1#include <linux/export.h>
2#include <linux/highmem.h>
3#include <linux/sched.h>
4#include <linux/smp.h>
5#include <linux/interrupt.h>
6#include <asm/fixmap.h>
7#include <asm/tlbflush.h>
8
9static pte_t *kmap_pte;
10
11unsigned long highstart_pfn, highend_pfn;
12
13void *kmap(struct page *page)
14{
15	might_sleep();
16	if (!PageHighMem(page))
17		return page_address(page);
18	return kmap_high(page);
19}
20EXPORT_SYMBOL(kmap);
21
22void kunmap(struct page *page)
23{
24	BUG_ON(in_interrupt());
25	if (!PageHighMem(page))
26		return;
27	kunmap_high(page);
28}
29EXPORT_SYMBOL(kunmap);
30
31/*
32 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
33 * no global lock is needed and because the kmap code must perform a global TLB
34 * invalidation when the kmap pool wraps.
35 *
36 * However when holding an atomic kmap is is not legal to sleep, so atomic
37 * kmaps are appropriate for short, tight code paths only.
38 */
39
40void *kmap_atomic(struct page *page)
41{
42	enum fixed_addresses idx;
43	unsigned long vaddr;
44	int type;
45
46	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
47	pagefault_disable();
48	if (!PageHighMem(page))
49		return page_address(page);
50
51	type = kmap_atomic_idx_push();
52	idx = type + KM_TYPE_NR * smp_processor_id();
53	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
54#ifdef CONFIG_DEBUG_HIGHMEM
55	BUG_ON(!pte_none(*(kmap_pte - idx)));
56#endif
57	set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL));
58
59	return (void *)vaddr;
60}
61EXPORT_SYMBOL(kmap_atomic);
62
63void __kunmap_atomic(void *kvaddr)
64{
65	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
66	int idx, type;
67
68	if (kvaddr >= (void *)FIXADDR_START) {
69		type = kmap_atomic_idx();
70		idx = type + KM_TYPE_NR * smp_processor_id();
71
72		/*
73		 * Force other mappings to Oops if they'll try to access this
74		 * pte without first remap it.  Keeping stale mappings around
75		 * is a bad idea also, in case the page changes cacheability
76		 * attributes or becomes a protected page in a hypervisor.
77		 */
78		pte_clear(&init_mm, vaddr, kmap_pte-idx);
79		flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
80
81		kmap_atomic_idx_pop();
82	}
83
84	pagefault_enable();
85}
86EXPORT_SYMBOL(__kunmap_atomic);
87
88/*
89 * This is the same as kmap_atomic() but can map memory that doesn't
90 * have a struct page associated with it.
91 */
92void *kmap_atomic_pfn(unsigned long pfn)
93{
94	enum fixed_addresses idx;
95	unsigned long vaddr;
96	int type;
97
98	pagefault_disable();
99
100	type = kmap_atomic_idx_push();
101	idx = type + KM_TYPE_NR * smp_processor_id();
102	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
103#ifdef CONFIG_DEBUG_HIGHMEM
104	BUG_ON(!pte_none(*(kmap_pte - idx)));
105#endif
106	set_pte(kmap_pte - idx, pfn_pte(pfn, PAGE_KERNEL));
107	flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
108
109	return (void *)vaddr;
110}
111
112struct page *kmap_atomic_to_page(void *ptr)
113{
114	unsigned long vaddr = (unsigned long)ptr;
115	int idx;
116	pte_t *pte;
117
118	if (vaddr < FIXADDR_START)
119		return virt_to_page(ptr);
120
121	idx = virt_to_fix(vaddr);
122	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
123	return pte_page(*pte);
124}
125
126void __init kmap_init(void)
127{
128	unsigned long kmap_vstart;
129
130	/* cache the first kmap pte */
131	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
132	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
133}
134