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#include <linux/module.h>
#include <linux/highmem.h>
#include <asm/tlbflush.h>
void *__kmap(struct page *page)
{
void *addr;
might_sleep();
if (!PageHighMem(page))
return page_address(page);
addr = kmap_high(page);
flush_tlb_one((unsigned long)addr);
return addr;
}
void __kunmap(struct page *page)
{
BUG_ON(in_interrupt());
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(struct page *page, enum km_type type)
{
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);
#ifdef CONFIG_DEBUG_HIGHMEM
BUG_ON(!pte_none(*(kmap_pte - idx)));
#endif
set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
local_flush_tlb_one((unsigned long)vaddr);
return (void*) vaddr;
}
void __kunmap_atomic(void *kvaddr, enum km_type type)
{
#ifdef CONFIG_DEBUG_HIGHMEM
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
if (vaddr < FIXADDR_START) { // FIXME
pagefault_enable();
return;
}
BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
/*
* force other mappings to Oops if they'll try to access
* this pte without first remap it
*/
pte_clear(&init_mm, vaddr, kmap_pte-idx);
local_flush_tlb_one(vaddr);
#endif
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));
flush_tlb_one(vaddr);
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);
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