source: mainline/genarch/src/mm/page_ht.c@ bc504ef2

/*
 * 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.
 */

#include <genarch/mm/page_ht.h>
#include <mm/page.h>
#include <mm/frame.h>
#include <mm/heap.h>
#include <mm/as.h>
#include <arch/mm/asid.h>
#include <arch/types.h>
#include <typedefs.h>
#include <arch/asm.h>
#include <synch/spinlock.h>
#include <arch.h>
#include <debug.h>
#include <memstr.h>

/**
 * This lock protects the page hash table.
 */
SPINLOCK_INITIALIZE(page_ht_lock);

/**
 * Page hash table pointer.
 * The page hash table may be accessed only when page_ht_lock is held.
 */
pte_t *page_ht = NULL;

static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags);
static pte_t *ht_mapping_find(as_t *as, __address page);

page_operations_t page_ht_operations = {
        .mapping_insert = ht_mapping_insert,
        .mapping_find = ht_mapping_find
};

/** Map page to frame using page hash table.
 *
 * Map virtual address 'page' to physical address 'frame'
 * using 'flags'. 
 *
 * The address space must be locked and interruptsmust be disabled.
 *
 * @param as Address space to which page belongs.
 * @param page Virtual address of the page to be mapped.
 * @param frame Physical address of memory frame to which the mapping is done.
 * @param flags Flags to be used for mapping.
 */
void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
{
        pte_t *t, *u;
        ipl_t ipl;
        
        ipl = interrupts_disable();
        spinlock_lock(&page_ht_lock);

        t = HT_HASH(page, as->asid);
        if (!HT_SLOT_EMPTY(t)) {
        
                /*
                 * The slot is occupied.
                 * Walk through the collision chain and append the mapping to its end.
                 */
                 
                do {
                        u = t;
                        if (HT_COMPARE(page, as->asid, t)) {
                                /*
                                 * Nothing to do,
                                 * the record is already there.
                                 */
                                spinlock_unlock(&page_ht_lock);
                                interrupts_restore(ipl);
                                return;
                        }
                } while ((t = HT_GET_NEXT(t)));
        
                t = (pte_t *) malloc(sizeof(pte_t));    /* FIXME: use slab allocator for this */
                if (!t)
                        panic("could not allocate memory\n");

                HT_SET_NEXT(u, t);
        }
        
        HT_SET_RECORD(t, page, as->asid, frame, flags);
        HT_SET_NEXT(t, NULL);
        
        spinlock_unlock(&page_ht_lock);
        interrupts_restore(ipl);
}

/** Find mapping for virtual page in page hash table.
 *
 * Find mapping for virtual page.
 *
 * The address space must be locked and interrupts must be disabled.
 *
 * @param as Address space to wich page belongs.
 * @param page Virtual page.
 *
 * @return NULL if there is no such mapping; requested mapping otherwise.
 */
pte_t *ht_mapping_find(as_t *as, __address page)
{
        pte_t *t;
        
        spinlock_lock(&page_ht_lock);
        t = HT_HASH(page, as->asid);
        if (!HT_SLOT_EMPTY(t)) {
                while (!HT_COMPARE(page, as->asid, t) && HT_GET_NEXT(t))
                        t = HT_GET_NEXT(t);
                t = HT_COMPARE(page, as->asid, t) ? t : NULL;
        } else {
                t = NULL;
        }
        spinlock_unlock(&page_ht_lock);
        return t;
}

/** Invalidate page hash table.
 *
 * Interrupts must be disabled.
 */
void ht_invalidate_all(void)
{
        pte_t *t, *u;
        int i;
        
        spinlock_lock(&page_ht_lock);
        for (i = 0; i < HT_ENTRIES; i++) {
                if (!HT_SLOT_EMPTY(&page_ht[i])) {
                        t = HT_GET_NEXT(&page_ht[i]);
                        while (t) {
                                u = t;
                                t = HT_GET_NEXT(t);
                                free(u);                /* FIXME: use slab allocator for this */
                        }
                        HT_INVALIDATE_SLOT(&page_ht[i]);
                }
        }
        spinlock_unlock(&page_ht_lock);
}