/*
 * Copyright 2008-2011, Ingo Weinhold, ingo_weinhold@gmx.de.
 * Copyright 2002-2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
 */

/*      (bonefish) Some explanatory words on how address translation is implemented
        for the 32 bit PPC architecture.

        I use the address type nomenclature as used in the PPC architecture
        specs, i.e.
        - effective address: An address as used by program instructions, i.e.
          that's what elsewhere (e.g. in the VM implementation) is called
          virtual address.
        - virtual address: An intermediate address computed from the effective
          address via the segment registers.
        - physical address: An address referring to physical storage.

        The hardware translates an effective address to a physical address using
        either of two mechanisms: 1) Block Address Translation (BAT) or
        2) segment + page translation. The first mechanism does this directly
        using two sets (for data/instructions) of special purpose registers.
        The latter mechanism is of more relevance here, though:

        effective address (32 bit):          [ 0 ESID  3 | 4  PIX 19 | 20 Byte 31 ]
                                                                           |           |            |
                                                             (segment registers)   |            |
                                                                               |           |            |
        virtual address (52 bit):   [ 0      VSID 23 | 24 PIX 39 | 40 Byte 51 ]
                                    [ 0             VPN       39 | 40 Byte 51 ]
                                                                                 |                  |
                                                                                   (page table)             |
                                                                                             |                  |
        physical address (32 bit):       [ 0        PPN       19 | 20 Byte 31 ]


        ESID: Effective Segment ID
        VSID: Virtual Segment ID
        PIX:  Page Index
        VPN:  Virtual Page Number
        PPN:  Physical Page Number


        Unlike on x86 we can't just switch the context to another team by just
        setting a register to another page directory, since we only have one
        page table containing both kernel and user address mappings. Instead we
        map the effective address space of kernel and *all* teams
        non-intersectingly into the virtual address space (which fortunately is
        20 bits wider), and use the segment registers to select the section of
        the virtual address space for the current team. Half of the 16 segment
        registers (8 - 15) map the kernel addresses, so they remain unchanged.

        The range of the virtual address space a team's effective address space
        is mapped to is defined by its PPCVMTranslationMap::fVSIDBase,
        which is the first of the 8 successive VSID values used for the team.

        Which fVSIDBase values are already taken is defined by the set bits in
        the bitmap sVSIDBaseBitmap.


        TODO:
        * If we want to continue to use the OF services, we would need to add
          its address mappings to the kernel space. Unfortunately some stuff
          (especially RAM) is mapped in an address range without the kernel
          address space. We probably need to map those into each team's address
          space as kernel read/write areas.
        * The current locking scheme is insufficient. The page table is a resource
          shared by all teams. We need to synchronize access to it. Probably via a
          spinlock.
 */

#include "paging/460/PPCVMTranslationMap460.h"

#include <stdlib.h>
#include <string.h>

#include <arch/cpu.h>
#include <arch_mmu.h>
#include <interrupts.h>
#include <thread.h>
#include <slab/Slab.h>
#include <smp.h>
#include <util/AutoLock.h>
#include <util/ThreadAutoLock.h>
#include <util/queue.h>
#include <vm/vm_page.h>
#include <vm/vm_priv.h>
#include <vm/VMAddressSpace.h>
#include <vm/VMCache.h>

#include "paging/460/PPCPagingMethod460.h"
#include "paging/460/PPCPagingStructures460.h"
#include "generic_vm_physical_page_mapper.h"
#include "generic_vm_physical_page_ops.h"
#include "GenericVMPhysicalPageMapper.h"


//#define TRACE_PPC_VM_TRANSLATION_MAP_460
#ifdef TRACE_PPC_VM_TRANSLATION_MAP_460
#       define TRACE(x...) dprintf(x)
#else
#       define TRACE(x...) ;
#endif


// The VSID is a 24 bit number. The lower three bits are defined by the
// (effective) segment number, which leaves us with a 21 bit space of
// VSID bases (= 2 * 1024 * 1024).
#define MAX_VSID_BASES (B_PAGE_SIZE * 8)
static uint32 sVSIDBaseBitmap[MAX_VSID_BASES / (sizeof(uint32) * 8)];
static spinlock sVSIDBaseBitmapLock;

#define VSID_BASE_SHIFT 3
#define VADDR_TO_VSID(vsidBase, vaddr) (vsidBase + ((vaddr) >> 28))


// #pragma mark -


PPCVMTranslationMap460::PPCVMTranslationMap460()
        :
        fPagingStructures(NULL)
{
}


PPCVMTranslationMap460::~PPCVMTranslationMap460()
{
        if (fPagingStructures == NULL)
                return;

#if 0//X86
        if (fPageMapper != NULL)
                fPageMapper->Delete();
#endif

        if (fMapCount > 0) {
                panic("vm_translation_map.destroy_tmap: map %p has positive map count %ld\n",
                        this, fMapCount);
        }

        // mark the vsid base not in use
        int baseBit = fVSIDBase >> VSID_BASE_SHIFT;
        atomic_and((int32 *)&sVSIDBaseBitmap[baseBit / 32],
                        ~(1 << (baseBit % 32)));

#if 0//X86
        if (fPagingStructures->pgdir_virt != NULL) {
                // cycle through and free all of the user space pgtables
                for (uint32 i = VADDR_TO_PDENT(USER_BASE);
                                i <= VADDR_TO_PDENT(USER_BASE + (USER_SIZE - 1)); i++) {
                        if ((fPagingStructures->pgdir_virt[i] & PPC_PDE_PRESENT) != 0) {
                                addr_t address = fPagingStructures->pgdir_virt[i]
                                        & PPC_PDE_ADDRESS_MASK;
                                vm_page* page = vm_lookup_page(address / B_PAGE_SIZE);
                                if (!page)
                                        panic("destroy_tmap: didn't find pgtable page\n");
                                DEBUG_PAGE_ACCESS_START(page);
                                vm_page_free_etc(NULL, page, &reservation);
                        }
                }
        }
#endif

        fPagingStructures->RemoveReference();
}


status_t
PPCVMTranslationMap460::Init(bool kernel)
{
        TRACE("PPCVMTranslationMap460::Init()\n");

        PPCVMTranslationMap::Init(kernel);

        cpu_status state = disable_interrupts();
        acquire_spinlock(&sVSIDBaseBitmapLock);

        // allocate a VSID base for this one
        if (kernel) {
                // The boot loader has set up the segment registers for identical
                // mapping. Two VSID bases are reserved for the kernel: 0 and 8. The
                // latter one for mapping the kernel address space (0x80000000...), the
                // former one for the lower addresses required by the Open Firmware
                // services.
                fVSIDBase = 0;
                sVSIDBaseBitmap[0] |= 0x3;
        } else {
                int i = 0;

                while (i < MAX_VSID_BASES) {
                        if (sVSIDBaseBitmap[i / 32] == 0xffffffff) {
                                i += 32;
                                continue;
                        }
                        if ((sVSIDBaseBitmap[i / 32] & (1 << (i % 32))) == 0) {
                                // we found it
                                sVSIDBaseBitmap[i / 32] |= 1 << (i % 32);
                                break;
                        }
                        i++;
                }
                if (i >= MAX_VSID_BASES)
                        panic("vm_translation_map_create: out of VSID bases\n");
                fVSIDBase = i << VSID_BASE_SHIFT;
        }

        release_spinlock(&sVSIDBaseBitmapLock);
        restore_interrupts(state);

        fPagingStructures = new(std::nothrow) PPCPagingStructures460;
        if (fPagingStructures == NULL)
                return B_NO_MEMORY;

        PPCPagingMethod460* method = PPCPagingMethod460::Method();

        if (!kernel) {
                // user
#if 0//X86
                // allocate a physical page mapper
                status_t error = method->PhysicalPageMapper()
                        ->CreateTranslationMapPhysicalPageMapper(&fPageMapper);
                if (error != B_OK)
                        return error;
#endif
#if 0//X86
                // allocate the page directory
                page_directory_entry* virtualPageDir = (page_directory_entry*)memalign(
                        B_PAGE_SIZE, B_PAGE_SIZE);
                if (virtualPageDir == NULL)
                        return B_NO_MEMORY;

                // look up the page directory's physical address
                phys_addr_t physicalPageDir;
                vm_get_page_mapping(VMAddressSpace::KernelID(),
                        (addr_t)virtualPageDir, &physicalPageDir);
#endif

                fPagingStructures->Init(/*NULL, 0,
                        method->KernelVirtualPageDirectory()*/method->PageTable());
        } else {
                // kernel
#if 0//X86
                // get the physical page mapper
                fPageMapper = method->KernelPhysicalPageMapper();
#endif

                // we already know the kernel pgdir mapping
                fPagingStructures->Init(/*method->KernelVirtualPageDirectory(),
                        method->KernelPhysicalPageDirectory(), NULL*/method->PageTable());
        }

        return B_OK;
}


void
PPCVMTranslationMap460::ChangeASID()
{
// this code depends on the kernel being at 0x80000000, fix if we change that
#if KERNEL_BASE != 0x80000000
#error fix me
#endif
        int vsidBase = VSIDBase();

        isync();        // synchronize context
        asm("mtsr       0,%0" : : "g"(vsidBase));
        asm("mtsr       1,%0" : : "g"(vsidBase + 1));
        asm("mtsr       2,%0" : : "g"(vsidBase + 2));
        asm("mtsr       3,%0" : : "g"(vsidBase + 3));
        asm("mtsr       4,%0" : : "g"(vsidBase + 4));
        asm("mtsr       5,%0" : : "g"(vsidBase + 5));
        asm("mtsr       6,%0" : : "g"(vsidBase + 6));
        asm("mtsr       7,%0" : : "g"(vsidBase + 7));
        isync();        // synchronize context
}


page_table_entry *
PPCVMTranslationMap460::LookupPageTableEntry(addr_t virtualAddress)
{
        // lookup the vsid based off the va
        uint32 virtualSegmentID = VADDR_TO_VSID(fVSIDBase, virtualAddress);

//      dprintf("vm_translation_map.lookup_page_table_entry: vsid %ld, va 0x%lx\n", virtualSegmentID, virtualAddress);

        PPCPagingMethod460* m = PPCPagingMethod460::Method();

        // Search for the page table entry using the primary hash value

        uint32 hash = page_table_entry::PrimaryHash(virtualSegmentID, virtualAddress);
        page_table_entry_group *group = &(m->PageTable())[hash & m->PageTableHashMask()];

        for (int i = 0; i < 8; i++) {
                page_table_entry *entry = &group->entry[i];

                if (entry->virtual_segment_id == virtualSegmentID
                        && entry->secondary_hash == false
                        && entry->abbr_page_index == ((virtualAddress >> 22) & 0x3f))
                        return entry;
        }

        // didn't find it, try the secondary hash value

        hash = page_table_entry::SecondaryHash(hash);
        group = &(m->PageTable())[hash & m->PageTableHashMask()];

        for (int i = 0; i < 8; i++) {
                page_table_entry *entry = &group->entry[i];

                if (entry->virtual_segment_id == virtualSegmentID
                        && entry->secondary_hash == true
                        && entry->abbr_page_index == ((virtualAddress >> 22) & 0x3f))
                        return entry;
        }

        return NULL;
}


bool
PPCVMTranslationMap460::RemovePageTableEntry(addr_t virtualAddress)
{
        page_table_entry *entry = LookupPageTableEntry(virtualAddress);
        if (entry == NULL)
                return false;

        entry->valid = 0;
        ppc_sync();
        tlbie(virtualAddress);
        eieio();
        tlbsync();
        ppc_sync();

        return true;
}


size_t
PPCVMTranslationMap460::MaxPagesNeededToMap(addr_t start, addr_t end) const
{
        return 0;
}


status_t
PPCVMTranslationMap460::Map(addr_t virtualAddress,
        phys_addr_t physicalAddress, uint32 attributes,
        uint32 memoryType, vm_page_reservation* reservation)
{
        TRACE("map_tmap: entry pa 0x%lx va 0x%lx\n", pa, va);

        // lookup the vsid based off the va
        uint32 virtualSegmentID = VADDR_TO_VSID(fVSIDBase, virtualAddress);
        uint32 protection = 0;

        // ToDo: check this
        // all kernel mappings are R/W to supervisor code
        if (attributes & (B_READ_AREA | B_WRITE_AREA))
                protection = (attributes & B_WRITE_AREA) ? PTE_READ_WRITE : PTE_READ_ONLY;

        //dprintf("vm_translation_map.map_tmap: vsid %d, pa 0x%lx, va 0x%lx\n", vsid, pa, va);

        PPCPagingMethod460* m = PPCPagingMethod460::Method();

        // Search for a free page table slot using the primary hash value
        uint32 hash = page_table_entry::PrimaryHash(virtualSegmentID, virtualAddress);
        page_table_entry_group *group = &(m->PageTable())[hash & m->PageTableHashMask()];

        for (int i = 0; i < 8; i++) {
                page_table_entry *entry = &group->entry[i];

                if (entry->valid)
                        continue;

                m->FillPageTableEntry(entry, virtualSegmentID, virtualAddress,
                        physicalAddress, protection, memoryType, false);
                fMapCount++;
                return B_OK;
        }

        // Didn't found one, try the secondary hash value

        hash = page_table_entry::SecondaryHash(hash);
        group = &(m->PageTable())[hash & m->PageTableHashMask()];

        for (int i = 0; i < 8; i++) {
                page_table_entry *entry = &group->entry[i];

                if (entry->valid)
                        continue;

                m->FillPageTableEntry(entry, virtualSegmentID, virtualAddress,
                        physicalAddress, protection, memoryType, false);
                fMapCount++;
                return B_OK;
        }

        panic("vm_translation_map.map_tmap: hash table full\n");
        return B_ERROR;

#if 0//X86
/*
        dprintf("pgdir at 0x%x\n", pgdir);
        dprintf("index is %d\n", va / B_PAGE_SIZE / 1024);
        dprintf("final at 0x%x\n", &pgdir[va / B_PAGE_SIZE / 1024]);
        dprintf("value is 0x%x\n", *(int *)&pgdir[va / B_PAGE_SIZE / 1024]);
        dprintf("present bit is %d\n", pgdir[va / B_PAGE_SIZE / 1024].present);
        dprintf("addr is %d\n", pgdir[va / B_PAGE_SIZE / 1024].addr);
*/
        page_directory_entry* pd = fPagingStructures->pgdir_virt;

        // check to see if a page table exists for this range
        uint32 index = VADDR_TO_PDENT(va);
        if ((pd[index] & PPC_PDE_PRESENT) == 0) {
                phys_addr_t pgtable;
                vm_page *page;

                // we need to allocate a pgtable
                page = vm_page_allocate_page(reservation,
                        PAGE_STATE_WIRED | VM_PAGE_ALLOC_CLEAR);

                DEBUG_PAGE_ACCESS_END(page);

                pgtable = (phys_addr_t)page->physical_page_number * B_PAGE_SIZE;

                TRACE("map_tmap: asked for free page for pgtable. 0x%lx\n", pgtable);

                // put it in the pgdir
                PPCPagingMethod460::PutPageTableInPageDir(&pd[index], pgtable,
                        attributes
                                | ((attributes & B_USER_PROTECTION) != 0
                                                ? B_WRITE_AREA : B_KERNEL_WRITE_AREA));

                // update any other page directories, if it maps kernel space
                if (index >= FIRST_KERNEL_PGDIR_ENT
                        && index < (FIRST_KERNEL_PGDIR_ENT + NUM_KERNEL_PGDIR_ENTS)) {
                        PPCPagingStructures460::UpdateAllPageDirs(index, pd[index]);
                }

                fMapCount++;
        }

        // now, fill in the pentry
        Thread* thread = thread_get_current_thread();
        ThreadCPUPinner pinner(thread);

        page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                pd[index] & PPC_PDE_ADDRESS_MASK);
        index = VADDR_TO_PTENT(va);

        ASSERT_PRINT((pt[index] & PPC_PTE_PRESENT) == 0,
                "virtual address: %#" B_PRIxADDR ", existing pte: %#" B_PRIx32, va,
                pt[index]);

        PPCPagingMethod460::PutPageTableEntryInTable(&pt[index], pa, attributes,
                memoryType, fIsKernelMap);

        pinner.Unlock();

        // Note: We don't need to invalidate the TLB for this address, as previously
        // the entry was not present and the TLB doesn't cache those entries.

        fMapCount++;

        return 0;
#endif
}


status_t
PPCVMTranslationMap460::Unmap(addr_t start, addr_t end)
{
        page_table_entry *entry;

        start = ROUNDDOWN(start, B_PAGE_SIZE);
        end = ROUNDUP(end, B_PAGE_SIZE);

        if (start >= end)
                return B_OK;

        TRACE("unmap_tmap: asked to free pages 0x%lx to 0x%lx\n", start, end);

//      dprintf("vm_translation_map.unmap_tmap: start 0x%lx, end 0x%lx\n", start, end);

        while (start < end) {
                if (RemovePageTableEntry(start))
                        fMapCount--;

                start += B_PAGE_SIZE;
        }

        return B_OK;

#if 0//X86

        start = ROUNDDOWN(start, B_PAGE_SIZE);
        if (start >= end)
                return B_OK;

        TRACE("unmap_tmap: asked to free pages 0x%lx to 0x%lx\n", start, end);

        page_directory_entry *pd = fPagingStructures->pgdir_virt;

        do {
                int index = VADDR_TO_PDENT(start);
                if ((pd[index] & PPC_PDE_PRESENT) == 0) {
                        // no page table here, move the start up to access the next page
                        // table
                        start = ROUNDUP(start + 1, kPageTableAlignment);
                        continue;
                }

                Thread* thread = thread_get_current_thread();
                ThreadCPUPinner pinner(thread);

                page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                        pd[index] & PPC_PDE_ADDRESS_MASK);

                for (index = VADDR_TO_PTENT(start); (index < 1024) && (start < end);
                                index++, start += B_PAGE_SIZE) {
                        if ((pt[index] & PPC_PTE_PRESENT) == 0) {
                                // page mapping not valid
                                continue;
                        }

                        TRACE("unmap_tmap: removing page 0x%lx\n", start);

                        page_table_entry oldEntry
                                = PPCPagingMethod460::ClearPageTableEntryFlags(&pt[index],
                                        PPC_PTE_PRESENT);
                        fMapCount--;

                        if ((oldEntry & PPC_PTE_ACCESSED) != 0) {
                                // Note, that we only need to invalidate the address, if the
                                // accessed flags was set, since only then the entry could have
                                // been in any TLB.
                                InvalidatePage(start);
                        }
                }
        } while (start != 0 && start < end);

        return B_OK;
#endif
}


status_t
PPCVMTranslationMap460::RemapAddressRange(addr_t *_virtualAddress,
        size_t size, bool unmap)
{
        addr_t virtualAddress = ROUNDDOWN(*_virtualAddress, B_PAGE_SIZE);
        size = ROUNDUP(*_virtualAddress + size - virtualAddress, B_PAGE_SIZE);

        VMAddressSpace *addressSpace = VMAddressSpace::Kernel();

        // reserve space in the address space
        void *newAddress = NULL;
        status_t error = vm_reserve_address_range(addressSpace->ID(), &newAddress,
                B_ANY_KERNEL_ADDRESS, size, B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA);
        if (error != B_OK)
                return error;

        // get the area's first physical page
        page_table_entry *entry = LookupPageTableEntry(virtualAddress);
        if (!entry)
                return B_ERROR;
        phys_addr_t physicalBase = (phys_addr_t)entry->physical_page_number << 12;

        // map the pages
        error = ppc_map_address_range((addr_t)newAddress, physicalBase, size);
        if (error != B_OK)
                return error;

        *_virtualAddress = (addr_t)newAddress;

        // unmap the old pages
        if (unmap)
                ppc_unmap_address_range(virtualAddress, size);

        return B_OK;
}


status_t
PPCVMTranslationMap460::UnmapPage(VMArea* area, addr_t address,
        bool updatePageQueue, bool deletingAddressSpace, uint32* _flags)
{
        ASSERT(address % B_PAGE_SIZE == 0);
        ASSERT(_flags == NULL || !updatePageQueue);

        RecursiveLocker locker(fLock);

        if (area->cache_type == CACHE_TYPE_DEVICE) {
                if (!RemovePageTableEntry(address))
                        return B_ENTRY_NOT_FOUND;

                fMapCount--;
                return B_OK;
        }

        page_table_entry* entry = LookupPageTableEntry(address);
        if (entry == NULL)
                return B_ENTRY_NOT_FOUND;

        page_num_t pageNumber = entry->physical_page_number;
        bool accessed = entry->referenced;
        bool modified = entry->changed;

        RemovePageTableEntry(address);

        fMapCount--;

        if (_flags == NULL) {
                locker.Detach();
                        // PageUnmapped() will unlock for us

                PageUnmapped(area, pageNumber, accessed, modified, updatePageQueue);
        } else {
                uint32 flags = PAGE_PRESENT;
                if (accessed)
                        flags |= PAGE_ACCESSED;
                if (modified)
                        flags |= PAGE_MODIFIED;
                *_flags = flags;
        }

        return B_OK;

#if 0//X86

        ASSERT(address % B_PAGE_SIZE == 0);

        page_directory_entry* pd = fPagingStructures->pgdir_virt;

        TRACE("PPCVMTranslationMap460::UnmapPage(%#" B_PRIxADDR ")\n", address);

        RecursiveLocker locker(fLock);

        int index = VADDR_TO_PDENT(address);
        if ((pd[index] & PPC_PDE_PRESENT) == 0)
                return B_ENTRY_NOT_FOUND;

        ThreadCPUPinner pinner(thread_get_current_thread());

        page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                pd[index] & PPC_PDE_ADDRESS_MASK);

        index = VADDR_TO_PTENT(address);
        page_table_entry oldEntry = PPCPagingMethod460::ClearPageTableEntry(
                &pt[index]);

        pinner.Unlock();

        if ((oldEntry & PPC_PTE_PRESENT) == 0) {
                // page mapping not valid
                return B_ENTRY_NOT_FOUND;
        }

        fMapCount--;

        if ((oldEntry & PPC_PTE_ACCESSED) != 0) {
                // Note, that we only need to invalidate the address, if the
                // accessed flags was set, since only then the entry could have been
                // in any TLB.
                InvalidatePage(address);
                Flush();

                // NOTE: Between clearing the page table entry and Flush() other
                // processors (actually even this processor with another thread of the
                // same team) could still access the page in question via their cached
                // entry. We can obviously lose a modified flag in this case, with the
                // effect that the page looks unmodified (and might thus be recycled),
                // but is actually modified.
                // In most cases this is harmless, but for vm_remove_all_page_mappings()
                // this is actually a problem.
                // Interestingly FreeBSD seems to ignore this problem as well
                // (cf. pmap_remove_all()), unless I've missed something.
        }

        locker.Detach();
                // PageUnmapped() will unlock for us

        PageUnmapped(area, (oldEntry & PPC_PTE_ADDRESS_MASK) / B_PAGE_SIZE,
                (oldEntry & PPC_PTE_ACCESSED) != 0, (oldEntry & PPC_PTE_DIRTY) != 0,
                updatePageQueue);

        return B_OK;
#endif
}


void
PPCVMTranslationMap460::UnmapPages(VMArea* area, addr_t base, size_t size,
        bool updatePageQueue, bool deletingAddressSpace)
{
        panic("%s: UNIMPLEMENTED", __FUNCTION__);
#if 0//X86
        if (size == 0)
                return;

        addr_t start = base;
        addr_t end = base + size - 1;

        TRACE("PPCVMTranslationMap460::UnmapPages(%p, %#" B_PRIxADDR ", %#"
                B_PRIxADDR ")\n", area, start, end);

        page_directory_entry* pd = fPagingStructures->pgdir_virt;

        VMAreaMappings queue;

        RecursiveLocker locker(fLock);

        do {
                int index = VADDR_TO_PDENT(start);
                if ((pd[index] & PPC_PDE_PRESENT) == 0) {
                        // no page table here, move the start up to access the next page
                        // table
                        start = ROUNDUP(start + 1, kPageTableAlignment);
                        continue;
                }

                Thread* thread = thread_get_current_thread();
                ThreadCPUPinner pinner(thread);

                page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                        pd[index] & PPC_PDE_ADDRESS_MASK);

                for (index = VADDR_TO_PTENT(start); (index < 1024) && (start < end);
                                index++, start += B_PAGE_SIZE) {
                        page_table_entry oldEntry
                                = PPCPagingMethod460::ClearPageTableEntry(&pt[index]);
                        if ((oldEntry & PPC_PTE_PRESENT) == 0)
                                continue;

                        fMapCount--;

                        if ((oldEntry & PPC_PTE_ACCESSED) != 0) {
                                // Note, that we only need to invalidate the address, if the
                                // accessed flags was set, since only then the entry could have
                                // been in any TLB.
                                if (!deletingAddressSpace)
                                        InvalidatePage(start);
                        }

                        if (area->cache_type != CACHE_TYPE_DEVICE) {
                                page_num_t page = (oldEntry & PPC_PTE_ADDRESS_MASK) / B_PAGE_SIZE;
                                PageUnmapped(area, page,
                                        (oldEntry & PPC_PTE_ACCESSED) != 0,
                                        (oldEntry & PPC_PTE_DIRTY) != 0,
                                        updatePageQueue, &queue);
                        }
                }

                Flush();
                        // flush explicitly, since we directly use the lock
        } while (start != 0 && start < end);

        // TODO: As in UnmapPage() we can lose page dirty flags here. ATM it's not
        // really critical here, as in all cases this method is used, the unmapped
        // area range is unmapped for good (resized/cut) and the pages will likely
        // be freed.

        locker.Unlock();

        // free removed mappings
        bool isKernelSpace = area->address_space == VMAddressSpace::Kernel();
        uint32 freeFlags = CACHE_DONT_WAIT_FOR_MEMORY
                | (isKernelSpace ? CACHE_DONT_LOCK_KERNEL_SPACE : 0);
        while (vm_page_mapping* mapping = queue.RemoveHead())
                vm_free_page_mapping(mapping->page->physical_page_number, mapping, freeFlags);
#endif
}


status_t
PPCVMTranslationMap460::Query(addr_t va, phys_addr_t *_outPhysical,
        uint32 *_outFlags)
{
        page_table_entry *entry;

        // default the flags to not present
        *_outFlags = 0;
        *_outPhysical = 0;

        entry = LookupPageTableEntry(va);
        if (entry == NULL)
                return B_NO_ERROR;

        // ToDo: check this!
        if (IS_KERNEL_ADDRESS(va))
                *_outFlags |= B_KERNEL_READ_AREA | (entry->page_protection == PTE_READ_ONLY ? 0 : B_KERNEL_WRITE_AREA);
        else
                *_outFlags |= B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA | B_READ_AREA | (entry->page_protection == PTE_READ_ONLY ? 0 : B_WRITE_AREA);

        *_outFlags |= entry->changed ? PAGE_MODIFIED : 0;
        *_outFlags |= entry->referenced ? PAGE_ACCESSED : 0;
        *_outFlags |= entry->valid ? PAGE_PRESENT : 0;

        *_outPhysical = entry->physical_page_number * B_PAGE_SIZE;

        return B_OK;

#if 0//X86
        // default the flags to not present
        *_flags = 0;
        *_physical = 0;

        int index = VADDR_TO_PDENT(va);
        page_directory_entry *pd = fPagingStructures->pgdir_virt;
        if ((pd[index] & PPC_PDE_PRESENT) == 0) {
                // no pagetable here
                return B_OK;
        }

        Thread* thread = thread_get_current_thread();
        ThreadCPUPinner pinner(thread);

        page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                pd[index] & PPC_PDE_ADDRESS_MASK);
        page_table_entry entry = pt[VADDR_TO_PTENT(va)];

        *_physical = entry & PPC_PDE_ADDRESS_MASK;

        // read in the page state flags
        if ((entry & PPC_PTE_USER) != 0) {
                *_flags |= ((entry & PPC_PTE_WRITABLE) != 0 ? B_WRITE_AREA : 0)
                        | B_READ_AREA;
        }

        *_flags |= ((entry & PPC_PTE_WRITABLE) != 0 ? B_KERNEL_WRITE_AREA : 0)
                | B_KERNEL_READ_AREA
                | ((entry & PPC_PTE_DIRTY) != 0 ? PAGE_MODIFIED : 0)
                | ((entry & PPC_PTE_ACCESSED) != 0 ? PAGE_ACCESSED : 0)
                | ((entry & PPC_PTE_PRESENT) != 0 ? PAGE_PRESENT : 0);

        pinner.Unlock();

        TRACE("query_tmap: returning pa 0x%lx for va 0x%lx\n", *_physical, va);

        return B_OK;
#endif
}


status_t
PPCVMTranslationMap460::QueryInterrupt(addr_t virtualAddress,
        phys_addr_t *_physicalAddress, uint32 *_flags)
{
        return PPCVMTranslationMap460::Query(virtualAddress, _physicalAddress, _flags);

#if 0//X86
        *_flags = 0;
        *_physical = 0;

        int index = VADDR_TO_PDENT(va);
        page_directory_entry* pd = fPagingStructures->pgdir_virt;
        if ((pd[index] & PPC_PDE_PRESENT) == 0) {
                // no pagetable here
                return B_OK;
        }

        // map page table entry
        page_table_entry* pt = (page_table_entry*)PPCPagingMethod460::Method()
                ->PhysicalPageMapper()->InterruptGetPageTableAt(
                        pd[index] & PPC_PDE_ADDRESS_MASK);
        page_table_entry entry = pt[VADDR_TO_PTENT(va)];

        *_physical = entry & PPC_PDE_ADDRESS_MASK;

        // read in the page state flags
        if ((entry & PPC_PTE_USER) != 0) {
                *_flags |= ((entry & PPC_PTE_WRITABLE) != 0 ? B_WRITE_AREA : 0)
                        | B_READ_AREA;
        }

        *_flags |= ((entry & PPC_PTE_WRITABLE) != 0 ? B_KERNEL_WRITE_AREA : 0)
                | B_KERNEL_READ_AREA
                | ((entry & PPC_PTE_DIRTY) != 0 ? PAGE_MODIFIED : 0)
                | ((entry & PPC_PTE_ACCESSED) != 0 ? PAGE_ACCESSED : 0)
                | ((entry & PPC_PTE_PRESENT) != 0 ? PAGE_PRESENT : 0);

        return B_OK;
#endif
}


status_t
PPCVMTranslationMap460::Protect(addr_t start, addr_t end, uint32 attributes,
        uint32 memoryType)
{
        // XXX finish
        return B_ERROR;
#if 0//X86
        start = ROUNDDOWN(start, B_PAGE_SIZE);
        if (start >= end)
                return B_OK;

        TRACE("protect_tmap: pages 0x%lx to 0x%lx, attributes %lx\n", start, end,
                attributes);

        // compute protection flags
        uint32 newProtectionFlags = 0;
        if ((attributes & B_USER_PROTECTION) != 0) {
                newProtectionFlags = PPC_PTE_USER;
                if ((attributes & B_WRITE_AREA) != 0)
                        newProtectionFlags |= PPC_PTE_WRITABLE;
        } else if ((attributes & B_KERNEL_WRITE_AREA) != 0)
                newProtectionFlags = PPC_PTE_WRITABLE;

        page_directory_entry *pd = fPagingStructures->pgdir_virt;

        do {
                int index = VADDR_TO_PDENT(start);
                if ((pd[index] & PPC_PDE_PRESENT) == 0) {
                        // no page table here, move the start up to access the next page
                        // table
                        start = ROUNDUP(start + 1, kPageTableAlignment);
                        continue;
                }

                Thread* thread = thread_get_current_thread();
                ThreadCPUPinner pinner(thread);

                page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                        pd[index] & PPC_PDE_ADDRESS_MASK);

                for (index = VADDR_TO_PTENT(start); index < 1024 && start < end;
                                index++, start += B_PAGE_SIZE) {
                        page_table_entry entry = pt[index];
                        if ((entry & PPC_PTE_PRESENT) == 0) {
                                // page mapping not valid
                                continue;
                        }

                        TRACE("protect_tmap: protect page 0x%lx\n", start);

                        // set the new protection flags -- we want to do that atomically,
                        // without changing the accessed or dirty flag
                        page_table_entry oldEntry;
                        while (true) {
                                oldEntry = PPCPagingMethod460::TestAndSetPageTableEntry(
                                        &pt[index],
                                        (entry & ~(PPC_PTE_PROTECTION_MASK
                                                        | PPC_PTE_MEMORY_TYPE_MASK))
                                                | newProtectionFlags
                                                | PPCPagingMethod460::MemoryTypeToPageTableEntryFlags(
                                                        memoryType),
                                        entry);
                                if (oldEntry == entry)
                                        break;
                                entry = oldEntry;
                        }

                        if ((oldEntry & PPC_PTE_ACCESSED) != 0) {
                                // Note, that we only need to invalidate the address, if the
                                // accessed flag was set, since only then the entry could have
                                // been in any TLB.
                                InvalidatePage(start);
                        }
                }
        } while (start != 0 && start < end);

        return B_OK;
#endif
}


status_t
PPCVMTranslationMap460::ClearFlags(addr_t virtualAddress, uint32 flags)
{
        page_table_entry *entry = LookupPageTableEntry(virtualAddress);
        if (entry == NULL)
                return B_NO_ERROR;

        bool modified = false;

        // clear the bits
        if (flags & PAGE_MODIFIED && entry->changed) {
                entry->changed = false;
                modified = true;
        }
        if (flags & PAGE_ACCESSED && entry->referenced) {
                entry->referenced = false;
                modified = true;
        }

        // synchronize
        if (modified) {
                tlbie(virtualAddress);
                eieio();
                tlbsync();
                ppc_sync();
        }

        return B_OK;

#if 0//X86
        int index = VADDR_TO_PDENT(va);
        page_directory_entry* pd = fPagingStructures->pgdir_virt;
        if ((pd[index] & PPC_PDE_PRESENT) == 0) {
                // no pagetable here
                return B_OK;
        }

        uint32 flagsToClear = ((flags & PAGE_MODIFIED) ? PPC_PTE_DIRTY : 0)
                | ((flags & PAGE_ACCESSED) ? PPC_PTE_ACCESSED : 0);

        Thread* thread = thread_get_current_thread();
        ThreadCPUPinner pinner(thread);

        page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                pd[index] & PPC_PDE_ADDRESS_MASK);
        index = VADDR_TO_PTENT(va);

        // clear out the flags we've been requested to clear
        page_table_entry oldEntry
                = PPCPagingMethod460::ClearPageTableEntryFlags(&pt[index],
                        flagsToClear);

        pinner.Unlock();

        if ((oldEntry & flagsToClear) != 0)
                InvalidatePage(va);

        return B_OK;
#endif
}


bool
PPCVMTranslationMap460::ClearAccessedAndModified(VMArea* area,
        addr_t address, bool unmapIfUnaccessed, bool& _modified)
{
        ASSERT(address % B_PAGE_SIZE == 0);

        // TODO: Implement for real! ATM this is just an approximation using
        // Query(), ClearFlags(), and UnmapPage(). See below!

        RecursiveLocker locker(fLock);

        uint32 flags;
        phys_addr_t physicalAddress;
        if (Query(address, &physicalAddress, &flags) != B_OK
                || (flags & PAGE_PRESENT) == 0) {
                return false;
        }

        _modified = (flags & PAGE_MODIFIED) != 0;

        if ((flags & (PAGE_ACCESSED | PAGE_MODIFIED)) != 0)
                ClearFlags(address, flags & (PAGE_ACCESSED | PAGE_MODIFIED));

        if ((flags & PAGE_ACCESSED) != 0)
                return true;

        if (!unmapIfUnaccessed)
                return false;

        locker.Unlock();

        UnmapPage(area, address, false);
                // TODO: Obvious race condition: Between querying and unmapping the
                // page could have been accessed. We try to compensate by considering
                // vm_page::{accessed,modified} (which would have been updated by
                // UnmapPage()) below, but that doesn't quite match the required
                // semantics of the method.

        vm_page* page = vm_lookup_page(physicalAddress / B_PAGE_SIZE);
        if (page == NULL)
                return false;

        _modified |= page->modified;

        return page->accessed;

#if 0//X86
        page_directory_entry* pd = fPagingStructures->pgdir_virt;

        TRACE("PPCVMTranslationMap460::ClearAccessedAndModified(%#" B_PRIxADDR
                ")\n", address);

        RecursiveLocker locker(fLock);

        int index = VADDR_TO_PDENT(address);
        if ((pd[index] & PPC_PDE_PRESENT) == 0)
                return false;

        ThreadCPUPinner pinner(thread_get_current_thread());

        page_table_entry* pt = (page_table_entry*)fPageMapper->GetPageTableAt(
                pd[index] & PPC_PDE_ADDRESS_MASK);

        index = VADDR_TO_PTENT(address);

        // perform the deed
        page_table_entry oldEntry;

        if (unmapIfUnaccessed) {
                while (true) {
                        oldEntry = pt[index];
                        if ((oldEntry & PPC_PTE_PRESENT) == 0) {
                                // page mapping not valid
                                return false;
                        }

                        if (oldEntry & PPC_PTE_ACCESSED) {
                                // page was accessed -- just clear the flags
                                oldEntry = PPCPagingMethod460::ClearPageTableEntryFlags(
                                        &pt[index], PPC_PTE_ACCESSED | PPC_PTE_DIRTY);
                                break;
                        }

                        // page hasn't been accessed -- unmap it
                        if (PPCPagingMethod460::TestAndSetPageTableEntry(&pt[index], 0,
                                        oldEntry) == oldEntry) {
                                break;
                        }

                        // something changed -- check again
                }
        } else {
                oldEntry = PPCPagingMethod460::ClearPageTableEntryFlags(&pt[index],
                        PPC_PTE_ACCESSED | PPC_PTE_DIRTY);
        }

        pinner.Unlock();

        _modified = (oldEntry & PPC_PTE_DIRTY) != 0;

        if ((oldEntry & PPC_PTE_ACCESSED) != 0) {
                // Note, that we only need to invalidate the address, if the
                // accessed flags was set, since only then the entry could have been
                // in any TLB.
                InvalidatePage(address);

                Flush();

                return true;
        }

        if (!unmapIfUnaccessed)
                return false;

        // We have unmapped the address. Do the "high level" stuff.

        fMapCount--;

        locker.Detach();
                // UnaccessedPageUnmapped() will unlock for us

        UnaccessedPageUnmapped(area,
                (oldEntry & PPC_PTE_ADDRESS_MASK) / B_PAGE_SIZE);

        return false;
#endif
}


PPCPagingStructures*
PPCVMTranslationMap460::PagingStructures() const
{
        return fPagingStructures;
}