page * page)21 void *kmap(struct page *page)
22 {
23 might_sleep();
24 if (!PageHighMem(page))
25 return page_address(page);
26 return kmap_high(page);
27 }
28 EXPORT_SYMBOL(kmap);
29
kunmap(struct page * page)30 void kunmap(struct page *page)
31 {
32 BUG_ON(in_interrupt());
33 if (!PageHighMem(page))
34 return;
35 kunmap_high(page);
36 }
37 EXPORT_SYMBOL(kunmap);
38
kmap_atomic(struct page * page)39 void *kmap_atomic(struct page *page)
40 {
41 unsigned int idx;
42 unsigned long vaddr;
43 void *kmap;
44 int type;
45
46 pagefault_disable();
47 if (!PageHighMem(page))
48 return page_address(page);
49
50 #ifdef CONFIG_DEBUG_HIGHMEM
51 /*
52 * There is no cache coherency issue when non VIVT, so force the
53 * dedicated kmap usage for better debugging purposes in that case.
54 */
55 if (!cache_is_vivt())
56 kmap = NULL;
57 else
58 #endif
59 kmap = kmap_high_get(page);
60 if (kmap)
61 return kmap;
62
63 type = kmap_atomic_idx_push();
64
65 idx = type + KM_TYPE_NR * smp_processor_id();
66 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
67 #ifdef CONFIG_DEBUG_HIGHMEM
68 /*
69 * With debugging enabled, kunmap_atomic forces that entry to 0.
70 * Make sure it was indeed properly unmapped.
71 */
72 BUG_ON(!pte_none(get_top_pte(vaddr)));
73 #endif
74 /*
75 * When debugging is off, kunmap_atomic leaves the previous mapping
76 * in place, so the contained TLB flush ensures the TLB is updated
77 * with the new mapping.
78 */
79 set_top_pte(vaddr, mk_pte(page, kmap_prot));
80
81 return (void *)vaddr;
82 }
83 EXPORT_SYMBOL(kmap_atomic);
84
__kunmap_atomic(void * kvaddr)85 void __kunmap_atomic(void *kvaddr)
86 {
87 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
88 int idx, type;
89
90 if (kvaddr >= (void *)FIXADDR_START) {
91 type = kmap_atomic_idx();
92 idx = type + KM_TYPE_NR * smp_processor_id();
93
94 if (cache_is_vivt())
95 __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
96 #ifdef CONFIG_DEBUG_HIGHMEM
97 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
98 set_top_pte(vaddr, __pte(0));
99 #else
100 (void) idx; /* to kill a warning */
101 #endif
102 kmap_atomic_idx_pop();
103 } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
104 /* this address was obtained through kmap_high_get() */
105 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
106 }
107 pagefault_enable();
108 }
109 EXPORT_SYMBOL(__kunmap_atomic);
110
kmap_atomic_pfn(unsigned long pfn)111 void *kmap_atomic_pfn(unsigned long pfn)
112 {
113 unsigned long vaddr;
114 int idx, type;
115
116 pagefault_disable();
117
118 type = kmap_atomic_idx_push();
119 idx = type + KM_TYPE_NR * smp_processor_id();
120 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
121 #ifdef CONFIG_DEBUG_HIGHMEM
122 BUG_ON(!pte_none(get_top_pte(vaddr)));
123 #endif
124 set_top_pte(vaddr, pfn_pte(pfn, kmap_prot));
125
126 return (void *)vaddr;
127 }
128
kmap_atomic_to_page(const void * ptr)129 struct page *kmap_atomic_to_page(const void *ptr)
130 {
131 unsigned long vaddr = (unsigned long)ptr;
132
133 if (vaddr < FIXADDR_START)
134 return virt_to_page(ptr);
135
136 return pte_page(get_top_pte(vaddr));
137 }
138