[deliverable/linux.git] / arch / powerpc / mm / highmem.c

/*
 * highmem.c: virtual kernel memory mappings for high memory
 *
 * PowerPC version, stolen from the i386 version.
 *
 * Used in CONFIG_HIGHMEM systems for memory pages which
 * are not addressable by direct kernel virtual addresses.
 *
 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
 *		      Gerhard.Wichert@pdb.siemens.de
 *
 *
 * Redesigned the x86 32-bit VM architecture to deal with
 * up to 16 Terrabyte physical memory. With current x86 CPUs
 * we now support up to 64 Gigabytes physical RAM.
 *
 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
 *
 * Reworked for PowerPC by various contributors. Moved from
 * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
 */

#include <linux/highmem.h>
#include <linux/module.h>

/*
 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
 * gives a more generic (and caching) interface. But kmap_atomic can
 * be used in IRQ contexts, so in some (very limited) cases we need
 * it.
 */
void *kmap_atomic_prot(struct page *page, pgprot_t prot)
{
	unsigned long vaddr;
	int idx, 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_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
	local_flush_tlb_page(NULL, vaddr);

	return (void*) vaddr;
}
EXPORT_SYMBOL(kmap_atomic_prot);

void __kunmap_atomic(void *kvaddr)
{
	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
	int type;

	if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
		pagefault_enable();
		preempt_enable();
		return;
	}

	type = kmap_atomic_idx();

#ifdef CONFIG_DEBUG_HIGHMEM
	{
		unsigned int idx;

		idx = type + KM_TYPE_NR * smp_processor_id();
		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_page(NULL, vaddr);
	}
#endif

	kmap_atomic_idx_pop();
	pagefault_enable();
	preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
Commit	Line	Data
850f6ac3 BH	1	/*
	2	* highmem.c: virtual kernel memory mappings for high memory
	3	*
	4	* PowerPC version, stolen from the i386 version.
	5	*
	6	* Used in CONFIG_HIGHMEM systems for memory pages which
	7	* are not addressable by direct kernel virtual addresses.
	8	*
	9	* Copyright (C) 1999 Gerhard Wichert, Siemens AG
	10	* Gerhard.Wichert@pdb.siemens.de
	11	*
	12	*
	13	* Redesigned the x86 32-bit VM architecture to deal with
	14	* up to 16 Terrabyte physical memory. With current x86 CPUs
	15	* we now support up to 64 Gigabytes physical RAM.
	16	*
	17	* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
	18	*
	19	* Reworked for PowerPC by various contributors. Moved from
	20	* highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
	21	*/
	22
	23	#include <linux/highmem.h>
	24	#include <linux/module.h>
	25
	26	/*
	27	* The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
	28	* gives a more generic (and caching) interface. But kmap_atomic can
	29	* be used in IRQ contexts, so in some (very limited) cases we need
	30	* it.
	31	*/
3e4d3af5	32	void kmap_atomic_prot(struct page page, pgprot_t prot)
850f6ac3	33	{
850f6ac3	34	unsigned long vaddr;
3e4d3af5	35	int idx, type;
850f6ac3	36
2cb7c9cb	37	preempt_disable();
850f6ac3 BH	38	pagefault_disable();
	39	if (!PageHighMem(page))
	40	return page_address(page);
	41
3e4d3af5	42	type = kmap_atomic_idx_push();
850f6ac3 BH	43	idx = type + KM_TYPE_NR*smp_processor_id();
	44	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
	45	#ifdef CONFIG_DEBUG_HIGHMEM
	46	BUG_ON(!pte_none(*(kmap_pte-idx)));
	47	#endif
	48	__set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
	49	local_flush_tlb_page(NULL, vaddr);
	50
	51	return (void*) vaddr;
	52	}
	53	EXPORT_SYMBOL(kmap_atomic_prot);
	54
3e4d3af5	55	void __kunmap_atomic(void *kvaddr)
850f6ac3	56	{
850f6ac3	57	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
3e4d3af5	58	int type;
850f6ac3 BH	59
	60	if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
	61	pagefault_enable();
2cb7c9cb	62	preempt_enable();
850f6ac3 BH	63	return;
	64	}
	65
20273941	66	type = kmap_atomic_idx();
850f6ac3	67
3e4d3af5 PZ	68	#ifdef CONFIG_DEBUG_HIGHMEM
	69	{
	70	unsigned int idx;
	71
	72	idx = type + KM_TYPE_NR * smp_processor_id();
	73	BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
	74
	75	/*
	76	* force other mappings to Oops if they'll try to access
	77	* this pte without first remap it
	78	*/
	79	pte_clear(&init_mm, vaddr, kmap_pte-idx);
	80	local_flush_tlb_page(NULL, vaddr);
	81	}
850f6ac3	82	#endif
20273941 PZ	83
20273941 PZ	84	kmap_atomic_idx_pop();
850f6ac3	85	pagefault_enable();
2cb7c9cb	86	preempt_enable();
850f6ac3	87	}
3e4d3af5	88	EXPORT_SYMBOL(__kunmap_atomic);