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