90 lines
2.0 KiB
C
90 lines
2.0 KiB
C
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#include <linux/highmem.h>
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void *kmap(struct page *page)
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{
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might_sleep();
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if (!PageHighMem(page))
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return page_address(page);
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return kmap_high(page);
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}
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void kunmap(struct page *page)
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{
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if (in_interrupt())
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BUG();
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if (!PageHighMem(page))
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return;
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kunmap_high(page);
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}
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/*
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* kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
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* no global lock is needed and because the kmap code must perform a global TLB
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* invalidation when the kmap pool wraps.
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*
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* However when holding an atomic kmap is is not legal to sleep, so atomic
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* kmaps are appropriate for short, tight code paths only.
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*/
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void *kmap_atomic(struct page *page, enum km_type type)
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{
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enum fixed_addresses idx;
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unsigned long vaddr;
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/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
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inc_preempt_count();
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if (!PageHighMem(page))
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return page_address(page);
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idx = type + KM_TYPE_NR*smp_processor_id();
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vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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#ifdef CONFIG_DEBUG_HIGHMEM
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if (!pte_none(*(kmap_pte-idx)))
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BUG();
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#endif
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set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
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__flush_tlb_one(vaddr);
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return (void*) vaddr;
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}
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void kunmap_atomic(void *kvaddr, enum km_type type)
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{
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#ifdef CONFIG_DEBUG_HIGHMEM
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unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
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enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
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if (vaddr < FIXADDR_START) { // FIXME
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dec_preempt_count();
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preempt_check_resched();
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return;
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}
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if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
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BUG();
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/*
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* force other mappings to Oops if they'll try to access
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* this pte without first remap it
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*/
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pte_clear(&init_mm, vaddr, kmap_pte-idx);
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__flush_tlb_one(vaddr);
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#endif
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dec_preempt_count();
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preempt_check_resched();
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}
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struct page *kmap_atomic_to_page(void *ptr)
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{
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unsigned long idx, vaddr = (unsigned long)ptr;
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pte_t *pte;
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if (vaddr < FIXADDR_START)
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return virt_to_page(ptr);
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idx = virt_to_fix(vaddr);
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pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
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return pte_page(*pte);
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}
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