[apple/xnu.git] / osfmk / i386 / user_ldt.c

/*
 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_OSREFERENCE_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_LICENSE_OSREFERENCE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon 
 * the rights to redistribute these changes.
 */

/*
 */

/*
 * User LDT management.
 * Each task may have its own LDT.
 */

#include <kern/kalloc.h>
#include <kern/thread.h>
#include <kern/misc_protos.h>

#include <vm/vm_kern.h>

#include <i386/seg.h>
#include <i386/thread.h>
#include <i386/user_ldt.h>
#include <i386/mp_desc.h>
#include <i386/proc_reg.h>
#include <i386/machdep_call.h>
#include <i386/mp.h>
#include <i386/machine_routines.h>

#include <sys/errno.h>

static void user_ldt_set_action(void *);

/*
 * Add the descriptors to the LDT, starting with
 * the descriptor for 'first_selector'.
 */

int
i386_set_ldt(
	int			*retval,
	uint32_t		start_sel,
	uint32_t		descs,	/* out */
	uint32_t		num_sels)
{
	user_ldt_t	new_ldt, old_ldt;
	struct real_descriptor *dp;
	unsigned int	i;
	unsigned int	min_selector = LDTSZ_MIN;	/* do not allow the system selectors to be changed */
	task_t		task = current_task();
	unsigned int	ldt_count;
	kern_return_t err;

	if (start_sel != LDT_AUTO_ALLOC
	    && (start_sel != 0 || num_sels != 0)
	    && (start_sel < min_selector || start_sel >= LDTSZ))
	    return EINVAL;
	if (start_sel != LDT_AUTO_ALLOC
	    && start_sel + num_sels > LDTSZ)
	    return EINVAL;

	task_lock(task);
	
	old_ldt = task->i386_ldt;

	if (start_sel == LDT_AUTO_ALLOC) {
	    if (old_ldt) {
		unsigned int null_count;
		struct real_descriptor null_ldt;
		
		bzero(&null_ldt, sizeof(null_ldt));

		/*
		 * Look for null selectors among the already-allocated
		 * entries.
		 */
		null_count = 0;
		i = 0;
		while (i < old_ldt->count)
		{
		    if (!memcmp(&old_ldt->ldt[i++], &null_ldt, sizeof(null_ldt))) {
			null_count++;
			if (null_count == num_sels)
			    break;  /* break out of while loop */
		    } else {
			null_count = 0;
		    }
		}

		/*
		 * If we broke out of the while loop, i points to the selector
		 * after num_sels null selectors.  Otherwise it points to the end
		 * of the old LDTs, and null_count is the number of null selectors
		 * at the end. 
		 *
		 * Either way, there are null_count null selectors just prior to
		 * the i-indexed selector, and either null_count >= num_sels,
		 * or we're at the end, so we can extend.
		 */
		start_sel = old_ldt->start + i - null_count;
	    } else {
		start_sel = LDTSZ_MIN;
	    }
		
	    if (start_sel + num_sels > LDTSZ) {
		task_unlock(task);
		return ENOMEM;
	    }
	}

	if (start_sel == 0 && num_sels == 0) {
	    new_ldt = NULL;
	} else {
	    /*
	     * Allocate new LDT
	     */

	    unsigned int    begin_sel = start_sel;
	    unsigned int    end_sel = begin_sel + num_sels;
	    
	    if (old_ldt != NULL) {
		if (old_ldt->start < begin_sel)
		    begin_sel = old_ldt->start;
		if (old_ldt->start + old_ldt->count > end_sel)
		    end_sel = old_ldt->start + old_ldt->count;
	    }

	    ldt_count = end_sel - begin_sel;

	    new_ldt = (user_ldt_t)kalloc(sizeof(struct user_ldt) + (ldt_count * sizeof(struct real_descriptor)));
	    if (new_ldt == NULL) {
		task_unlock(task);
		return ENOMEM;
	    }

	    new_ldt->start = begin_sel;
	    new_ldt->count = ldt_count;

	    /*
	     * Have new LDT.  If there was a an old ldt, copy descriptors
	     * from old to new.
	     */
	    if (old_ldt) {
		bcopy(&old_ldt->ldt[0],
		      &new_ldt->ldt[old_ldt->start - begin_sel],
		      old_ldt->count * sizeof(struct real_descriptor));

		/*
		 * If the old and new LDTs are non-overlapping, fill the 
		 * center in with null selectors.
		 */
		 		 
		if (old_ldt->start + old_ldt->count < start_sel)
		    bzero(&new_ldt->ldt[old_ldt->count],
			  (start_sel - (old_ldt->start + old_ldt->count)) * sizeof(struct real_descriptor));
		else if (old_ldt->start > start_sel + num_sels)
		    bzero(&new_ldt->ldt[num_sels],
			  (old_ldt->start - (start_sel + num_sels)) * sizeof(struct real_descriptor));
	    }

	    /*
	     * Install new descriptors.
	     */
	    if (descs != 0) {
		err = copyin(descs, (char *)&new_ldt->ldt[start_sel - begin_sel],
			     num_sels * sizeof(struct real_descriptor));
		if (err != 0)
		{
		    task_unlock(task);
		    user_ldt_free(new_ldt);
		    return err;
		}
	    } else {
		bzero(&new_ldt->ldt[start_sel - begin_sel], num_sels * sizeof(struct real_descriptor));
	    }

	    /*
	     * Validate descriptors.
	     * Only allow descriptors with user priviledges.
	     */
	    for (i = 0, dp = (struct real_descriptor *) &new_ldt->ldt[start_sel - begin_sel];
		 i < num_sels;
		 i++, dp++)
	    {
		switch (dp->access & ~ACC_A) {
		    case 0:
		    case ACC_P:
			/* valid empty descriptor */
			break;
		    case ACC_P | ACC_PL_U | ACC_DATA:
		    case ACC_P | ACC_PL_U | ACC_DATA_W:
		    case ACC_P | ACC_PL_U | ACC_DATA_E:
		    case ACC_P | ACC_PL_U | ACC_DATA_EW:
		    case ACC_P | ACC_PL_U | ACC_CODE:
		    case ACC_P | ACC_PL_U | ACC_CODE_R:
		    case ACC_P | ACC_PL_U | ACC_CODE_C:
		    case ACC_P | ACC_PL_U | ACC_CODE_CR:
		    case ACC_P | ACC_PL_U | ACC_CALL_GATE_16:
		    case ACC_P | ACC_PL_U | ACC_CALL_GATE:
			break;
		    default:
			task_unlock(task);
			user_ldt_free(new_ldt);
			return EACCES;
		}
	    }
	}

	task->i386_ldt = new_ldt; /* new LDT for task */

	/*
	 * Switch to new LDT.  We need to do this on all CPUs, since
	 * another thread in this same task may be currently running,
	 * and we need to make sure the new LDT is in place
	 * throughout the task before returning to the user.
	 */
	mp_rendezvous_no_intrs(user_ldt_set_action, task);

	task_unlock(task);

	/* free old LDT.  We can't do this until after we've
	 * rendezvoused with all CPUs, in case another thread
	 * in this task was in the process of context switching.
	 */
	if (old_ldt)
	    user_ldt_free(old_ldt);

	*retval = start_sel;

	return 0;
}

int
i386_get_ldt(
	int			*retval,
	uint32_t		start_sel,
	uint32_t		descs,	/* out */
	uint32_t		num_sels)
{
	user_ldt_t	user_ldt;
	task_t		task = current_task();
	unsigned int	ldt_count;
	kern_return_t	err;

	if (start_sel >= 8192)
	    return EINVAL;
	if (start_sel + num_sels > 8192)
	    return EINVAL;
	if (descs == 0)
	    return EINVAL;

	task_lock(task);

	user_ldt = task->i386_ldt;
	err = 0;

	/*
	 * copy out the descriptors
	 */

	if (user_ldt != 0)
	    ldt_count = user_ldt->start + user_ldt->count;
	else
	    ldt_count = LDTSZ_MIN;


	if (start_sel < ldt_count)
	{
	    unsigned int copy_sels = num_sels;

	    if (start_sel + num_sels > ldt_count)
		copy_sels = ldt_count - start_sel;

	    err = copyout((char *)(current_ldt() + start_sel),
			  descs, copy_sels * sizeof(struct real_descriptor));
	}

	task_unlock(task);

	*retval = ldt_count;

	return err;
}

void
user_ldt_free(
	user_ldt_t	user_ldt)
{
	kfree(user_ldt, sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor)));
}

user_ldt_t
user_ldt_copy(
	user_ldt_t	user_ldt)
{
	if (user_ldt != NULL) {
	    size_t	size = sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor));
	    user_ldt_t	new_ldt = (user_ldt_t)kalloc(size);
	    if (new_ldt != NULL)
		bcopy(user_ldt, new_ldt, size);
	    return new_ldt;
	}
	
	return 0;
}

void
user_ldt_set_action(
	void *arg)
{
	task_t		arg_task = (task_t)arg;

	if (arg_task == current_task())	{
	    user_ldt_set(current_thread());
	}
}

/*
 * Set the LDT for the given thread on the current CPU.  Should be invoked
 * with interrupts disabled.
 */
void
user_ldt_set(
	thread_t thread)
{
        task_t		task = thread->task;
	user_ldt_t	user_ldt;

	user_ldt = task->i386_ldt;

	if (user_ldt != 0) {
	    struct real_descriptor *ldtp = (struct real_descriptor *)current_ldt();

	    if (user_ldt->start > LDTSZ_MIN) {
		bzero(&ldtp[LDTSZ_MIN],
		      sizeof(struct real_descriptor) * (user_ldt->start - LDTSZ_MIN));
	    }
	    
	    bcopy(user_ldt->ldt, &ldtp[user_ldt->start],
		  sizeof(struct real_descriptor) * (user_ldt->count));

	    gdt_desc_p(USER_LDT)->limit_low = (sizeof(struct real_descriptor) * (user_ldt->start + user_ldt->count)) - 1;

	    ml_cpu_set_ldt(USER_LDT);
	} else {
	    ml_cpu_set_ldt(KERNEL_LDT);
	}
}
Commit	Line	Data
1c79356b	1	/*
91447636	2	* Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
1c79356b	3	*
8ad349bb	4	* @APPLE_LICENSE_OSREFERENCE_HEADER_START@
1c79356b	5	*
8ad349bb A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the
	10	* License may not be used to create, or enable the creation or
	11	* redistribution of, unlawful or unlicensed copies of an Apple operating
	12	* system, or to circumvent, violate, or enable the circumvention or
	13	* violation of, any terms of an Apple operating system software license
	14	* agreement.
	15	*
	16	* Please obtain a copy of the License at
	17	* http://www.opensource.apple.com/apsl/ and read it before using this
	18	* file.
	19	*
	20	* The Original Code and all software distributed under the License are
	21	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	22	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	23	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	24	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	25	* Please see the License for the specific language governing rights and
	26	* limitations under the License.
	27	*
	28	* @APPLE_LICENSE_OSREFERENCE_HEADER_END@
1c79356b A	29	*/
	30	/*
	31	* @OSF_COPYRIGHT@
	32	*/
	33	/*
	34	* Mach Operating System
	35	* Copyright (c) 1991 Carnegie Mellon University
	36	* All Rights Reserved.
	37	*
	38	* Permission to use, copy, modify and distribute this software and its
	39	* documentation is hereby granted, provided that both the copyright
	40	* notice and this permission notice appear in all copies of the
	41	* software, derivative works or modified versions, and any portions
	42	* thereof, and that both notices appear in supporting documentation.
	43	*
	44	* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
	45	* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
	46	* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
	47	*
	48	* Carnegie Mellon requests users of this software to return to
	49	*
	50	* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
	51	* School of Computer Science
	52	* Carnegie Mellon University
	53	* Pittsburgh PA 15213-3890
	54	*
	55	* any improvements or extensions that they make and grant Carnegie Mellon
	56	* the rights to redistribute these changes.
	57	*/
	58
	59	/*
	60	*/
	61
	62	/*
	63	* User LDT management.
5d5c5d0d	64	* Each task may have its own LDT.
1c79356b A	65	*/
	66
	67	#include <kern/kalloc.h>
	68	#include <kern/thread.h>
	69	#include <kern/misc_protos.h>
	70
	71	#include <vm/vm_kern.h>
	72
	73	#include <i386/seg.h>
	74	#include <i386/thread.h>
	75	#include <i386/user_ldt.h>
5d5c5d0d A	76	#include <i386/mp_desc.h>
	77	#include <i386/proc_reg.h>
	78	#include <i386/machdep_call.h>
	79	#include <i386/mp.h>
	80	#include <i386/machine_routines.h>
1c79356b	81
5d5c5d0d	82	#include <sys/errno.h>
8ad349bb	83
5d5c5d0d	84	static void user_ldt_set_action(void *);
1c79356b A	85
	86	/*
	87	* Add the descriptors to the LDT, starting with
	88	* the descriptor for 'first_selector'.
	89	*/
	90
5d5c5d0d	91	int
1c79356b	92	i386_set_ldt(
5d5c5d0d A	93	int *retval,
	94	uint32_t start_sel,
	95	uint32_t descs, /* out */
	96	uint32_t num_sels)
1c79356b	97	{
5d5c5d0d	98	user_ldt_t new_ldt, old_ldt;
1c79356b	99	struct real_descriptor *dp;
5d5c5d0d A	100	unsigned int i;
	101	unsigned int min_selector = LDTSZ_MIN; /* do not allow the system selectors to be changed */
	102	task_t task = current_task();
	103	unsigned int ldt_count;
	104	kern_return_t err;
c0fea474	105
5d5c5d0d A	106	if (start_sel != LDT_AUTO_ALLOC
	107	&& (start_sel != 0 \|\| num_sels != 0)
	108	&& (start_sel < min_selector \|\| start_sel >= LDTSZ))
	109	return EINVAL;
	110	if (start_sel != LDT_AUTO_ALLOC
	111	&& start_sel + num_sels > LDTSZ)
	112	return EINVAL;
c0fea474	113
5d5c5d0d A	114	task_lock(task);
	115
	116	old_ldt = task->i386_ldt;
	117
	118	if (start_sel == LDT_AUTO_ALLOC) {
	119	if (old_ldt) {
	120	unsigned int null_count;
	121	struct real_descriptor null_ldt;
	122
	123	bzero(&null_ldt, sizeof(null_ldt));
	124
	125	/*
	126	* Look for null selectors among the already-allocated
	127	* entries.
	128	*/
	129	null_count = 0;
	130	i = 0;
	131	while (i < old_ldt->count)
	132	{
	133	if (!memcmp(&old_ldt->ldt[i++], &null_ldt, sizeof(null_ldt))) {
	134	null_count++;
	135	if (null_count == num_sels)
	136	break; /* break out of while loop */
	137	} else {
	138	null_count = 0;
	139	}
	140	}
	141
	142	/*
	143	* If we broke out of the while loop, i points to the selector
	144	* after num_sels null selectors. Otherwise it points to the end
	145	* of the old LDTs, and null_count is the number of null selectors
	146	* at the end.
	147	*
	148	* Either way, there are null_count null selectors just prior to
	149	* the i-indexed selector, and either null_count >= num_sels,
	150	* or we're at the end, so we can extend.
	151	*/
	152	start_sel = old_ldt->start + i - null_count;
	153	} else {
	154	start_sel = LDTSZ_MIN;
	155	}
	156
	157	if (start_sel + num_sels > LDTSZ) {
	158	task_unlock(task);
	159	return ENOMEM;
1c79356b A	160	}
1c79356b A	161	}
5d5c5d0d A	162
	163	if (start_sel == 0 && num_sels == 0) {
	164	new_ldt = NULL;
	165	} else {
1c79356b	166	/*
5d5c5d0d	167	* Allocate new LDT
1c79356b	168	*/
5d5c5d0d A	169
	170	unsigned int begin_sel = start_sel;
	171	unsigned int end_sel = begin_sel + num_sels;
	172
	173	if (old_ldt != NULL) {
	174	if (old_ldt->start < begin_sel)
	175	begin_sel = old_ldt->start;
	176	if (old_ldt->start + old_ldt->count > end_sel)
	177	end_sel = old_ldt->start + old_ldt->count;
	178	}
	179
	180	ldt_count = end_sel - begin_sel;
	181
	182	new_ldt = (user_ldt_t)kalloc(sizeof(struct user_ldt) + (ldt_count * sizeof(struct real_descriptor)));
	183	if (new_ldt == NULL) {
	184	task_unlock(task);
	185	return ENOMEM;
1c79356b A	186	}
1c79356b A	187
5d5c5d0d A	188	new_ldt->start = begin_sel;
	189	new_ldt->count = ldt_count;
	190
1c79356b A	191	/*
1c79356b A	192	* Have new LDT. If there was a an old ldt, copy descriptors
5d5c5d0d	193	* from old to new.
1c79356b A	194	*/
1c79356b A	195	if (old_ldt) {
5d5c5d0d A	196	bcopy(&old_ldt->ldt[0],
	197	&new_ldt->ldt[old_ldt->start - begin_sel],
	198	old_ldt->count * sizeof(struct real_descriptor));
	199
	200	/*
	201	* If the old and new LDTs are non-overlapping, fill the
	202	* center in with null selectors.
	203	*/
	204
	205	if (old_ldt->start + old_ldt->count < start_sel)
	206	bzero(&new_ldt->ldt[old_ldt->count],
	207	(start_sel - (old_ldt->start + old_ldt->count)) * sizeof(struct real_descriptor));
	208	else if (old_ldt->start > start_sel + num_sels)
	209	bzero(&new_ldt->ldt[num_sels],
	210	(old_ldt->start - (start_sel + num_sels)) * sizeof(struct real_descriptor));
1c79356b	211	}
5d5c5d0d A	212
	213	/*
	214	* Install new descriptors.
	215	*/
	216	if (descs != 0) {
	217	err = copyin(descs, (char *)&new_ldt->ldt[start_sel - begin_sel],
	218	num_sels * sizeof(struct real_descriptor));
	219	if (err != 0)
	220	{
	221	task_unlock(task);
	222	user_ldt_free(new_ldt);
	223	return err;
1c79356b	224	}
5d5c5d0d A	225	} else {
5d5c5d0d A	226	bzero(&new_ldt->ldt[start_sel - begin_sel], num_sels * sizeof(struct real_descriptor));
1c79356b A	227	}
1c79356b A	228
5d5c5d0d A	229	/*
	230	* Validate descriptors.
	231	* Only allow descriptors with user priviledges.
	232	*/
	233	for (i = 0, dp = (struct real_descriptor *) &new_ldt->ldt[start_sel - begin_sel];
	234	i < num_sels;
	235	i++, dp++)
	236	{
	237	switch (dp->access & ~ACC_A) {
	238	case 0:
	239	case ACC_P:
	240	/* valid empty descriptor */
	241	break;
	242	case ACC_P \| ACC_PL_U \| ACC_DATA:
	243	case ACC_P \| ACC_PL_U \| ACC_DATA_W:
	244	case ACC_P \| ACC_PL_U \| ACC_DATA_E:
	245	case ACC_P \| ACC_PL_U \| ACC_DATA_EW:
	246	case ACC_P \| ACC_PL_U \| ACC_CODE:
	247	case ACC_P \| ACC_PL_U \| ACC_CODE_R:
	248	case ACC_P \| ACC_PL_U \| ACC_CODE_C:
	249	case ACC_P \| ACC_PL_U \| ACC_CODE_CR:
	250	case ACC_P \| ACC_PL_U \| ACC_CALL_GATE_16:
	251	case ACC_P \| ACC_PL_U \| ACC_CALL_GATE:
	252	break;
	253	default:
	254	task_unlock(task);
	255	user_ldt_free(new_ldt);
	256	return EACCES;
	257	}
	258	}
8ad349bb	259	}
c0fea474	260
5d5c5d0d A	261	task->i386_ldt = new_ldt; /* new LDT for task */
5d5c5d0d A	262
1c79356b	263	/*
5d5c5d0d A	264	* Switch to new LDT. We need to do this on all CPUs, since
	265	* another thread in this same task may be currently running,
	266	* and we need to make sure the new LDT is in place
	267	* throughout the task before returning to the user.
1c79356b	268	*/
5d5c5d0d	269	mp_rendezvous_no_intrs(user_ldt_set_action, task);
1c79356b	270
5d5c5d0d	271	task_unlock(task);
1c79356b	272
5d5c5d0d A	273	/* free old LDT. We can't do this until after we've
	274	* rendezvoused with all CPUs, in case another thread
	275	* in this task was in the process of context switching.
8ad349bb	276	*/
5d5c5d0d A	277	if (old_ldt)
	278	user_ldt_free(old_ldt);
	279
	280	*retval = start_sel;
	281
	282	return 0;
1c79356b A	283	}
1c79356b A	284
5d5c5d0d	285	int
1c79356b	286	i386_get_ldt(
5d5c5d0d A	287	int *retval,
	288	uint32_t start_sel,
	289	uint32_t descs, /* out */
	290	uint32_t num_sels)
1c79356b	291	{
5d5c5d0d A	292	user_ldt_t user_ldt;
5d5c5d0d A	293	task_t task = current_task();
1c79356b	294	unsigned int ldt_count;
5d5c5d0d	295	kern_return_t err;
1c79356b	296
5d5c5d0d A	297	if (start_sel >= 8192)
	298	return EINVAL;
	299	if (start_sel + num_sels > 8192)
	300	return EINVAL;
	301	if (descs == 0)
	302	return EINVAL;
1c79356b	303
5d5c5d0d	304	task_lock(task);
1c79356b	305
5d5c5d0d A	306	user_ldt = task->i386_ldt;
5d5c5d0d A	307	err = 0;
c0fea474	308
5d5c5d0d A	309	/*
	310	* copy out the descriptors
	311	*/
	312
	313	if (user_ldt != 0)
	314	ldt_count = user_ldt->start + user_ldt->count;
	315	else
	316	ldt_count = LDTSZ_MIN;
1c79356b	317
1c79356b	318
5d5c5d0d A	319	if (start_sel < ldt_count)
	320	{
	321	unsigned int copy_sels = num_sels;
1c79356b	322
5d5c5d0d A	323	if (start_sel + num_sels > ldt_count)
5d5c5d0d A	324	copy_sels = ldt_count - start_sel;
1c79356b	325
5d5c5d0d A	326	err = copyout((char *)(current_ldt() + start_sel),
5d5c5d0d A	327	descs, copy_sels * sizeof(struct real_descriptor));
1c79356b A	328	}
1c79356b A	329
5d5c5d0d	330	task_unlock(task);
1c79356b	331
5d5c5d0d	332	*retval = ldt_count;
1c79356b	333
5d5c5d0d A	334	return err;
5d5c5d0d A	335	}
1c79356b	336
5d5c5d0d A	337	void
	338	user_ldt_free(
	339	user_ldt_t user_ldt)
	340	{
	341	kfree(user_ldt, sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor)));
	342	}
1c79356b	343
5d5c5d0d A	344	user_ldt_t
	345	user_ldt_copy(
	346	user_ldt_t user_ldt)
	347	{
	348	if (user_ldt != NULL) {
	349	size_t size = sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor));
	350	user_ldt_t new_ldt = (user_ldt_t)kalloc(size);
	351	if (new_ldt != NULL)
	352	bcopy(user_ldt, new_ldt, size);
	353	return new_ldt;
1c79356b	354	}
5d5c5d0d A	355
	356	return 0;
	357	}
1c79356b	358
5d5c5d0d A	359	void
	360	user_ldt_set_action(
	361	void *arg)
	362	{
	363	task_t arg_task = (task_t)arg;
	364
	365	if (arg_task == current_task()) {
	366	user_ldt_set(current_thread());
	367	}
1c79356b A	368	}
1c79356b A	369
5d5c5d0d A	370	/*
	371	* Set the LDT for the given thread on the current CPU. Should be invoked
	372	* with interrupts disabled.
	373	*/
1c79356b	374	void
5d5c5d0d A	375	user_ldt_set(
5d5c5d0d A	376	thread_t thread)
1c79356b	377	{
5d5c5d0d A	378	task_t task = thread->task;
	379	user_ldt_t user_ldt;
	380
	381	user_ldt = task->i386_ldt;
	382
	383	if (user_ldt != 0) {
	384	struct real_descriptor ldtp = (struct real_descriptor )current_ldt();
	385
	386	if (user_ldt->start > LDTSZ_MIN) {
	387	bzero(&ldtp[LDTSZ_MIN],
	388	sizeof(struct real_descriptor) * (user_ldt->start - LDTSZ_MIN));
	389	}
	390
	391	bcopy(user_ldt->ldt, &ldtp[user_ldt->start],
	392	sizeof(struct real_descriptor) * (user_ldt->count));
	393
	394	gdt_desc_p(USER_LDT)->limit_low = (sizeof(struct real_descriptor) * (user_ldt->start + user_ldt->count)) - 1;
	395
	396	ml_cpu_set_ldt(USER_LDT);
	397	} else {
	398	ml_cpu_set_ldt(KERNEL_LDT);
	399	}
1c79356b	400	}