source: mainline/arch/mips32/src/mm/tlb.c@ 4b2c872d

/*
 * 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>
#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_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)
{
        entry_lo_t lo;
        entry_hi_t hi;  
        __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_hi(&hi, VM->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);
        }
        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)
{
        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(&VM->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);
        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)
{
        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(&VM->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);
        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);
}

/** Invalidate TLB entries with specified ASID
 *
 * Invalidate TLB entries with specified ASID.
 *
 * @param asid ASID.
 */
void tlb_invalidate(asid_t asid)
{
        entry_hi_t hi;
        ipl_t ipl;
        int i;  
        
        ASSERT(asid != ASID_INVALID);

        ipl = interrupts_disable();
        
        for (i = 0; i < TLB_SIZE; i++) {
                cp0_index_write(i);
                tlbr();
                
                hi.value = cp0_entry_hi_read();
                if (hi.asid == asid) {
                        cp0_pagemask_write(TLB_PAGE_MASK_16K);
                        cp0_entry_hi_write(0);
                        cp0_entry_lo0_write(0);
                        cp0_entry_lo1_write(0);
                        tlbwi();
                }
        }
        
        interrupts_restore(ipl);
}

/** 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)
{
        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 != VM->asid) {
                printf("EntryHi.asid=%d, VM->asid=%d\n", hi.asid, VM->asid);
                return NULL;
        }
        
        /*
         * Handler cannot succeed if badvaddr has no mapping.
         */
        pte = find_mapping(badvaddr, 0);
        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;
}