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/*

 * Copyright (C) 2003-2004 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 <arch/mm/tlb.h>

#include <arch/mm/asid.h>

#include <mm/tlb.h>

#include <mm/page.h>

#include <mm/vm.h>

#include <arch/cp0.h>

#include <panic.h>

#include <arch.h>

#include <symtab.h>

#include <synch/spinlock.h>

#include <print.h>

static void tlb_refill_fail(struct exception_regdump *pstate);

static void tlb_invalid_fail(struct exception_regdump *pstate);

static void tlb_modified_fail(struct exception_regdump *pstate);

static pte_t *find_mapping_and_check(__address badvaddr);

static void prepare_entry_lo(struct entry_lo *lo, bool g, bool v, bool d, int c, __address pfn);

/** Initialize TLB

 *

 * Initialize TLB.

 * Invalidate all entries and mark wired entries.

 */

void tlb_init_arch(void)

{

    int i;

    cp0_pagemask_write(TLB_PAGE_MASK_16K);

    cp0_entry_hi_write(0);

    cp0_entry_lo0_write(0);

    cp0_entry_lo1_write(0);

    /*

     * Invalidate all entries.

     */

    for (i = 0; i < TLB_SIZE; i++) {

        cp0_index_write(i);

        tlbwi();

    }

    /*

     * The kernel is going to make use of some wired

     * entries (e.g. mapping kernel stacks in kseg3).

     */

    cp0_wired_write(TLB_WIRED);

}

/** Process TLB Refill Exception

 *

 * Process TLB Refill Exception.

 *

 * @param pstate Interrupted register context.

 */

void tlb_refill(struct exception_regdump *pstate)

{

    struct entry_lo lo;

    __address badvaddr;

    pte_t *pte;

    badvaddr = cp0_badvaddr_read();

    spinlock_lock(&VM->lock);      

    pte = find_mapping_and_check(badvaddr);

    if (!pte)

        goto fail;

    /*

     * Record access to PTE.

     */

    pte->a = 1;

    prepare_entry_lo(&lo, pte->g, pte->v, pte->d, pte->c, pte->pfn);

    /*

     * New entry is to be inserted into TLB

     */

    if ((badvaddr/PAGE_SIZE) % 2 == 0) {

        cp0_entry_lo0_write(*((__u32 *) &lo));

        cp0_entry_lo1_write(0);

    }

    else {

        cp0_entry_lo0_write(0);

        cp0_entry_lo1_write(*((__u32 *) &lo));

    }

    tlbwr();

    spinlock_unlock(&VM->lock);

    return;

fail:

    spinlock_unlock(&VM->lock);

    tlb_refill_fail(pstate);

}

/** Process TLB Invalid Exception

 *

 * Process TLB Invalid Exception.

 *

 * @param pstate Interrupted register context.

 */

void tlb_invalid(struct exception_regdump *pstate)

{

    struct index index;

    __address badvaddr;

    struct entry_lo lo;

    pte_t *pte;

    badvaddr = cp0_badvaddr_read();

    /*

     * Locate the faulting entry in TLB.

     */

    tlbp();

    *((__u32 *) &index) = cp0_index_read();

    spinlock_lock(&VM->lock);  

    /*

     * Fail if the entry is not in TLB.

     */

    if (index.p)

        goto fail;

    pte = find_mapping_and_check(badvaddr);

    if (!pte)

        goto fail;

    /*

     * Read the faulting TLB entry.

     */

    tlbr();

    /*

     * Record access to PTE.

     */

    pte->a = 1;

    prepare_entry_lo(&lo, pte->g, pte->v, pte->d, pte->c, pte->pfn);

    /*

     * The entry is to be updated in TLB.

     */

    if ((badvaddr/PAGE_SIZE) % 2 == 0)

        cp0_entry_lo0_write(*((__u32 *) &lo));

    else

        cp0_entry_lo1_write(*((__u32 *) &lo));

    tlbwi();

    spinlock_unlock(&VM->lock);

    return;

fail:

    spinlock_unlock(&VM->lock);

    tlb_invalid_fail(pstate);

}

/** Process TLB Modified Exception

 *

 * Process TLB Modified Exception.

 *

 * @param pstate Interrupted register context.

 */

void tlb_modified(struct exception_regdump *pstate)

{

    struct index index;

    __address badvaddr;

    struct entry_lo lo;

    pte_t *pte;

    badvaddr = cp0_badvaddr_read();

    /*

     * Locate the faulting entry in TLB.

     */

    tlbp();

    *((__u32 *) &index) = cp0_index_read();

    spinlock_lock(&VM->lock);  

    /*

     * Fail if the entry is not in TLB.

     */

    if (index.p)

        goto fail;

    pte = find_mapping_and_check(badvaddr);

    if (!pte)

        goto fail;

    /*

     * Fail if the page is not writable.

     */

    if (!pte->w)

        goto fail;

    /*

     * Read the faulting TLB entry.

     */

    tlbr();

    /*

     * Record access and write to PTE.

     */

    pte->a = 1;

    pte->d = 1;

    prepare_entry_lo(&lo, pte->g, pte->v, pte->w, pte->c, pte->pfn);

    /*

     * The entry is to be updated in TLB.

     */

    if ((badvaddr/PAGE_SIZE) % 2 == 0)

        cp0_entry_lo0_write(*((__u32 *) &lo));

    else

        cp0_entry_lo1_write(*((__u32 *) &lo));

    tlbwi();

    spinlock_unlock(&VM->lock);

    return;

fail:

    spinlock_unlock(&VM->lock);

    tlb_modified_fail(pstate);

}

void tlb_refill_fail(struct exception_regdump *pstate)

{

    char *symbol = "";

    char *sym2 = "";

    char *s = get_symtab_entry(pstate->epc);

    if (s)

        symbol = s;

    s = get_symtab_entry(pstate->ra);

    if (s)

        sym2 = s;

    panic("%X: TLB Refill Exception at %X(%s<-%s)\n", cp0_badvaddr_read(), pstate->epc, symbol, sym2);

}

void tlb_invalid_fail(struct exception_regdump *pstate)

{

    char *symbol = "";

    char *s = get_symtab_entry(pstate->epc);

    if (s)

        symbol = s;

    panic("%X: TLB Invalid Exception at %X(%s)\n", cp0_badvaddr_read(), pstate->epc, symbol);

}

void tlb_modified_fail(struct exception_regdump *pstate)

{

    char *symbol = "";

    char *s = get_symtab_entry(pstate->epc);

    if (s)

        symbol = s;

    panic("%X: TLB Modified Exception at %X(%s)\n", cp0_badvaddr_read(), pstate->epc, symbol);

}

void tlb_invalidate(int asid)

{

    pri_t pri;

    pri = cpu_priority_high();

    // TODO

    cpu_priority_restore(pri);

}

/** Try to find PTE for faulting address

 *

 * Try to find PTE for faulting address.

 * The VM->lock must be held on entry to this function.

 *

 * @param badvaddr Faulting virtual address.

 *

 * @return PTE on success, NULL otherwise.

 */

pte_t *find_mapping_and_check(__address badvaddr)

{

    struct entry_hi hi;

    pte_t *pte;

    *((__u32 *) &hi) = cp0_entry_hi_read();

    /*

     * Handler cannot succeed if the ASIDs don't match.

     */

    if (hi.asid != VM->asid)

        return NULL;

    /*

     * Handler cannot succeed if badvaddr has no mapping.

     */

    pte = find_mapping(badvaddr, 0);

    if (!pte)

        return NULL;

    /*

     * Handler cannot succeed if the mapping is marked as invalid.

     */

    if (!pte->v)

        return NULL;

    return pte;

}

void prepare_entry_lo(struct entry_lo *lo, bool g, bool v, bool d, int c, __address pfn)

{

    lo->g = g;

    lo->v = v;

    lo->d = d;

    lo->c = c;

    lo->pfn = pfn;

    lo->zero = 0;

}