[deliverable/linux.git] / arch / x86 / um / ldt.c

/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
#include <os.h>
#include <skas.h>
#include <sysdep/tls.h>

static inline int modify_ldt (int func, void *ptr, unsigned long bytecount)
{
	return syscall(__NR_modify_ldt, func, ptr, bytecount);
}

static long write_ldt_entry(struct mm_id *mm_idp, int func,
		     struct user_desc *desc, void **addr, int done)
{
	long res;
	void *stub_addr;
	res = syscall_stub_data(mm_idp, (unsigned long *)desc,
				(sizeof(*desc) + sizeof(long) - 1) &
				    ~(sizeof(long) - 1),
				addr, &stub_addr);
	if (!res) {
		unsigned long args[] = { func,
					 (unsigned long)stub_addr,
					 sizeof(*desc),
					 0, 0, 0 };
		res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
				       0, addr, done);
	}

	return res;
}

/*
 * In skas mode, we hold our own ldt data in UML.
 * Thus, the code implementing sys_modify_ldt_skas
 * is very similar to (and mostly stolen from) sys_modify_ldt
 * for arch/i386/kernel/ldt.c
 * The routines copied and modified in part are:
 * - read_ldt
 * - read_default_ldt
 * - write_ldt
 * - sys_modify_ldt_skas
 */

static int read_ldt(void __user * ptr, unsigned long bytecount)
{
	int i, err = 0;
	unsigned long size;
	uml_ldt_t *ldt = &current->mm->context.arch.ldt;

	if (!ldt->entry_count)
		goto out;
	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
	err = bytecount;

	mutex_lock(&ldt->lock);
	if (ldt->entry_count <= LDT_DIRECT_ENTRIES) {
		size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
		if (size > bytecount)
			size = bytecount;
		if (copy_to_user(ptr, ldt->u.entries, size))
			err = -EFAULT;
		bytecount -= size;
		ptr += size;
	}
	else {
		for (i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
		     i++) {
			size = PAGE_SIZE;
			if (size > bytecount)
				size = bytecount;
			if (copy_to_user(ptr, ldt->u.pages[i], size)) {
				err = -EFAULT;
				break;
			}
			bytecount -= size;
			ptr += size;
		}
	}
	mutex_unlock(&ldt->lock);

	if (bytecount == 0 || err == -EFAULT)
		goto out;

	if (clear_user(ptr, bytecount))
		err = -EFAULT;

out:
	return err;
}

static int read_default_ldt(void __user * ptr, unsigned long bytecount)
{
	int err;

	if (bytecount > 5*LDT_ENTRY_SIZE)
		bytecount = 5*LDT_ENTRY_SIZE;

	err = bytecount;
	/*
	 * UML doesn't support lcall7 and lcall27.
	 * So, we don't really have a default ldt, but emulate
	 * an empty ldt of common host default ldt size.
	 */
	if (clear_user(ptr, bytecount))
		err = -EFAULT;

	return err;
}

static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
{
	uml_ldt_t *ldt = &current->mm->context.arch.ldt;
	struct mm_id * mm_idp = &current->mm->context.id;
	int i, err;
	struct user_desc ldt_info;
	struct ldt_entry entry0, *ldt_p;
	void *addr = NULL;

	err = -EINVAL;
	if (bytecount != sizeof(ldt_info))
		goto out;
	err = -EFAULT;
	if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
		goto out;

	err = -EINVAL;
	if (ldt_info.entry_number >= LDT_ENTRIES)
		goto out;
	if (ldt_info.contents == 3) {
		if (func == 1)
			goto out;
		if (ldt_info.seg_not_present == 0)
			goto out;
	}

	mutex_lock(&ldt->lock);

	err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
	if (err)
		goto out_unlock;

	if (ldt_info.entry_number >= ldt->entry_count &&
	    ldt_info.entry_number >= LDT_DIRECT_ENTRIES) {
		for (i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
		     i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
		     i++) {
			if (i == 0)
				memcpy(&entry0, ldt->u.entries,
				       sizeof(entry0));
			ldt->u.pages[i] = (struct ldt_entry *)
				__get_free_page(GFP_KERNEL|__GFP_ZERO);
			if (!ldt->u.pages[i]) {
				err = -ENOMEM;
				/* Undo the change in host */
				memset(&ldt_info, 0, sizeof(ldt_info));
				write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
				goto out_unlock;
			}
			if (i == 0) {
				memcpy(ldt->u.pages[0], &entry0,
				       sizeof(entry0));
				memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
				       sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
			}
			ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
		}
	}
	if (ldt->entry_count <= ldt_info.entry_number)
		ldt->entry_count = ldt_info.entry_number + 1;

	if (ldt->entry_count <= LDT_DIRECT_ENTRIES)
		ldt_p = ldt->u.entries + ldt_info.entry_number;
	else
		ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
			ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;

	if (ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
	   (func == 1 || LDT_empty(&ldt_info))) {
		ldt_p->a = 0;
		ldt_p->b = 0;
	}
	else{
		if (func == 1)
			ldt_info.useable = 0;
		ldt_p->a = LDT_entry_a(&ldt_info);
		ldt_p->b = LDT_entry_b(&ldt_info);
	}
	err = 0;

out_unlock:
	mutex_unlock(&ldt->lock);
out:
	return err;
}

static long do_modify_ldt_skas(int func, void __user *ptr,
			       unsigned long bytecount)
{
	int ret = -ENOSYS;

	switch (func) {
		case 0:
			ret = read_ldt(ptr, bytecount);
			break;
		case 1:
		case 0x11:
			ret = write_ldt(ptr, bytecount, func);
			break;
		case 2:
			ret = read_default_ldt(ptr, bytecount);
			break;
	}
	return ret;
}

static DEFINE_SPINLOCK(host_ldt_lock);
static short dummy_list[9] = {0, -1};
static short * host_ldt_entries = NULL;

static void ldt_get_host_info(void)
{
	long ret;
	struct ldt_entry * ldt;
	short *tmp;
	int i, size, k, order;

	spin_lock(&host_ldt_lock);

	if (host_ldt_entries != NULL) {
		spin_unlock(&host_ldt_lock);
		return;
	}
	host_ldt_entries = dummy_list+1;

	spin_unlock(&host_ldt_lock);

	for (i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++)
		;

	ldt = (struct ldt_entry *)
	      __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
	if (ldt == NULL) {
		printk(KERN_ERR "ldt_get_host_info: couldn't allocate buffer "
		       "for host ldt\n");
		return;
	}

	ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
	if (ret < 0) {
		printk(KERN_ERR "ldt_get_host_info: couldn't read host ldt\n");
		goto out_free;
	}
	if (ret == 0) {
		/* default_ldt is active, simply write an empty entry 0 */
		host_ldt_entries = dummy_list;
		goto out_free;
	}

	for (i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++) {
		if (ldt[i].a != 0 || ldt[i].b != 0)
			size++;
	}

	if (size < ARRAY_SIZE(dummy_list))
		host_ldt_entries = dummy_list;
	else {
		size = (size + 1) * sizeof(dummy_list[0]);
		tmp = kmalloc(size, GFP_KERNEL);
		if (tmp == NULL) {
			printk(KERN_ERR "ldt_get_host_info: couldn't allocate "
			       "host ldt list\n");
			goto out_free;
		}
		host_ldt_entries = tmp;
	}

	for (i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++) {
		if (ldt[i].a != 0 || ldt[i].b != 0)
			host_ldt_entries[k++] = i;
	}
	host_ldt_entries[k] = -1;

out_free:
	free_pages((unsigned long)ldt, order);
}

long init_new_ldt(struct mm_context *new_mm, struct mm_context *from_mm)
{
	struct user_desc desc;
	short * num_p;
	int i;
	long page, err=0;
	void *addr = NULL;


	mutex_init(&new_mm->arch.ldt.lock);

	if (!from_mm) {
		memset(&desc, 0, sizeof(desc));
		/*
		 * Now we try to retrieve info about the ldt, we
		 * inherited from the host. All ldt-entries found
		 * will be reset in the following loop
		 */
		ldt_get_host_info();
		for (num_p=host_ldt_entries; *num_p != -1; num_p++) {
			desc.entry_number = *num_p;
			err = write_ldt_entry(&new_mm->id, 1, &desc,
					      &addr, *(num_p + 1) == -1);
			if (err)
				break;
		}
		new_mm->arch.ldt.entry_count = 0;

		goto out;
	}

	/*
	 * Our local LDT is used to supply the data for
	 * modify_ldt(READLDT), if PTRACE_LDT isn't available,
	 * i.e., we have to use the stub for modify_ldt, which
	 * can't handle the big read buffer of up to 64kB.
	 */
	mutex_lock(&from_mm->arch.ldt.lock);
	if (from_mm->arch.ldt.entry_count <= LDT_DIRECT_ENTRIES)
		memcpy(new_mm->arch.ldt.u.entries, from_mm->arch.ldt.u.entries,
		       sizeof(new_mm->arch.ldt.u.entries));
	else {
		i = from_mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
		while (i-->0) {
			page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
			if (!page) {
				err = -ENOMEM;
				break;
			}
			new_mm->arch.ldt.u.pages[i] =
				(struct ldt_entry *) page;
			memcpy(new_mm->arch.ldt.u.pages[i],
			       from_mm->arch.ldt.u.pages[i], PAGE_SIZE);
		}
	}
	new_mm->arch.ldt.entry_count = from_mm->arch.ldt.entry_count;
	mutex_unlock(&from_mm->arch.ldt.lock);

    out:
	return err;
}


void free_ldt(struct mm_context *mm)
{
	int i;

	if (mm->arch.ldt.entry_count > LDT_DIRECT_ENTRIES) {
		i = mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
		while (i-- > 0)
			free_page((long) mm->arch.ldt.u.pages[i]);
	}
	mm->arch.ldt.entry_count = 0;
}

int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
{
	return do_modify_ldt_skas(func, ptr, bytecount);
}
Commit	Line	Data
1da177e4	1	/*
ba180fd4	2	* Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
1da177e4 LT	3	* Licensed under the GPL
	4	*/
	5
8192ab42 JD	6	#include <linux/mm.h>
8192ab42 JD	7	#include <linux/sched.h>
5a0e3ad6	8	#include <linux/slab.h>
1d04c8d7	9	#include <linux/uaccess.h>
8192ab42	10	#include <asm/unistd.h>
37185b33	11	#include <os.h>
37185b33	12	#include <skas.h>
37185b33	13	#include <sysdep/tls.h>
ba180fd4	14
37e81a01 HWH	15	static inline int modify_ldt (int func, void *ptr, unsigned long bytecount)
	16	{
	17	return syscall(__NR_modify_ldt, func, ptr, bytecount);
	18	}
858259cf	19
99764fa4 WC	20	static long write_ldt_entry(struct mm_id *mm_idp, int func,
99764fa4 WC	21	struct user_desc desc, void *addr, int done)
858259cf BS	22	{
858259cf BS	23	long res;
d0b5e15f RW	24	void *stub_addr;
	25	res = syscall_stub_data(mm_idp, (unsigned long *)desc,
	26	(sizeof(*desc) + sizeof(long) - 1) &
	27	~(sizeof(long) - 1),
	28	addr, &stub_addr);
	29	if (!res) {
	30	unsigned long args[] = { func,
	31	(unsigned long)stub_addr,
	32	sizeof(*desc),
	33	0, 0, 0 };
	34	res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
	35	0, addr, done);
858259cf BS	36	}
858259cf BS	37
858259cf BS	38	return res;
	39	}
	40
	41	/*
	42	* In skas mode, we hold our own ldt data in UML.
	43	* Thus, the code implementing sys_modify_ldt_skas
	44	* is very similar to (and mostly stolen from) sys_modify_ldt
	45	* for arch/i386/kernel/ldt.c
	46	* The routines copied and modified in part are:
	47	* - read_ldt
	48	* - read_default_ldt
	49	* - write_ldt
	50	* - sys_modify_ldt_skas
	51	*/
	52
	53	static int read_ldt(void __user * ptr, unsigned long bytecount)
	54	{
	55	int i, err = 0;
	56	unsigned long size;
b3ee571e	57	uml_ldt_t *ldt = &current->mm->context.arch.ldt;
858259cf	58
ba180fd4	59	if (!ldt->entry_count)
858259cf	60	goto out;
ba180fd4	61	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
858259cf BS	62	bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
	63	err = bytecount;
	64
01ac835f	65	mutex_lock(&ldt->lock);
ba180fd4	66	if (ldt->entry_count <= LDT_DIRECT_ENTRIES) {
858259cf	67	size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
ba180fd4	68	if (size > bytecount)
858259cf	69	size = bytecount;
ba180fd4	70	if (copy_to_user(ptr, ldt->u.entries, size))
858259cf BS	71	err = -EFAULT;
	72	bytecount -= size;
	73	ptr += size;
	74	}
	75	else {
ba180fd4 JD	76	for (i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
ba180fd4 JD	77	i++) {
858259cf	78	size = PAGE_SIZE;
ba180fd4	79	if (size > bytecount)
858259cf	80	size = bytecount;
ba180fd4	81	if (copy_to_user(ptr, ldt->u.pages[i], size)) {
858259cf BS	82	err = -EFAULT;
	83	break;
	84	}
	85	bytecount -= size;
	86	ptr += size;
	87	}
	88	}
01ac835f	89	mutex_unlock(&ldt->lock);
858259cf	90
ba180fd4	91	if (bytecount == 0 \|\| err == -EFAULT)
858259cf BS	92	goto out;
858259cf BS	93
ba180fd4	94	if (clear_user(ptr, bytecount))
858259cf BS	95	err = -EFAULT;
	96
	97	out:
	98	return err;
	99	}
	100
	101	static int read_default_ldt(void __user * ptr, unsigned long bytecount)
	102	{
	103	int err;
	104
ba180fd4	105	if (bytecount > 5*LDT_ENTRY_SIZE)
858259cf BS	106	bytecount = 5*LDT_ENTRY_SIZE;
	107
	108	err = bytecount;
ba180fd4 JD	109	/*
ba180fd4 JD	110	* UML doesn't support lcall7 and lcall27.
858259cf BS	111	* So, we don't really have a default ldt, but emulate
	112	* an empty ldt of common host default ldt size.
	113	*/
ba180fd4	114	if (clear_user(ptr, bytecount))
858259cf BS	115	err = -EFAULT;
	116
	117	return err;
	118	}
	119
	120	static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
	121	{
b3ee571e	122	uml_ldt_t *ldt = &current->mm->context.arch.ldt;
6c738ffa	123	struct mm_id * mm_idp = &current->mm->context.id;
858259cf BS	124	int i, err;
	125	struct user_desc ldt_info;
	126	struct ldt_entry entry0, *ldt_p;
	127	void *addr = NULL;
	128
	129	err = -EINVAL;
ba180fd4	130	if (bytecount != sizeof(ldt_info))
858259cf BS	131	goto out;
858259cf BS	132	err = -EFAULT;
ba180fd4	133	if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
858259cf BS	134	goto out;
	135
	136	err = -EINVAL;
ba180fd4	137	if (ldt_info.entry_number >= LDT_ENTRIES)
858259cf	138	goto out;
ba180fd4	139	if (ldt_info.contents == 3) {
858259cf BS	140	if (func == 1)
	141	goto out;
	142	if (ldt_info.seg_not_present == 0)
	143	goto out;
	144	}
	145
d0b5e15f	146	mutex_lock(&ldt->lock);
858259cf BS	147
858259cf BS	148	err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
ba180fd4	149	if (err)
858259cf	150	goto out_unlock;
ba180fd4 JD	151
	152	if (ldt_info.entry_number >= ldt->entry_count &&
	153	ldt_info.entry_number >= LDT_DIRECT_ENTRIES) {
	154	for (i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
	155	i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
	156	i++) {
	157	if (i == 0)
e23181de JD	158	memcpy(&entry0, ldt->u.entries,
	159	sizeof(entry0));
	160	ldt->u.pages[i] = (struct ldt_entry *)
	161	__get_free_page(GFP_KERNEL\|__GFP_ZERO);
ba180fd4	162	if (!ldt->u.pages[i]) {
858259cf BS	163	err = -ENOMEM;
	164	/* Undo the change in host */
	165	memset(&ldt_info, 0, sizeof(ldt_info));
	166	write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
	167	goto out_unlock;
	168	}
ba180fd4	169	if (i == 0) {
e23181de JD	170	memcpy(ldt->u.pages[0], &entry0,
	171	sizeof(entry0));
	172	memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
858259cf BS	173	sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
	174	}
	175	ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
	176	}
	177	}
ba180fd4	178	if (ldt->entry_count <= ldt_info.entry_number)
858259cf BS	179	ldt->entry_count = ldt_info.entry_number + 1;
858259cf BS	180
ba180fd4	181	if (ldt->entry_count <= LDT_DIRECT_ENTRIES)
e23181de	182	ldt_p = ldt->u.entries + ldt_info.entry_number;
858259cf	183	else
e23181de	184	ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
858259cf BS	185	ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
858259cf BS	186
ba180fd4 JD	187	if (ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
ba180fd4 JD	188	(func == 1 \|\| LDT_empty(&ldt_info))) {
858259cf BS	189	ldt_p->a = 0;
	190	ldt_p->b = 0;
	191	}
	192	else{
	193	if (func == 1)
	194	ldt_info.useable = 0;
	195	ldt_p->a = LDT_entry_a(&ldt_info);
	196	ldt_p->b = LDT_entry_b(&ldt_info);
	197	}
	198	err = 0;
	199
	200	out_unlock:
01ac835f	201	mutex_unlock(&ldt->lock);
858259cf BS	202	out:
	203	return err;
	204	}
	205
	206	static long do_modify_ldt_skas(int func, void __user *ptr,
	207	unsigned long bytecount)
	208	{
	209	int ret = -ENOSYS;
	210
	211	switch (func) {
	212	case 0:
	213	ret = read_ldt(ptr, bytecount);
	214	break;
	215	case 1:
	216	case 0x11:
	217	ret = write_ldt(ptr, bytecount, func);
	218	break;
	219	case 2:
	220	ret = read_default_ldt(ptr, bytecount);
	221	break;
	222	}
	223	return ret;
	224	}
	225
af727902 JD	226	static DEFINE_SPINLOCK(host_ldt_lock);
	227	static short dummy_list[9] = {0, -1};
	228	static short * host_ldt_entries = NULL;
858259cf	229
af727902	230	static void ldt_get_host_info(void)
858259cf BS	231	{
858259cf BS	232	long ret;
622e6969 JD	233	struct ldt_entry * ldt;
622e6969 JD	234	short *tmp;
858259cf BS	235	int i, size, k, order;
858259cf BS	236
af727902 JD	237	spin_lock(&host_ldt_lock);
af727902 JD	238
ba180fd4	239	if (host_ldt_entries != NULL) {
af727902 JD	240	spin_unlock(&host_ldt_lock);
	241	return;
	242	}
858259cf BS	243	host_ldt_entries = dummy_list+1;
858259cf BS	244
af727902 JD	245	spin_unlock(&host_ldt_lock);
af727902 JD	246
ba180fd4 JD	247	for (i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++)
ba180fd4 JD	248	;
858259cf BS	249
	250	ldt = (struct ldt_entry *)
	251	__get_free_pages(GFP_KERNEL\|__GFP_ZERO, order);
ba180fd4 JD	252	if (ldt == NULL) {
	253	printk(KERN_ERR "ldt_get_host_info: couldn't allocate buffer "
	254	"for host ldt\n");
858259cf BS	255	return;
	256	}
	257
	258	ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
ba180fd4 JD	259	if (ret < 0) {
ba180fd4 JD	260	printk(KERN_ERR "ldt_get_host_info: couldn't read host ldt\n");
858259cf BS	261	goto out_free;
858259cf BS	262	}
ba180fd4	263	if (ret == 0) {
858259cf BS	264	/* default_ldt is active, simply write an empty entry 0 */
	265	host_ldt_entries = dummy_list;
	266	goto out_free;
	267	}
	268
ba180fd4 JD	269	for (i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++) {
ba180fd4 JD	270	if (ldt[i].a != 0 \|\| ldt[i].b != 0)
858259cf BS	271	size++;
	272	}
	273
ba180fd4	274	if (size < ARRAY_SIZE(dummy_list))
858259cf	275	host_ldt_entries = dummy_list;
858259cf BS	276	else {
858259cf BS	277	size = (size + 1) * sizeof(dummy_list[0]);
af727902	278	tmp = kmalloc(size, GFP_KERNEL);
ba180fd4 JD	279	if (tmp == NULL) {
	280	printk(KERN_ERR "ldt_get_host_info: couldn't allocate "
	281	"host ldt list\n");
858259cf BS	282	goto out_free;
858259cf BS	283	}
af727902	284	host_ldt_entries = tmp;
858259cf BS	285	}
858259cf BS	286
ba180fd4 JD	287	for (i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++) {
ba180fd4 JD	288	if (ldt[i].a != 0 \|\| ldt[i].b != 0)
858259cf	289	host_ldt_entries[k++] = i;
858259cf BS	290	}
	291	host_ldt_entries[k] = -1;
	292
	293	out_free:
	294	free_pages((unsigned long)ldt, order);
	295	}
	296
6c738ffa	297	long init_new_ldt(struct mm_context new_mm, struct mm_context from_mm)
858259cf BS	298	{
	299	struct user_desc desc;
	300	short * num_p;
	301	int i;
	302	long page, err=0;
	303	void *addr = NULL;
	304
858259cf	305
d0b5e15f	306	mutex_init(&new_mm->arch.ldt.lock);
858259cf	307
ba180fd4	308	if (!from_mm) {
12919aa6	309	memset(&desc, 0, sizeof(desc));
858259cf	310	/*
d0b5e15f RW	311	* Now we try to retrieve info about the ldt, we
	312	* inherited from the host. All ldt-entries found
	313	* will be reset in the following loop
858259cf	314	*/
d0b5e15f RW	315	ldt_get_host_info();
	316	for (num_p=host_ldt_entries; *num_p != -1; num_p++) {
	317	desc.entry_number = *num_p;
	318	err = write_ldt_entry(&new_mm->id, 1, &desc,
	319	&addr, *(num_p + 1) == -1);
	320	if (err)
	321	break;
858259cf	322	}
b3ee571e	323	new_mm->arch.ldt.entry_count = 0;
12919aa6 BS	324
12919aa6 BS	325	goto out;
858259cf	326	}
12919aa6	327
d0b5e15f RW	328	/*
	329	* Our local LDT is used to supply the data for
	330	* modify_ldt(READLDT), if PTRACE_LDT isn't available,
	331	* i.e., we have to use the stub for modify_ldt, which
	332	* can't handle the big read buffer of up to 64kB.
	333	*/
	334	mutex_lock(&from_mm->arch.ldt.lock);
	335	if (from_mm->arch.ldt.entry_count <= LDT_DIRECT_ENTRIES)
	336	memcpy(new_mm->arch.ldt.u.entries, from_mm->arch.ldt.u.entries,
	337	sizeof(new_mm->arch.ldt.u.entries));
	338	else {
	339	i = from_mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
	340	while (i-->0) {
	341	page = __get_free_page(GFP_KERNEL\|__GFP_ZERO);
	342	if (!page) {
	343	err = -ENOMEM;
	344	break;
858259cf	345	}
d0b5e15f RW	346	new_mm->arch.ldt.u.pages[i] =
	347	(struct ldt_entry *) page;
	348	memcpy(new_mm->arch.ldt.u.pages[i],
	349	from_mm->arch.ldt.u.pages[i], PAGE_SIZE);
858259cf	350	}
858259cf	351	}
d0b5e15f RW	352	new_mm->arch.ldt.entry_count = from_mm->arch.ldt.entry_count;
d0b5e15f RW	353	mutex_unlock(&from_mm->arch.ldt.lock);
858259cf	354
12919aa6	355	out:
858259cf BS	356	return err;
	357	}
	358
	359
6c738ffa	360	void free_ldt(struct mm_context *mm)
858259cf BS	361	{
	362	int i;
	363
d0b5e15f	364	if (mm->arch.ldt.entry_count > LDT_DIRECT_ENTRIES) {
b3ee571e	365	i = mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
ba180fd4	366	while (i-- > 0)
b3ee571e	367	free_page((long) mm->arch.ldt.u.pages[i]);
858259cf	368	}
b3ee571e	369	mm->arch.ldt.entry_count = 0;
858259cf	370	}
858259cf BS	371
	372	int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
	373	{
6aa802ce	374	return do_modify_ldt_skas(func, ptr, bytecount);
858259cf	375	}