1#include <linux/module.h>
2#include <linux/highmem.h>
3#include <linux/sched.h>
4#include <linux/smp.h>
5#include <asm/fixmap.h>
6#include <asm/tlbflush.h>
7
8static pte_t *kmap_pte;
9
10unsigned long highstart_pfn, highend_pfn;
11
12void *kmap(struct page *page)
13{
14	void *addr;
15
16	might_sleep();
17	if (!PageHighMem(page))
18		return page_address(page);
19	addr = kmap_high(page);
20	flush_tlb_one((unsigned long)addr);
21
22	return addr;
23}
24EXPORT_SYMBOL(kmap);
25
26void kunmap(struct page *page)
27{
28	BUG_ON(in_interrupt());
29	if (!PageHighMem(page))
30		return;
31	kunmap_high(page);
32}
33EXPORT_SYMBOL(kunmap);
34
35/*
36 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
37 * no global lock is needed and because the kmap code must perform a global TLB
38 * invalidation when the kmap pool wraps.
39 *
40 * However when holding an atomic kmap is is not legal to sleep, so atomic
41 * kmaps are appropriate for short, tight code paths only.
42 */
43
44void *kmap_atomic(struct page *page)
45{
46	unsigned long vaddr;
47	int idx, type;
48
49	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
50	pagefault_disable();
51	if (!PageHighMem(page))
52		return page_address(page);
53
54	type = kmap_atomic_idx_push();
55	idx = type + KM_TYPE_NR*smp_processor_id();
56	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
57#ifdef CONFIG_DEBUG_HIGHMEM
58	BUG_ON(!pte_none(*(kmap_pte - idx)));
59#endif
60	set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
61	local_flush_tlb_one((unsigned long)vaddr);
62
63	return (void*) vaddr;
64}
65EXPORT_SYMBOL(kmap_atomic);
66
67void __kunmap_atomic(void *kvaddr)
68{
69	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
70	int type;
71
72	if (vaddr < FIXADDR_START) { // FIXME
73		pagefault_enable();
74		return;
75	}
76
77	type = kmap_atomic_idx();
78#ifdef CONFIG_DEBUG_HIGHMEM
79	{
80		int idx = type + KM_TYPE_NR * smp_processor_id();
81
82		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
83
84		/*
85		 * force other mappings to Oops if they'll try to access
86		 * this pte without first remap it
87		 */
88		pte_clear(&init_mm, vaddr, kmap_pte-idx);
89		local_flush_tlb_one(vaddr);
90	}
91#endif
92	kmap_atomic_idx_pop();
93	pagefault_enable();
94}
95EXPORT_SYMBOL(__kunmap_atomic);
96
97/*
98 * This is the same as kmap_atomic() but can map memory that doesn't
99 * have a struct page associated with it.
100 */
101void *kmap_atomic_pfn(unsigned long pfn)
102{
103	unsigned long vaddr;
104	int idx, type;
105
106	pagefault_disable();
107
108	type = kmap_atomic_idx_push();
109	idx = type + KM_TYPE_NR*smp_processor_id();
110	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
111	set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
112	flush_tlb_one(vaddr);
113
114	return (void*) vaddr;
115}
116
117struct page *kmap_atomic_to_page(void *ptr)
118{
119	unsigned long idx, vaddr = (unsigned long)ptr;
120	pte_t *pte;
121
122	if (vaddr < FIXADDR_START)
123		return virt_to_page(ptr);
124
125	idx = virt_to_fix(vaddr);
126	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
127	return pte_page(*pte);
128}
129
130void __init kmap_init(void)
131{
132	unsigned long kmap_vstart;
133
134	/* cache the first kmap pte */
135	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
136	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
137}
138