WebSVN – HelenOS – Blame – /trunk/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
1266	jermar	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>
727	jermar	65	#include <arch.h>
788	jermar	66	#include <adt/list.h>
727	jermar	67	#include <debug.h>
		68
		69	/**
823	jermar	70	* asidlock protects the asids_allocated counter.
727	jermar	71	*/
		72	SPINLOCK_INITIALIZE(asidlock);
		73
		74	static count_t asids_allocated = 0;
		75
		76	/** Allocate free address space identifier.
		77	*
1637	jermar	78	* Interrupts must be disabled and inactive_as_with_asid_lock must be held
823	jermar	79	* prior to this call
727	jermar	80	*
		81	* @return New ASID.
		82	*/
		83	asid_t asid_get(void)
		84	{
		85	asid_t asid;
		86	link_t *tmp;
		87	as_t *as;
		88
		89	/*
		90	* Check if there is an unallocated ASID.
		91	*/
		92
		93	spinlock_lock(&asidlock);
753	jermar	94	if (asids_allocated == ASIDS_ALLOCABLE) {
727	jermar	95
		96	/*
		97	* All ASIDs are already allocated.
		98	* Resort to stealing.
		99	*/
		100
		101	/*
		102	* Remove the first item on the list.
		103	* It is guaranteed to belong to an
		104	* inactive address space.
		105	*/
823	jermar	106	ASSERT(!list_empty(&inactive_as_with_asid_head));
		107	tmp = inactive_as_with_asid_head.next;
727	jermar	108	list_remove(tmp);
		109
823	jermar	110	as = list_get_instance(tmp, as_t, inactive_as_with_asid_link);
1380	jermar	111	mutex_lock_active(&as->lock);
727	jermar	112
		113	/*
		114	* Steal the ASID.
		115	* Note that the stolen ASID is not active.
		116	*/
		117	asid = as->asid;
		118	ASSERT(asid != ASID_INVALID);
		119
		120	/*
741	jermar	121	* Notify the address space from wich the ASID
		122	* was stolen by invalidating its asid member.
		123	*/
		124	as->asid = ASID_INVALID;
1889	jermar	125
		126	/*
		127	* If the architecture uses some software cache
		128	* of TLB entries (e.g. TSB on sparc64), the
		129	* cache must be invalidated as well.
		130	*/
1891	jermar	131	as_invalidate_translation_cache(as, 0, (count_t) -1);
1889	jermar	132
1380	jermar	133	mutex_unlock(&as->lock);
741	jermar	134
		135	/*
727	jermar	136	* Get the system rid of the stolen ASID.
		137	*/
		138	tlb_shootdown_start(TLB_INVL_ASID, asid, 0, 0);
1636	jermar	139	tlb_invalidate_asid(asid);
727	jermar	140	tlb_shootdown_finalize();
		141	} else {
		142
		143	/*
		144	* There is at least one unallocated ASID.
		145	* Find it and assign it.
		146	*/
		147
		148	asid = asid_find_free();
		149	asids_allocated++;
1636	jermar	150
		151	/*
1889	jermar	152	* Purge the allocated ASID from TLBs.
1636	jermar	153	*/
		154	tlb_shootdown_start(TLB_INVL_ASID, asid, 0, 0);
		155	tlb_invalidate_asid(asid);
		156	tlb_shootdown_finalize();
727	jermar	157	}
		158
		159	spinlock_unlock(&asidlock);
		160
		161	return asid;
		162	}
		163
		164	/** Release address space identifier.
		165	*
		166	* This code relies on architecture
		167	* dependent functionality.
		168	*
		169	* @param asid ASID to be released.
		170	*/
		171	void asid_put(asid_t asid)
		172	{
		173	ipl_t ipl;
		174
		175	ipl = interrupts_disable();
		176	spinlock_lock(&asidlock);
		177
		178	asids_allocated--;
		179	asid_put_arch(asid);
		180
		181	spinlock_unlock(&asidlock);
		182	interrupts_restore(ipl);
		183	}
1702	cejka	184
1851	jermar	185	/** @}
1702	cejka	186	*/

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