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
set_fixmap_pte(int idx,pte_t pte)21 static inline void set_fixmap_pte(int idx, pte_t pte)
22 {
23 unsigned long vaddr = __fix_to_virt(idx);
24 pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
25
26 set_pte_ext(ptep, pte, 0);
27 local_flush_tlb_kernel_page(vaddr);
28 }
29
get_fixmap_pte(unsigned long vaddr)30 static inline pte_t get_fixmap_pte(unsigned long vaddr)
31 {
32 pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
33
34 return *ptep;
35 }
36
kmap(struct page * page)37 void *kmap(struct page *page)
38 {
39 might_sleep();
40 if (!PageHighMem(page))
41 return page_address(page);
42 return kmap_high(page);
43 }
44 EXPORT_SYMBOL(kmap);
45
kunmap(struct page * page)46 void kunmap(struct page *page)
47 {
48 BUG_ON(in_interrupt());
49 if (!PageHighMem(page))
50 return;
51 kunmap_high(page);
52 }
53 EXPORT_SYMBOL(kunmap);
54
kmap_atomic(struct page * page)55 void *kmap_atomic(struct page *page)
56 {
57 unsigned int idx;
58 unsigned long vaddr;
59 void *kmap;
60 int type;
61
62 preempt_disable();
63 pagefault_disable();
64 if (!PageHighMem(page))
65 return page_address(page);
66
67 #ifdef CONFIG_DEBUG_HIGHMEM
68 /*
69 * There is no cache coherency issue when non VIVT, so force the
70 * dedicated kmap usage for better debugging purposes in that case.
71 */
72 if (!cache_is_vivt())
73 kmap = NULL;
74 else
75 #endif
76 kmap = kmap_high_get(page);
77 if (kmap)
78 return kmap;
79
80 type = kmap_atomic_idx_push();
81
82 idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
83 vaddr = __fix_to_virt(idx);
84 #ifdef CONFIG_DEBUG_HIGHMEM
85 /*
86 * With debugging enabled, kunmap_atomic forces that entry to 0.
87 * Make sure it was indeed properly unmapped.
88 */
89 BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
90 #endif
91 /*
92 * When debugging is off, kunmap_atomic leaves the previous mapping
93 * in place, so the contained TLB flush ensures the TLB is updated
94 * with the new mapping.
95 */
96 set_fixmap_pte(idx, mk_pte(page, kmap_prot));
97
98 return (void *)vaddr;
99 }
100 EXPORT_SYMBOL(kmap_atomic);
101
__kunmap_atomic(void * kvaddr)102 void __kunmap_atomic(void *kvaddr)
103 {
104 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
105 int idx, type;
106
107 if (kvaddr >= (void *)FIXADDR_START) {
108 type = kmap_atomic_idx();
109 idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
110
111 if (cache_is_vivt())
112 __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
113 #ifdef CONFIG_DEBUG_HIGHMEM
114 BUG_ON(vaddr != __fix_to_virt(idx));
115 set_fixmap_pte(idx, __pte(0));
116 #else
117 (void) idx; /* to kill a warning */
118 #endif
119 kmap_atomic_idx_pop();
120 } else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
121 /* this address was obtained through kmap_high_get() */
122 kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
123 }
124 pagefault_enable();
125 preempt_enable();
126 }
127 EXPORT_SYMBOL(__kunmap_atomic);
128
kmap_atomic_pfn(unsigned long pfn)129 void *kmap_atomic_pfn(unsigned long pfn)
130 {
131 unsigned long vaddr;
132 int idx, type;
133 struct page *page = pfn_to_page(pfn);
134
135 preempt_disable();
136 pagefault_disable();
137 if (!PageHighMem(page))
138 return page_address(page);
139
140 type = kmap_atomic_idx_push();
141 idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
142 vaddr = __fix_to_virt(idx);
143 #ifdef CONFIG_DEBUG_HIGHMEM
144 BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
145 #endif
146 set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
147
148 return (void *)vaddr;
149 }
150