[linux-block.git] / arch / x86 / um / tls_32.c

/*
 * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
 * Licensed under the GPL
 */

#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <asm/ptrace-abi.h>
#include <os.h>
#include <skas.h>
#include <sysdep/tls.h>
#include <asm/desc.h>

/*
 * If needed we can detect when it's uninitialized.
 *
 * These are initialized in an initcall and unchanged thereafter.
 */
static int host_supports_tls = -1;
int host_gdt_entry_tls_min;

static int do_set_thread_area(struct user_desc *info)
{
	int ret;
	u32 cpu;

	cpu = get_cpu();
	ret = os_set_thread_area(info, userspace_pid[cpu]);
	put_cpu();

	if (ret)
		printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, "
		       "index = %d\n", ret, info->entry_number);

	return ret;
}

/*
 * sys_get_thread_area: get a yet unused TLS descriptor index.
 * XXX: Consider leaving one free slot for glibc usage at first place. This must
 * be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else.
 *
 * Also, this must be tested when compiling in SKAS mode with dynamic linking
 * and running against NPTL.
 */
static int get_free_idx(struct task_struct* task)
{
	struct thread_struct *t = &task->thread;
	int idx;

	for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
		if (!t->arch.tls_array[idx].present)
			return idx + GDT_ENTRY_TLS_MIN;
	return -ESRCH;
}

static inline void clear_user_desc(struct user_desc* info)
{
	/* Postcondition: LDT_empty(info) returns true. */
	memset(info, 0, sizeof(*info));

	/*
	 * Check the LDT_empty or the i386 sys_get_thread_area code - we obtain
	 * indeed an empty user_desc.
	 */
	info->read_exec_only = 1;
	info->seg_not_present = 1;
}

#define O_FORCE 1

static int load_TLS(int flags, struct task_struct *to)
{
	int ret = 0;
	int idx;

	for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
		struct uml_tls_struct* curr =
			&to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];

		/*
		 * Actually, now if it wasn't flushed it gets cleared and
		 * flushed to the host, which will clear it.
		 */
		if (!curr->present) {
			if (!curr->flushed) {
				clear_user_desc(&curr->tls);
				curr->tls.entry_number = idx;
			} else {
				WARN_ON(!LDT_empty(&curr->tls));
				continue;
			}
		}

		if (!(flags & O_FORCE) && curr->flushed)
			continue;

		ret = do_set_thread_area(&curr->tls);
		if (ret)
			goto out;

		curr->flushed = 1;
	}
out:
	return ret;
}

/*
 * Verify if we need to do a flush for the new process, i.e. if there are any
 * present desc's, only if they haven't been flushed.
 */
static inline int needs_TLS_update(struct task_struct *task)
{
	int i;
	int ret = 0;

	for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
		struct uml_tls_struct* curr =
			&task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];

		/*
		 * Can't test curr->present, we may need to clear a descriptor
		 * which had a value.
		 */
		if (curr->flushed)
			continue;
		ret = 1;
		break;
	}
	return ret;
}

/*
 * On a newly forked process, the TLS descriptors haven't yet been flushed. So
 * we mark them as such and the first switch_to will do the job.
 */
void clear_flushed_tls(struct task_struct *task)
{
	int i;

	for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
		struct uml_tls_struct* curr =
			&task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];

		/*
		 * Still correct to do this, if it wasn't present on the host it
		 * will remain as flushed as it was.
		 */
		if (!curr->present)
			continue;

		curr->flushed = 0;
	}
}

/*
 * In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a
 * common host process. So this is needed in SKAS0 too.
 *
 * However, if each thread had a different host process (and this was discussed
 * for SMP support) this won't be needed.
 *
 * And this will not need be used when (and if) we'll add support to the host
 * SKAS patch.
 */

int arch_switch_tls(struct task_struct *to)
{
	if (!host_supports_tls)
		return 0;

	/*
	 * We have no need whatsoever to switch TLS for kernel threads; beyond
	 * that, that would also result in us calling os_set_thread_area with
	 * userspace_pid[cpu] == 0, which gives an error.
	 */
	if (likely(to->mm))
		return load_TLS(O_FORCE, to);

	return 0;
}

static int set_tls_entry(struct task_struct* task, struct user_desc *info,
			 int idx, int flushed)
{
	struct thread_struct *t = &task->thread;

	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
		return -EINVAL;

	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;

	return 0;
}

int arch_set_tls(struct task_struct *new, unsigned long tls)
{
	struct user_desc info;
	int idx, ret = -EFAULT;

	if (copy_from_user(&info, (void __user *) tls, sizeof(info)))
		goto out;

	ret = -EINVAL;
	if (LDT_empty(&info))
		goto out;

	idx = info.entry_number;

	ret = set_tls_entry(new, &info, idx, 0);
out:
	return ret;
}

static int get_tls_entry(struct task_struct *task, struct user_desc *info,
			 int idx)
{
	struct thread_struct *t = &task->thread;

	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
		return -EINVAL;

	if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present)
		goto clear;

	*info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls;

out:
	/*
	 * Temporary debugging check, to make sure that things have been
	 * flushed. This could be triggered if load_TLS() failed.
	 */
	if (unlikely(task == current &&
		     !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) {
		printk(KERN_ERR "get_tls_entry: task with pid %d got here "
				"without flushed TLS.", current->pid);
	}

	return 0;
clear:
	/*
	 * When the TLS entry has not been set, the values read to user in the
	 * tls_array are 0 (because it's cleared at boot, see
	 * arch/i386/kernel/head.S:cpu_gdt_table). Emulate that.
	 */
	clear_user_desc(info);
	info->entry_number = idx;
	goto out;
}

SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
{
	struct user_desc info;
	int idx, ret;

	if (!host_supports_tls)
		return -ENOSYS;

	if (copy_from_user(&info, user_desc, sizeof(info)))
		return -EFAULT;

	idx = info.entry_number;

	if (idx == -1) {
		idx = get_free_idx(current);
		if (idx < 0)
			return idx;
		info.entry_number = idx;
		/* Tell the user which slot we chose for him.*/
		if (put_user(idx, &user_desc->entry_number))
			return -EFAULT;
	}

	ret = do_set_thread_area(&info);
	if (ret)
		return ret;
	return set_tls_entry(current, &info, idx, 1);
}

/*
 * Perform set_thread_area on behalf of the traced child.
 * Note: error handling is not done on the deferred load, and this differ from
 * i386. However the only possible error are caused by bugs.
 */
int ptrace_set_thread_area(struct task_struct *child, int idx,
			   struct user_desc __user *user_desc)
{
	struct user_desc info;

	if (!host_supports_tls)
		return -EIO;

	if (copy_from_user(&info, user_desc, sizeof(info)))
		return -EFAULT;

	return set_tls_entry(child, &info, idx, 0);
}

SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
{
	struct user_desc info;
	int idx, ret;

	if (!host_supports_tls)
		return -ENOSYS;

	if (get_user(idx, &user_desc->entry_number))
		return -EFAULT;

	ret = get_tls_entry(current, &info, idx);
	if (ret < 0)
		goto out;

	if (copy_to_user(user_desc, &info, sizeof(info)))
		ret = -EFAULT;

out:
	return ret;
}

/*
 * Perform get_thread_area on behalf of the traced child.
 */
int ptrace_get_thread_area(struct task_struct *child, int idx,
		struct user_desc __user *user_desc)
{
	struct user_desc info;
	int ret;

	if (!host_supports_tls)
		return -EIO;

	ret = get_tls_entry(child, &info, idx);
	if (ret < 0)
		goto out;

	if (copy_to_user(user_desc, &info, sizeof(info)))
		ret = -EFAULT;
out:
	return ret;
}

/*
 * This code is really i386-only, but it detects and logs x86_64 GDT indexes
 * if a 32-bit UML is running on a 64-bit host.
 */
static int __init __setup_host_supports_tls(void)
{
	check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min);
	if (host_supports_tls) {
		printk(KERN_INFO "Host TLS support detected\n");
		printk(KERN_INFO "Detected host type: ");
		switch (host_gdt_entry_tls_min) {
		case GDT_ENTRY_TLS_MIN_I386:
			printk(KERN_CONT "i386");
			break;
		case GDT_ENTRY_TLS_MIN_X86_64:
			printk(KERN_CONT "x86_64");
			break;
		}
		printk(KERN_CONT " (GDT indexes %d to %d)\n",
		       host_gdt_entry_tls_min,
		       host_gdt_entry_tls_min + GDT_ENTRY_TLS_ENTRIES);
	} else
		printk(KERN_ERR "  Host TLS support NOT detected! "
				"TLS support inside UML will not work\n");
	return 0;
}

__initcall(__setup_host_supports_tls);
Commit	Line	Data
aa6758d4 PBG	1	/*
	2	* Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
	3	* Licensed under the GPL
	4	*/
	5
37185b33 AV	6	#include <linux/percpu.h>
37185b33 AV	7	#include <linux/sched.h>
2cf09666	8	#include <linux/syscalls.h>
7c0f6ba6	9	#include <linux/uaccess.h>
da028d5e	10	#include <asm/ptrace-abi.h>
37185b33 AV	11	#include <os.h>
	12	#include <skas.h>
	13	#include <sysdep/tls.h>
7911b650	14	#include <asm/desc.h>
aa6758d4	15
65a58ab0 JD	16	/*
	17	* If needed we can detect when it's uninitialized.
	18	*
	19	* These are initialized in an initcall and unchanged thereafter.
	20	*/
3feb8856	21	static int host_supports_tls = -1;
65a58ab0	22	int host_gdt_entry_tls_min;
3feb8856	23
53471c57	24	static int do_set_thread_area(struct user_desc *info)
aa6758d4 PBG	25	{
	26	int ret;
	27	u32 cpu;
	28
	29	cpu = get_cpu();
	30	ret = os_set_thread_area(info, userspace_pid[cpu]);
	31	put_cpu();
b8bec829 JD	32
	33	if (ret)
	34	printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, "
	35	"index = %d\n", ret, info->entry_number);
	36
aa6758d4 PBG	37	return ret;
	38	}
	39
aa6758d4 PBG	40	/*
	41	* sys_get_thread_area: get a yet unused TLS descriptor index.
	42	* XXX: Consider leaving one free slot for glibc usage at first place. This must
	43	* be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else.
	44	*
b60745b9	45	* Also, this must be tested when compiling in SKAS mode with dynamic linking
aa6758d4 PBG	46	* and running against NPTL.
	47	*/
	48	static int get_free_idx(struct task_struct* task)
	49	{
	50	struct thread_struct *t = &task->thread;
	51	int idx;
	52
aa6758d4 PBG	53	for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
	54	if (!t->arch.tls_array[idx].present)
	55	return idx + GDT_ENTRY_TLS_MIN;
	56	return -ESRCH;
	57	}
	58
aa6758d4 PBG	59	static inline void clear_user_desc(struct user_desc* info)
	60	{
	61	/* Postcondition: LDT_empty(info) returns true. */
	62	memset(info, 0, sizeof(*info));
	63
ba180fd4 JD	64	/*
ba180fd4 JD	65	* Check the LDT_empty or the i386 sys_get_thread_area code - we obtain
aa6758d4 PBG	66	* indeed an empty user_desc.
	67	*/
	68	info->read_exec_only = 1;
	69	info->seg_not_present = 1;
	70	}
	71
54d8d3b5 PBG	72	#define O_FORCE 1
54d8d3b5 PBG	73
aa6758d4 PBG	74	static int load_TLS(int flags, struct task_struct *to)
	75	{
	76	int ret = 0;
	77	int idx;
	78
	79	for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
ba180fd4 JD	80	struct uml_tls_struct* curr =
ba180fd4 JD	81	&to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
aa6758d4	82
ba180fd4 JD	83	/*
	84	* Actually, now if it wasn't flushed it gets cleared and
	85	* flushed to the host, which will clear it.
	86	*/
aa6758d4 PBG	87	if (!curr->present) {
	88	if (!curr->flushed) {
	89	clear_user_desc(&curr->tls);
	90	curr->tls.entry_number = idx;
	91	} else {
	92	WARN_ON(!LDT_empty(&curr->tls));
	93	continue;
	94	}
	95	}
	96
	97	if (!(flags & O_FORCE) && curr->flushed)
	98	continue;
	99
	100	ret = do_set_thread_area(&curr->tls);
	101	if (ret)
	102	goto out;
	103
	104	curr->flushed = 1;
	105	}
	106	out:
	107	return ret;
	108	}
	109
ba180fd4 JD	110	/*
ba180fd4 JD	111	* Verify if we need to do a flush for the new process, i.e. if there are any
aa6758d4 PBG	112	* present desc's, only if they haven't been flushed.
	113	*/
	114	static inline int needs_TLS_update(struct task_struct *task)
	115	{
	116	int i;
	117	int ret = 0;
	118
	119	for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
ba180fd4 JD	120	struct uml_tls_struct* curr =
ba180fd4 JD	121	&task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
aa6758d4	122
ba180fd4 JD	123	/*
	124	* Can't test curr->present, we may need to clear a descriptor
	125	* which had a value.
	126	*/
aa6758d4 PBG	127	if (curr->flushed)
	128	continue;
	129	ret = 1;
	130	break;
	131	}
	132	return ret;
	133	}
	134
ba180fd4 JD	135	/*
ba180fd4 JD	136	* On a newly forked process, the TLS descriptors haven't yet been flushed. So
aa6758d4 PBG	137	* we mark them as such and the first switch_to will do the job.
	138	*/
	139	void clear_flushed_tls(struct task_struct *task)
	140	{
	141	int i;
	142
	143	for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
ba180fd4 JD	144	struct uml_tls_struct* curr =
ba180fd4 JD	145	&task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
aa6758d4	146
ba180fd4 JD	147	/*
	148	* Still correct to do this, if it wasn't present on the host it
	149	* will remain as flushed as it was.
	150	*/
aa6758d4 PBG	151	if (!curr->present)
	152	continue;
	153
	154	curr->flushed = 0;
	155	}
	156	}
	157
ba180fd4 JD	158	/*
ba180fd4 JD	159	* In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a
3feb8856 PBG	160	* common host process. So this is needed in SKAS0 too.
	161	*
	162	* However, if each thread had a different host process (and this was discussed
	163	* for SMP support) this won't be needed.
	164	*
	165	* And this will not need be used when (and if) we'll add support to the host
ba180fd4 JD	166	* SKAS patch.
ba180fd4 JD	167	*/
3feb8856	168
291248fd	169	int arch_switch_tls(struct task_struct *to)
aa6758d4	170	{
3feb8856 PBG	171	if (!host_supports_tls)
	172	return 0;
	173
ba180fd4 JD	174	/*
ba180fd4 JD	175	* We have no need whatsoever to switch TLS for kernel threads; beyond
54d8d3b5	176	* that, that would also result in us calling os_set_thread_area with
ba180fd4 JD	177	* userspace_pid[cpu] == 0, which gives an error.
ba180fd4 JD	178	*/
54d8d3b5 PBG	179	if (likely(to->mm))
	180	return load_TLS(O_FORCE, to);
	181
	182	return 0;
aa6758d4 PBG	183	}
aa6758d4 PBG	184
aa6758d4 PBG	185	static int set_tls_entry(struct task_struct* task, struct user_desc *info,
	186	int idx, int flushed)
	187	{
	188	struct thread_struct *t = &task->thread;
	189
	190	if (idx < GDT_ENTRY_TLS_MIN \|\| idx > GDT_ENTRY_TLS_MAX)
	191	return -EINVAL;
	192
	193	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
	194	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
	195	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;
	196
	197	return 0;
	198	}
	199
457677c7	200	int arch_set_tls(struct task_struct *new, unsigned long tls)
aa6758d4 PBG	201	{
	202	struct user_desc info;
	203	int idx, ret = -EFAULT;
	204
457677c7	205	if (copy_from_user(&info, (void __user *) tls, sizeof(info)))
aa6758d4 PBG	206	goto out;
	207
	208	ret = -EINVAL;
	209	if (LDT_empty(&info))
	210	goto out;
	211
	212	idx = info.entry_number;
	213
	214	ret = set_tls_entry(new, &info, idx, 0);
	215	out:
	216	return ret;
	217	}
	218
b2cf7707 JD	219	static int get_tls_entry(struct task_struct task, struct user_desc info,
b2cf7707 JD	220	int idx)
aa6758d4 PBG	221	{
	222	struct thread_struct *t = &task->thread;
	223
aa6758d4 PBG	224	if (idx < GDT_ENTRY_TLS_MIN \|\| idx > GDT_ENTRY_TLS_MAX)
	225	return -EINVAL;
	226
	227	if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present)
	228	goto clear;
	229
	230	*info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls;
	231
	232	out:
ba180fd4 JD	233	/*
ba180fd4 JD	234	* Temporary debugging check, to make sure that things have been
aa6758d4 PBG	235	* flushed. This could be triggered if load_TLS() failed.
aa6758d4 PBG	236	*/
ba180fd4 JD	237	if (unlikely(task == current &&
ba180fd4 JD	238	!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) {
aa6758d4 PBG	239	printk(KERN_ERR "get_tls_entry: task with pid %d got here "
	240	"without flushed TLS.", current->pid);
	241	}
	242
	243	return 0;
	244	clear:
ba180fd4 JD	245	/*
ba180fd4 JD	246	* When the TLS entry has not been set, the values read to user in the
aa6758d4 PBG	247	* tls_array are 0 (because it's cleared at boot, see
	248	* arch/i386/kernel/head.S:cpu_gdt_table). Emulate that.
	249	*/
	250	clear_user_desc(info);
	251	info->entry_number = idx;
	252	goto out;
	253	}
	254
2cf09666	255	SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
aa6758d4 PBG	256	{
	257	struct user_desc info;
	258	int idx, ret;
	259
3feb8856 PBG	260	if (!host_supports_tls)
	261	return -ENOSYS;
	262
aa6758d4 PBG	263	if (copy_from_user(&info, user_desc, sizeof(info)))
	264	return -EFAULT;
	265
	266	idx = info.entry_number;
	267
	268	if (idx == -1) {
	269	idx = get_free_idx(current);
	270	if (idx < 0)
	271	return idx;
	272	info.entry_number = idx;
	273	/* Tell the user which slot we chose for him.*/
	274	if (put_user(idx, &user_desc->entry_number))
	275	return -EFAULT;
	276	}
	277
6aa802ce	278	ret = do_set_thread_area(&info);
aa6758d4 PBG	279	if (ret)
	280	return ret;
	281	return set_tls_entry(current, &info, idx, 1);
	282	}
	283
	284	/*
	285	* Perform set_thread_area on behalf of the traced child.
	286	* Note: error handling is not done on the deferred load, and this differ from
	287	* i386. However the only possible error are caused by bugs.
	288	*/
	289	int ptrace_set_thread_area(struct task_struct *child, int idx,
b2cf7707	290	struct user_desc __user *user_desc)
aa6758d4 PBG	291	{
	292	struct user_desc info;
	293
3feb8856 PBG	294	if (!host_supports_tls)
	295	return -EIO;
	296
aa6758d4 PBG	297	if (copy_from_user(&info, user_desc, sizeof(info)))
	298	return -EFAULT;
	299
	300	return set_tls_entry(child, &info, idx, 0);
	301	}
	302
2cf09666	303	SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
aa6758d4 PBG	304	{
	305	struct user_desc info;
	306	int idx, ret;
	307
3feb8856 PBG	308	if (!host_supports_tls)
	309	return -ENOSYS;
	310
aa6758d4 PBG	311	if (get_user(idx, &user_desc->entry_number))
	312	return -EFAULT;
	313
	314	ret = get_tls_entry(current, &info, idx);
	315	if (ret < 0)
	316	goto out;
	317
	318	if (copy_to_user(user_desc, &info, sizeof(info)))
	319	ret = -EFAULT;
	320
	321	out:
	322	return ret;
	323	}
	324
	325	/*
	326	* Perform get_thread_area on behalf of the traced child.
	327	*/
	328	int ptrace_get_thread_area(struct task_struct *child, int idx,
	329	struct user_desc __user *user_desc)
	330	{
	331	struct user_desc info;
	332	int ret;
	333
3feb8856 PBG	334	if (!host_supports_tls)
	335	return -EIO;
	336
aa6758d4 PBG	337	ret = get_tls_entry(child, &info, idx);
	338	if (ret < 0)
	339	goto out;
	340
	341	if (copy_to_user(user_desc, &info, sizeof(info)))
	342	ret = -EFAULT;
	343	out:
	344	return ret;
	345	}
54d8d3b5	346
ba180fd4	347	/*
b8bec829 JD	348	* This code is really i386-only, but it detects and logs x86_64 GDT indexes
b8bec829 JD	349	* if a 32-bit UML is running on a 64-bit host.
ba180fd4	350	*/
65a58ab0 JD	351	static int __init __setup_host_supports_tls(void)
65a58ab0 JD	352	{
3feb8856 PBG	353	check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min);
	354	if (host_supports_tls) {
	355	printk(KERN_INFO "Host TLS support detected\n");
	356	printk(KERN_INFO "Detected host type: ");
	357	switch (host_gdt_entry_tls_min) {
b8bec829 JD	358	case GDT_ENTRY_TLS_MIN_I386:
	359	printk(KERN_CONT "i386");
	360	break;
	361	case GDT_ENTRY_TLS_MIN_X86_64:
	362	printk(KERN_CONT "x86_64");
	363	break;
3feb8856	364	}
b8bec829 JD	365	printk(KERN_CONT " (GDT indexes %d to %d)\n",
	366	host_gdt_entry_tls_min,
	367	host_gdt_entry_tls_min + GDT_ENTRY_TLS_ENTRIES);
3feb8856 PBG	368	} else
	369	printk(KERN_ERR " Host TLS support NOT detected! "
	370	"TLS support inside UML will not work\n");
a5d2f46a	371	return 0;
3feb8856 PBG	372	}
	373
	374	__initcall(__setup_host_supports_tls);