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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/as.h>

#include <arch/cp0.h>

#include <panic.h>

#include <arch.h>

#include <symtab.h>

#include <synch/spinlock.h>

#include <print.h>

#include <debug.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(entry_lo_t *lo, bool g, bool v, bool d, int c, __address pfn);

static void prepare_entry_hi(entry_hi_t *hi, asid_t asid, __address addr);

/** Initialize TLB

 *

 * Initialize TLB.

 * Invalidate all entries and mark wired entries.

 */

void tlb_arch_init(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);

    /* Clear and initialize TLB. */

    for (i = 0; i < TLB_ENTRY_COUNT; 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)

{

    entry_lo_t lo;

    entry_hi_t hi; 

    __address badvaddr;

    pte_t *pte;

    badvaddr = cp0_badvaddr_read();

    spinlock_lock(&AS->lock);      

    pte = find_mapping_and_check(badvaddr);

    if (!pte)

        goto fail;

    /*

     * Record access to PTE.

     */

    pte->a = 1;

    prepare_entry_hi(&hi, AS->asid, badvaddr);

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

    /*

     * New entry is to be inserted into TLB

     */

    cp0_entry_hi_write(hi.value);

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

        cp0_entry_lo0_write(lo.value);

        cp0_entry_lo1_write(0);

    }

    else {

        cp0_entry_lo0_write(0);

        cp0_entry_lo1_write(lo.value);

    }

    cp0_pagemask_write(TLB_PAGE_MASK_16K);

    tlbwr();

    spinlock_unlock(&AS->lock);

    return;

fail:

    spinlock_unlock(&AS->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)

{

    tlb_index_t index;

    __address badvaddr;

    entry_lo_t lo;

    entry_hi_t hi;

    pte_t *pte;

    badvaddr = cp0_badvaddr_read();

    /*

     * Locate the faulting entry in TLB.

     */

    hi.value = cp0_entry_hi_read();

    prepare_entry_hi(&hi, hi.asid, badvaddr);

    cp0_entry_hi_write(hi.value);

    tlbp();

    index.value = cp0_index_read();

    spinlock_lock(&AS->lock);  

    /*

     * Fail if the entry is not in TLB.

     */

    if (index.p) {

        printf("TLB entry not found.\n");

        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->lo.g, pte->lo.v, pte->lo.d, pte->lo.c, pte->lo.pfn);

    /*

     * The entry is to be updated in TLB.

     */

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

        cp0_entry_lo0_write(lo.value);

    else

        cp0_entry_lo1_write(lo.value);

    cp0_pagemask_write(TLB_PAGE_MASK_16K);

    tlbwi();

    spinlock_unlock(&AS->lock);

    return;

fail:

    spinlock_unlock(&AS->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)

{

    tlb_index_t index;

    __address badvaddr;

    entry_lo_t lo;

    entry_hi_t hi;

    pte_t *pte;

    badvaddr = cp0_badvaddr_read();

    /*

     * Locate the faulting entry in TLB.

     */

    hi.value = cp0_entry_hi_read();

    prepare_entry_hi(&hi, hi.asid, badvaddr);

    cp0_entry_hi_write(hi.value);

    tlbp();

    index.value = cp0_index_read();

    spinlock_lock(&AS->lock);  

    /*

     * Fail if the entry is not in TLB.

     */

    if (index.p) {

        printf("TLB entry not found.\n");

        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->lo.d = 1;

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

    /*

     * The entry is to be updated in TLB.

     */

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

        cp0_entry_lo0_write(lo.value);

    else

        cp0_entry_lo1_write(lo.value);

    cp0_pagemask_write(TLB_PAGE_MASK_16K);

    tlbwi();

    spinlock_unlock(&AS->lock);

    return;

fail:

    spinlock_unlock(&AS->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);

}

/** 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.

 */

pte_t *find_mapping_and_check(__address badvaddr)

{

    entry_hi_t hi;

    pte_t *pte;

    hi.value = cp0_entry_hi_read();

    /*

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

     */

    if (hi.asid != AS->asid) {

        printf("EntryHi.asid=%d, AS->asid=%d\n", hi.asid, AS->asid);

        return NULL;

    }

    /*

     * Check if the mapping exists in page tables.

     */

    pte = page_mapping_find(badvaddr, AS->asid, 0);

    if (pte && pte->lo.v) {

        /*

         * Mapping found in page tables.

         * Immediately succeed.

         */

        return pte;

    } else {

        /*

         * Mapping not found in page tables.

         * Resort to higher-level page fault handler.

         */

        if (as_page_fault(badvaddr)) {

            /*

             * The higher-level page fault handler succeeded,

             * The mapping ought to be in place.

             */

            pte = page_mapping_find(badvaddr, AS->asid, 0);

            ASSERT(pte && pte->lo.v);

            return pte;

        }

    }

    /*

     * Handler cannot succeed if badvaddr has no mapping.

     */

    if (!pte) {

        printf("No such mapping.\n");

        return NULL;

    }

    /*

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

     */

    if (!pte->lo.v) {

        printf("Invalid mapping.\n");

        return NULL;

    }

    return pte;

}

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

{

    lo->value = 0;

    lo->g = g;

    lo->v = v;

    lo->d = d;

    lo->c = c;

    lo->pfn = pfn;

}

void prepare_entry_hi(entry_hi_t *hi, asid_t asid, __address addr)

{

    hi->value = (((addr/PAGE_SIZE)/2)*PAGE_SIZE*2);

    hi->asid = asid;

}

/** Print contents of TLB. */

void tlb_print(void)

{

    page_mask_t mask;

    entry_lo_t lo0, lo1;

    entry_hi_t hi, hi_save;

    int i;

    hi_save.value = cp0_entry_hi_read();

    printf("TLB:\n");

    for (i = 0; i < TLB_ENTRY_COUNT; i++) {

        cp0_index_write(i);

        tlbr();

        mask.value = cp0_pagemask_read();

        hi.value = cp0_entry_hi_read();

        lo0.value = cp0_entry_lo0_read();

        lo1.value = cp0_entry_lo1_read();

        printf("%d: asid=%d, vpn2=%d, mask=%d\tg[0]=%d, v[0]=%d, d[0]=%d, c[0]=%B, pfn[0]=%d\n"

               "\t\t\t\tg[1]=%d, v[1]=%d, d[1]=%d, c[1]=%B, pfn[1]=%d\n",

               i, hi.asid, hi.vpn2, mask.mask, lo0.g, lo0.v, lo0.d, lo0.c, lo0.pfn,

               lo1.g, lo1.v, lo1.d, lo1.c, lo1.pfn);

    }

    cp0_entry_hi_write(hi_save.value);

}

/** Invalidate all not wired TLB entries. */

void tlb_invalidate_all(void)

{

    ipl_t ipl;

    entry_lo_t lo0, lo1;

    entry_hi_t hi_save;

    int i;

    hi_save.value = cp0_entry_hi_read();

    ipl = interrupts_disable();

    for (i = TLB_WIRED; i < TLB_ENTRY_COUNT; i++) {

        cp0_index_write(i);

        tlbr();

        lo0.value = cp0_entry_lo0_read();

        lo1.value = cp0_entry_lo1_read();

        lo0.v = 0;

        lo1.v = 0;

        cp0_entry_lo0_write(lo0.value);

        cp0_entry_lo1_write(lo1.value);

        tlbwi();

    }

    interrupts_restore(ipl);

    cp0_entry_hi_write(hi_save.value);

}

/** Invalidate all TLB entries belonging to specified address space.

 *

 * @param asid Address space identifier.

 */

void tlb_invalidate_asid(asid_t asid)

{

    ipl_t ipl;

    entry_lo_t lo0, lo1;

    entry_hi_t hi, hi_save;

    int i;

    ASSERT(asid != ASID_INVALID);

    hi_save.value = cp0_entry_hi_read();

    ipl = interrupts_disable();

    for (i = 0; i < TLB_ENTRY_COUNT; i++) {

        cp0_index_write(i);

        tlbr();

        hi.value = cp0_entry_hi_read();

        if (hi.asid == asid) {

            lo0.value = cp0_entry_lo0_read();

            lo1.value = cp0_entry_lo1_read();

            lo0.v = 0;

            lo1.v = 0;

            cp0_entry_lo0_write(lo0.value);

            cp0_entry_lo1_write(lo1.value);

            tlbwi();

        }

    }

    interrupts_restore(ipl);

    cp0_entry_hi_write(hi_save.value);

}

/** Invalidate TLB entry for specified page belonging to specified address space.

 *

 * @param asid Address space identifier.

 * @param page Page whose TLB entry is to be invalidated.

 */

void tlb_invalidate_page(asid_t asid, __address page)

{

    ipl_t ipl;

    entry_lo_t lo0, lo1;

    entry_hi_t hi, hi_save;

    tlb_index_t index;

    ASSERT(asid != ASID_INVALID);

    hi_save.value = cp0_entry_hi_read();

    ipl = interrupts_disable();

    hi.value = 0;

    prepare_entry_hi(&hi, asid, page);

    cp0_entry_hi_write(hi.value);

    tlbp();

    index.value = cp0_index_read();

    if (!index.p) {

        /* Entry was found, index register contains valid index. */

        tlbr();

        lo0.value = cp0_entry_lo0_read();

        lo1.value = cp0_entry_lo1_read();

        lo0.v = 0;

        lo1.v = 0;

        cp0_entry_lo0_write(lo0.value);

        cp0_entry_lo1_write(lo1.value);

        tlbwi();

    }

    interrupts_restore(ipl);

    cp0_entry_hi_write(hi_save.value);

}