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}
12
13void kunmap(struct page *page)
14{
15 if (in_interrupt())
16 BUG();
17 if (!PageHighMem(page))
18 return;
19 kunmap_high(page);
20}
21
22/*
23 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
24 * no global lock is needed and because the kmap code must perform a global TLB
25 * invalidation when the kmap pool wraps.
26 *
27 * However when holding an atomic kmap it is not legal to sleep, so atomic
28 * kmaps are appropriate for short, tight code paths only.
29 */
30void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
31{
32 enum fixed_addresses idx;
33 unsigned long vaddr;
34
35 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
36 pagefault_disable();
37
38 if (!PageHighMem(page))
39 return page_address(page);
40
41 debug_kmap_atomic(type);
42
43 idx = type + KM_TYPE_NR*smp_processor_id();
44 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
45 BUG_ON(!pte_none(*(kmap_pte-idx)));
46 set_pte(kmap_pte-idx, mk_pte(page, prot));
47
48 return (void *)vaddr;
49}
50
51void *kmap_atomic(struct page *page, enum km_type type)
52{
53 return kmap_atomic_prot(page, type, kmap_prot);
54}
55
56void kunmap_atomic(void *kvaddr, enum km_type type)
57{
58 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
59 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
60
61 /*
62 * Force other mappings to Oops if they'll try to access this pte
63 * without first remap it. Keeping stale mappings around is a bad idea
64 * also, in case the page changes cacheability attributes or becomes
65 * a protected page in a hypervisor.
66 */
67 if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
68 kpte_clear_flush(kmap_pte-idx, vaddr);
69 else {
70#ifdef CONFIG_DEBUG_HIGHMEM
71 BUG_ON(vaddr < PAGE_OFFSET);
72 BUG_ON(vaddr >= (unsigned long)high_memory);
73#endif
74 }
75
76 pagefault_enable();
77}
78
79/*
80 * This is the same as kmap_atomic() but can map memory that doesn't
81 * have a struct page associated with it.
82 */
83void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
84{
85 return kmap_atomic_prot_pfn(pfn, type, kmap_prot);
86}
87EXPORT_SYMBOL_GPL(kmap_atomic_pfn); /* temporarily in use by i915 GEM until vmap */
88
89struct page *kmap_atomic_to_page(void *ptr)
90{
91 unsigned long idx, vaddr = (unsigned long)ptr;
92 pte_t *pte;
93
94 if (vaddr < FIXADDR_START)
95 return virt_to_page(ptr);
96
97 idx = virt_to_fix(vaddr);
98 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
99 return pte_page(*pte);
100}
101
102EXPORT_SYMBOL(kmap);
103EXPORT_SYMBOL(kunmap);
104EXPORT_SYMBOL(kmap_atomic);
105EXPORT_SYMBOL(kunmap_atomic);
106EXPORT_SYMBOL(kmap_atomic_prot);
107EXPORT_SYMBOL(kmap_atomic_to_page);
108
109void __init set_highmem_pages_init(void)
110{
111 struct zone *zone;
112 int nid;
113
114 for_each_zone(zone) {
115 unsigned long zone_start_pfn, zone_end_pfn;
116
117 if (!is_highmem(zone))
118 continue;
119
120 zone_start_pfn = zone->zone_start_pfn;
121 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
122
123 nid = zone_to_nid(zone);
124 printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
125 zone->name, nid, zone_start_pfn, zone_end_pfn);
126
127 add_highpages_with_active_regions(nid, zone_start_pfn,
128 zone_end_pfn);
129 }
130 totalram_pages += totalhigh_pages;
131}