This is xnu-8019. See this file in:
/*
 * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
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 */

#include <IOKit/IOLib.h>
#include <IOKit/IOMultiMemoryDescriptor.h>

#define super IOMemoryDescriptor
OSDefineMetaClassAndStructors(IOMultiMemoryDescriptor, IOMemoryDescriptor)

IOMultiMemoryDescriptor * IOMultiMemoryDescriptor::withDescriptors(
	IOMemoryDescriptor * *descriptors,
	UInt32                withCount,
	IODirection           withDirection,
	bool                  asReference )
{
	//
	// Create a new IOMultiMemoryDescriptor.  The "buffer" is made up of several
	// memory descriptors, that are to be chained end-to-end to make up a single
	// memory descriptor.
	//
	// Passing the ranges as a reference will avoid an extra allocation.
	//

	IOMultiMemoryDescriptor * me = new IOMultiMemoryDescriptor;

	if (me && me->initWithDescriptors(
		    /* descriptors   */ descriptors,
		    /* withCount     */ withCount,
		    /* withDirection */ withDirection,
		    /* asReference   */ asReference ) == false) {
		me->release();
		me = NULL;
	}

	return me;
}

bool
IOMultiMemoryDescriptor::initWithDescriptors(
	IOMemoryDescriptor ** descriptors,
	UInt32                withCount,
	IODirection           withDirection,
	bool                  asReference )
{
	unsigned index;
	IOOptionBits copyFlags;
	//
	// Initialize an IOMultiMemoryDescriptor. The "buffer" is made up of several
	// memory descriptors, that are to be chained end-to-end to make up a single
	// memory descriptor.
	//
	// Passing the ranges as a reference will avoid an extra allocation.
	//

	assert(descriptors);

	// Release existing descriptors, if any
	if (_descriptors) {
		for (unsigned index = 0; index < _descriptorsCount; index++) {
			_descriptors[index]->release();
		}

		if (_descriptorsIsAllocated) {
			IODelete(_descriptors, IOMemoryDescriptor *, _descriptorsCount);
		}
	} else {
		// Ask our superclass' opinion.
		if (super::init() == false) {
			return false;
		}
	}

	// Initialize our minimal state.

	_descriptors            = NULL;
	_descriptorsCount       = withCount;
	_descriptorsIsAllocated = asReference ? false : true;
	_flags                  = withDirection;
#ifndef __LP64__
	_direction              = (IODirection) (_flags & kIOMemoryDirectionMask);
#endif /* !__LP64__ */
	_length                 = 0;
	_mappings               = NULL;
	_tag                    = 0;

	if (asReference) {
		_descriptors = descriptors;
	} else {
		_descriptors = IONew(IOMemoryDescriptor *, withCount);
		if (_descriptors == NULL) {
			return false;
		}

		bcopy( /* from  */ descriptors,
		    /* to    */ _descriptors,
		    /* bytes */ withCount * sizeof(IOMemoryDescriptor *));
	}

	for (index = 0; index < withCount; index++) {
		descriptors[index]->retain();
		_length += descriptors[index]->getLength();
		if (_tag == 0) {
			_tag = descriptors[index]->getTag();
		}
		assert(descriptors[index]->getDirection() ==
		    (withDirection & kIOMemoryDirectionMask));
	}

	enum { kCopyFlags = kIOMemoryBufferPageable };
	copyFlags = 0;
	for (index = 0; index < withCount; index++) {
		if (!index) {
			copyFlags =  (kCopyFlags & descriptors[index]->_flags);
		} else if (copyFlags != (kCopyFlags & descriptors[index]->_flags)) {
			break;
		}
	}
	if (index < withCount) {
		return false;
	}
	_flags |= copyFlags;

	return true;
}

void
IOMultiMemoryDescriptor::free()
{
	//
	// Free all of this object's outstanding resources.
	//

	if (_descriptors) {
		for (unsigned index = 0; index < _descriptorsCount; index++) {
			_descriptors[index]->release();
		}

		if (_descriptorsIsAllocated) {
			IODelete(_descriptors, IOMemoryDescriptor *, _descriptorsCount);
		}
	}

	super::free();
}

IOReturn
IOMultiMemoryDescriptor::prepare(IODirection forDirection)
{
	//
	// Prepare the memory for an I/O transfer.
	//
	// This involves paging in the memory and wiring it down for the duration
	// of the transfer.  The complete() method finishes the processing of the
	// memory after the I/O transfer finishes.
	//

	unsigned index;
	IOReturn status = kIOReturnInternalError;
	IOReturn statusUndo;

	if (forDirection == kIODirectionNone) {
		forDirection = getDirection();
	}

	for (index = 0; index < _descriptorsCount; index++) {
		status = _descriptors[index]->prepare(forDirection);
		if (status != kIOReturnSuccess) {
			break;
		}
	}

	if (status != kIOReturnSuccess) {
		for (unsigned indexUndo = 0; indexUndo < index; indexUndo++) {
			statusUndo = _descriptors[indexUndo]->complete(forDirection);
			assert(statusUndo == kIOReturnSuccess);
		}
	}

	return status;
}

IOReturn
IOMultiMemoryDescriptor::complete(IODirection forDirection)
{
	//
	// Complete processing of the memory after an I/O transfer finishes.
	//
	// This method shouldn't be called unless a prepare() was previously issued;
	// the prepare() and complete() must occur in pairs, before and after an I/O
	// transfer.
	//

	IOReturn status;
	IOReturn statusFinal = kIOReturnSuccess;

	if (forDirection == kIODirectionNone) {
		forDirection = getDirection();
	}

	for (unsigned index = 0; index < _descriptorsCount; index++) {
		status = _descriptors[index]->complete(forDirection);
		if (status != kIOReturnSuccess) {
			statusFinal = status;
		}
		assert(status == kIOReturnSuccess);
	}

	return statusFinal;
}

addr64_t
IOMultiMemoryDescriptor::getPhysicalSegment(IOByteCount   offset,
    IOByteCount * length,
    IOOptionBits  options)
{
	//
	// This method returns the physical address of the byte at the given offset
	// into the memory,  and optionally the length of the physically contiguous
	// segment from that offset.
	//

	assert(offset <= _length);

	for (unsigned index = 0; index < _descriptorsCount; index++) {
		if (offset < _descriptors[index]->getLength()) {
			return _descriptors[index]->getPhysicalSegment(offset, length, options);
		}
		offset -= _descriptors[index]->getLength();
	}

	if (length) {
		*length = 0;
	}

	return 0;
}

#include "IOKitKernelInternal.h"

IOReturn
IOMultiMemoryDescriptor::doMap(vm_map_t           __addressMap,
    IOVirtualAddress *  __address,
    IOOptionBits       options,
    IOByteCount        __offset,
    IOByteCount        __length)
{
	IOMemoryMap *     mapping = (IOMemoryMap *) *__address;
	vm_map_t          map     = mapping->fAddressMap;
	mach_vm_size_t    offset  = mapping->fOffset;
	mach_vm_size_t    length  = mapping->fLength;
	mach_vm_address_t address = mapping->fAddress;

	kern_return_t     err;
	IOOptionBits      subOptions;
	mach_vm_size_t    mapOffset;
	mach_vm_size_t    bytesRemaining, chunk;
	mach_vm_address_t nextAddress;
	IOMemoryDescriptorMapAllocRef ref;
	vm_prot_t                     prot;

	do{
		prot = VM_PROT_READ;
		if (!(kIOMapReadOnly & options)) {
			prot |= VM_PROT_WRITE;
		}

		if (kIOMapOverwrite & options) {
			if ((map == kernel_map) && (kIOMemoryBufferPageable & _flags)) {
				map = IOPageableMapForAddress(address);
			}
			err = KERN_SUCCESS;
		} else {
			ref.map     = map;
			ref.tag     = IOMemoryTag(map);
			ref.options = options;
			ref.size    = length;
			ref.prot    = prot;
			if (options & kIOMapAnywhere) {
				// vm_map looks for addresses above here, even when VM_FLAGS_ANYWHERE
				ref.mapped = 0;
			} else {
				ref.mapped = mapping->fAddress;
			}

			if ((ref.map == kernel_map) && (kIOMemoryBufferPageable & _flags)) {
				err = IOIteratePageableMaps(ref.size, &IOMemoryDescriptorMapAlloc, &ref);
			} else {
				err = IOMemoryDescriptorMapAlloc(ref.map, &ref);
			}

			if (KERN_SUCCESS != err) {
				break;
			}

			address = ref.mapped;
			mapping->fAddress = address;
		}

		mapOffset = offset;
		bytesRemaining = length;
		nextAddress = address;
		assert(mapOffset <= _length);
		subOptions = (options & ~kIOMapAnywhere) | kIOMapOverwrite;

		for (unsigned index = 0; bytesRemaining && (index < _descriptorsCount); index++) {
			chunk = _descriptors[index]->getLength();
			if (mapOffset >= chunk) {
				mapOffset -= chunk;
				continue;
			}
			chunk -= mapOffset;
			if (chunk > bytesRemaining) {
				chunk = bytesRemaining;
			}
			IOMemoryMap * subMap;
			subMap = _descriptors[index]->createMappingInTask(mapping->fAddressTask, nextAddress, subOptions, mapOffset, chunk );
			if (!subMap) {
				break;
			}
			subMap->release(); // kIOMapOverwrite means it will not deallocate

			bytesRemaining -= chunk;
			nextAddress += chunk;
			mapOffset = 0;
		}
		if (bytesRemaining) {
			err = kIOReturnUnderrun;
		}
	}while (false);

	if (kIOReturnSuccess == err) {
#if IOTRACKING
		IOTrackingAddUser(gIOMapTracking, &mapping->fTracking, mapping->fLength);
#endif
	}

	return err;
}

IOReturn
IOMultiMemoryDescriptor::setPurgeable( IOOptionBits newState,
    IOOptionBits * oldState )
{
	IOReturn     err;
	IOOptionBits totalState, state;

	totalState = kIOMemoryPurgeableNonVolatile;
	err = kIOReturnSuccess;
	for (unsigned index = 0; index < _descriptorsCount; index++) {
		err = _descriptors[index]->setPurgeable(newState, &state);
		if (kIOReturnSuccess != err) {
			break;
		}

		if (kIOMemoryPurgeableEmpty == state) {
			totalState = kIOMemoryPurgeableEmpty;
		} else if (kIOMemoryPurgeableEmpty == totalState) {
			continue;
		} else if (kIOMemoryPurgeableVolatile == totalState) {
			continue;
		} else if (kIOMemoryPurgeableVolatile == state) {
			totalState = kIOMemoryPurgeableVolatile;
		} else {
			totalState = kIOMemoryPurgeableNonVolatile;
		}
	}
	if (oldState) {
		*oldState = totalState;
	}

	return err;
}

IOReturn
IOMultiMemoryDescriptor::setOwnership( task_t newOwner,
    int newLedgerTag,
    IOOptionBits newLedgerOptions )
{
	IOReturn     err;

	if (iokit_iomd_setownership_enabled == FALSE) {
		return kIOReturnUnsupported;
	}

	err = kIOReturnSuccess;
	for (unsigned index = 0; index < _descriptorsCount; index++) {
		err = _descriptors[index]->setOwnership(newOwner, newLedgerTag, newLedgerOptions);
		if (kIOReturnSuccess != err) {
			break;
		}
	}

	return err;
}

IOReturn
IOMultiMemoryDescriptor::getPageCounts(IOByteCount * pResidentPageCount,
    IOByteCount * pDirtyPageCount)
{
	IOReturn    err;
	IOByteCount totalResidentPageCount, totalDirtyPageCount;
	IOByteCount residentPageCount, dirtyPageCount;

	err = kIOReturnSuccess;
	totalResidentPageCount = totalDirtyPageCount = 0;
	for (unsigned index = 0; index < _descriptorsCount; index++) {
		err = _descriptors[index]->getPageCounts(&residentPageCount, &dirtyPageCount);
		if (kIOReturnSuccess != err) {
			break;
		}
		totalResidentPageCount += residentPageCount;
		totalDirtyPageCount    += dirtyPageCount;
	}

	if (pResidentPageCount) {
		*pResidentPageCount = totalResidentPageCount;
	}
	if (pDirtyPageCount) {
		*pDirtyPageCount = totalDirtyPageCount;
	}

	return err;
}

uint64_t
IOMultiMemoryDescriptor::getPreparationID( void )
{
	if (!super::getKernelReserved()) {
		return kIOPreparationIDUnsupported;
	}

	for (unsigned index = 0; index < _descriptorsCount; index++) {
		uint64_t preparationID = _descriptors[index]->getPreparationID();

		if (preparationID == kIOPreparationIDUnsupported) {
			return kIOPreparationIDUnsupported;
		}

		if (preparationID == kIOPreparationIDUnprepared) {
			return kIOPreparationIDUnprepared;
		}
	}

	super::setPreparationID();

	return super::getPreparationID();
}