tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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, enum km_type type)
45{
46 enum fixed_addresses idx;
47 unsigned long vaddr;
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 debug_kmap_atomic(type);
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, enum km_type type)
68{
69#ifdef CONFIG_DEBUG_HIGHMEM
70 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
71 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
72
73 if (vaddr < FIXADDR_START) { // FIXME
74 pagefault_enable();
75 return;
76 }
77
78 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
79
80 /*
81 * force other mappings to Oops if they'll try to access
82 * this pte without first remap it
83 */
84 pte_clear(&init_mm, vaddr, kmap_pte-idx);
85 local_flush_tlb_one(vaddr);
86#endif
87
88 pagefault_enable();
89}
90EXPORT_SYMBOL(__kunmap_atomic);
91
92/*
93 * This is the same as kmap_atomic() but can map memory that doesn't
94 * have a struct page associated with it.
95 */
96void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
97{
98 enum fixed_addresses idx;
99 unsigned long vaddr;
100
101 pagefault_disable();
102
103 debug_kmap_atomic(type);
104 idx = type + KM_TYPE_NR*smp_processor_id();
105 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
106 set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
107 flush_tlb_one(vaddr);
108
109 return (void*) vaddr;
110}
111
112struct page *__kmap_atomic_to_page(void *ptr)
113{
114 unsigned long idx, vaddr = (unsigned long)ptr;
115 pte_t *pte;
116
117 if (vaddr < FIXADDR_START)
118 return virt_to_page(ptr);
119
120 idx = virt_to_fix(vaddr);
121 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
122 return pte_page(*pte);
123}
124
125void __init kmap_init(void)
126{
127 unsigned long kmap_vstart;
128
129 /* cache the first kmap pte */
130 kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
131 kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
132}