xnu-6153.81.5.tar.gz

[apple/xnu.git] / bsd / kern / kern_subr.c

/*
 * Copyright (c) 2000-2006 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.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1982, 1986, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 *
 *	@(#)kern_subr.c	8.3 (Berkeley) 1/21/94
 */

#include <machine/atomic.h>

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc_internal.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <vm/pmap.h>
#include <sys/uio_internal.h>
#include <kern/kalloc.h>

#include <kdebug.h>

#include <sys/kdebug.h>
#define DBG_UIO_COPYOUT 16
#define DBG_UIO_COPYIN  17

#if DEBUG
#include <kern/simple_lock.h>

static uint32_t                         uio_t_count = 0;
#endif /* DEBUG */

#define IS_VALID_UIO_SEGFLG(segflg)  \
	( (segflg) == UIO_USERSPACE || \
	  (segflg) == UIO_SYSSPACE || \
	  (segflg) == UIO_USERSPACE32 || \
	  (segflg) == UIO_USERSPACE64 || \
	  (segflg) == UIO_SYSSPACE32 || \
	  (segflg) == UIO_USERISPACE || \
	  (segflg) == UIO_PHYS_USERSPACE || \
	  (segflg) == UIO_PHYS_SYSSPACE || \
	  (segflg) == UIO_USERISPACE32 || \
	  (segflg) == UIO_PHYS_USERSPACE32 || \
	  (segflg) == UIO_USERISPACE64 || \
	  (segflg) == UIO_PHYS_USERSPACE64 )

/*
 * Returns:	0			Success
 *	uiomove64:EFAULT
 *
 * Notes:	The first argument should be a caddr_t, but const poisoning
 *		for typedef'ed types doesn't work in gcc.
 */
int
uiomove(const char * cp, int n, uio_t uio)
{
	return uiomove64((const addr64_t)(uintptr_t)cp, n, uio);
}

/*
 * Returns:	0			Success
 *		EFAULT
 *	copyout:EFAULT
 *	copyin:EFAULT
 *	copywithin:EFAULT
 *	copypv:EFAULT
 */
int
uiomove64(const addr64_t c_cp, int n, struct uio *uio)
{
	addr64_t cp = c_cp;
	uint64_t acnt;
	int error = 0;

#if DIAGNOSTIC
	if (uio->uio_rw != UIO_READ && uio->uio_rw != UIO_WRITE) {
		panic("uiomove: mode");
	}
#endif

#if LP64_DEBUG
	if (IS_VALID_UIO_SEGFLG(uio->uio_segflg) == 0) {
		panic("%s :%d - invalid uio_segflg\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	while (n > 0 && uio_resid(uio)) {
		uio_update(uio, 0);
		acnt = uio_curriovlen(uio);
		if (acnt == 0) {
			continue;
		}
		if (n > 0 && acnt > (uint64_t)n) {
			acnt = n;
		}

		switch ((int) uio->uio_segflg) {
		case UIO_USERSPACE64:
		case UIO_USERISPACE64:
		case UIO_USERSPACE32:
		case UIO_USERISPACE32:
		case UIO_USERSPACE:
		case UIO_USERISPACE:
			// LP64 - 3rd argument in debug code is 64 bit, expected to be 32 bit
			if (uio->uio_rw == UIO_READ) {
				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_START,
				    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 0, 0);

				error = copyout( CAST_DOWN(caddr_t, cp), uio->uio_iovs.uiovp->iov_base, acnt );

				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_END,
				    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 0, 0);
			} else {
				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_START,
				    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 0, 0);

				error = copyin(uio->uio_iovs.uiovp->iov_base, CAST_DOWN(caddr_t, cp), acnt);

				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_END,
				    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 0, 0);
			}
			if (error) {
				return error;
			}
			break;

		case UIO_SYSSPACE32:
		case UIO_SYSSPACE:
			if (uio->uio_rw == UIO_READ) {
				error = copywithin(CAST_DOWN(caddr_t, cp), CAST_DOWN(caddr_t, uio->uio_iovs.kiovp->iov_base),
				    acnt);
			} else {
				error = copywithin(CAST_DOWN(caddr_t, uio->uio_iovs.kiovp->iov_base), CAST_DOWN(caddr_t, cp),
				    acnt);
			}
			break;

		case UIO_PHYS_USERSPACE64:
		case UIO_PHYS_USERSPACE32:
		case UIO_PHYS_USERSPACE:
			if (uio->uio_rw == UIO_READ) {
				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_START,
				    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 1, 0);

				error = copypv((addr64_t)cp, uio->uio_iovs.uiovp->iov_base, acnt, cppvPsrc | cppvNoRefSrc);
				if (error) {    /* Copy physical to virtual */
					error = EFAULT;
				}

				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_END,
				    (int)cp, (uintptr_t)uio->uio_iovs.uiovp->iov_base, acnt, 1, 0);
			} else {
				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_START,
				    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 1, 0);

				error = copypv(uio->uio_iovs.uiovp->iov_base, (addr64_t)cp, acnt, cppvPsnk | cppvNoRefSrc | cppvNoModSnk);
				if (error) {    /* Copy virtual to physical */
					error = EFAULT;
				}

				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_END,
				    (uintptr_t)uio->uio_iovs.uiovp->iov_base, (int)cp, acnt, 1, 0);
			}
			if (error) {
				return error;
			}
			break;

		case UIO_PHYS_SYSSPACE:
			if (uio->uio_rw == UIO_READ) {
				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_START,
				    (int)cp, (uintptr_t)uio->uio_iovs.kiovp->iov_base, acnt, 2, 0);

				error = copypv((addr64_t)cp, uio->uio_iovs.kiovp->iov_base, acnt, cppvKmap | cppvPsrc | cppvNoRefSrc);
				if (error) {    /* Copy physical to virtual */
					error = EFAULT;
				}

				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYOUT)) | DBG_FUNC_END,
				    (int)cp, (uintptr_t)uio->uio_iovs.kiovp->iov_base, acnt, 2, 0);
			} else {
				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_START,
				    (uintptr_t)uio->uio_iovs.kiovp->iov_base, (int)cp, acnt, 2, 0);

				error = copypv(uio->uio_iovs.kiovp->iov_base, (addr64_t)cp, acnt, cppvKmap | cppvPsnk | cppvNoRefSrc | cppvNoModSnk);
				if (error) {    /* Copy virtual to physical */
					error = EFAULT;
				}

				KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, DBG_UIO_COPYIN)) | DBG_FUNC_END,
				    (uintptr_t)uio->uio_iovs.kiovp->iov_base, (int)cp, acnt, 2, 0);
			}
			if (error) {
				return error;
			}
			break;

		default:
			break;
		}
		uio_update(uio, acnt);
		cp += acnt;
		n -= acnt;
	}
	return error;
}

/*
 * Give next character to user as result of read.
 */
int
ureadc(int c, struct uio *uio)
{
	if (uio_resid(uio) <= 0) {
		panic("ureadc: non-positive resid");
	}
	uio_update(uio, 0);
	if (uio->uio_iovcnt == 0) {
		panic("ureadc: non-positive iovcnt");
	}
	if (uio_curriovlen(uio) <= 0) {
		panic("ureadc: non-positive iovlen");
	}

	switch ((int) uio->uio_segflg) {
	case UIO_USERSPACE32:
	case UIO_USERSPACE:
	case UIO_USERISPACE32:
	case UIO_USERISPACE:
	case UIO_USERSPACE64:
	case UIO_USERISPACE64:
		if (subyte((user_addr_t)uio->uio_iovs.uiovp->iov_base, c) < 0) {
			return EFAULT;
		}
		break;

	case UIO_SYSSPACE32:
	case UIO_SYSSPACE:
		*(CAST_DOWN(caddr_t, uio->uio_iovs.kiovp->iov_base)) = c;
		break;

	default:
		break;
	}
	uio_update(uio, 1);
	return 0;
}

/*
 * General routine to allocate a hash table.
 */
void *
hashinit(int elements, int type, u_long *hashmask)
{
	long hashsize;
	LIST_HEAD(generic, generic) * hashtbl;
	int i;

	if (elements <= 0) {
		panic("hashinit: bad cnt");
	}
	for (hashsize = 1; hashsize <= elements; hashsize <<= 1) {
		continue;
	}
	hashsize >>= 1;
	MALLOC(hashtbl, struct generic *,
	    hashsize * sizeof(*hashtbl), type, M_WAITOK | M_ZERO);
	if (hashtbl != NULL) {
		for (i = 0; i < hashsize; i++) {
			LIST_INIT(&hashtbl[i]);
		}
		*hashmask = hashsize - 1;
	}
	return hashtbl;
}

/*
 * uio_resid - return the residual IO value for the given uio_t
 */
user_ssize_t
uio_resid( uio_t a_uio )
{
#if DEBUG
	if (a_uio == NULL) {
		printf("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
/*      if (IS_VALID_UIO_SEGFLG(a_uio->uio_segflg) == 0) { */
/*              panic("%s :%d - invalid uio_segflg\n", __FILE__, __LINE__);  */
/*      } */
#endif /* DEBUG */

	/* return 0 if there are no active iovecs */
	if (a_uio == NULL) {
		return 0;
	}

	return a_uio->uio_resid_64;
}

/*
 * uio_setresid - set the residual IO value for the given uio_t
 */
void
uio_setresid( uio_t a_uio, user_ssize_t a_value )
{
#if DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
/*      if (IS_VALID_UIO_SEGFLG(a_uio->uio_segflg) == 0) { */
/*              panic("%s :%d - invalid uio_segflg\n", __FILE__, __LINE__);  */
/*      } */
#endif /* DEBUG */

	if (a_uio == NULL) {
		return;
	}

	a_uio->uio_resid_64 = a_value;
	return;
}

/*
 * uio_curriovbase - return the base address of the current iovec associated
 *	with the given uio_t.  May return 0.
 */
user_addr_t
uio_curriovbase( uio_t a_uio )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL || a_uio->uio_iovcnt < 1) {
		return 0;
	}

	if (UIO_IS_USER_SPACE(a_uio)) {
		return a_uio->uio_iovs.uiovp->iov_base;
	}
	return (user_addr_t)a_uio->uio_iovs.kiovp->iov_base;
}

/*
 * uio_curriovlen - return the length value of the current iovec associated
 *	with the given uio_t.
 */
user_size_t
uio_curriovlen( uio_t a_uio )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL || a_uio->uio_iovcnt < 1) {
		return 0;
	}

	if (UIO_IS_USER_SPACE(a_uio)) {
		return a_uio->uio_iovs.uiovp->iov_len;
	}
	return (user_size_t)a_uio->uio_iovs.kiovp->iov_len;
}

/*
 * uio_setcurriovlen - set the length value of the current iovec associated
 *	with the given uio_t.
 */
__private_extern__ void
uio_setcurriovlen( uio_t a_uio, user_size_t a_value )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL) {
		return;
	}

	if (UIO_IS_USER_SPACE(a_uio)) {
		a_uio->uio_iovs.uiovp->iov_len = a_value;
	} else {
#if LP64_DEBUG
		if (a_value > 0xFFFFFFFFull) {
			panic("%s :%d - invalid a_value\n", __FILE__, __LINE__);
		}
#endif /* LP64_DEBUG */
		a_uio->uio_iovs.kiovp->iov_len = (size_t)a_value;
	}
	return;
}

/*
 * uio_iovcnt - return count of active iovecs for the given uio_t
 */
int
uio_iovcnt( uio_t a_uio )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL) {
		return 0;
	}

	return a_uio->uio_iovcnt;
}

/*
 * uio_offset - return the current offset value for the given uio_t
 */
off_t
uio_offset( uio_t a_uio )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL) {
		return 0;
	}
	return a_uio->uio_offset;
}

/*
 * uio_setoffset - set the current offset value for the given uio_t
 */
void
uio_setoffset( uio_t a_uio, off_t a_offset )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL) {
		return;
	}
	a_uio->uio_offset = a_offset;
	return;
}

/*
 * uio_rw - return the read / write flag for the given uio_t
 */
int
uio_rw( uio_t a_uio )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL) {
		return -1;
	}
	return a_uio->uio_rw;
}

/*
 * uio_setrw - set the read / write flag for the given uio_t
 */
void
uio_setrw( uio_t a_uio, int a_value )
{
	if (a_uio == NULL) {
#if LP64_DEBUG
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
		return;
	}

#if LP64_DEBUG
	if (!(a_value == UIO_READ || a_value == UIO_WRITE)) {
		panic("%s :%d - invalid a_value\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_value == UIO_READ || a_value == UIO_WRITE) {
		a_uio->uio_rw = a_value;
	}
	return;
}

/*
 * uio_isuserspace - return non zero value if the address space
 * flag is for a user address space (could be 32 or 64 bit).
 */
int
uio_isuserspace( uio_t a_uio )
{
	if (a_uio == NULL) {
#if LP64_DEBUG
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
		return 0;
	}

	if (UIO_SEG_IS_USER_SPACE(a_uio->uio_segflg)) {
		return 1;
	}
	return 0;
}


/*
 * uio_create - create an uio_t.
 *      Space is allocated to hold up to a_iovcount number of iovecs.  The uio_t
 *	is not fully initialized until all iovecs are added using uio_addiov calls.
 *	a_iovcount is the maximum number of iovecs you may add.
 */
uio_t
uio_create( int a_iovcount,                     /* number of iovecs */
    off_t a_offset,                                             /* current offset */
    int a_spacetype,                                            /* type of address space */
    int a_iodirection )                                 /* read or write flag */
{
	void *                          my_buf_p;
	size_t                          my_size;
	uio_t                           my_uio;

	my_size = UIO_SIZEOF(a_iovcount);
	my_buf_p = kalloc(my_size);
	my_uio = uio_createwithbuffer( a_iovcount,
	    a_offset,
	    a_spacetype,
	    a_iodirection,
	    my_buf_p,
	    my_size );
	if (my_uio != 0) {
		/* leave a note that we allocated this uio_t */
		my_uio->uio_flags |= UIO_FLAGS_WE_ALLOCED;
#if DEBUG
		os_atomic_inc(&uio_t_count, relaxed);
#endif
	}

	return my_uio;
}


/*
 * uio_createwithbuffer - create an uio_t.
 *      Create a uio_t using the given buffer.  The uio_t
 *	is not fully initialized until all iovecs are added using uio_addiov calls.
 *	a_iovcount is the maximum number of iovecs you may add.
 *	This call may fail if the given buffer is not large enough.
 */
__private_extern__ uio_t
uio_createwithbuffer( int a_iovcount,                   /* number of iovecs */
    off_t a_offset,                                                             /* current offset */
    int a_spacetype,                                                            /* type of address space */
    int a_iodirection,                                                          /* read or write flag */
    void *a_buf_p,                                                              /* pointer to a uio_t buffer */
    size_t a_buffer_size )                                                      /* size of uio_t buffer */
{
	uio_t                           my_uio = (uio_t) a_buf_p;
	size_t                          my_size;

	my_size = UIO_SIZEOF(a_iovcount);
	if (a_buffer_size < my_size) {
#if DEBUG
		panic("%s :%d - a_buffer_size is too small\n", __FILE__, __LINE__);
#endif /* DEBUG */
		return NULL;
	}
	my_size = a_buffer_size;

#if DEBUG
	if (my_uio == 0) {
		panic("%s :%d - could not allocate uio_t\n", __FILE__, __LINE__);
	}
	if (!IS_VALID_UIO_SEGFLG(a_spacetype)) {
		panic("%s :%d - invalid address space type\n", __FILE__, __LINE__);
	}
	if (!(a_iodirection == UIO_READ || a_iodirection == UIO_WRITE)) {
		panic("%s :%d - invalid IO direction flag\n", __FILE__, __LINE__);
	}
	if (a_iovcount > UIO_MAXIOV) {
		panic("%s :%d - invalid a_iovcount\n", __FILE__, __LINE__);
	}
#endif /* DEBUG */

	bzero(my_uio, my_size);
	my_uio->uio_size = my_size;

	/*
	 * we use uio_segflg to indicate if the uio_t is the new format or
	 * old (pre LP64 support) legacy format
	 * This switch statement should canonicalize incoming space type
	 * to one of UIO_USERSPACE32/64, UIO_PHYS_USERSPACE32/64, or
	 * UIO_SYSSPACE/UIO_PHYS_SYSSPACE
	 */
	switch (a_spacetype) {
	case UIO_USERSPACE:
		my_uio->uio_segflg = UIO_USERSPACE32;
		break;
	case UIO_SYSSPACE32:
		my_uio->uio_segflg = UIO_SYSSPACE;
		break;
	case UIO_PHYS_USERSPACE:
		my_uio->uio_segflg = UIO_PHYS_USERSPACE32;
		break;
	default:
		my_uio->uio_segflg = a_spacetype;
		break;
	}

	if (a_iovcount > 0) {
		my_uio->uio_iovs.uiovp = (struct user_iovec *)
		    (((uint8_t *)my_uio) + sizeof(struct uio));
	} else {
		my_uio->uio_iovs.uiovp = NULL;
	}

	my_uio->uio_max_iovs = a_iovcount;
	my_uio->uio_offset = a_offset;
	my_uio->uio_rw = a_iodirection;
	my_uio->uio_flags = UIO_FLAGS_INITED;

	return my_uio;
}

/*
 * uio_spacetype - return the address space type for the given uio_t
 */
__private_extern__ int
uio_spacetype( uio_t a_uio )
{
	if (a_uio == NULL) {
#if LP64_DEBUG
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
		return -1;
	}

	return a_uio->uio_segflg;
}

/*
 * uio_iovsaddr - get the address of the iovec array for the given uio_t.
 * This returns the location of the iovecs within the uio.
 * NOTE - for compatibility mode we just return the current value in uio_iovs
 * which will increase as the IO is completed and is NOT embedded within the
 * uio, it is a seperate array of one or more iovecs.
 */
__private_extern__ struct user_iovec *
uio_iovsaddr( uio_t a_uio )
{
	struct user_iovec *             my_addr;

	if (a_uio == NULL) {
		return NULL;
	}

	if (UIO_SEG_IS_USER_SPACE(a_uio->uio_segflg)) {
		/* we need this for compatibility mode. */
		my_addr = (struct user_iovec *) a_uio->uio_iovs.uiovp;
	} else {
#if DEBUG
		panic("uio_iovsaddr called for UIO_SYSSPACE request");
#endif
		my_addr = 0;
	}
	return my_addr;
}

/*
 * uio_reset - reset an uio_t.
 *      Reset the given uio_t to initial values.  The uio_t is not fully initialized
 *      until all iovecs are added using uio_addiov calls.
 *	The a_iovcount value passed in the uio_create is the maximum number of
 *	iovecs you may add.
 */
void
uio_reset( uio_t a_uio,
    off_t a_offset,                                             /* current offset */
    int a_spacetype,                                            /* type of address space */
    int a_iodirection )                                         /* read or write flag */
{
	vm_size_t       my_size;
	int                     my_max_iovs;
	u_int32_t       my_old_flags;

#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - could not allocate uio_t\n", __FILE__, __LINE__);
	}
	if (!IS_VALID_UIO_SEGFLG(a_spacetype)) {
		panic("%s :%d - invalid address space type\n", __FILE__, __LINE__);
	}
	if (!(a_iodirection == UIO_READ || a_iodirection == UIO_WRITE)) {
		panic("%s :%d - invalid IO direction flag\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL) {
		return;
	}

	my_size = a_uio->uio_size;
	my_old_flags = a_uio->uio_flags;
	my_max_iovs = a_uio->uio_max_iovs;
	bzero(a_uio, my_size);
	a_uio->uio_size = my_size;

	/*
	 * we use uio_segflg to indicate if the uio_t is the new format or
	 * old (pre LP64 support) legacy format
	 * This switch statement should canonicalize incoming space type
	 * to one of UIO_USERSPACE32/64, UIO_PHYS_USERSPACE32/64, or
	 * UIO_SYSSPACE/UIO_PHYS_SYSSPACE
	 */
	switch (a_spacetype) {
	case UIO_USERSPACE:
		a_uio->uio_segflg = UIO_USERSPACE32;
		break;
	case UIO_SYSSPACE32:
		a_uio->uio_segflg = UIO_SYSSPACE;
		break;
	case UIO_PHYS_USERSPACE:
		a_uio->uio_segflg = UIO_PHYS_USERSPACE32;
		break;
	default:
		a_uio->uio_segflg = a_spacetype;
		break;
	}

	if (my_max_iovs > 0) {
		a_uio->uio_iovs.uiovp = (struct user_iovec *)
		    (((uint8_t *)a_uio) + sizeof(struct uio));
	} else {
		a_uio->uio_iovs.uiovp = NULL;
	}

	a_uio->uio_max_iovs = my_max_iovs;
	a_uio->uio_offset = a_offset;
	a_uio->uio_rw = a_iodirection;
	a_uio->uio_flags = my_old_flags;

	return;
}

/*
 * uio_free - free a uio_t allocated via uio_init.  this also frees all
 *      associated iovecs.
 */
void
uio_free( uio_t a_uio )
{
#if DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - passing NULL uio_t\n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio != NULL && (a_uio->uio_flags & UIO_FLAGS_WE_ALLOCED) != 0) {
#if DEBUG
		if (os_atomic_dec_orig(&uio_t_count, relaxed) == 0) {
			panic("%s :%d - uio_t_count underflow\n", __FILE__, __LINE__);
		}
#endif
		kfree(a_uio, a_uio->uio_size);
	}
}

/*
 * uio_addiov - add an iovec to the given uio_t.  You may call this up to
 *      the a_iovcount number that was passed to uio_create.  This call will
 *      increment the residual IO count as iovecs are added to the uio_t.
 *	returns 0 if add was successful else non zero.
 */
int
uio_addiov( uio_t a_uio, user_addr_t a_baseaddr, user_size_t a_length )
{
	int i;
	user_size_t resid;

	if (a_uio == NULL) {
#if DEBUG
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif
		return -1;
	}

	if (os_add_overflow(a_length, a_uio->uio_resid_64, &resid)) {
#if DEBUG
		panic("%s :%d - invalid length %lu\n", __FILE__, __LINE__, (unsigned long)a_length);
#endif
		return -1;
	}

	if (UIO_IS_USER_SPACE(a_uio)) {
		for (i = 0; i < a_uio->uio_max_iovs; i++) {
			if (a_uio->uio_iovs.uiovp[i].iov_len == 0 && a_uio->uio_iovs.uiovp[i].iov_base == 0) {
				a_uio->uio_iovs.uiovp[i].iov_len = a_length;
				a_uio->uio_iovs.uiovp[i].iov_base = a_baseaddr;
				a_uio->uio_iovcnt++;
				a_uio->uio_resid_64 = resid;
				return 0;
			}
		}
	} else {
		for (i = 0; i < a_uio->uio_max_iovs; i++) {
			if (a_uio->uio_iovs.kiovp[i].iov_len == 0 && a_uio->uio_iovs.kiovp[i].iov_base == 0) {
				a_uio->uio_iovs.kiovp[i].iov_len = (u_int64_t)a_length;
				a_uio->uio_iovs.kiovp[i].iov_base = (u_int64_t)a_baseaddr;
				a_uio->uio_iovcnt++;
				a_uio->uio_resid_64 = resid;
				return 0;
			}
		}
	}

	return -1;
}

/*
 * uio_getiov - get iovec data associated with the given uio_t.  Use
 *  a_index to iterate over each iovec (0 to (uio_iovcnt(uio_t) - 1)).
 *  a_baseaddr_p and a_length_p may be NULL.
 *      returns -1 when a_index is >= uio_t.uio_iovcnt or invalid uio_t.
 *	returns 0 when data is returned.
 */
int
uio_getiov( uio_t a_uio,
    int a_index,
    user_addr_t * a_baseaddr_p,
    user_size_t * a_length_p )
{
	if (a_uio == NULL) {
#if DEBUG
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* DEBUG */
		return -1;
	}
	if (a_index < 0 || a_index >= a_uio->uio_iovcnt) {
		return -1;
	}

	if (UIO_IS_USER_SPACE(a_uio)) {
		if (a_baseaddr_p != NULL) {
			*a_baseaddr_p = a_uio->uio_iovs.uiovp[a_index].iov_base;
		}
		if (a_length_p != NULL) {
			*a_length_p = a_uio->uio_iovs.uiovp[a_index].iov_len;
		}
	} else {
		if (a_baseaddr_p != NULL) {
			*a_baseaddr_p = a_uio->uio_iovs.kiovp[a_index].iov_base;
		}
		if (a_length_p != NULL) {
			*a_length_p = a_uio->uio_iovs.kiovp[a_index].iov_len;
		}
	}

	return 0;
}

/*
 * uio_calculateresid - runs through all iovecs associated with this
 *	uio_t and calculates (and sets) the residual IO count.
 */
__private_extern__ int
uio_calculateresid( uio_t a_uio )
{
	int                     i;
	u_int64_t               resid = 0;

	if (a_uio == NULL) {
#if LP64_DEBUG
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
#endif /* LP64_DEBUG */
		return EINVAL;
	}

	a_uio->uio_iovcnt = a_uio->uio_max_iovs;
	if (UIO_IS_USER_SPACE(a_uio)) {
		a_uio->uio_resid_64 = 0;
		for (i = 0; i < a_uio->uio_max_iovs; i++) {
			if (a_uio->uio_iovs.uiovp[i].iov_len != 0 && a_uio->uio_iovs.uiovp[i].iov_base != 0) {
				if (a_uio->uio_iovs.uiovp[i].iov_len > LONG_MAX) {
					return EINVAL;
				}
				resid += a_uio->uio_iovs.uiovp[i].iov_len;
				if (resid > LONG_MAX) {
					return EINVAL;
				}
			}
		}
		a_uio->uio_resid_64 = resid;

		/* position to first non zero length iovec (4235922) */
		while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.uiovp->iov_len == 0) {
			a_uio->uio_iovcnt--;
			if (a_uio->uio_iovcnt > 0) {
				a_uio->uio_iovs.uiovp++;
			}
		}
	} else {
		a_uio->uio_resid_64 = 0;
		for (i = 0; i < a_uio->uio_max_iovs; i++) {
			if (a_uio->uio_iovs.kiovp[i].iov_len != 0 && a_uio->uio_iovs.kiovp[i].iov_base != 0) {
				if (a_uio->uio_iovs.kiovp[i].iov_len > LONG_MAX) {
					return EINVAL;
				}
				resid += a_uio->uio_iovs.kiovp[i].iov_len;
				if (resid > LONG_MAX) {
					return EINVAL;
				}
			}
		}
		a_uio->uio_resid_64 = resid;

		/* position to first non zero length iovec (4235922) */
		while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.kiovp->iov_len == 0) {
			a_uio->uio_iovcnt--;
			if (a_uio->uio_iovcnt > 0) {
				a_uio->uio_iovs.kiovp++;
			}
		}
	}

	return 0;
}

/*
 * uio_update - update the given uio_t for a_count of completed IO.
 *	This call decrements the current iovec length and residual IO value
 *	and increments the current iovec base address and offset value.
 *	If the current iovec length is 0 then advance to the next
 *	iovec (if any).
 *      If the a_count passed in is 0, than only do the advancement
 *	over any 0 length iovec's.
 */
void
uio_update( uio_t a_uio, user_size_t a_count )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
	if (UIO_IS_32_BIT_SPACE(a_uio) && a_count > 0xFFFFFFFFull) {
		panic("%s :%d - invalid count value \n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL || a_uio->uio_iovcnt < 1) {
		return;
	}

	if (UIO_IS_USER_SPACE(a_uio)) {
		/*
		 * if a_count == 0, then we are asking to skip over
		 * any empty iovs
		 */
		if (a_count) {
			if (a_count > a_uio->uio_iovs.uiovp->iov_len) {
				a_uio->uio_iovs.uiovp->iov_base += a_uio->uio_iovs.uiovp->iov_len;
				a_uio->uio_iovs.uiovp->iov_len = 0;
			} else {
				a_uio->uio_iovs.uiovp->iov_base += a_count;
				a_uio->uio_iovs.uiovp->iov_len -= a_count;
			}
			if (a_count > (user_size_t)a_uio->uio_resid_64) {
				a_uio->uio_offset += a_uio->uio_resid_64;
				a_uio->uio_resid_64 = 0;
			} else {
				a_uio->uio_offset += a_count;
				a_uio->uio_resid_64 -= a_count;
			}
		}
		/*
		 * advance to next iovec if current one is totally consumed
		 */
		while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.uiovp->iov_len == 0) {
			a_uio->uio_iovcnt--;
			if (a_uio->uio_iovcnt > 0) {
				a_uio->uio_iovs.uiovp++;
			}
		}
	} else {
		/*
		 * if a_count == 0, then we are asking to skip over
		 * any empty iovs
		 */
		if (a_count) {
			if (a_count > a_uio->uio_iovs.kiovp->iov_len) {
				a_uio->uio_iovs.kiovp->iov_base += a_uio->uio_iovs.kiovp->iov_len;
				a_uio->uio_iovs.kiovp->iov_len = 0;
			} else {
				a_uio->uio_iovs.kiovp->iov_base += a_count;
				a_uio->uio_iovs.kiovp->iov_len -= a_count;
			}
			if (a_count > (user_size_t)a_uio->uio_resid_64) {
				a_uio->uio_offset += a_uio->uio_resid_64;
				a_uio->uio_resid_64 = 0;
			} else {
				a_uio->uio_offset += a_count;
				a_uio->uio_resid_64 -= a_count;
			}
		}
		/*
		 * advance to next iovec if current one is totally consumed
		 */
		while (a_uio->uio_iovcnt > 0 && a_uio->uio_iovs.kiovp->iov_len == 0) {
			a_uio->uio_iovcnt--;
			if (a_uio->uio_iovcnt > 0) {
				a_uio->uio_iovs.kiovp++;
			}
		}
	}
	return;
}

/*
 * uio_pushback - undo uncommitted I/O by subtracting from the
 * current base address and offset, and incrementing the residiual
 * IO. If the UIO was previously exhausted, this call will panic.
 * New code should not use this functionality.
 */
__private_extern__ void
uio_pushback( uio_t a_uio, user_size_t a_count )
{
#if LP64_DEBUG
	if (a_uio == NULL) {
		panic("%s :%d - invalid uio_t\n", __FILE__, __LINE__);
	}
	if (UIO_IS_32_BIT_SPACE(a_uio) && a_count > 0xFFFFFFFFull) {
		panic("%s :%d - invalid count value \n", __FILE__, __LINE__);
	}
#endif /* LP64_DEBUG */

	if (a_uio == NULL || a_count == 0) {
		return;
	}

	if (a_uio->uio_iovcnt < 1) {
		panic("Invalid uio for pushback");
	}

	if (UIO_IS_USER_SPACE(a_uio)) {
		a_uio->uio_iovs.uiovp->iov_base -= a_count;
		a_uio->uio_iovs.uiovp->iov_len += a_count;
	} else {
		a_uio->uio_iovs.kiovp->iov_base -= a_count;
		a_uio->uio_iovs.kiovp->iov_len += a_count;
	}

	a_uio->uio_offset -= a_count;
	a_uio->uio_resid_64 += a_count;

	return;
}


/*
 * uio_duplicate - allocate a new uio and make a copy of the given uio_t.
 *	may return NULL.
 */
uio_t
uio_duplicate( uio_t a_uio )
{
	uio_t           my_uio;
	int                     i;

	if (a_uio == NULL) {
		return NULL;
	}

	my_uio = (uio_t) kalloc(a_uio->uio_size);
	if (my_uio == 0) {
		panic("%s :%d - allocation failed\n", __FILE__, __LINE__);
	}

	bcopy((void *)a_uio, (void *)my_uio, a_uio->uio_size);
	/* need to set our iovec pointer to point to first active iovec */
	if (my_uio->uio_max_iovs > 0) {
		my_uio->uio_iovs.uiovp = (struct user_iovec *)
		    (((uint8_t *)my_uio) + sizeof(struct uio));

		/* advance to first nonzero iovec */
		if (my_uio->uio_iovcnt > 0) {
			for (i = 0; i < my_uio->uio_max_iovs; i++) {
				if (UIO_IS_USER_SPACE(a_uio)) {
					if (my_uio->uio_iovs.uiovp->iov_len != 0) {
						break;
					}
					my_uio->uio_iovs.uiovp++;
				} else {
					if (my_uio->uio_iovs.kiovp->iov_len != 0) {
						break;
					}
					my_uio->uio_iovs.kiovp++;
				}
			}
		}
	}

	my_uio->uio_flags = UIO_FLAGS_WE_ALLOCED | UIO_FLAGS_INITED;
#if DEBUG
	os_atomic_inc(&uio_t_count, relaxed);
#endif


	return my_uio;
}

int
copyin_user_iovec_array(user_addr_t uaddr, int spacetype, int count, struct user_iovec *dst)
{
	size_t size_of_iovec = (spacetype == UIO_USERSPACE64 ? sizeof(struct user64_iovec) : sizeof(struct user32_iovec));
	int error;
	int i;

	// copyin to the front of "dst", without regard for putting records in the right places
	error = copyin(uaddr, dst, count * size_of_iovec);
	if (error) {
		return error;
	}

	// now, unpack the entries in reverse order, so we don't overwrite anything
	for (i = count - 1; i >= 0; i--) {
		if (spacetype == UIO_USERSPACE64) {
			struct user64_iovec iovec = ((struct user64_iovec *)dst)[i];
			dst[i].iov_base = iovec.iov_base;
			dst[i].iov_len = iovec.iov_len;
		} else {
			struct user32_iovec iovec = ((struct user32_iovec *)dst)[i];
			dst[i].iov_base = iovec.iov_base;
			dst[i].iov_len = iovec.iov_len;
		}
	}

	return 0;
}