[linux-2.6-block.git] / arch / powerpc / mm / highmem.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 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);
	WARN_ON(IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !pte_none(*(kmap_pte - idx)));
	__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;

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

	if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM)) {
		int type = kmap_atomic_idx();
		unsigned int idx;

		idx = type + KM_TYPE_NR * smp_processor_id();
		WARN_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);
	}

	kmap_atomic_idx_pop();
	pagefault_enable();
	preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
850f6ac3 BH	2	/*
	3	* highmem.c: virtual kernel memory mappings for high memory
	4	*
	5	* PowerPC version, stolen from the i386 version.
	6	*
	7	* Used in CONFIG_HIGHMEM systems for memory pages which
	8	* are not addressable by direct kernel virtual addresses.
	9	*
	10	* Copyright (C) 1999 Gerhard Wichert, Siemens AG
	11	* Gerhard.Wichert@pdb.siemens.de
	12	*
	13	*
	14	* Redesigned the x86 32-bit VM architecture to deal with
	15	* up to 16 Terrabyte physical memory. With current x86 CPUs
	16	* we now support up to 64 Gigabytes physical RAM.
	17	*
	18	* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
	19	*
	20	* Reworked for PowerPC by various contributors. Moved from
	21	* highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
	22	*/
	23
	24	#include <linux/highmem.h>
	25	#include <linux/module.h>
	26
	27	/*
	28	* The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
	29	* gives a more generic (and caching) interface. But kmap_atomic can
	30	* be used in IRQ contexts, so in some (very limited) cases we need
	31	* it.
	32	*/
3e4d3af5	33	void kmap_atomic_prot(struct page page, pgprot_t prot)
850f6ac3	34	{
850f6ac3	35	unsigned long vaddr;
3e4d3af5	36	int idx, type;
850f6ac3	37
2cb7c9cb	38	preempt_disable();
850f6ac3 BH	39	pagefault_disable();
	40	if (!PageHighMem(page))
	41	return page_address(page);
	42
3e4d3af5	43	type = kmap_atomic_idx_push();
850f6ac3 BH	44	idx = type + KM_TYPE_NR*smp_processor_id();
850f6ac3 BH	45	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
6c84f8c5	46	WARN_ON(IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !pte_none(*(kmap_pte - idx)));
850f6ac3 BH	47	__set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
	48	local_flush_tlb_page(NULL, vaddr);
	49
	50	return (void*) vaddr;
	51	}
	52	EXPORT_SYMBOL(kmap_atomic_prot);
	53
3e4d3af5	54	void __kunmap_atomic(void *kvaddr)
850f6ac3	55	{
850f6ac3	56	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
850f6ac3 BH	57
	58	if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
	59	pagefault_enable();
2cb7c9cb	60	preempt_enable();
850f6ac3 BH	61	return;
	62	}
	63
6c84f8c5 CL	64	if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM)) {
6c84f8c5 CL	65	int type = kmap_atomic_idx();
3e4d3af5 PZ	66	unsigned int idx;
	67
	68	idx = type + KM_TYPE_NR * smp_processor_id();
6c84f8c5	69	WARN_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
3e4d3af5 PZ	70
	71	/*
	72	* force other mappings to Oops if they'll try to access
	73	* this pte without first remap it
	74	*/
	75	pte_clear(&init_mm, vaddr, kmap_pte-idx);
	76	local_flush_tlb_page(NULL, vaddr);
	77	}
20273941 PZ	78
20273941 PZ	79	kmap_atomic_idx_pop();
850f6ac3	80	pagefault_enable();
2cb7c9cb	81	preempt_enable();
850f6ac3	82	}
3e4d3af5	83	EXPORT_SYMBOL(__kunmap_atomic);