1#include <linux/compiler.h>
2#include <linux/module.h>
3#include <linux/highmem.h>
4#include <linux/sched.h>
5#include <linux/smp.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	void *addr;
16
17	might_sleep();
18	if (!PageHighMem(page))
19		return page_address(page);
20	addr = kmap_high(page);
21	flush_tlb_one((unsigned long)addr);
22
23	return addr;
24}
25EXPORT_SYMBOL(kmap);
26
27void kunmap(struct page *page)
28{
29	BUG_ON(in_interrupt());
30	if (!PageHighMem(page))
31		return;
32	kunmap_high(page);
33}
34EXPORT_SYMBOL(kunmap);
35
36/*
37 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
38 * no global lock is needed and because the kmap code must perform a global TLB
39 * invalidation when the kmap pool wraps.
40 *
41 * However when holding an atomic kmap is is not legal to sleep, so atomic
42 * kmaps are appropriate for short, tight code paths only.
43 */
44
45void *kmap_atomic(struct page *page)
46{
47	unsigned long vaddr;
48	int idx, type;
49
50	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
51	pagefault_disable();
52	if (!PageHighMem(page))
53		return page_address(page);
54
55	type = kmap_atomic_idx_push();
56	idx = type + KM_TYPE_NR*smp_processor_id();
57	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
58#ifdef CONFIG_DEBUG_HIGHMEM
59	BUG_ON(!pte_none(*(kmap_pte - idx)));
60#endif
61	set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
62	local_flush_tlb_one((unsigned long)vaddr);
63
64	return (void*) vaddr;
65}
66EXPORT_SYMBOL(kmap_atomic);
67
68void __kunmap_atomic(void *kvaddr)
69{
70	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
71	int type __maybe_unused;
72
73	if (vaddr < FIXADDR_START) { // FIXME
74		pagefault_enable();
75		return;
76	}
77
78	type = kmap_atomic_idx();
79#ifdef CONFIG_DEBUG_HIGHMEM
80	{
81		int idx = type + KM_TYPE_NR * smp_processor_id();
82
83		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
84
85		/*
86		 * force other mappings to Oops if they'll try to access
87		 * this pte without first remap it
88		 */
89		pte_clear(&init_mm, vaddr, kmap_pte-idx);
90		local_flush_tlb_one(vaddr);
91	}
92#endif
93	kmap_atomic_idx_pop();
94	pagefault_enable();
95}
96EXPORT_SYMBOL(__kunmap_atomic);
97
98/*
99 * This is the same as kmap_atomic() but can map memory that doesn't
100 * have a struct page associated with it.
101 */
102void *kmap_atomic_pfn(unsigned long pfn)
103{
104	unsigned long vaddr;
105	int idx, type;
106
107	pagefault_disable();
108
109	type = kmap_atomic_idx_push();
110	idx = type + KM_TYPE_NR*smp_processor_id();
111	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
112	set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
113	flush_tlb_one(vaddr);
114
115	return (void*) vaddr;
116}
117
118struct page *kmap_atomic_to_page(void *ptr)
119{
120	unsigned long idx, vaddr = (unsigned long)ptr;
121	pte_t *pte;
122
123	if (vaddr < FIXADDR_START)
124		return virt_to_page(ptr);
125
126	idx = virt_to_fix(vaddr);
127	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
128	return pte_page(*pte);
129}
130
131void __init kmap_init(void)
132{
133	unsigned long kmap_vstart;
134
135	/* cache the first kmap pte */
136	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
137	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
138}
139