[apple/xnu.git] / osfmk / i386 / user_ldt.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@
 */
/*
 * @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(
	uint32_t		*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
	    && (uint64_t)start_sel + (uint64_t)num_sels > LDTSZ) /* cast to uint64_t to detect wrap-around */
	    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 ((uint64_t)start_sel + (uint64_t)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(
	uint32_t		*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 ((uint64_t)start_sel + (uint64_t)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	/*
2d21ac55	2	* Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
1c79356b	3	*
2d21ac55	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
1c79356b	5	*
2d21ac55 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 License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
8f6c56a5	14	*
2d21ac55 A	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
8f6c56a5 A	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
8f6c56a5 A	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
2d21ac55 A	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
8f6c56a5	25	*
2d21ac55	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
1c79356b A	27	*/
	28	/*
	29	* @OSF_COPYRIGHT@
	30	*/
	31	/*
	32	* Mach Operating System
	33	* Copyright (c) 1991 Carnegie Mellon University
	34	* All Rights Reserved.
	35	*
	36	* Permission to use, copy, modify and distribute this software and its
	37	* documentation is hereby granted, provided that both the copyright
	38	* notice and this permission notice appear in all copies of the
	39	* software, derivative works or modified versions, and any portions
	40	* thereof, and that both notices appear in supporting documentation.
	41	*
	42	* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
	43	* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
	44	* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
	45	*
	46	* Carnegie Mellon requests users of this software to return to
	47	*
	48	* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
	49	* School of Computer Science
	50	* Carnegie Mellon University
	51	* Pittsburgh PA 15213-3890
	52	*
	53	* any improvements or extensions that they make and grant Carnegie Mellon
	54	* the rights to redistribute these changes.
	55	*/
	56
	57	/*
	58	*/
	59
	60	/*
	61	* User LDT management.
0c530ab8	62	* Each task may have its own LDT.
1c79356b A	63	*/
	64
	65	#include <kern/kalloc.h>
	66	#include <kern/thread.h>
	67	#include <kern/misc_protos.h>
	68
	69	#include <vm/vm_kern.h>
	70
	71	#include <i386/seg.h>
	72	#include <i386/thread.h>
	73	#include <i386/user_ldt.h>
0c530ab8 A	74	#include <i386/mp_desc.h>
	75	#include <i386/proc_reg.h>
	76	#include <i386/machdep_call.h>
	77	#include <i386/mp.h>
	78	#include <i386/machine_routines.h>
1c79356b	79
0c530ab8	80	#include <sys/errno.h>
6601e61a	81
0c530ab8	82	static void user_ldt_set_action(void *);
1c79356b A	83
	84	/*
	85	* Add the descriptors to the LDT, starting with
	86	* the descriptor for 'first_selector'.
	87	*/
	88
0c530ab8	89	int
1c79356b	90	i386_set_ldt(
2d21ac55	91	uint32_t *retval,
0c530ab8 A	92	uint32_t start_sel,
	93	uint32_t descs, /* out */
	94	uint32_t num_sels)
1c79356b	95	{
0c530ab8	96	user_ldt_t new_ldt, old_ldt;
1c79356b	97	struct real_descriptor *dp;
0c530ab8 A	98	unsigned int i;
	99	unsigned int min_selector = LDTSZ_MIN; /* do not allow the system selectors to be changed */
	100	task_t task = current_task();
	101	unsigned int ldt_count;
	102	kern_return_t err;
4452a7af	103
0c530ab8 A	104	if (start_sel != LDT_AUTO_ALLOC
	105	&& (start_sel != 0 \|\| num_sels != 0)
	106	&& (start_sel < min_selector \|\| start_sel >= LDTSZ))
	107	return EINVAL;
	108	if (start_sel != LDT_AUTO_ALLOC
2d21ac55	109	&& (uint64_t)start_sel + (uint64_t)num_sels > LDTSZ) /* cast to uint64_t to detect wrap-around */
0c530ab8	110	return EINVAL;
4452a7af	111
0c530ab8 A	112	task_lock(task);
	113
	114	old_ldt = task->i386_ldt;
	115
	116	if (start_sel == LDT_AUTO_ALLOC) {
	117	if (old_ldt) {
	118	unsigned int null_count;
	119	struct real_descriptor null_ldt;
	120
	121	bzero(&null_ldt, sizeof(null_ldt));
	122
	123	/*
	124	* Look for null selectors among the already-allocated
	125	* entries.
	126	*/
	127	null_count = 0;
	128	i = 0;
	129	while (i < old_ldt->count)
	130	{
	131	if (!memcmp(&old_ldt->ldt[i++], &null_ldt, sizeof(null_ldt))) {
	132	null_count++;
	133	if (null_count == num_sels)
	134	break; /* break out of while loop */
	135	} else {
	136	null_count = 0;
	137	}
	138	}
	139
	140	/*
	141	* If we broke out of the while loop, i points to the selector
	142	* after num_sels null selectors. Otherwise it points to the end
	143	* of the old LDTs, and null_count is the number of null selectors
	144	* at the end.
	145	*
	146	* Either way, there are null_count null selectors just prior to
	147	* the i-indexed selector, and either null_count >= num_sels,
	148	* or we're at the end, so we can extend.
	149	*/
	150	start_sel = old_ldt->start + i - null_count;
	151	} else {
	152	start_sel = LDTSZ_MIN;
	153	}
	154
593a1d5f	155	if ((uint64_t)start_sel + (uint64_t)num_sels > LDTSZ) {
0c530ab8 A	156	task_unlock(task);
0c530ab8 A	157	return ENOMEM;
1c79356b A	158	}
1c79356b A	159	}
0c530ab8 A	160
	161	if (start_sel == 0 && num_sels == 0) {
	162	new_ldt = NULL;
	163	} else {
1c79356b	164	/*
0c530ab8	165	* Allocate new LDT
1c79356b	166	*/
0c530ab8 A	167
	168	unsigned int begin_sel = start_sel;
	169	unsigned int end_sel = begin_sel + num_sels;
	170
	171	if (old_ldt != NULL) {
	172	if (old_ldt->start < begin_sel)
	173	begin_sel = old_ldt->start;
	174	if (old_ldt->start + old_ldt->count > end_sel)
	175	end_sel = old_ldt->start + old_ldt->count;
	176	}
	177
	178	ldt_count = end_sel - begin_sel;
	179
	180	new_ldt = (user_ldt_t)kalloc(sizeof(struct user_ldt) + (ldt_count * sizeof(struct real_descriptor)));
	181	if (new_ldt == NULL) {
	182	task_unlock(task);
	183	return ENOMEM;
5d5c5d0d A	184	}
5d5c5d0d A	185
0c530ab8 A	186	new_ldt->start = begin_sel;
	187	new_ldt->count = ldt_count;
	188
1c79356b A	189	/*
1c79356b A	190	* Have new LDT. If there was a an old ldt, copy descriptors
0c530ab8	191	* from old to new.
1c79356b A	192	*/
1c79356b A	193	if (old_ldt) {
0c530ab8 A	194	bcopy(&old_ldt->ldt[0],
	195	&new_ldt->ldt[old_ldt->start - begin_sel],
	196	old_ldt->count * sizeof(struct real_descriptor));
	197
	198	/*
	199	* If the old and new LDTs are non-overlapping, fill the
	200	* center in with null selectors.
	201	*/
	202
	203	if (old_ldt->start + old_ldt->count < start_sel)
	204	bzero(&new_ldt->ldt[old_ldt->count],
	205	(start_sel - (old_ldt->start + old_ldt->count)) * sizeof(struct real_descriptor));
	206	else if (old_ldt->start > start_sel + num_sels)
	207	bzero(&new_ldt->ldt[num_sels],
	208	(old_ldt->start - (start_sel + num_sels)) * sizeof(struct real_descriptor));
1c79356b	209	}
0c530ab8 A	210
	211	/*
	212	* Install new descriptors.
	213	*/
	214	if (descs != 0) {
	215	err = copyin(descs, (char *)&new_ldt->ldt[start_sel - begin_sel],
	216	num_sels * sizeof(struct real_descriptor));
	217	if (err != 0)
	218	{
	219	task_unlock(task);
	220	user_ldt_free(new_ldt);
	221	return err;
1c79356b	222	}
0c530ab8 A	223	} else {
0c530ab8 A	224	bzero(&new_ldt->ldt[start_sel - begin_sel], num_sels * sizeof(struct real_descriptor));
1c79356b A	225	}
1c79356b A	226
0c530ab8 A	227	/*
	228	* Validate descriptors.
	229	* Only allow descriptors with user priviledges.
	230	*/
	231	for (i = 0, dp = (struct real_descriptor *) &new_ldt->ldt[start_sel - begin_sel];
	232	i < num_sels;
	233	i++, dp++)
	234	{
	235	switch (dp->access & ~ACC_A) {
	236	case 0:
	237	case ACC_P:
	238	/* valid empty descriptor */
	239	break;
	240	case ACC_P \| ACC_PL_U \| ACC_DATA:
	241	case ACC_P \| ACC_PL_U \| ACC_DATA_W:
	242	case ACC_P \| ACC_PL_U \| ACC_DATA_E:
	243	case ACC_P \| ACC_PL_U \| ACC_DATA_EW:
	244	case ACC_P \| ACC_PL_U \| ACC_CODE:
	245	case ACC_P \| ACC_PL_U \| ACC_CODE_R:
	246	case ACC_P \| ACC_PL_U \| ACC_CODE_C:
	247	case ACC_P \| ACC_PL_U \| ACC_CODE_CR:
	248	case ACC_P \| ACC_PL_U \| ACC_CALL_GATE_16:
	249	case ACC_P \| ACC_PL_U \| ACC_CALL_GATE:
	250	break;
	251	default:
	252	task_unlock(task);
	253	user_ldt_free(new_ldt);
	254	return EACCES;
	255	}
	256	}
6601e61a	257	}
4452a7af	258
0c530ab8 A	259	task->i386_ldt = new_ldt; /* new LDT for task */
0c530ab8 A	260
1c79356b	261	/*
0c530ab8 A	262	* Switch to new LDT. We need to do this on all CPUs, since
	263	* another thread in this same task may be currently running,
	264	* and we need to make sure the new LDT is in place
	265	* throughout the task before returning to the user.
1c79356b	266	*/
0c530ab8	267	mp_rendezvous_no_intrs(user_ldt_set_action, task);
89b3af67	268
0c530ab8	269	task_unlock(task);
4452a7af	270
0c530ab8 A	271	/* free old LDT. We can't do this until after we've
	272	* rendezvoused with all CPUs, in case another thread
	273	* in this task was in the process of context switching.
6601e61a	274	*/
0c530ab8 A	275	if (old_ldt)
	276	user_ldt_free(old_ldt);
	277
	278	*retval = start_sel;
	279
	280	return 0;
1c79356b A	281	}
1c79356b A	282
0c530ab8	283	int
1c79356b	284	i386_get_ldt(
2d21ac55	285	uint32_t *retval,
0c530ab8 A	286	uint32_t start_sel,
	287	uint32_t descs, /* out */
	288	uint32_t num_sels)
1c79356b	289	{
0c530ab8 A	290	user_ldt_t user_ldt;
0c530ab8 A	291	task_t task = current_task();
1c79356b	292	unsigned int ldt_count;
0c530ab8	293	kern_return_t err;
c0fea474	294
0c530ab8 A	295	if (start_sel >= 8192)
0c530ab8 A	296	return EINVAL;
593a1d5f	297	if ((uint64_t)start_sel + (uint64_t)num_sels > 8192)
0c530ab8 A	298	return EINVAL;
	299	if (descs == 0)
	300	return EINVAL;
5d5c5d0d	301
0c530ab8	302	task_lock(task);
89b3af67	303
0c530ab8 A	304	user_ldt = task->i386_ldt;
0c530ab8 A	305	err = 0;
4452a7af	306
0c530ab8 A	307	/*
	308	* copy out the descriptors
	309	*/
	310
	311	if (user_ldt != 0)
	312	ldt_count = user_ldt->start + user_ldt->count;
	313	else
	314	ldt_count = LDTSZ_MIN;
1c79356b	315
1c79356b	316
0c530ab8 A	317	if (start_sel < ldt_count)
	318	{
	319	unsigned int copy_sels = num_sels;
1c79356b	320
0c530ab8 A	321	if (start_sel + num_sels > ldt_count)
0c530ab8 A	322	copy_sels = ldt_count - start_sel;
1c79356b	323
0c530ab8 A	324	err = copyout((char *)(current_ldt() + start_sel),
0c530ab8 A	325	descs, copy_sels * sizeof(struct real_descriptor));
1c79356b A	326	}
1c79356b A	327
0c530ab8	328	task_unlock(task);
1c79356b	329
0c530ab8	330	*retval = ldt_count;
1c79356b	331
0c530ab8 A	332	return err;
0c530ab8 A	333	}
1c79356b	334
0c530ab8 A	335	void
	336	user_ldt_free(
	337	user_ldt_t user_ldt)
	338	{
	339	kfree(user_ldt, sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor)));
	340	}
1c79356b	341
0c530ab8 A	342	user_ldt_t
	343	user_ldt_copy(
	344	user_ldt_t user_ldt)
	345	{
	346	if (user_ldt != NULL) {
	347	size_t size = sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor));
	348	user_ldt_t new_ldt = (user_ldt_t)kalloc(size);
	349	if (new_ldt != NULL)
	350	bcopy(user_ldt, new_ldt, size);
	351	return new_ldt;
1c79356b	352	}
0c530ab8 A	353
	354	return 0;
	355	}
5d5c5d0d	356
0c530ab8 A	357	void
	358	user_ldt_set_action(
	359	void *arg)
	360	{
	361	task_t arg_task = (task_t)arg;
	362
	363	if (arg_task == current_task()) {
	364	user_ldt_set(current_thread());
	365	}
1c79356b A	366	}
1c79356b A	367
0c530ab8 A	368	/*
	369	* Set the LDT for the given thread on the current CPU. Should be invoked
	370	* with interrupts disabled.
	371	*/
1c79356b	372	void
0c530ab8 A	373	user_ldt_set(
0c530ab8 A	374	thread_t thread)
1c79356b	375	{
0c530ab8 A	376	task_t task = thread->task;
	377	user_ldt_t user_ldt;
	378
	379	user_ldt = task->i386_ldt;
	380
	381	if (user_ldt != 0) {
	382	struct real_descriptor ldtp = (struct real_descriptor )current_ldt();
	383
	384	if (user_ldt->start > LDTSZ_MIN) {
	385	bzero(&ldtp[LDTSZ_MIN],
	386	sizeof(struct real_descriptor) * (user_ldt->start - LDTSZ_MIN));
	387	}
	388
	389	bcopy(user_ldt->ldt, &ldtp[user_ldt->start],
	390	sizeof(struct real_descriptor) * (user_ldt->count));
	391
	392	gdt_desc_p(USER_LDT)->limit_low = (sizeof(struct real_descriptor) * (user_ldt->start + user_ldt->count)) - 1;
	393
	394	ml_cpu_set_ldt(USER_LDT);
	395	} else {
	396	ml_cpu_set_ldt(KERNEL_LDT);
	397	}
1c79356b	398	}