/* * 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 13 bits on sparc64), 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 #include #include #include #include #include #include /** * 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++; }