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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).", 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).", 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).", 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).", 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).", 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).", 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);

			*pfrc = AS_PF_FAULT;

			return NULL;

			break;

		default:

			panic("Unexpected rc (%d).", 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);

}

/** @}

 */