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684 jermar 1 
/*
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 * Copyright (C) 2006 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <genarch/mm/page_ht.h>
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#include <mm/page.h>
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#include <mm/frame.h>
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#include <mm/heap.h>
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#include <mm/as.h>
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#include <arch/mm/asid.h>
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#include <arch/types.h>
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#include <typedefs.h>
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#include <arch/asm.h>
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#include <synch/spinlock.h>
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#include <arch.h>
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#include <debug.h>
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/**
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 * This lock protects the page hash table. Note that software must
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 * be still careful about ordering of writes to ensure consistent
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 * view of the page hash table for hardware helpers such as VHPT
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 * walker on ia64.
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 */
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SPINLOCK_INITIALIZE(page_ht_lock);
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/**
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 * Page hash table pointer.
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 * The page hash table may be accessed only when page_ht_lock is held.
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 */
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pte_t *page_ht = NULL;
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static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags, __address root);
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static pte_t *ht_mapping_find(as_t *as, __address page, __address root);
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page_operations_t page_ht_operations = {
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    .mapping_insert = ht_mapping_insert,
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    .mapping_find = ht_mapping_find
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};
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/** Map page to frame using page hash table.
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 *
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 * Map virtual address 'page' to physical address 'frame'
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 * using 'flags'. In order not to disturb hardware searching,
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 * new mappings are appended to the end of the collision
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 * chain.
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 *
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 * @param as Address space to which page belongs. Must be locked prior the call.
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 * @param page Virtual address of the page to be mapped.
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 * @param frame Physical address of memory frame to which the mapping is done.
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 * @param flags Flags to be used for mapping.
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 * @param root Ignored.
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 */
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void ht_mapping_insert(as_t *as, __address page, __address frame, int flags, __address root)
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{
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    pte_t *t, *u;
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    ipl_t ipl;
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    ipl = interrupts_disable();
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    spinlock_lock(&page_ht_lock);
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    t = HT_HASH(page, as->asid);
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    if (!HT_SLOT_EMPTY(t)) {
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        /*
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         * The slot is occupied.
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         * Walk through the collision chain and append the mapping to its end.
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         */
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        do {
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            u = t;
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            if (HT_COMPARE(page, as->asid, t)) {
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                /*
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                 * Nothing to do,
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                 * the record is already there.
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                 */
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                spinlock_unlock(&page_ht_lock);
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                interrupts_restore(ipl);
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                return;
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            }
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        } while ((t = HT_GET_NEXT(t)));
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        t = (pte_t *) malloc(sizeof(pte_t));    /* FIXME: use slab allocator for this */
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        if (!t)
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            panic("could not allocate memory\n");
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        HT_SET_NEXT(u, t);
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    }
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    HT_SET_RECORD(t, page, as->asid, frame, flags);
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    HT_SET_NEXT(t, NULL);
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    spinlock_unlock(&page_ht_lock);
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    interrupts_restore(ipl);
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}
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/** Find mapping for virtual page in page hash table.
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 *
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 * Find mapping for virtual page.
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 *
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 * Interrupts must be disabled.
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 *
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 * @param as Address space to wich page belongs. Must be locked prior the call.
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 * @param page Virtual page.
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 * @param root Ignored.
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 *
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 * @return NULL if there is no such mapping; requested mapping otherwise.
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 */
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pte_t *ht_mapping_find(as_t *as, __address page, __address root)
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{
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    pte_t *t;
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    spinlock_lock(&page_ht_lock);
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    t = HT_HASH(page, as->asid);
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    if (!HT_SLOT_EMPTY(t)) {
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        while (!HT_COMPARE(page, as->asid, t) && HT_GET_NEXT(t))
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            t = HT_GET_NEXT(t);
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        t = HT_COMPARE(page, as->asid, t) ? t : NULL;
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    } else {
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        t = NULL;
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    }
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    spinlock_unlock(&page_ht_lock);
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    return t;
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}
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/** Invalidate page hash table.
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 *
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 * Interrupts must be disabled.
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 */
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void ht_invalidate_all(void)
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{
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    pte_t *t, *u;
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    int i;
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    spinlock_lock(&page_ht_lock);
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    for (i = 0; i < HT_ENTRIES; i++) {
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        if (!HT_SLOT_EMPTY(&page_ht[i])) {
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            t = HT_GET_NEXT(&page_ht[i]);
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            while (t) {
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                u = t;
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                t = HT_GET_NEXT(t);
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                free(u);        /* FIXME: use slab allocator for this */
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            }
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            HT_INVALIDATE_SLOT(&page_ht[i]);
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        }
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    }
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    spinlock_unlock(&page_ht_lock);
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}