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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.

 */

/** @addtogroup mips32mm   

 * @{

 */

/** @file

 */

#include <arch/mm/tlb.h>

#include <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>

#include <align.h>

#include <interrupt.h>

static void tlb_refill_fail(istate_t *);

static void tlb_invalid_fail(istate_t *);

static void tlb_modified_fail(istate_t *);

static pte_t *find_mapping_and_check(uintptr_t, int, istate_t *, int *);

/** 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.

 *

 * @param istate    Interrupted register context.

 */

void tlb_refill(istate_t *istate)

{

    entry_lo_t lo;

    entry_hi_t hi;

    asid_t asid;

    uintptr_t badvaddr;

    pte_t *pte;

    int pfrc;

    badvaddr = cp0_badvaddr_read();

    spinlock_lock(&AS->lock);

    asid = AS->asid;

    spinlock_unlock(&AS->lock);

    page_table_lock(AS, true);

    pte = find_mapping_and_check(badvaddr, PF_ACCESS_READ, istate, &pfrc);

    if (!pte) {

        switch (pfrc) {

        case AS_PF_FAULT:

            goto fail;

            break;

        case AS_PF_DEFER:

            /*

             * The page fault came during copy_from_uspace()

             * or copy_to_uspace().

             */

            page_table_unlock(AS, true);

            return;

        default:

            panic("unexpected pfrc (%d)\n", pfrc);

        }

    }

    /*

     * Record access to PTE.

     */

    pte->a = 1;

    tlb_prepare_entry_hi(&hi, asid, badvaddr);

    tlb_prepare_entry_lo(&lo, pte->g, pte->p, pte->d, pte->cacheable,

        pte->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();

    page_table_unlock(AS, true);

    return;

fail:

    page_table_unlock(AS, true);

    tlb_refill_fail(istate);

}

/** Process TLB Invalid Exception.

 *

 * @param istate    Interrupted register context.

 */

void tlb_invalid(istate_t *istate)

{

    tlb_index_t index;

    uintptr_t badvaddr;

    entry_lo_t lo;

    entry_hi_t hi;

    pte_t *pte;

    int pfrc;

    badvaddr = cp0_badvaddr_read();

    /*

     * Locate the faulting entry in TLB.

     */

    hi.value = cp0_entry_hi_read();

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

    cp0_entry_hi_write(hi.value);

    tlbp();

    index.value = cp0_index_read();

    page_table_lock(AS, true); 

    /*

     * 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, PF_ACCESS_READ, istate, &pfrc);

    if (!pte) {

        switch (pfrc) {

        case AS_PF_FAULT:

            goto fail;

            break;

        case AS_PF_DEFER:

            /*

             * The page fault came during copy_from_uspace()

             * or copy_to_uspace().

             */

            page_table_unlock(AS, true);             

            return;

        default:

            panic("unexpected pfrc (%d)\n", pfrc);

        }

    }

    /*

     * Read the faulting TLB entry.

     */

    tlbr();

    /*

     * Record access to PTE.

     */

    pte->a = 1;

    tlb_prepare_entry_lo(&lo, pte->g, pte->p, pte->d, pte->cacheable,

        pte->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();

    page_table_unlock(AS, true);

    return;

fail:

    page_table_unlock(AS, true);

    tlb_invalid_fail(istate);

}

/** Process TLB Modified Exception.

 *

 * @param istate    Interrupted register context.

 */

void tlb_modified(istate_t *istate)

{

    tlb_index_t index;

    uintptr_t badvaddr;

    entry_lo_t lo;

    entry_hi_t hi;

    pte_t *pte;

    int pfrc;

    badvaddr = cp0_badvaddr_read();

    /*

     * Locate the faulting entry in TLB.

     */

    hi.value = cp0_entry_hi_read();

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

    cp0_entry_hi_write(hi.value);

    tlbp();

    index.value = cp0_index_read();

    page_table_lock(AS, true); 

    /*

     * 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, PF_ACCESS_WRITE, istate, &pfrc);

    if (!pte) {

        switch (pfrc) {

        case AS_PF_FAULT:

            goto fail;

            break;

        case AS_PF_DEFER:

            /*

             * The page fault came during copy_from_uspace()

             * or copy_to_uspace().

             */

            page_table_unlock(AS, true);             

            return;

        default:

            panic("unexpected pfrc (%d)\n", pfrc);

        }

    }

    /*

     * Read the faulting TLB entry.

     */

    tlbr();

    /*

     * Record access and write to PTE.

     */

    pte->a = 1;

    pte->d = 1;

    tlb_prepare_entry_lo(&lo, pte->g, pte->p, pte->w, pte->cacheable,

        pte->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();

    page_table_unlock(AS, true);

    return;

fail:

    page_table_unlock(AS, true);

    tlb_modified_fail(istate);

}

void tlb_refill_fail(istate_t *istate)

{

    char *symbol = "";

    char *sym2 = "";

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

    if (s)

        symbol = s;

    s = get_symtab_entry(istate->ra);

    if (s)

        sym2 = s;

    fault_if_from_uspace(istate, "TLB Refill Exception on %p",

        cp0_badvaddr_read());

    panic("%x: TLB Refill Exception at %x(%s<-%s)\n", cp0_badvaddr_read(),

        istate->epc, symbol, sym2);

}

void tlb_invalid_fail(istate_t *istate)

{

    char *symbol = "";

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

    if (s)

        symbol = s;

    fault_if_from_uspace(istate, "TLB Invalid Exception on %p",

        cp0_badvaddr_read());

    panic("%x: TLB Invalid Exception at %x(%s)\n", cp0_badvaddr_read(),

        istate->epc, symbol);

}

void tlb_modified_fail(istate_t *istate)

{

    char *symbol = "";

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

    if (s)

        symbol = s;

    fault_if_from_uspace(istate, "TLB Modified Exception on %p",

        cp0_badvaddr_read());

    panic("%x: TLB Modified Exception at %x(%s)\n", cp0_badvaddr_read(),

        istate->epc, symbol);

}

/** Try to find PTE for faulting address.

 *

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

 *

 * @param badvaddr  Faulting virtual address.

 * @param access    Access mode that caused the fault.

 * @param istate    Pointer to interrupted state.

 * @param pfrc      Pointer to variable where as_page_fault() return code

 *          will be stored.

 *

 * @return      PTE on success, NULL otherwise.

 */

pte_t *

find_mapping_and_check(uintptr_t badvaddr, int access, istate_t *istate,

    int *pfrc)

{

    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(AS, badvaddr);

    if (pte && pte->p && (pte->w || access != PF_ACCESS_WRITE)) {

        /*

         * Mapping found in page tables.

         * Immediately succeed.

         */

        return pte;

    } else {

        int rc;

        /*

         * Mapping not found in page tables.

         * Resort to higher-level page fault handler.

         */

        page_table_unlock(AS, true);

        switch (rc = as_page_fault(badvaddr, access, istate)) {

        case AS_PF_OK:

            /*

             * 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);

            ASSERT(pte->w || access != PF_ACCESS_WRITE);

            return pte;

            break;

        case AS_PF_DEFER:

            page_table_lock(AS, true);

            *pfrc = AS_PF_DEFER;

            return NULL;

            break;

        case AS_PF_FAULT:

            page_table_lock(AS, true);

            printf("Page fault.\n");

            *pfrc = AS_PF_FAULT;

            return NULL;

            break;

        default:

            panic("unexpected rc (%d)\n", rc);

        }

    }

}

void

tlb_prepare_entry_lo(entry_lo_t *lo, bool g, bool v, bool d, bool cacheable,

    uintptr_t pfn)

{

    lo->value = 0;

    lo->g = g;

    lo->v = v;

    lo->d = d;

    lo->c = cacheable ? PAGE_CACHEABLE_EXC_WRITE : PAGE_UNCACHED;

    lo->pfn = pfn;

}

void tlb_prepare_entry_hi(entry_hi_t *hi, asid_t asid, uintptr_t addr)

{

    hi->value = ALIGN_DOWN(addr, 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;

    unsigned int i;

    hi_save.value = cp0_entry_hi_read();

    printf("#  ASID VPN2   MASK G V D C PFN\n");

    printf("-- ---- ------ ---- - - - - ------\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("%-2u %-4u %#6x %#4x %1u %1u %1u %1u %#6x\n",

            i, hi.asid, hi.vpn2, mask.mask,

            lo0.g, lo0.v, lo0.d, lo0.c, lo0.pfn);

        printf("                    %1u %1u %1u %1u %#6x\n",

            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 entries for specified page range belonging to specified

 * address space.

 *

 * @param asid      Address space identifier.

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

 * @param cnt       Number of entries to invalidate.

 */

void tlb_invalidate_pages(asid_t asid, uintptr_t page, count_t cnt)

{

    unsigned int i;

    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();

    for (i = 0; i < cnt + 1; i += 2) {

        hi.value = 0;

        tlb_prepare_entry_hi(&hi, asid, page + i * PAGE_SIZE);

        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);

}

/** @}

 */