WebSVN – HelenOS – Blame – //branches/network/kernel/genarch/src/mm/asid.c

Rev	Author	Line No.	Line
727	jermar	1	/*
2071	jermar	2	* Copyright (c) 2006 Jakub Jermar
727	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
1851	jermar	29	/** @addtogroup genarchmm
1702	cejka	30	* @{
		31	*/
		32
1266	jermar	33	/**
1702	cejka	34	* @file
4153	mejdrech	35	* @brief ASID management.
727	jermar	36	*
		37	* Modern processor architectures optimize TLB utilization
		38	* by using ASIDs (a.k.a. memory contexts on sparc64 and
		39	* region identifiers on ia64). These ASIDs help to associate
		40	* each TLB item with an address space, thus making
		41	* finer-grained TLB invalidation possible.
		42	*
		43	* Unfortunatelly, there are usually less ASIDs available than
		44	* there can be unique as_t structures (i.e. address spaces
		45	* recognized by the kernel).
		46	*
		47	* When system runs short of ASIDs, it will attempt to steal
		48	* ASID from an address space that has not been active for
		49	* a while.
		50	*
823	jermar	51	* This code depends on the fact that ASIDS_ALLOCABLE
		52	* is greater than number of supported CPUs (i.e. the
		53	* amount of concurently active address spaces).
		54	*
727	jermar	55	* Architectures that don't have hardware support for address
		56	* spaces do not compile with this file.
		57	*/
		58
		59	#include <mm/asid.h>
		60	#include <mm/as.h>
		61	#include <mm/tlb.h>
		62	#include <arch/mm/asid.h>
		63	#include <synch/spinlock.h>
1380	jermar	64	#include <synch/mutex.h>
788	jermar	65	#include <adt/list.h>
727	jermar	66	#include <debug.h>
		67
		68	static count_t asids_allocated = 0;
		69
		70	/** Allocate free address space identifier.
		71	*
1637	jermar	72	* Interrupts must be disabled and inactive_as_with_asid_lock must be held
823	jermar	73	* prior to this call
727	jermar	74	*
		75	* @return New ASID.
		76	*/
		77	asid_t asid_get(void)
		78	{
		79	asid_t asid;
		80	link_t *tmp;
		81	as_t *as;
		82
		83	/*
		84	* Check if there is an unallocated ASID.
		85	*/
		86
753	jermar	87	if (asids_allocated == ASIDS_ALLOCABLE) {
727	jermar	88
		89	/*
		90	* All ASIDs are already allocated.
		91	* Resort to stealing.
		92	*/
		93
		94	/*
		95	* Remove the first item on the list.
		96	* It is guaranteed to belong to an
		97	* inactive address space.
		98	*/
823	jermar	99	ASSERT(!list_empty(&inactive_as_with_asid_head));
		100	tmp = inactive_as_with_asid_head.next;
727	jermar	101	list_remove(tmp);
		102
823	jermar	103	as = list_get_instance(tmp, as_t, inactive_as_with_asid_link);
727	jermar	104
		105	/*
		106	* Steal the ASID.
		107	* Note that the stolen ASID is not active.
		108	*/
		109	asid = as->asid;
		110	ASSERT(asid != ASID_INVALID);
		111
		112	/*
741	jermar	113	* Notify the address space from wich the ASID
		114	* was stolen by invalidating its asid member.
		115	*/
		116	as->asid = ASID_INVALID;
1889	jermar	117
		118	/*
		119	* If the architecture uses some software cache
		120	* of TLB entries (e.g. TSB on sparc64), the
		121	* cache must be invalidated as well.
		122	*/
1891	jermar	123	as_invalidate_translation_cache(as, 0, (count_t) -1);
1889	jermar	124
741	jermar	125	/*
727	jermar	126	* Get the system rid of the stolen ASID.
		127	*/
		128	tlb_shootdown_start(TLB_INVL_ASID, asid, 0, 0);
1636	jermar	129	tlb_invalidate_asid(asid);
727	jermar	130	tlb_shootdown_finalize();
		131	} else {
		132
		133	/*
		134	* There is at least one unallocated ASID.
		135	* Find it and assign it.
		136	*/
		137
		138	asid = asid_find_free();
		139	asids_allocated++;
1636	jermar	140
		141	/*
1889	jermar	142	* Purge the allocated ASID from TLBs.
1636	jermar	143	*/
		144	tlb_shootdown_start(TLB_INVL_ASID, asid, 0, 0);
		145	tlb_invalidate_asid(asid);
		146	tlb_shootdown_finalize();
727	jermar	147	}
		148
		149	return asid;
		150	}
		151
		152	/** Release address space identifier.
		153	*
		154	* This code relies on architecture
		155	* dependent functionality.
		156	*
		157	* @param asid ASID to be released.
		158	*/
		159	void asid_put(asid_t asid)
		160	{
		161	asids_allocated--;
		162	asid_put_arch(asid);
		163	}
1702	cejka	164
1851	jermar	165	/** @}
1702	cejka	166	*/

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