| #include <linux/export.h> |
| #include <linux/highmem.h> |
| #include <linux/sched.h> |
| #include <linux/smp.h> |
| #include <linux/interrupt.h> |
| #include <asm/fixmap.h> |
| #include <asm/tlbflush.h> |
| |
| static pte_t *kmap_pte; |
| |
| unsigned long highstart_pfn, highend_pfn; |
| |
| void *kmap(struct page *page) |
| { |
| might_sleep(); |
| if (!PageHighMem(page)) |
| return page_address(page); |
| return kmap_high(page); |
| } |
| EXPORT_SYMBOL(kmap); |
| |
| void kunmap(struct page *page) |
| { |
| BUG_ON(in_interrupt()); |
| if (!PageHighMem(page)) |
| return; |
| kunmap_high(page); |
| } |
| EXPORT_SYMBOL(kunmap); |
| |
| /* |
| * 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(struct page *page) |
| { |
| enum fixed_addresses idx; |
| unsigned long vaddr; |
| int type; |
| |
| preempt_disable(); |
| pagefault_disable(); |
| if (!PageHighMem(page)) |
| return page_address(page); |
| |
| type = kmap_atomic_idx_push(); |
| idx = type + KM_TYPE_NR * smp_processor_id(); |
| vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| #ifdef CONFIG_DEBUG_HIGHMEM |
| BUG_ON(!pte_none(*(kmap_pte - idx))); |
| #endif |
| set_pte(kmap_pte - idx, mk_pte(page, PAGE_KERNEL)); |
| |
| return (void *)vaddr; |
| } |
| EXPORT_SYMBOL(kmap_atomic); |
| |
| void __kunmap_atomic(void *kvaddr) |
| { |
| unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
| int idx, type; |
| |
| if (kvaddr >= (void *)FIXADDR_START) { |
| type = kmap_atomic_idx(); |
| 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. |
| */ |
| pte_clear(&init_mm, vaddr, kmap_pte-idx); |
| flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); |
| |
| kmap_atomic_idx_pop(); |
| } |
| |
| pagefault_enable(); |
| preempt_enable(); |
| } |
| EXPORT_SYMBOL(__kunmap_atomic); |
| |
| /* |
| * 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 fixed_addresses idx; |
| unsigned long vaddr; |
| int type; |
| |
| preempt_disable(); |
| pagefault_disable(); |
| |
| type = kmap_atomic_idx_push(); |
| idx = type + KM_TYPE_NR * smp_processor_id(); |
| vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| #ifdef CONFIG_DEBUG_HIGHMEM |
| BUG_ON(!pte_none(*(kmap_pte - idx))); |
| #endif |
| set_pte(kmap_pte - idx, pfn_pte(pfn, PAGE_KERNEL)); |
| flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); |
| |
| return (void *)vaddr; |
| } |
| |
| void __init kmap_init(void) |
| { |
| unsigned long kmap_vstart; |
| |
| /* cache the first kmap pte */ |
| kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN); |
| kmap_pte = kmap_get_fixmap_pte(kmap_vstart); |
| } |