1#include <linux/module.h>
  2#include <linux/highmem.h>
  3#include <linux/sched.h>
  4#include <linux/smp.h>
  5#include <asm/fixmap.h>
  6#include <asm/tlbflush.h>
  7
  8static pte_t *kmap_pte;
  9
 10unsigned long highstart_pfn, highend_pfn;
 11
 12void *kmap(struct page *page)
 13{
 14	void *addr;
 15
 16	might_sleep();
 17	if (!PageHighMem(page))
 18		return page_address(page);
 19	addr = kmap_high(page);
 20	flush_tlb_one((unsigned long)addr);
 21
 22	return addr;
 23}
 24EXPORT_SYMBOL(kmap);
 25
 26void kunmap(struct page *page)
 27{
 28	BUG_ON(in_interrupt());
 29	if (!PageHighMem(page))
 30		return;
 31	kunmap_high(page);
 32}
 33EXPORT_SYMBOL(kunmap);
 34
 35/*
 36 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
 37 * no global lock is needed and because the kmap code must perform a global TLB
 38 * invalidation when the kmap pool wraps.
 39 *
 40 * However when holding an atomic kmap is is not legal to sleep, so atomic
 41 * kmaps are appropriate for short, tight code paths only.
 42 */
 43
 44void *kmap_atomic(struct page *page)
 45{
 46	unsigned long vaddr;
 47	int idx, type;
 48
 49	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
 50	pagefault_disable();
 51	if (!PageHighMem(page))
 52		return page_address(page);
 53
 54	type = kmap_atomic_idx_push();
 55	idx = type + KM_TYPE_NR*smp_processor_id();
 56	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 57#ifdef CONFIG_DEBUG_HIGHMEM
 58	BUG_ON(!pte_none(*(kmap_pte - idx)));
 59#endif
 60	set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL));
 61	local_flush_tlb_one((unsigned long)vaddr);
 62
 63	return (void*) vaddr;
 64}
 65EXPORT_SYMBOL(kmap_atomic);
 66
 67void __kunmap_atomic(void *kvaddr)
 68{
 69	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
 70	int type;
 71
 72	if (vaddr < FIXADDR_START) { // FIXME
 73		pagefault_enable();
 74		return;
 75	}
 76
 77	type = kmap_atomic_idx();
 78#ifdef CONFIG_DEBUG_HIGHMEM
 79	{
 80		int idx = type + KM_TYPE_NR * smp_processor_id();
 81
 82		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 83
 84		/*
 85		 * force other mappings to Oops if they'll try to access
 86		 * this pte without first remap it
 87		 */
 88		pte_clear(&init_mm, vaddr, kmap_pte-idx);
 89		local_flush_tlb_one(vaddr);
 90	}
 91#endif
 92	kmap_atomic_idx_pop();
 93	pagefault_enable();
 94}
 95EXPORT_SYMBOL(__kunmap_atomic);
 96
 97/*
 98 * This is the same as kmap_atomic() but can map memory that doesn't
 99 * have a struct page associated with it.
100 */
101void *kmap_atomic_pfn(unsigned long pfn)
102{
103	unsigned long vaddr;
104	int idx, type;
105
106	pagefault_disable();
107
108	type = kmap_atomic_idx_push();
109	idx = type + KM_TYPE_NR*smp_processor_id();
110	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
111	set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
112	flush_tlb_one(vaddr);
113
114	return (void*) vaddr;
115}
116
117struct page *kmap_atomic_to_page(void *ptr)
118{
119	unsigned long idx, vaddr = (unsigned long)ptr;
120	pte_t *pte;
121
122	if (vaddr < FIXADDR_START)
123		return virt_to_page(ptr);
124
125	idx = virt_to_fix(vaddr);
126	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
127	return pte_page(*pte);
128}
129
130void __init kmap_init(void)
131{
132	unsigned long kmap_vstart;
133
134	/* cache the first kmap pte */
135	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
136	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
137}