WebSVN – HelenOS-historic – Blame – /kernel/trunk/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
		29	/**
		30	* @file backend_anon.c
		31	* @brief Backend for anonymous memory address space areas.
		32	*
		33	*/
		34
		35	#include <mm/as.h>
		36	#include <mm/page.h>
		37	#include <genarch/mm/page_pt.h>
		38	#include <genarch/mm/page_ht.h>
		39	#include <mm/frame.h>
		40	#include <mm/slab.h>
		41	#include <synch/mutex.h>
		42	#include <adt/list.h>
		43	#include <adt/btree.h>
		44	#include <errno.h>
		45	#include <arch/types.h>
		46	#include <typedefs.h>
		47	#include <align.h>
		48	#include <arch.h>
		49
		50	static int anon_page_fault(as_area_t *area, __address addr, pf_access_t access);
		51	static void anon_frame_free(as_area_t *area, __address page, __address frame);
		52	static void anon_share(as_area_t *area);
		53
		54	mem_backend_t anon_backend = {
		55	.page_fault = anon_page_fault,
		56	.frame_free = anon_frame_free,
		57	.share = anon_share
		58	};
		59
		60	/** Service a page fault in the anonymous memory address space area.
		61	*
		62	* The address space area and page tables must be already locked.
		63	*
		64	* @param area Pointer to the address space area.
		65	* @param addr Faulting virtual address.
		66	* @param access Access mode that caused the fault (i.e. read/write/exec).
		67	*
		68	* @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced).
		69	*/
		70	int anon_page_fault(as_area_t *area, __address addr, pf_access_t access)
		71	{
		72	__address frame;
		73
		74	if (!as_area_check_access(area, access))
		75	return AS_PF_FAULT;
		76
		77	if (area->sh_info) {
		78	btree_node_t *leaf;
		79
		80	/*
		81	* The area is shared, chances are that the mapping can be found
		82	* in the pagemap of the address space area share info structure.
		83	* In the case that the pagemap does not contain the respective
		84	* mapping, a new frame is allocated and the mapping is created.
		85	*/
		86	mutex_lock(&area->sh_info->lock);
		87	frame = (__address) btree_search(&area->sh_info->pagemap,
		88	ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
		89	if (!frame) {
		90	bool allocate = true;
		91	int i;
		92
		93	/*
		94	* Zero can be returned as a valid frame address.
		95	* Just a small workaround.
		96	*/
		97	for (i = 0; i < leaf->keys; i++) {
		98	if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) {
		99	allocate = false;
		100	break;
		101	}
		102	}
		103	if (allocate) {
		104	frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
		105	memsetb(PA2KA(frame), FRAME_SIZE, 0);
		106
		107	/*
		108	* Insert the address of the newly allocated frame to the pagemap.
		109	*/
		110	btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base, (void *) frame, leaf);
		111	}
		112	}
1545	jermar	113	frame_reference_add(ADDR2PFN(frame));
1424	jermar	114	mutex_unlock(&area->sh_info->lock);
		115	} else {
		116
		117	/*
		118	* In general, there can be several reasons that
		119	* can have caused this fault.
		120	*
		121	* - non-existent mapping: the area is an anonymous
		122	* area (e.g. heap or stack) and so far has not been
		123	* allocated a frame for the faulting page
		124	*
		125	* - non-present mapping: another possibility,
		126	* currently not implemented, would be frame
		127	* reuse; when this becomes a possibility,
		128	* do not forget to distinguish between
		129	* the different causes
		130	*/
		131	frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
		132	memsetb(PA2KA(frame), FRAME_SIZE, 0);
		133	}
		134
		135	/*
		136	* Map 'page' to 'frame'.
		137	* Note that TLB shootdown is not attempted as only new information is being
		138	* inserted into page tables.
		139	*/
		140	page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
		141	if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
		142	panic("Could not insert used space.\n");
		143
		144	return AS_PF_OK;
		145	}
		146
		147	/** Free a frame that is backed by the anonymous memory backend.
		148	*
		149	* The address space area and page tables must be already locked.
		150	*
		151	* @param area Ignored.
		152	* @param page Ignored.
		153	* @param frame Frame to be released.
		154	*/
		155	void anon_frame_free(as_area_t *area, __address page, __address frame)
		156	{
		157	frame_free(ADDR2PFN(frame));
		158	}
		159
		160	/** Share the anonymous address space area.
		161	*
		162	* Sharing of anonymous area is done by duplicating its entire mapping
		163	* to the pagemap. Page faults will primarily search for frames there.
		164	*
1426	jermar	165	* The address space and address space area must be already locked.
1424	jermar	166	*
		167	* @param area Address space area to be shared.
		168	*/
		169	void anon_share(as_area_t *area)
		170	{
		171	link_t *cur;
		172
		173	/*
		174	* Copy used portions of the area to sh_info's page map.
		175	*/
		176	mutex_lock(&area->sh_info->lock);
		177	for (cur = area->used_space.leaf_head.next; cur != &area->used_space.leaf_head; cur = cur->next) {
		178	btree_node_t *node;
		179	int i;
		180
		181	node = list_get_instance(cur, btree_node_t, leaf_link);
		182	for (i = 0; i < node->keys; i++) {
		183	__address base = node->key[i];
		184	count_t count = (count_t) node->value[i];
		185	int j;
		186
		187	for (j = 0; j < count; j++) {
		188	pte_t *pte;
		189
		190	page_table_lock(area->as, false);
		191	pte = page_mapping_find(area->as, base + j*PAGE_SIZE);
		192	ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
		193	btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base,
		194	(void *) PTE_GET_FRAME(pte), NULL);
		195	page_table_unlock(area->as, false);
1545	jermar	196	frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte)));
1424	jermar	197	}
		198
		199	}
		200	}
		201	mutex_unlock(&area->sh_info->lock);
		202	}

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