Subversion Repositories HelenOS-historic

Rev

Rev 742 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
740 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 
 
29 
/*
30 
 * ASID management.
31 
 *
32 
 * Because ia64 has much wider ASIDs (18-24 bits) compared to other
742 jermar 33 
 * architectures (e.g. 8 bits on mips32 and 13 bits on sparc64), it is
740 jermar 34 
 * inappropriate to use same methods (i.e. genarch/mm/asid_fifo.c) for
35 
 * all of them.
36 
 *
37 
 * Instead, ia64 assigns ASID values from a counter that eventually
38 
 * overflows. When this happens, the counter is reset and all TLBs are
39 
 * entirely invalidated. Furthermore, all address space structures,
40 
 * except for the one with asid == ASID_KERNEL, are assigned new ASID.
41 
 *
42 
 * It is important to understand that, in SPARTAN, one ASID represents
43 
 * RIDS_PER_ASID consecutive hardware RIDs (Region ID's).
44 
 *
45 
 * Note that the algorithm used can handle only the maximum of
46 
 * ASID_OVERFLOW-ASID_START address spaces at a time.
47 
 */
48 
 
49 
#include <arch/mm/asid.h>
50 
#include <mm/asid.h>
51 
#include <mm/as.h>
749 jermar 52 
#include <genarch/mm/page_ht.h>
740 jermar 53 
#include <mm/tlb.h>
54 
#include <list.h>
55 
#include <typedefs.h>
56 
#include <debug.h>
57 
 
58 
/**
59 
 * Stores the ASID to be returned next.
60 
 * Must be only accessed when asidlock is held.
61 
 */
62 
static asid_t next_asid = ASID_START;
63 
 
64 
/** Assign next ASID.
65 
 *
66 
 * On ia64, this function is used only to allocate ASID
67 
 * for a newly created address space. As a side effect,
68 
 * it might attempt to shootdown TLBs and reassign
69 
 * ASIDs to existing address spaces.
70 
 *
71 
 * When calling this function, interrupts must be disabled
72 
 * and the asidlock must be held.
73 
 *
74 
 * @return ASID for new address space.
75 
 */
76 
asid_t asid_find_free(void)
77 
{
78 
    as_t *as;
79 
    link_t *cur;
80 
 
81 
    if (next_asid == ASID_OVERFLOW) {
82 
        /*
83 
         * The counter has overflown.
84 
         */
85 
 
86 
        /*
87 
         * Reset the counter.
88 
         */
89 
        next_asid = ASID_START;
90 
 
91 
        /*
92 
         * Initiate TLB shootdown.
93 
         */
94 
        tlb_shootdown_start(TLB_INVL_ALL, 0, 0, 0);
95 
 
96 
        /*
97 
         * Reassign ASIDs to existing address spaces.
98 
         */
99 
        for (cur = as_with_asid_head.next; cur != &as_with_asid_head; cur = cur->next) {
100 
            ASSERT(next_asid < ASID_OVERFLOW);
101 
 
102 
            as = list_get_instance(cur, as_t, as_with_asid_link);
103 
 
104 
            spinlock_lock(&as->lock);
105 
            as->asid = next_asid++;
106 
            spinlock_unlock(&as->lock);
107 
        }
749 jermar 108 
 
109 
        /*
110 
         * The page hash table uses VHPT long format PTE's.
111 
         * Unfortunatelly, this format has no space to
112 
         * store as_t pointer, so it is necessary to
113 
         * invalidate the whole structure after all ASIDs
114 
         * have been reassigned. The information swept out
115 
         * from the page hash table can be later reconstructed
116 
         * from as_t structures on demand.
117 
         */
118 
        ht_invalidate_all();
740 jermar 119 
 
120 
        /*
121 
         * Finish TLB shootdown.
122 
         */
123 
        tlb_shootdown_finalize();
124 
        tlb_invalidate_all();
125 
    }
126 
 
127 
    ASSERT(next_asid < ASID_OVERFLOW);
128 
    return next_asid++;
129 
}