[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / arch / i386 / mm / highmem.c

#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(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);
	if (!pte_none(*(kmap_pte-idx)))
		BUG();
	set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));

	return (void*) vaddr;
}

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();

#ifdef CONFIG_DEBUG_HIGHMEM
	if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
		pagefault_enable();
		return;
	}

	if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
		BUG();
#endif
	/*
	 * 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.
	 */
	kpte_clear_flush(kmap_pte-idx, vaddr);

	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));

	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);
Commit	Line	Data
1da177e4	1	#include <linux/highmem.h>
129f6946	2	#include <linux/module.h>
1da177e4 LT	3
	4	void kmap(struct page page)
	5	{
	6	might_sleep();
	7	if (!PageHighMem(page))
	8	return page_address(page);
	9	return kmap_high(page);
	10	}
	11
	12	void kunmap(struct page *page)
	13	{
	14	if (in_interrupt())
	15	BUG();
	16	if (!PageHighMem(page))
	17	return;
	18	kunmap_high(page);
	19	}
	20
	21	/*
	22	* kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
	23	* no global lock is needed and because the kmap code must perform a global TLB
	24	* invalidation when the kmap pool wraps.
	25	*
	26	* However when holding an atomic kmap is is not legal to sleep, so atomic
	27	* kmaps are appropriate for short, tight code paths only.
	28	*/
	29	void kmap_atomic(struct page page, enum km_type type)
	30	{
	31	enum fixed_addresses idx;
	32	unsigned long vaddr;
	33
	34	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
a866374a	35	pagefault_disable();
1da177e4 LT	36	if (!PageHighMem(page))
	37	return page_address(page);
	38
	39	idx = type + KM_TYPE_NR*smp_processor_id();
	40	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
1da177e4 LT	41	if (!pte_none(*(kmap_pte-idx)))
1da177e4 LT	42	BUG();
1da177e4	43	set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
1da177e4 LT	44
	45	return (void*) vaddr;
	46	}
	47
	48	void kunmap_atomic(void *kvaddr, enum km_type type)
	49	{
1da177e4 LT	50	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
	51	enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
	52
23002d88	53	#ifdef CONFIG_DEBUG_HIGHMEM
ba9c231f	54	if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
a866374a	55	pagefault_enable();
1da177e4 LT	56	return;
	57	}
	58
	59	if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
	60	BUG();
23002d88	61	#endif
1da177e4	62	/*
23002d88 ZA	63	* Force other mappings to Oops if they'll try to access this pte
	64	* without first remap it. Keeping stale mappings around is a bad idea
	65	* also, in case the page changes cacheability attributes or becomes
	66	* a protected page in a hypervisor.
1da177e4	67	*/
23002d88	68	kpte_clear_flush(kmap_pte-idx, vaddr);
1da177e4	69
a866374a	70	pagefault_enable();
1da177e4 LT	71	}
1da177e4 LT	72
60e64d46 VG	73	/* This is the same as kmap_atomic() but can map memory that doesn't
	74	* have a struct page associated with it.
	75	*/
	76	void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
	77	{
	78	enum fixed_addresses idx;
	79	unsigned long vaddr;
	80
a866374a	81	pagefault_disable();
60e64d46 VG	82
	83	idx = type + KM_TYPE_NR*smp_processor_id();
	84	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
	85	set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
60e64d46 VG	86
	87	return (void*) vaddr;
	88	}
	89
1da177e4 LT	90	struct page kmap_atomic_to_page(void ptr)
	91	{
	92	unsigned long idx, vaddr = (unsigned long)ptr;
	93	pte_t *pte;
	94
	95	if (vaddr < FIXADDR_START)
	96	return virt_to_page(ptr);
	97
	98	idx = virt_to_fix(vaddr);
	99	pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
	100	return pte_page(*pte);
	101	}
	102
129f6946 AD	103	EXPORT_SYMBOL(kmap);
	104	EXPORT_SYMBOL(kunmap);
	105	EXPORT_SYMBOL(kmap_atomic);
	106	EXPORT_SYMBOL(kunmap_atomic);
	107	EXPORT_SYMBOL(kmap_atomic_to_page);