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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * 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. 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_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 thread in a 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>

char	acc_type[8][3] = {
    /*	code	stack	data */
    {	0,	0,	1	},	/* data */
    {	0,	1,	1	},	/* data, writable */
    {	0,	0,	1	},	/* data, expand-down */
    {	0,	1,	1	},	/* data, writable, expand-down */
    {	1,	0,	0	},	/* code */
    {	1,	0,	1	},	/* code, readable */
    {	1,	0,	0	},	/* code, conforming */
    {	1,	0,	1	},	/* code, readable, conforming */
};

extern struct fake_descriptor ldt[];	/* for system call gate */

#if 0
/* Forward */

extern boolean_t	selector_check(
				thread_t		thread,
				int			sel,
				int			type);

boolean_t
selector_check(
	thread_t		thread,
	int			sel,
	int			type)
{
	struct user_ldt	*ldt;
	int	access;

	ldt = thread->top_act->mact.pcb->ims.ldt;
	if (ldt == 0) {
	    switch (type) {
		case S_CODE:
		    return sel == USER_CS;
		case S_STACK:
		    return sel == USER_DS;
		case S_DATA:
		    return sel == 0 ||
			   sel == USER_CS ||
			   sel == USER_DS;
	    }
	}

	if (type != S_DATA && sel == 0)
	    return FALSE;
	if ((sel & (SEL_LDTS|SEL_PL)) != (SEL_LDTS|SEL_PL_U)
	  || sel > ldt->desc.limit_low)
		return FALSE;

	access = ldt->ldt[sel_idx(sel)].access;
	
	if ((access & (ACC_P|ACC_PL|ACC_TYPE_USER))
		!= (ACC_P|ACC_PL_U|ACC_TYPE_USER))
	    return FALSE;
		/* present, pl == pl.user, not system */

	return acc_type[(access & 0xe)>>1][type];
}

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

kern_return_t
i386_set_ldt(
	thread_act_t		thr_act,
	int			first_selector,
	descriptor_list_t	desc_list,
	mach_msg_type_number_t	count)
{
	user_ldt_t	new_ldt, old_ldt, temp;
	struct real_descriptor *dp;
	int		i;
	int		min_selector = 0;
	pcb_t		pcb;
	vm_size_t	ldt_size_needed;
	int		first_desc = sel_idx(first_selector);
	vm_map_copy_t	old_copy_object;
	thread_t		thread;

	if (first_desc < min_selector || first_desc > 8191)
	    return KERN_INVALID_ARGUMENT;
	if (first_desc + count >= 8192)
	    return KERN_INVALID_ARGUMENT;
	if (thr_act == THR_ACT_NULL)
	    return KERN_INVALID_ARGUMENT;
	if ((thread = act_lock_thread(thr_act)) == THREAD_NULL) {
		act_unlock_thread(thr_act);
	    return KERN_INVALID_ARGUMENT;
	}
	if (thread == current_thread())
		min_selector = LDTSZ;
	act_unlock_thread(thr_act);

	/*
	 * We must copy out desc_list to the kernel map, and wire
	 * it down (we touch it while the PCB is locked).
	 *
	 * We make a copy of the copyin object, and clear
	 * out the old one, so that the MIG stub will have a
	 * a empty (but valid) copyin object to discard.
	 */
	{
	    kern_return_t	kr;
	    vm_offset_t		dst_addr;

	    old_copy_object = (vm_map_copy_t) desc_list;

	    kr = vm_map_copyout(ipc_kernel_map, &dst_addr,
				vm_map_copy_copy(old_copy_object));
	    if (kr != KERN_SUCCESS)
		return kr;

	    (void) vm_map_wire(ipc_kernel_map,
			trunc_page(dst_addr),
			round_page(dst_addr + 
				count * sizeof(struct real_descriptor)),
			VM_PROT_READ|VM_PROT_WRITE, FALSE);
	    desc_list = (descriptor_list_t) dst_addr;
	}

	for (i = 0, dp = (struct real_descriptor *) desc_list;
	     i < count;
	     i++, dp++)
	{
	    switch (dp->access & ~ACC_A) {
		case 0:
		case ACC_P:
		    /* valid empty descriptor */
		    break;
		case ACC_P | ACC_CALL_GATE:
		    /* Mach kernel call */
		    *dp = *(struct real_descriptor *)
				&ldt[sel_idx(USER_SCALL)];
		    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:
		    (void) vm_map_remove(ipc_kernel_map, 
					 (vm_offset_t) desc_list,
					 count * sizeof(struct real_descriptor),
					 VM_MAP_REMOVE_KUNWIRE);
		    return KERN_INVALID_ARGUMENT;
	    }
	}
	ldt_size_needed = sizeof(struct real_descriptor)
			* (first_desc + count);

	pcb = thr_act->mact.pcb;
	new_ldt = 0;
    Retry:
	simple_lock(&pcb->lock);
	old_ldt = pcb->ims.ldt;
	if (old_ldt == 0 ||
	    old_ldt->desc.limit_low + 1 < ldt_size_needed)
	{
	    /*
	     * No old LDT, or not big enough
	     */
	    if (new_ldt == 0) {
		simple_unlock(&pcb->lock);

		new_ldt = (user_ldt_t) kalloc(ldt_size_needed
					      + sizeof(struct real_descriptor));
		new_ldt->desc.limit_low   = ldt_size_needed - 1;
		new_ldt->desc.limit_high  = 0;
		new_ldt->desc.base_low    = 
				((vm_offset_t)&new_ldt->ldt[0]) & 0xffff;
		new_ldt->desc.base_med    = 
				(((vm_offset_t)&new_ldt->ldt[0]) >> 16)
						 & 0xff;
		new_ldt->desc.base_high   = 
				((vm_offset_t)&new_ldt->ldt[0]) >> 24;
		new_ldt->desc.access      = ACC_P | ACC_LDT;
		new_ldt->desc.granularity = 0;

		goto Retry;
	    }

	    /*
	     * Have new LDT.  If there was a an old ldt, copy descriptors
	     * from old to new.  Otherwise copy the default ldt.
	     */
	    if (old_ldt) {
		bcopy((char *)&old_ldt->ldt[0],
		      (char *)&new_ldt->ldt[0],
		      old_ldt->desc.limit_low + 1);
	    }
	    else if (thr_act == current_act()) {
		struct real_descriptor template = {0, 0, 0, ACC_P, 0, 0 ,0};

		for (dp = &new_ldt->ldt[0], i = 0; i < first_desc; i++, dp++) {
		    if (i < LDTSZ)
		    	*dp = *(struct real_descriptor *) &ldt[i];
		    else
			*dp = template;
		}
	    }

	    temp = old_ldt;
	    old_ldt = new_ldt;	/* use new LDT from now on */
	    new_ldt = temp;	/* discard old LDT */

	    pcb->ims.ldt = old_ldt;	/* new LDT for thread */
	}

	/*
	 * Install new descriptors.
	 */
	bcopy((char *)desc_list,
	      (char *)&old_ldt->ldt[first_desc],
	      count * sizeof(struct real_descriptor));

	simple_unlock(&pcb->lock);

	if (new_ldt)
	    kfree((vm_offset_t)new_ldt,
		  new_ldt->desc.limit_low+1+sizeof(struct real_descriptor));

	/*
	 * Free the descriptor list.
	 */
	(void) vm_map_remove(ipc_kernel_map, (vm_offset_t) desc_list,
			count * sizeof(struct real_descriptor),
			VM_MAP_REMOVE_KUNWIRE);
	return KERN_SUCCESS;
}

kern_return_t
i386_get_ldt(
	thread_act_t		thr_act,
	int			first_selector,
	int			selector_count,	/* number wanted */
	descriptor_list_t	*desc_list,	/* in/out */
	mach_msg_type_number_t	*count)		/* in/out */
{
	struct user_ldt *user_ldt;
	pcb_t		pcb = thr_act->mact.pcb;
	int		first_desc = sel_idx(first_selector);
	unsigned int	ldt_count;
	vm_size_t	ldt_size;
	vm_size_t	size, size_needed;
	vm_offset_t	addr;
	thread_t		thread;

	if (thr_act == THR_ACT_NULL || (thread = thr_act->thread)==THREAD_NULL)
	    return KERN_INVALID_ARGUMENT;

	if (first_desc < 0 || first_desc > 8191)
	    return KERN_INVALID_ARGUMENT;
	if (first_desc + selector_count >= 8192)
	    return KERN_INVALID_ARGUMENT;

	addr = 0;
	size = 0;

	for (;;) {
	    simple_lock(&pcb->lock);
	    user_ldt = pcb->ims.ldt;
	    if (user_ldt == 0) {
		simple_unlock(&pcb->lock);
		if (addr)
		    kmem_free(ipc_kernel_map, addr, size);
		*count = 0;
		return KERN_SUCCESS;
	    }

	    /*
	     * Find how many descriptors we should return.
	     */
	    ldt_count = (user_ldt->desc.limit_low + 1) /
			sizeof (struct real_descriptor);
	    ldt_count -= first_desc;
	    if (ldt_count > selector_count)
		ldt_count = selector_count;

	    ldt_size = ldt_count * sizeof(struct real_descriptor);

	    /*
	     * Do we have the memory we need?
	     */
	    if (ldt_count <= *count)
		break;		/* fits in-line */

	    size_needed = round_page(ldt_size);
	    if (size_needed <= size)
		break;

	    /*
	     * Unlock the pcb and allocate more memory
	     */
	    simple_unlock(&pcb->lock);

	    if (size != 0)
		kmem_free(ipc_kernel_map, addr, size);

	    size = size_needed;

	    if (kmem_alloc(ipc_kernel_map, &addr, size)
			!= KERN_SUCCESS)
		return KERN_RESOURCE_SHORTAGE;
	}

	/*
	 * copy out the descriptors
	 */
	bcopy((char *)&user_ldt->ldt[first_desc],
	      (char *)addr,
	      ldt_size);
	*count = ldt_count;
	simple_unlock(&pcb->lock);

	if (addr) {
	    vm_size_t		size_used, size_left;
	    vm_map_copy_t	memory;

	    /*
	     * Free any unused memory beyond the end of the last page used
	     */
	    size_used = round_page(ldt_size);
	    if (size_used != size)
		kmem_free(ipc_kernel_map,
			addr + size_used, size - size_used);

	    /*
	     * Zero the remainder of the page being returned.
	     */
	    size_left = size_used - ldt_size;
	    if (size_left > 0)
		bzero((char *)addr + ldt_size, size_left);

	    /*
	     * Unwire the memory and make it into copyin form.
	     */
	    (void) vm_map_unwire(ipc_kernel_map, trunc_page(addr),
				 round_page(addr + size_used), FALSE);
	    (void) vm_map_copyin(ipc_kernel_map, addr, size_used,
				TRUE, &memory);
	    *desc_list = (descriptor_list_t) memory;
	}

	return KERN_SUCCESS;
}

#endif 
void
user_ldt_free(
	user_ldt_t	user_ldt)
{
	kfree((vm_offset_t)user_ldt,
		user_ldt->desc.limit_low+1+sizeof(struct real_descriptor));
}
Commit	Line	Data
1c79356b A	1	/*
	2	* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
43866e37	6	* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
1c79356b	7	*
43866e37 A	8	* This file contains Original Code and/or Modifications of Original Code
	9	* as defined in and that are subject to the Apple Public Source License
	10	* Version 2.0 (the 'License'). You may not use this file except in
	11	* compliance with the License. Please obtain a copy of the License at
	12	* http://www.opensource.apple.com/apsl/ and read it before using this
	13	* file.
	14	*
	15	* The Original Code and all software distributed under the License are
	16	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
1c79356b A	17	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
1c79356b A	18	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
43866e37 A	19	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	20	* Please see the License for the specific language governing rights and
	21	* limitations under the License.
1c79356b A	22	*
	23	* @APPLE_LICENSE_HEADER_END@
	24	*/
	25	/*
	26	* @OSF_COPYRIGHT@
	27	*/
	28	/*
	29	* Mach Operating System
	30	* Copyright (c) 1991 Carnegie Mellon University
	31	* All Rights Reserved.
	32	*
	33	* Permission to use, copy, modify and distribute this software and its
	34	* documentation is hereby granted, provided that both the copyright
	35	* notice and this permission notice appear in all copies of the
	36	* software, derivative works or modified versions, and any portions
	37	* thereof, and that both notices appear in supporting documentation.
	38	*
	39	* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
	40	* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
	41	* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
	42	*
	43	* Carnegie Mellon requests users of this software to return to
	44	*
	45	* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
	46	* School of Computer Science
	47	* Carnegie Mellon University
	48	* Pittsburgh PA 15213-3890
	49	*
	50	* any improvements or extensions that they make and grant Carnegie Mellon
	51	* the rights to redistribute these changes.
	52	*/
	53
	54	/*
	55	*/
	56
	57	/*
	58	* User LDT management.
	59	* Each thread in a task may have its own LDT.
	60	*/
	61
	62	#include <kern/kalloc.h>
	63	#include <kern/thread.h>
	64	#include <kern/misc_protos.h>
	65
	66	#include <vm/vm_kern.h>
	67
	68	#include <i386/seg.h>
	69	#include <i386/thread.h>
	70	#include <i386/user_ldt.h>
	71
	72	char acc_type[8][3] = {
	73	/* code stack data */
	74	{ 0, 0, 1 }, /* data */
	75	{ 0, 1, 1 }, /* data, writable */
	76	{ 0, 0, 1 }, /* data, expand-down */
	77	{ 0, 1, 1 }, /* data, writable, expand-down */
	78	{ 1, 0, 0 }, /* code */
	79	{ 1, 0, 1 }, /* code, readable */
	80	{ 1, 0, 0 }, /* code, conforming */
	81	{ 1, 0, 1 }, /* code, readable, conforming */
	82	};
	83
	84	extern struct fake_descriptor ldt[]; /* for system call gate */
	85
86	#if 0
87	/* Forward */
88
89	extern boolean_t selector_check(
90	thread_t thread,
91	int sel,
92	int type);
93
94	boolean_t
95	selector_check(
96	thread_t thread,
97	int sel,
98	int type)
99	{
100	struct user_ldt *ldt;
101	int access;
102
103	ldt = thread->top_act->mact.pcb->ims.ldt;
104	if (ldt == 0) {
105	switch (type) {
106	case S_CODE:
107	return sel == USER_CS;
108	case S_STACK:
109	return sel == USER_DS;
110	case S_DATA:
111	return sel == 0 \|\|
112	sel == USER_CS \|\|
113	sel == USER_DS;
114	}
115	}
116
117	if (type != S_DATA && sel == 0)
118	return FALSE;
119	if ((sel & (SEL_LDTS\|SEL_PL)) != (SEL_LDTS\|SEL_PL_U)
120	\|\| sel > ldt->desc.limit_low)
121	return FALSE;
122
123	access = ldt->ldt[sel_idx(sel)].access;
124
125	if ((access & (ACC_P\|ACC_PL\|ACC_TYPE_USER))
126	!= (ACC_P\|ACC_PL_U\|ACC_TYPE_USER))
127	return FALSE;
128	/* present, pl == pl.user, not system */
129
130	return acc_type[(access & 0xe)>>1][type];
131	}
132
133	/*
134	* Add the descriptors to the LDT, starting with
135	* the descriptor for 'first_selector'.
136	*/
137
138	kern_return_t
139	i386_set_ldt(
140	thread_act_t thr_act,
141	int first_selector,
142	descriptor_list_t desc_list,
143	mach_msg_type_number_t count)
144	{
145	user_ldt_t new_ldt, old_ldt, temp;
146	struct real_descriptor *dp;
147	int i;
148	int min_selector = 0;
149	pcb_t pcb;
150	vm_size_t ldt_size_needed;
151	int first_desc = sel_idx(first_selector);
152	vm_map_copy_t old_copy_object;
153	thread_t thread;
154
155	if (first_desc < min_selector \|\| first_desc > 8191)
156	return KERN_INVALID_ARGUMENT;
157	if (first_desc + count >= 8192)
158	return KERN_INVALID_ARGUMENT;
159	if (thr_act == THR_ACT_NULL)
160	return KERN_INVALID_ARGUMENT;
161	if ((thread = act_lock_thread(thr_act)) == THREAD_NULL) {
162	act_unlock_thread(thr_act);
163	return KERN_INVALID_ARGUMENT;
164	}
165	if (thread == current_thread())
166	min_selector = LDTSZ;
167	act_unlock_thread(thr_act);
168
169	/*
170	* We must copy out desc_list to the kernel map, and wire
171	* it down (we touch it while the PCB is locked).
172	*
173	* We make a copy of the copyin object, and clear
174	* out the old one, so that the MIG stub will have a
175	* a empty (but valid) copyin object to discard.
176	*/
177	{
178	kern_return_t kr;
179	vm_offset_t dst_addr;
180
181	old_copy_object = (vm_map_copy_t) desc_list;
182
183	kr = vm_map_copyout(ipc_kernel_map, &dst_addr,
184	vm_map_copy_copy(old_copy_object));
185	if (kr != KERN_SUCCESS)
186	return kr;
187
188	(void) vm_map_wire(ipc_kernel_map,
189	trunc_page(dst_addr),
190	round_page(dst_addr +
191	count * sizeof(struct real_descriptor)),
192	VM_PROT_READ\|VM_PROT_WRITE, FALSE);
193	desc_list = (descriptor_list_t) dst_addr;
194	}
195
196	for (i = 0, dp = (struct real_descriptor *) desc_list;
197	i < count;
198	i++, dp++)
199	{
200	switch (dp->access & ~ACC_A) {
201	case 0:
202	case ACC_P:
203	/* valid empty descriptor */
204	break;
205	case ACC_P \| ACC_CALL_GATE:
206	/* Mach kernel call */
207	dp = (struct real_descriptor *)
208	&ldt[sel_idx(USER_SCALL)];
209	break;
210	case ACC_P \| ACC_PL_U \| ACC_DATA:
211	case ACC_P \| ACC_PL_U \| ACC_DATA_W:
212	case ACC_P \| ACC_PL_U \| ACC_DATA_E:
213	case ACC_P \| ACC_PL_U \| ACC_DATA_EW:
214	case ACC_P \| ACC_PL_U \| ACC_CODE:
215	case ACC_P \| ACC_PL_U \| ACC_CODE_R:
216	case ACC_P \| ACC_PL_U \| ACC_CODE_C:
217	case ACC_P \| ACC_PL_U \| ACC_CODE_CR:
218	case ACC_P \| ACC_PL_U \| ACC_CALL_GATE_16:
219	case ACC_P \| ACC_PL_U \| ACC_CALL_GATE:
220	break;
221	default:
222	(void) vm_map_remove(ipc_kernel_map,
223	(vm_offset_t) desc_list,
224	count * sizeof(struct real_descriptor),
225	VM_MAP_REMOVE_KUNWIRE);
226	return KERN_INVALID_ARGUMENT;
227	}
228	}
229	ldt_size_needed = sizeof(struct real_descriptor)
230	* (first_desc + count);
231
232	pcb = thr_act->mact.pcb;
233	new_ldt = 0;
234	Retry:
235	simple_lock(&pcb->lock);
236	old_ldt = pcb->ims.ldt;
237	if (old_ldt == 0 \|\|
238	old_ldt->desc.limit_low + 1 < ldt_size_needed)
239	{
240	/*
241	* No old LDT, or not big enough
242	*/
243	if (new_ldt == 0) {
244	simple_unlock(&pcb->lock);
245
246	new_ldt = (user_ldt_t) kalloc(ldt_size_needed
247	+ sizeof(struct real_descriptor));
248	new_ldt->desc.limit_low = ldt_size_needed - 1;
249	new_ldt->desc.limit_high = 0;
250	new_ldt->desc.base_low =
251	((vm_offset_t)&new_ldt->ldt[0]) & 0xffff;
252	new_ldt->desc.base_med =
253	(((vm_offset_t)&new_ldt->ldt[0]) >> 16)
254	& 0xff;
255	new_ldt->desc.base_high =
256	((vm_offset_t)&new_ldt->ldt[0]) >> 24;
257	new_ldt->desc.access = ACC_P \| ACC_LDT;
258	new_ldt->desc.granularity = 0;
259
260	goto Retry;
261	}
262
263	/*
264	* Have new LDT. If there was a an old ldt, copy descriptors
265	* from old to new. Otherwise copy the default ldt.
266	*/
267	if (old_ldt) {
268	bcopy((char *)&old_ldt->ldt[0],
269	(char *)&new_ldt->ldt[0],
270	old_ldt->desc.limit_low + 1);
271	}
272	else if (thr_act == current_act()) {
273	struct real_descriptor template = {0, 0, 0, ACC_P, 0, 0 ,0};
274
275	for (dp = &new_ldt->ldt[0], i = 0; i < first_desc; i++, dp++) {
276	if (i < LDTSZ)
277	dp = (struct real_descriptor *) &ldt[i];
278	else
279	*dp = template;
280	}
281	}
282
283	temp = old_ldt;
284	old_ldt = new_ldt; /* use new LDT from now on */
285	new_ldt = temp; /* discard old LDT */
286
287	pcb->ims.ldt = old_ldt; /* new LDT for thread */
288	}
289
290	/*
291	* Install new descriptors.
292	*/
293	bcopy((char *)desc_list,
294	(char *)&old_ldt->ldt[first_desc],
295	count * sizeof(struct real_descriptor));
296
297	simple_unlock(&pcb->lock);
298
299	if (new_ldt)
300	kfree((vm_offset_t)new_ldt,
301	new_ldt->desc.limit_low+1+sizeof(struct real_descriptor));
302
303	/*
304	* Free the descriptor list.
305	*/
306	(void) vm_map_remove(ipc_kernel_map, (vm_offset_t) desc_list,
307	count * sizeof(struct real_descriptor),
308	VM_MAP_REMOVE_KUNWIRE);
309	return KERN_SUCCESS;
310	}
311
312	kern_return_t
313	i386_get_ldt(
314	thread_act_t thr_act,
315	int first_selector,
316	int selector_count, /* number wanted */
317	descriptor_list_t desc_list, / in/out */
318	mach_msg_type_number_t count) / in/out */
319	{
320	struct user_ldt *user_ldt;
321	pcb_t pcb = thr_act->mact.pcb;
322	int first_desc = sel_idx(first_selector);
323	unsigned int ldt_count;
324	vm_size_t ldt_size;
325	vm_size_t size, size_needed;
326	vm_offset_t addr;
327	thread_t thread;
328
329	if (thr_act == THR_ACT_NULL \|\| (thread = thr_act->thread)==THREAD_NULL)
330	return KERN_INVALID_ARGUMENT;
331
332	if (first_desc < 0 \|\| first_desc > 8191)
333	return KERN_INVALID_ARGUMENT;
334	if (first_desc + selector_count >= 8192)
335	return KERN_INVALID_ARGUMENT;
336
337	addr = 0;
338	size = 0;
339
340	for (;;) {
341	simple_lock(&pcb->lock);
342	user_ldt = pcb->ims.ldt;
343	if (user_ldt == 0) {
344	simple_unlock(&pcb->lock);
345	if (addr)
346	kmem_free(ipc_kernel_map, addr, size);
347	*count = 0;
348	return KERN_SUCCESS;
349	}
350
351	/*
352	* Find how many descriptors we should return.
353	*/
354	ldt_count = (user_ldt->desc.limit_low + 1) /
355	sizeof (struct real_descriptor);
356	ldt_count -= first_desc;
357	if (ldt_count > selector_count)
358	ldt_count = selector_count;
359
360	ldt_size = ldt_count * sizeof(struct real_descriptor);
361
362	/*
363	* Do we have the memory we need?
364	*/
365	if (ldt_count <= *count)
366	break; /* fits in-line */
367
368	size_needed = round_page(ldt_size);
369	if (size_needed <= size)
370	break;
371
372	/*
373	* Unlock the pcb and allocate more memory
374	*/
375	simple_unlock(&pcb->lock);
376
377	if (size != 0)
378	kmem_free(ipc_kernel_map, addr, size);
379
380	size = size_needed;
381
382	if (kmem_alloc(ipc_kernel_map, &addr, size)
383	!= KERN_SUCCESS)
384	return KERN_RESOURCE_SHORTAGE;
385	}
386
387	/*
388	* copy out the descriptors
389	*/
390	bcopy((char *)&user_ldt->ldt[first_desc],
391	(char *)addr,
392	ldt_size);
393	*count = ldt_count;
394	simple_unlock(&pcb->lock);
395
396	if (addr) {
397	vm_size_t size_used, size_left;
398	vm_map_copy_t memory;
399
400	/*
401	* Free any unused memory beyond the end of the last page used
402	*/
403	size_used = round_page(ldt_size);
404	if (size_used != size)
405	kmem_free(ipc_kernel_map,
406	addr + size_used, size - size_used);
407
408	/*
409	* Zero the remainder of the page being returned.
410	*/
411	size_left = size_used - ldt_size;
412	if (size_left > 0)
413	bzero((char *)addr + ldt_size, size_left);
414
415	/*
416	* Unwire the memory and make it into copyin form.
417	*/
418	(void) vm_map_unwire(ipc_kernel_map, trunc_page(addr),
419	round_page(addr + size_used), FALSE);
420	(void) vm_map_copyin(ipc_kernel_map, addr, size_used,
421	TRUE, &memory);
422	*desc_list = (descriptor_list_t) memory;
423	}
424
425	return KERN_SUCCESS;
426	}
427
428	#endif
429	void
430	user_ldt_free(
431	user_ldt_t user_ldt)
432	{
433	kfree((vm_offset_t)user_ldt,
434	user_ldt->desc.limit_low+1+sizeof(struct real_descriptor));
435	}