1 #include <linux/highmem.h>
2 #include <linux/module.h>
4 void *kmap(struct page *page)
7 if (!PageHighMem(page))
8 return page_address(page);
9 return kmap_high(page);
12 void kunmap(struct page *page)
16 if (!PageHighMem(page))
22 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
23 * no global lock is needed and because the kmap code must perform a global TLB
24 * invalidation when the kmap pool wraps.
26 * However when holding an atomic kmap is is not legal to sleep, so atomic
27 * kmaps are appropriate for short, tight code paths only.
29 static void *__kmap_atomic(struct page *page, enum km_type type, pgprot_t prot)
31 enum fixed_addresses idx;
34 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
36 if (!PageHighMem(page))
37 return page_address(page);
39 idx = type + KM_TYPE_NR*smp_processor_id();
40 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
41 if (!pte_none(*(kmap_pte-idx)))
43 set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
48 void *kmap_atomic(struct page *page, enum km_type type)
50 return __kmap_atomic(page, type, kmap_prot);
53 /* Same as kmap_atomic but with PAGE_KERNEL_RO page protection. */
54 void *kmap_atomic_pte(struct page *page, enum km_type type)
56 return __kmap_atomic(page, type, PAGE_KERNEL_RO);
59 void kunmap_atomic(void *kvaddr, enum km_type type)
61 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
62 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
65 * Force other mappings to Oops if they'll try to access this pte
66 * without first remap it. Keeping stale mappings around is a bad idea
67 * also, in case the page changes cacheability attributes or becomes
68 * a protected page in a hypervisor.
70 if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx)) {
71 kpte_clear_flush(kmap_pte-idx, vaddr);
72 __flush_tlb_one(vaddr);
74 #ifdef CONFIG_DEBUG_HIGHMEM
75 BUG_ON(vaddr < PAGE_OFFSET);
76 BUG_ON(vaddr >= (unsigned long)high_memory);
83 /* This is the same as kmap_atomic() but can map memory that doesn't
84 * have a struct page associated with it.
86 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
88 enum fixed_addresses idx;
93 idx = type + KM_TYPE_NR*smp_processor_id();
94 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
95 set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
100 struct page *kmap_atomic_to_page(void *ptr)
102 unsigned long idx, vaddr = (unsigned long)ptr;
105 if (vaddr < FIXADDR_START)
106 return virt_to_page(ptr);
108 idx = virt_to_fix(vaddr);
109 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
110 return pte_page(*pte);
114 EXPORT_SYMBOL(kunmap);
115 EXPORT_SYMBOL(kmap_atomic);
116 EXPORT_SYMBOL(kunmap_atomic);
117 EXPORT_SYMBOL(kmap_atomic_to_page);