/*
* Copyright (C) 2006 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* ASID management.
*
* Because ia64 has much wider ASIDs (18-24 bits) compared to other
* architectures (e.g. 8 bits on mips32 and 12 bits on sparc32), it is
* inappropriate to use same methods (i.e. genarch/mm/asid_fifo.c) for
* all of them.
*
* Instead, ia64 assigns ASID values from a counter that eventually
* overflows. When this happens, the counter is reset and all TLBs are
* entirely invalidated. Furthermore, all address space structures,
* except for the one with asid == ASID_KERNEL, are assigned new ASID.
*
* It is important to understand that, in SPARTAN, one ASID represents
* RIDS_PER_ASID consecutive hardware RIDs (Region ID's).
*
* Note that the algorithm used can handle only the maximum of
* ASID_OVERFLOW-ASID_START address spaces at a time.
*/
#include <arch/mm/asid.h>
#include <mm/asid.h>
#include <mm/as.h>
#include <mm/tlb.h>
#include <list.h>
#include <typedefs.h>
#include <debug.h>
/**
* Stores the ASID to be returned next.
* Must be only accessed when asidlock is held.
*/
static asid_t next_asid = ASID_START;
/** Assign next ASID.
*
* On ia64, this function is used only to allocate ASID
* for a newly created address space. As a side effect,
* it might attempt to shootdown TLBs and reassign
* ASIDs to existing address spaces.
*
* When calling this function, interrupts must be disabled
* and the asidlock must be held.
*
* @return ASID for new address space.
*/
asid_t asid_find_free(void)
{
as_t *as;
link_t *cur;
if (next_asid == ASID_OVERFLOW) {
/*
* The counter has overflown.
*/
/*
* Reset the counter.
*/
next_asid = ASID_START;
/*
* Initiate TLB shootdown.
*/
tlb_shootdown_start(TLB_INVL_ALL, 0, 0, 0);
/*
* Reassign ASIDs to existing address spaces.
*/
for (cur = as_with_asid_head.next; cur != &as_with_asid_head; cur = cur->next) {
ASSERT(next_asid < ASID_OVERFLOW);
as = list_get_instance(cur, as_t, as_with_asid_link);
spinlock_lock(&as->lock);
as->asid = next_asid++;
spinlock_unlock(&as->lock);
}
/*
* Finish TLB shootdown.
*/
tlb_shootdown_finalize();
tlb_invalidate_all();
}
ASSERT(next_asid < ASID_OVERFLOW);
return next_asid++;
}