#include <linux/highmem.h> #include <linux/module.h> void *kmap(struct page *page) { might_sleep(); if (!PageHighMem(page)) return page_address(page); return kmap_high(page); } void kunmap(struct page *page) { if (in_interrupt()) BUG(); if (!PageHighMem(page)) return; kunmap_high(page); } /* * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because * no global lock is needed and because the kmap code must perform a global TLB * invalidation when the kmap pool wraps. * * However when holding an atomic kmap is is not legal to sleep, so atomic * kmaps are appropriate for short, tight code paths only. */ void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot) { enum fixed_addresses idx; unsigned long vaddr; /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ pagefault_disable(); if (!PageHighMem(page)) return page_address(page); idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); BUG_ON(!pte_none(*(kmap_pte-idx))); set_pte(kmap_pte-idx, mk_pte(page, prot)); arch_flush_lazy_mmu_mode(); return (void *)vaddr; } void *kmap_atomic(struct page *page, enum km_type type) { return kmap_atomic_prot(page, type, kmap_prot); } void kunmap_atomic(void *kvaddr, enum km_type type) { unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); /* * Force other mappings to Oops if they'll try to access this pte * without first remap it. Keeping stale mappings around is a bad idea * also, in case the page changes cacheability attributes or becomes * a protected page in a hypervisor. */ if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx)) kpte_clear_flush(kmap_pte-idx, vaddr); else { #ifdef CONFIG_DEBUG_HIGHMEM BUG_ON(vaddr < PAGE_OFFSET); BUG_ON(vaddr >= (unsigned long)high_memory); #endif } arch_flush_lazy_mmu_mode(); pagefault_enable(); } /* This is the same as kmap_atomic() but can map memory that doesn't * have a struct page associated with it. */ void *kmap_atomic_pfn(unsigned long pfn, enum km_type type) { enum fixed_addresses idx; unsigned long vaddr; pagefault_disable(); idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot)); arch_flush_lazy_mmu_mode(); return (void*) vaddr; } struct page *kmap_atomic_to_page(void *ptr) { unsigned long idx, vaddr = (unsigned long)ptr; pte_t *pte; if (vaddr < FIXADDR_START) return virt_to_page(ptr); idx = virt_to_fix(vaddr); pte = kmap_pte - (idx - FIX_KMAP_BEGIN); return pte_page(*pte); } EXPORT_SYMBOL(kmap); EXPORT_SYMBOL(kunmap); EXPORT_SYMBOL(kmap_atomic); EXPORT_SYMBOL(kunmap_atomic); EXPORT_SYMBOL(kmap_atomic_to_page);