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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, bool 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, bool c, __address pfn)

{

	lo->g = g;

	lo->v = v;

	lo->d = d;

	lo->c = c;

	lo->pfn = pfn;

	lo->zero = 0;

}