1 #include <linux/kernel.h> 2 #include <linux/errno.h> 3 #include <linux/sched.h> 4 #include <linux/user.h> 5 #include <linux/regset.h> 6 #include <linux/syscalls.h> 7 8 #include <asm/uaccess.h> 9 #include <asm/desc.h> 10 #include <asm/ldt.h> 11 #include <asm/processor.h> 12 #include <asm/proto.h> 13 14 #include "tls.h" 15 16 /* 17 * sys_alloc_thread_area: get a yet unused TLS descriptor index. 18 */ 19 static int get_free_idx(void) 20 { 21 struct thread_struct *t = ¤t->thread; 22 int idx; 23 24 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) 25 if (desc_empty(&t->tls_array[idx])) 26 return idx + GDT_ENTRY_TLS_MIN; 27 return -ESRCH; 28 } 29 30 static void set_tls_desc(struct task_struct *p, int idx, 31 const struct user_desc *info, int n) 32 { 33 struct thread_struct *t = &p->thread; 34 struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN]; 35 int cpu; 36 37 /* 38 * We must not get preempted while modifying the TLS. 39 */ 40 cpu = get_cpu(); 41 42 while (n-- > 0) { 43 if (LDT_empty(info)) 44 desc->a = desc->b = 0; 45 else 46 fill_ldt(desc, info); 47 ++info; 48 ++desc; 49 } 50 51 if (t == ¤t->thread) 52 load_TLS(t, cpu); 53 54 put_cpu(); 55 } 56 57 /* 58 * Set a given TLS descriptor: 59 */ 60 int do_set_thread_area(struct task_struct *p, int idx, 61 struct user_desc __user *u_info, 62 int can_allocate) 63 { 64 struct user_desc info; 65 66 if (copy_from_user(&info, u_info, sizeof(info))) 67 return -EFAULT; 68 69 if (idx == -1) 70 idx = info.entry_number; 71 72 /* 73 * index -1 means the kernel should try to find and 74 * allocate an empty descriptor: 75 */ 76 if (idx == -1 && can_allocate) { 77 idx = get_free_idx(); 78 if (idx < 0) 79 return idx; 80 if (put_user(idx, &u_info->entry_number)) 81 return -EFAULT; 82 } 83 84 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 85 return -EINVAL; 86 87 set_tls_desc(p, idx, &info, 1); 88 89 return 0; 90 } 91 92 SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, u_info) 93 { 94 return do_set_thread_area(current, -1, u_info, 1); 95 } 96 97 98 /* 99 * Get the current Thread-Local Storage area: 100 */ 101 102 static void fill_user_desc(struct user_desc *info, int idx, 103 const struct desc_struct *desc) 104 105 { 106 memset(info, 0, sizeof(*info)); 107 info->entry_number = idx; 108 info->base_addr = get_desc_base(desc); 109 info->limit = get_desc_limit(desc); 110 info->seg_32bit = desc->d; 111 info->contents = desc->type >> 2; 112 info->read_exec_only = !(desc->type & 2); 113 info->limit_in_pages = desc->g; 114 info->seg_not_present = !desc->p; 115 info->useable = desc->avl; 116 #ifdef CONFIG_X86_64 117 info->lm = desc->l; 118 #endif 119 } 120 121 int do_get_thread_area(struct task_struct *p, int idx, 122 struct user_desc __user *u_info) 123 { 124 struct user_desc info; 125 126 if (idx == -1 && get_user(idx, &u_info->entry_number)) 127 return -EFAULT; 128 129 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 130 return -EINVAL; 131 132 fill_user_desc(&info, idx, 133 &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]); 134 135 if (copy_to_user(u_info, &info, sizeof(info))) 136 return -EFAULT; 137 return 0; 138 } 139 140 SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, u_info) 141 { 142 return do_get_thread_area(current, -1, u_info); 143 } 144 145 int regset_tls_active(struct task_struct *target, 146 const struct user_regset *regset) 147 { 148 struct thread_struct *t = &target->thread; 149 int n = GDT_ENTRY_TLS_ENTRIES; 150 while (n > 0 && desc_empty(&t->tls_array[n - 1])) 151 --n; 152 return n; 153 } 154 155 int regset_tls_get(struct task_struct *target, const struct user_regset *regset, 156 unsigned int pos, unsigned int count, 157 void *kbuf, void __user *ubuf) 158 { 159 const struct desc_struct *tls; 160 161 if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) || 162 (pos % sizeof(struct user_desc)) != 0 || 163 (count % sizeof(struct user_desc)) != 0) 164 return -EINVAL; 165 166 pos /= sizeof(struct user_desc); 167 count /= sizeof(struct user_desc); 168 169 tls = &target->thread.tls_array[pos]; 170 171 if (kbuf) { 172 struct user_desc *info = kbuf; 173 while (count-- > 0) 174 fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++, 175 tls++); 176 } else { 177 struct user_desc __user *u_info = ubuf; 178 while (count-- > 0) { 179 struct user_desc info; 180 fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++); 181 if (__copy_to_user(u_info++, &info, sizeof(info))) 182 return -EFAULT; 183 } 184 } 185 186 return 0; 187 } 188 189 int regset_tls_set(struct task_struct *target, const struct user_regset *regset, 190 unsigned int pos, unsigned int count, 191 const void *kbuf, const void __user *ubuf) 192 { 193 struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES]; 194 const struct user_desc *info; 195 196 if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) || 197 (pos % sizeof(struct user_desc)) != 0 || 198 (count % sizeof(struct user_desc)) != 0) 199 return -EINVAL; 200 201 if (kbuf) 202 info = kbuf; 203 else if (__copy_from_user(infobuf, ubuf, count)) 204 return -EFAULT; 205 else 206 info = infobuf; 207 208 set_tls_desc(target, 209 GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)), 210 info, count / sizeof(struct user_desc)); 211 212 return 0; 213 } 214