tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <linux/highmem.h>
2#include <linux/module.h>
3#include <linux/swap.h> /* for totalram_pages */
4
5void *kmap(struct page *page)
6{
7 might_sleep();
8 if (!PageHighMem(page))
9 return page_address(page);
10 return kmap_high(page);
11}
12EXPORT_SYMBOL(kmap);
13
14void kunmap(struct page *page)
15{
16 if (in_interrupt())
17 BUG();
18 if (!PageHighMem(page))
19 return;
20 kunmap_high(page);
21}
22EXPORT_SYMBOL(kunmap);
23
24/*
25 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
26 * no global lock is needed and because the kmap code must perform a global TLB
27 * invalidation when the kmap pool wraps.
28 *
29 * However when holding an atomic kmap it is not legal to sleep, so atomic
30 * kmaps are appropriate for short, tight code paths only.
31 */
32void *kmap_atomic_prot(struct page *page, pgprot_t prot)
33{
34 unsigned long vaddr;
35 int idx, type;
36
37 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
38 pagefault_disable();
39
40 if (!PageHighMem(page))
41 return page_address(page);
42
43 type = kmap_atomic_idx_push();
44 idx = type + KM_TYPE_NR*smp_processor_id();
45 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
46 BUG_ON(!pte_none(*(kmap_pte-idx)));
47 set_pte(kmap_pte-idx, mk_pte(page, prot));
48 arch_flush_lazy_mmu_mode();
49
50 return (void *)vaddr;
51}
52EXPORT_SYMBOL(kmap_atomic_prot);
53
54void *kmap_atomic(struct page *page)
55{
56 return kmap_atomic_prot(page, kmap_prot);
57}
58EXPORT_SYMBOL(kmap_atomic);
59
60/*
61 * This is the same as kmap_atomic() but can map memory that doesn't
62 * have a struct page associated with it.
63 */
64void *kmap_atomic_pfn(unsigned long pfn)
65{
66 return kmap_atomic_prot_pfn(pfn, kmap_prot);
67}
68EXPORT_SYMBOL_GPL(kmap_atomic_pfn);
69
70void __kunmap_atomic(void *kvaddr)
71{
72 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
73
74 if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
75 vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
76 int idx, type;
77
78 type = kmap_atomic_idx();
79 idx = type + KM_TYPE_NR * smp_processor_id();
80
81#ifdef CONFIG_DEBUG_HIGHMEM
82 WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
83#endif
84 /*
85 * Force other mappings to Oops if they'll try to access this
86 * pte without first remap it. Keeping stale mappings around
87 * is a bad idea also, in case the page changes cacheability
88 * attributes or becomes a protected page in a hypervisor.
89 */
90 kpte_clear_flush(kmap_pte-idx, vaddr);
91 kmap_atomic_idx_pop();
92 arch_flush_lazy_mmu_mode();
93 }
94#ifdef CONFIG_DEBUG_HIGHMEM
95 else {
96 BUG_ON(vaddr < PAGE_OFFSET);
97 BUG_ON(vaddr >= (unsigned long)high_memory);
98 }
99#endif
100
101 pagefault_enable();
102}
103EXPORT_SYMBOL(__kunmap_atomic);
104
105struct page *kmap_atomic_to_page(void *ptr)
106{
107 unsigned long idx, vaddr = (unsigned long)ptr;
108 pte_t *pte;
109
110 if (vaddr < FIXADDR_START)
111 return virt_to_page(ptr);
112
113 idx = virt_to_fix(vaddr);
114 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
115 return pte_page(*pte);
116}
117EXPORT_SYMBOL(kmap_atomic_to_page);
118
119void __init set_highmem_pages_init(void)
120{
121 struct zone *zone;
122 int nid;
123
124 for_each_zone(zone) {
125 unsigned long zone_start_pfn, zone_end_pfn;
126
127 if (!is_highmem(zone))
128 continue;
129
130 zone_start_pfn = zone->zone_start_pfn;
131 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
132
133 nid = zone_to_nid(zone);
134 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
135 zone->name, nid, zone_start_pfn, zone_end_pfn);
136
137 add_highpages_with_active_regions(nid, zone_start_pfn,
138 zone_end_pfn);
139 }
140 totalram_pages += totalhigh_pages;
141}