summaryrefslogtreecommitdiffstats
path: root/arch/arm/mm/highmem.c
blob: 9df5f09585ca49bc48c209f8588a395ca5f8d449 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
/*
 * arch/arm/mm/highmem.c -- ARM highmem support
 *
 * Author:	Nicolas Pitre
 * Created:	september 8, 2008
 * Copyright:	Marvell Semiconductors Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/interrupt.h>
#include <asm/fixmap.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include "mm.h"

static inline void set_fixmap_pte(int idx, pte_t pte)
{
	unsigned long vaddr = __fix_to_virt(idx);
	pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);

	set_pte_ext(ptep, pte, 0);
	local_flush_tlb_kernel_page(vaddr);
}

static inline pte_t get_fixmap_pte(unsigned long vaddr)
{
	pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);

	return *ptep;
}

void *kmap(struct page *page)
{
	might_sleep();
	if (!PageHighMem(page))
		return page_address(page);
	return kmap_high(page);
}
EXPORT_SYMBOL(kmap);

void kunmap(struct page *page)
{
	BUG_ON(in_interrupt());
	if (!PageHighMem(page))
		return;
	kunmap_high(page);
}
EXPORT_SYMBOL(kunmap);

void *kmap_atomic(struct page *page)
{
	unsigned int idx;
	unsigned long vaddr;
	void *kmap;
	int type;

	preempt_disable();
	pagefault_disable();
	if (!PageHighMem(page))
		return page_address(page);

#ifdef CONFIG_DEBUG_HIGHMEM
	/*
	 * There is no cache coherency issue when non VIVT, so force the
	 * dedicated kmap usage for better debugging purposes in that case.
	 */
	if (!cache_is_vivt())
		kmap = NULL;
	else
#endif
		kmap = kmap_high_get(page);
	if (kmap)
		return kmap;

	type = kmap_atomic_idx_push();

	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
	vaddr = __fix_to_virt(idx);
#ifdef CONFIG_DEBUG_HIGHMEM
	/*
	 * With debugging enabled, kunmap_atomic forces that entry to 0.
	 * Make sure it was indeed properly unmapped.
	 */
	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
#endif
	/*
	 * When debugging is off, kunmap_atomic leaves the previous mapping
	 * in place, so the contained TLB flush ensures the TLB is updated
	 * with the new mapping.
	 */
	set_fixmap_pte(idx, mk_pte(page, kmap_prot));

	return (void *)vaddr;
}
EXPORT_SYMBOL(kmap_atomic);

void __kunmap_atomic(void *kvaddr)
{
	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
	int idx, type;

	if (kvaddr >= (void *)FIXADDR_START) {
		type = kmap_atomic_idx();
		idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();

		if (cache_is_vivt())
			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
#ifdef CONFIG_DEBUG_HIGHMEM
		BUG_ON(vaddr != __fix_to_virt(idx));
		set_fixmap_pte(idx, __pte(0));
#else
		(void) idx;  /* to kill a warning */
#endif
		kmap_atomic_idx_pop();
	} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
		/* this address was obtained through kmap_high_get() */
		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
	}
	pagefault_enable();
	preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

void *kmap_atomic_pfn(unsigned long pfn)
{
	unsigned long vaddr;
	int idx, type;
	struct page *page = pfn_to_page(pfn);

	preempt_disable();
	pagefault_disable();
	if (!PageHighMem(page))
		return page_address(page);

	type = kmap_atomic_idx_push();
	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
	vaddr = __fix_to_virt(idx);
#ifdef CONFIG_DEBUG_HIGHMEM
	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
#endif
	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));

	return (void *)vaddr;
}

struct page *kmap_atomic_to_page(const void *ptr)
{
	unsigned long vaddr = (unsigned long)ptr;

	if (vaddr < FIXADDR_START)
		return virt_to_page(ptr);

	return pte_page(get_fixmap_pte(vaddr));
}