WebSVN – HelenOS – Blame – /trunk/kernel/generic/src/mm/backend_anon.c

Rev	Author	Line No.	Line
1424	jermar	1	/*
		2	* Copyright (C) 2006 Jakub Jermar
		3	* All rights reserved.
		4	*
		5	* Redistribution and use in source and binary forms, with or without
		6	* modification, are permitted provided that the following conditions
		7	* are met:
		8	*
		9	* - Redistributions of source code must retain the above copyright
		10	* notice, this list of conditions and the following disclaimer.
		11	* - Redistributions in binary form must reproduce the above copyright
		12	* notice, this list of conditions and the following disclaimer in the
		13	* documentation and/or other materials provided with the distribution.
		14	* - The name of the author may not be used to endorse or promote products
		15	* derived from this software without specific prior written permission.
		16	*
		17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
		18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
		20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		27	*/
		28
1757	jermar	29	/** @addtogroup genericmm
1702	cejka	30	* @{
		31	*/
		32
1424	jermar	33	/**
1702	cejka	34	* @file
1424	jermar	35	* @brief Backend for anonymous memory address space areas.
		36	*
		37	*/
		38
		39	#include <mm/as.h>
		40	#include <mm/page.h>
		41	#include <genarch/mm/page_pt.h>
		42	#include <genarch/mm/page_ht.h>
		43	#include <mm/frame.h>
		44	#include <mm/slab.h>
		45	#include <synch/mutex.h>
		46	#include <adt/list.h>
		47	#include <adt/btree.h>
		48	#include <errno.h>
		49	#include <arch/types.h>
		50	#include <typedefs.h>
		51	#include <align.h>
		52	#include <arch.h>
		53
1780	jermar	54	static int anon_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access);
		55	static void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame);
1424	jermar	56	static void anon_share(as_area_t *area);
		57
		58	mem_backend_t anon_backend = {
		59	.page_fault = anon_page_fault,
		60	.frame_free = anon_frame_free,
		61	.share = anon_share
		62	};
		63
		64	/** Service a page fault in the anonymous memory address space area.
		65	*
		66	* The address space area and page tables must be already locked.
		67	*
		68	* @param area Pointer to the address space area.
		69	* @param addr Faulting virtual address.
		70	* @param access Access mode that caused the fault (i.e. read/write/exec).
		71	*
		72	* @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced).
		73	*/
1780	jermar	74	int anon_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access)
1424	jermar	75	{
1780	jermar	76	uintptr_t frame;
1424	jermar	77
		78	if (!as_area_check_access(area, access))
		79	return AS_PF_FAULT;
		80
		81	if (area->sh_info) {
		82	btree_node_t *leaf;
		83
		84	/*
		85	* The area is shared, chances are that the mapping can be found
		86	* in the pagemap of the address space area share info structure.
		87	* In the case that the pagemap does not contain the respective
		88	* mapping, a new frame is allocated and the mapping is created.
		89	*/
		90	mutex_lock(&area->sh_info->lock);
1780	jermar	91	frame = (uintptr_t) btree_search(&area->sh_info->pagemap,
1424	jermar	92	ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
		93	if (!frame) {
		94	bool allocate = true;
		95	int i;
		96
		97	/*
		98	* Zero can be returned as a valid frame address.
		99	* Just a small workaround.
		100	*/
		101	for (i = 0; i < leaf->keys; i++) {
		102	if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) {
		103	allocate = false;
		104	break;
		105	}
		106	}
		107	if (allocate) {
1780	jermar	108	frame = (uintptr_t) frame_alloc(ONE_FRAME, 0);
1424	jermar	109	memsetb(PA2KA(frame), FRAME_SIZE, 0);
		110
		111	/*
		112	* Insert the address of the newly allocated frame to the pagemap.
		113	*/
		114	btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base, (void *) frame, leaf);
		115	}
		116	}
1545	jermar	117	frame_reference_add(ADDR2PFN(frame));
1424	jermar	118	mutex_unlock(&area->sh_info->lock);
		119	} else {
		120
		121	/*
		122	* In general, there can be several reasons that
		123	* can have caused this fault.
		124	*
		125	* - non-existent mapping: the area is an anonymous
		126	* area (e.g. heap or stack) and so far has not been
		127	* allocated a frame for the faulting page
		128	*
		129	* - non-present mapping: another possibility,
		130	* currently not implemented, would be frame
		131	* reuse; when this becomes a possibility,
		132	* do not forget to distinguish between
		133	* the different causes
		134	*/
1780	jermar	135	frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
1424	jermar	136	memsetb(PA2KA(frame), FRAME_SIZE, 0);
		137	}
		138
		139	/*
		140	* Map 'page' to 'frame'.
		141	* Note that TLB shootdown is not attempted as only new information is being
		142	* inserted into page tables.
		143	*/
		144	page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
		145	if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
		146	panic("Could not insert used space.\n");
		147
		148	return AS_PF_OK;
		149	}
		150
		151	/** Free a frame that is backed by the anonymous memory backend.
		152	*
		153	* The address space area and page tables must be already locked.
		154	*
		155	* @param area Ignored.
		156	* @param page Ignored.
		157	* @param frame Frame to be released.
		158	*/
1780	jermar	159	void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
1424	jermar	160	{
1760	palkovsky	161	frame_free(frame);
1424	jermar	162	}
		163
		164	/** Share the anonymous address space area.
		165	*
		166	* Sharing of anonymous area is done by duplicating its entire mapping
		167	* to the pagemap. Page faults will primarily search for frames there.
		168	*
1426	jermar	169	* The address space and address space area must be already locked.
1424	jermar	170	*
		171	* @param area Address space area to be shared.
		172	*/
		173	void anon_share(as_area_t *area)
		174	{
		175	link_t *cur;
		176
		177	/*
		178	* Copy used portions of the area to sh_info's page map.
		179	*/
		180	mutex_lock(&area->sh_info->lock);
		181	for (cur = area->used_space.leaf_head.next; cur != &area->used_space.leaf_head; cur = cur->next) {
		182	btree_node_t *node;
		183	int i;
		184
		185	node = list_get_instance(cur, btree_node_t, leaf_link);
		186	for (i = 0; i < node->keys; i++) {
1780	jermar	187	uintptr_t base = node->key[i];
1424	jermar	188	count_t count = (count_t) node->value[i];
		189	int j;
		190
		191	for (j = 0; j < count; j++) {
		192	pte_t *pte;
		193
		194	page_table_lock(area->as, false);
		195	pte = page_mapping_find(area->as, base + j*PAGE_SIZE);
		196	ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
		197	btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base,
		198	(void *) PTE_GET_FRAME(pte), NULL);
		199	page_table_unlock(area->as, false);
1545	jermar	200	frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte)));
1424	jermar	201	}
		202
		203	}
		204	}
		205	mutex_unlock(&area->sh_info->lock);
		206	}
1702	cejka	207
1757	jermar	208	/** @}
1702	cejka	209	*/

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(root)/trunk/kernel/generic/src/mm/backend_anon.c @ 4148 – Rev 1780