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/*
 * Copyright (C) 2006 Martin Decky
 * 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 <arch/mm/tlb.h>
#include <arch/types.h>
#include <mm/tlb.h>
#include <mm/page.h>
#include <mm/as.h>
#include <arch.h>
#include <print.h>
#include <symtab.h>


/** Initialize Page Hash Table.
 *
 * Setup the Page Hash Table with no entries.
 *
 */
void tlb_arch_init(void)
{
}


/** Try to find PTE for faulting address
 *
 * Try to find PTE for faulting address.
 * The AS->lock must be held on entry to this function.
 *
 * @param badvaddr Faulting virtual address.
 * @return         PTE on success, NULL otherwise.
 *
 */
static pte_t *find_mapping_and_check(__address badvaddr)
{
    /*
     * Check if the mapping exists in page tables.
     */ 
    pte_t *pte = page_mapping_find(AS, badvaddr);
    if ((pte) && (pte->p)) {
        /*
         * Mapping found in page tables.
         * Immediately succeed.
         */
        return pte;
    } else {
        /*
         * Mapping not found in page tables.
         * Resort to higher-level page fault handler.
         */
        page_table_unlock(AS, true);
        if (as_page_fault(badvaddr)) {
            /*
             * The higher-level page fault handler succeeded,
             * The mapping ought to be in place.
             */
            page_table_lock(AS, true);
            pte = page_mapping_find(AS, badvaddr);
            ASSERT((pte) && (pte->p));
            return pte;
        } else {
            page_table_lock(AS, true);
            printf("Page fault.\n");
            return NULL;
        }
        
    }
}


static void pht_refill_fail(__address badvaddr, istate_t *istate)
{
    char *symbol = "";
    char *sym2 = "";

    char *s = get_symtab_entry(istate->pc);
    if (s)
        symbol = s;
    s = get_symtab_entry(istate->lr);
    if (s)
        sym2 = s;
    panic("%X: PHT Refill Exception at %X(%s<-%s)\n", badvaddr, istate->pc, symbol, sym2);
}


/** Process Data Storage Interrupt
 *
 * @param istate Interrupted register context.
 *
 */
void pht_refill(istate_t *istate)
{
    asid_t asid;
    __address badvaddr;
    pte_t *pte;
    
    __asm__ volatile (
        "mfdar %0\n"
        : "=r" (badvaddr)
    );
    
    spinlock_lock(&AS->lock);
    asid = AS->asid;
    spinlock_unlock(&AS->lock);
    
    page_table_lock(AS, true);
    
    pte = find_mapping_and_check(badvaddr);
    if (!pte)
        goto fail;

    /*
     * Record access to PTE.
     */
    pte->a = 1;
    
    // FIXME: Insert entry into PHT

    page_table_unlock(AS, true);
    return;
    
fail:
    page_table_unlock(AS, true);
    pht_refill_fail(badvaddr, istate);
}


/** Print contents of Page Hash Table. */
void tlb_print(void)
{
}