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/arch/x86_64/ia32/tls32.c

https://bitbucket.org/evzijst/gittest
C | 163 lines | 116 code | 30 blank | 17 comment | 21 complexity | 53a2ee13e9ca9f98930ffda5257aac57 MD5 | raw file
  1#include <linux/kernel.h>
  2#include <linux/errno.h>
  3#include <linux/sched.h>
  4#include <linux/user.h>
  5
  6#include <asm/uaccess.h>
  7#include <asm/desc.h>
  8#include <asm/system.h>
  9#include <asm/ldt.h>
 10#include <asm/processor.h>
 11#include <asm/proto.h>
 12
 13/*
 14 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
 15 */
 16static int get_free_idx(void)
 17{
 18	struct thread_struct *t = &current->thread;
 19	int idx;
 20
 21	for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
 22		if (desc_empty((struct n_desc_struct *)(t->tls_array) + idx))
 23			return idx + GDT_ENTRY_TLS_MIN;
 24	return -ESRCH;
 25}
 26
 27/*
 28 * Set a given TLS descriptor:
 29 * When you want addresses > 32bit use arch_prctl() 
 30 */
 31int do_set_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
 32{
 33	struct user_desc info;
 34	struct n_desc_struct *desc;
 35	int cpu, idx;
 36
 37	if (copy_from_user(&info, u_info, sizeof(info)))
 38		return -EFAULT;
 39
 40	idx = info.entry_number;
 41
 42	/*
 43	 * index -1 means the kernel should try to find and
 44	 * allocate an empty descriptor:
 45	 */
 46	if (idx == -1) {
 47		idx = get_free_idx();
 48		if (idx < 0)
 49			return idx;
 50		if (put_user(idx, &u_info->entry_number))
 51			return -EFAULT;
 52	}
 53
 54	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
 55		return -EINVAL;
 56
 57	desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;
 58
 59	/*
 60	 * We must not get preempted while modifying the TLS.
 61	 */
 62	cpu = get_cpu();
 63
 64	if (LDT_empty(&info)) {
 65		desc->a = 0;
 66		desc->b = 0;
 67	} else {
 68		desc->a = LDT_entry_a(&info);
 69		desc->b = LDT_entry_b(&info);
 70	}
 71	if (t == &current->thread)
 72		load_TLS(t, cpu);
 73
 74	put_cpu();
 75	return 0;
 76}
 77
 78asmlinkage long sys32_set_thread_area(struct user_desc __user *u_info)
 79{ 
 80	return do_set_thread_area(&current->thread, u_info); 
 81} 
 82
 83
 84/*
 85 * Get the current Thread-Local Storage area:
 86 */
 87
 88#define GET_BASE(desc) ( \
 89	(((desc)->a >> 16) & 0x0000ffff) | \
 90	(((desc)->b << 16) & 0x00ff0000) | \
 91	( (desc)->b        & 0xff000000)   )
 92
 93#define GET_LIMIT(desc) ( \
 94	((desc)->a & 0x0ffff) | \
 95	 ((desc)->b & 0xf0000) )
 96	
 97#define GET_32BIT(desc)		(((desc)->b >> 22) & 1)
 98#define GET_CONTENTS(desc)	(((desc)->b >> 10) & 3)
 99#define GET_WRITABLE(desc)	(((desc)->b >>  9) & 1)
100#define GET_LIMIT_PAGES(desc)	(((desc)->b >> 23) & 1)
101#define GET_PRESENT(desc)	(((desc)->b >> 15) & 1)
102#define GET_USEABLE(desc)	(((desc)->b >> 20) & 1)
103#define GET_LONGMODE(desc)	(((desc)->b >> 21) & 1)
104
105int do_get_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
106{
107	struct user_desc info;
108	struct n_desc_struct *desc;
109	int idx;
110
111	if (get_user(idx, &u_info->entry_number))
112		return -EFAULT;
113	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
114		return -EINVAL;
115
116	desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;
117
118	memset(&info, 0, sizeof(struct user_desc));
119	info.entry_number = idx;
120	info.base_addr = GET_BASE(desc);
121	info.limit = GET_LIMIT(desc);
122	info.seg_32bit = GET_32BIT(desc);
123	info.contents = GET_CONTENTS(desc);
124	info.read_exec_only = !GET_WRITABLE(desc);
125	info.limit_in_pages = GET_LIMIT_PAGES(desc);
126	info.seg_not_present = !GET_PRESENT(desc);
127	info.useable = GET_USEABLE(desc);
128	info.lm = GET_LONGMODE(desc);
129
130	if (copy_to_user(u_info, &info, sizeof(info)))
131		return -EFAULT;
132	return 0;
133}
134
135asmlinkage long sys32_get_thread_area(struct user_desc __user *u_info)
136{
137	return do_get_thread_area(&current->thread, u_info);
138} 
139
140
141int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs)
142{
143	struct n_desc_struct *desc;
144	struct user_desc info;
145	struct user_desc __user *cp;
146	int idx;
147	
148	cp = (void __user *)childregs->rsi;
149	if (copy_from_user(&info, cp, sizeof(info)))
150		return -EFAULT;
151	if (LDT_empty(&info))
152		return -EINVAL;
153	
154	idx = info.entry_number;
155	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
156		return -EINVAL;
157	
158	desc = (struct n_desc_struct *)(p->thread.tls_array) + idx - GDT_ENTRY_TLS_MIN;
159	desc->a = LDT_entry_a(&info);
160	desc->b = LDT_entry_b(&info);
161
162	return 0;
163}