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

Rev	Author	Line No.	Line
727	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
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;
1380	jermar	125	mutex_unlock(&as->lock);
741	jermar	126
		127	/*
727	jermar	128	* Get the system rid of the stolen ASID.
		129	*/
		130	tlb_shootdown_start(TLB_INVL_ASID, asid, 0, 0);
1636	jermar	131	tlb_invalidate_asid(asid);
727	jermar	132	tlb_shootdown_finalize();
		133	} else {
		134
		135	/*
		136	* There is at least one unallocated ASID.
		137	* Find it and assign it.
		138	*/
		139
		140	asid = asid_find_free();
		141	asids_allocated++;
1636	jermar	142
		143	/*
		144	* Purge the allocated rid from TLBs.
		145	*/
		146	tlb_shootdown_start(TLB_INVL_ASID, asid, 0, 0);
		147	tlb_invalidate_asid(asid);
		148	tlb_shootdown_finalize();
727	jermar	149	}
		150
		151	spinlock_unlock(&asidlock);
		152
		153	return asid;
		154	}
		155
		156	/** Release address space identifier.
		157	*
		158	* This code relies on architecture
		159	* dependent functionality.
		160	*
		161	* @param asid ASID to be released.
		162	*/
		163	void asid_put(asid_t asid)
		164	{
		165	ipl_t ipl;
		166
		167	ipl = interrupts_disable();
		168	spinlock_lock(&asidlock);
		169
		170	asids_allocated--;
		171	asid_put_arch(asid);
		172
		173	spinlock_unlock(&asidlock);
		174	interrupts_restore(ipl);
		175	}
1702	cejka	176
1851	jermar	177	/** @}
1702	cejka	178	*/

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