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 7#include <asm/uaccess.h> 8#include <asm/desc.h> 9#include <asm/system.h> 10#include <asm/ldt.h> 11#include <asm/processor.h> 12#include <asm/proto.h> 13#include <asm/syscalls.h> 14 15#include "tls.h" 16 17/* 18 * sys_alloc_thread_area: get a yet unused TLS descriptor index. 19 */ 20static int get_free_idx(void) 21{ 22 struct thread_struct *t = ¤t->thread; 23 int idx; 24 25 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) 26 if (desc_empty(&t->tls_array[idx])) 27 return idx + GDT_ENTRY_TLS_MIN; 28 return -ESRCH; 29} 30 31static void set_tls_desc(struct task_struct *p, int idx, 32 const struct user_desc *info, int n) 33{ 34 struct thread_struct *t = &p->thread; 35 struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN]; 36 int cpu; 37 38 /* 39 * We must not get preempted while modifying the TLS. 40 */ 41 cpu = get_cpu(); 42 43 while (n-- > 0) { 44 if (LDT_empty(info)) 45 desc->a = desc->b = 0; 46 else 47 fill_ldt(desc, info); 48 ++info; 49 ++desc; 50 } 51 52 if (t == ¤t->thread) 53 load_TLS(t, cpu); 54 55 put_cpu(); 56} 57 58/* 59 * Set a given TLS descriptor: 60 */ 61int do_set_thread_area(struct task_struct *p, int idx, 62 struct user_desc __user *u_info, 63 int can_allocate) 64{ 65 struct user_desc info; 66 67 if (copy_from_user(&info, u_info, sizeof(info))) 68 return -EFAULT; 69 70 if (idx == -1) 71 idx = info.entry_number; 72 73 /* 74 * index -1 means the kernel should try to find and 75 * allocate an empty descriptor: 76 */ 77 if (idx == -1 && can_allocate) { 78 idx = get_free_idx(); 79 if (idx < 0) 80 return idx; 81 if (put_user(idx, &u_info->entry_number)) 82 return -EFAULT; 83 } 84 85 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 86 return -EINVAL; 87 88 set_tls_desc(p, idx, &info, 1); 89 90 return 0; 91} 92 93asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) 94{ 95 int ret = do_set_thread_area(current, -1, u_info, 1); 96 asmlinkage_protect(1, ret, u_info); 97 return ret; 98} 99 100 101/* 102 * Get the current Thread-Local Storage area: 103 */ 104 105static void fill_user_desc(struct user_desc *info, int idx, 106 const struct desc_struct *desc) 107 108{ 109 memset(info, 0, sizeof(*info)); 110 info->entry_number = idx; 111 info->base_addr = get_desc_base(desc); 112 info->limit = get_desc_limit(desc); 113 info->seg_32bit = desc->d; 114 info->contents = desc->type >> 2; 115 info->read_exec_only = !(desc->type & 2); 116 info->limit_in_pages = desc->g; 117 info->seg_not_present = !desc->p; 118 info->useable = desc->avl; 119#ifdef CONFIG_X86_64 120 info->lm = desc->l; 121#endif 122} 123 124int do_get_thread_area(struct task_struct *p, int idx, 125 struct user_desc __user *u_info) 126{ 127 struct user_desc info; 128 129 if (idx == -1 && get_user(idx, &u_info->entry_number)) 130 return -EFAULT; 131 132 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 133 return -EINVAL; 134 135 fill_user_desc(&info, idx, 136 &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]); 137 138 if (copy_to_user(u_info, &info, sizeof(info))) 139 return -EFAULT; 140 return 0; 141} 142 143asmlinkage int sys_get_thread_area(struct user_desc __user *u_info) 144{ 145 int ret = do_get_thread_area(current, -1, u_info); 146 asmlinkage_protect(1, ret, u_info); 147 return ret; 148} 149 150int regset_tls_active(struct task_struct *target, 151 const struct user_regset *regset) 152{ 153 struct thread_struct *t = &target->thread; 154 int n = GDT_ENTRY_TLS_ENTRIES; 155 while (n > 0 && desc_empty(&t->tls_array[n - 1])) 156 --n; 157 return n; 158} 159 160int regset_tls_get(struct task_struct *target, const struct user_regset *regset, 161 unsigned int pos, unsigned int count, 162 void *kbuf, void __user *ubuf) 163{ 164 const struct desc_struct *tls; 165 166 if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) || 167 (pos % sizeof(struct user_desc)) != 0 || 168 (count % sizeof(struct user_desc)) != 0) 169 return -EINVAL; 170 171 pos /= sizeof(struct user_desc); 172 count /= sizeof(struct user_desc); 173 174 tls = &target->thread.tls_array[pos]; 175 176 if (kbuf) { 177 struct user_desc *info = kbuf; 178 while (count-- > 0) 179 fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++, 180 tls++); 181 } else { 182 struct user_desc __user *u_info = ubuf; 183 while (count-- > 0) { 184 struct user_desc info; 185 fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++); 186 if (__copy_to_user(u_info++, &info, sizeof(info))) 187 return -EFAULT; 188 } 189 } 190 191 return 0; 192} 193 194int regset_tls_set(struct task_struct *target, const struct user_regset *regset, 195 unsigned int pos, unsigned int count, 196 const void *kbuf, const void __user *ubuf) 197{ 198 struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES]; 199 const struct user_desc *info; 200 201 if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) || 202 (pos % sizeof(struct user_desc)) != 0 || 203 (count % sizeof(struct user_desc)) != 0) 204 return -EINVAL; 205 206 if (kbuf) 207 info = kbuf; 208 else if (__copy_from_user(infobuf, ubuf, count)) 209 return -EFAULT; 210 else 211 info = infobuf; 212 213 set_tls_desc(target, 214 GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)), 215 info, count / sizeof(struct user_desc)); 216 217 return 0; 218} 219