tls.c 3.7 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/user.h>

#include <asm/uaccess.h>
#include <asm/desc.h>
#include <asm/system.h>
#include <asm/ldt.h>
#include <asm/processor.h>
#include <asm/proto.h>

/*
 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
 */
static int get_free_idx(void)
{
	struct thread_struct *t = &current->thread;
	int idx;

	for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
		if (desc_empty((struct n_desc_struct *)(t->tls_array) + idx))
			return idx + GDT_ENTRY_TLS_MIN;
	return -ESRCH;
}

/*
 * Set a given TLS descriptor:
R
Roland McGrath 已提交
29
 * When you want addresses > 32bit use arch_prctl()
L
Linus Torvalds 已提交
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78
 */
int do_set_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
{
	struct user_desc info;
	struct n_desc_struct *desc;
	int cpu, idx;

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

	idx = info.entry_number;

	/*
	 * index -1 means the kernel should try to find and
	 * allocate an empty descriptor:
	 */
	if (idx == -1) {
		idx = get_free_idx();
		if (idx < 0)
			return idx;
		if (put_user(idx, &u_info->entry_number))
			return -EFAULT;
	}

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

	desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;

	/*
	 * We must not get preempted while modifying the TLS.
	 */
	cpu = get_cpu();

	if (LDT_empty(&info)) {
		desc->a = 0;
		desc->b = 0;
	} else {
		desc->a = LDT_entry_a(&info);
		desc->b = LDT_entry_b(&info);
	}
	if (t == &current->thread)
		load_TLS(t, cpu);

	put_cpu();
	return 0;
}

asmlinkage long sys32_set_thread_area(struct user_desc __user *u_info)
R
Roland McGrath 已提交
79 80 81
{
	return do_set_thread_area(&current->thread, u_info);
}
L
Linus Torvalds 已提交
82 83 84 85 86 87 88 89 90


/*
 * Get the current Thread-Local Storage area:
 */

#define GET_LIMIT(desc) ( \
	((desc)->a & 0x0ffff) | \
	 ((desc)->b & 0xf0000) )
R
Roland McGrath 已提交
91

L
Linus Torvalds 已提交
92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114
#define GET_32BIT(desc)		(((desc)->b >> 22) & 1)
#define GET_CONTENTS(desc)	(((desc)->b >> 10) & 3)
#define GET_WRITABLE(desc)	(((desc)->b >>  9) & 1)
#define GET_LIMIT_PAGES(desc)	(((desc)->b >> 23) & 1)
#define GET_PRESENT(desc)	(((desc)->b >> 15) & 1)
#define GET_USEABLE(desc)	(((desc)->b >> 20) & 1)
#define GET_LONGMODE(desc)	(((desc)->b >> 21) & 1)

int do_get_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
{
	struct user_desc info;
	struct n_desc_struct *desc;
	int idx;

	if (get_user(idx, &u_info->entry_number))
		return -EFAULT;
	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
		return -EINVAL;

	desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;

	memset(&info, 0, sizeof(struct user_desc));
	info.entry_number = idx;
R
Roland McGrath 已提交
115
	info.base_addr = get_desc_base(desc);
L
Linus Torvalds 已提交
116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
	info.limit = GET_LIMIT(desc);
	info.seg_32bit = GET_32BIT(desc);
	info.contents = GET_CONTENTS(desc);
	info.read_exec_only = !GET_WRITABLE(desc);
	info.limit_in_pages = GET_LIMIT_PAGES(desc);
	info.seg_not_present = !GET_PRESENT(desc);
	info.useable = GET_USEABLE(desc);
	info.lm = GET_LONGMODE(desc);

	if (copy_to_user(u_info, &info, sizeof(info)))
		return -EFAULT;
	return 0;
}

asmlinkage long sys32_get_thread_area(struct user_desc __user *u_info)
{
	return do_get_thread_area(&current->thread, u_info);
R
Roland McGrath 已提交
133
}
L
Linus Torvalds 已提交
134 135 136 137 138 139 140 141


int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs)
{
	struct n_desc_struct *desc;
	struct user_desc info;
	struct user_desc __user *cp;
	int idx;
R
Roland McGrath 已提交
142

L
Linus Torvalds 已提交
143 144 145 146 147
	cp = (void __user *)childregs->rsi;
	if (copy_from_user(&info, cp, sizeof(info)))
		return -EFAULT;
	if (LDT_empty(&info))
		return -EINVAL;
R
Roland McGrath 已提交
148

L
Linus Torvalds 已提交
149 150 151
	idx = info.entry_number;
	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
		return -EINVAL;
R
Roland McGrath 已提交
152

L
Linus Torvalds 已提交
153 154 155 156 157 158
	desc = (struct n_desc_struct *)(p->thread.tls_array) + idx - GDT_ENTRY_TLS_MIN;
	desc->a = LDT_entry_a(&info);
	desc->b = LDT_entry_b(&info);

	return 0;
}