1
2
3
4
5
6#include <linux/percpu.h>
7#include <linux/sched.h>
8#include <linux/syscalls.h>
9#include <linux/uaccess.h>
10#include <asm/ptrace-abi.h>
11#include <os.h>
12#include <skas.h>
13#include <sysdep/tls.h>
14
15
16
17
18
19
20static int host_supports_tls = -1;
21int host_gdt_entry_tls_min;
22
23int do_set_thread_area(struct user_desc *info)
24{
25 int ret;
26 u32 cpu;
27
28 cpu = get_cpu();
29 ret = os_set_thread_area(info, userspace_pid[cpu]);
30 put_cpu();
31
32 if (ret)
33 printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, "
34 "index = %d\n", ret, info->entry_number);
35
36 return ret;
37}
38
39int do_get_thread_area(struct user_desc *info)
40{
41 int ret;
42 u32 cpu;
43
44 cpu = get_cpu();
45 ret = os_get_thread_area(info, userspace_pid[cpu]);
46 put_cpu();
47
48 if (ret)
49 printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, "
50 "index = %d\n", ret, info->entry_number);
51
52 return ret;
53}
54
55
56
57
58
59
60
61
62
63static int get_free_idx(struct task_struct* task)
64{
65 struct thread_struct *t = &task->thread;
66 int idx;
67
68 if (!t->arch.tls_array)
69 return GDT_ENTRY_TLS_MIN;
70
71 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
72 if (!t->arch.tls_array[idx].present)
73 return idx + GDT_ENTRY_TLS_MIN;
74 return -ESRCH;
75}
76
77static inline void clear_user_desc(struct user_desc* info)
78{
79
80 memset(info, 0, sizeof(*info));
81
82
83
84
85
86 info->read_exec_only = 1;
87 info->seg_not_present = 1;
88}
89
90#define O_FORCE 1
91
92static int load_TLS(int flags, struct task_struct *to)
93{
94 int ret = 0;
95 int idx;
96
97 for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
98 struct uml_tls_struct* curr =
99 &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
100
101
102
103
104
105 if (!curr->present) {
106 if (!curr->flushed) {
107 clear_user_desc(&curr->tls);
108 curr->tls.entry_number = idx;
109 } else {
110 WARN_ON(!LDT_empty(&curr->tls));
111 continue;
112 }
113 }
114
115 if (!(flags & O_FORCE) && curr->flushed)
116 continue;
117
118 ret = do_set_thread_area(&curr->tls);
119 if (ret)
120 goto out;
121
122 curr->flushed = 1;
123 }
124out:
125 return ret;
126}
127
128
129
130
131
132static inline int needs_TLS_update(struct task_struct *task)
133{
134 int i;
135 int ret = 0;
136
137 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
138 struct uml_tls_struct* curr =
139 &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
140
141
142
143
144
145 if (curr->flushed)
146 continue;
147 ret = 1;
148 break;
149 }
150 return ret;
151}
152
153
154
155
156
157void clear_flushed_tls(struct task_struct *task)
158{
159 int i;
160
161 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
162 struct uml_tls_struct* curr =
163 &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
164
165
166
167
168
169 if (!curr->present)
170 continue;
171
172 curr->flushed = 0;
173 }
174}
175
176
177
178
179
180
181
182
183
184
185
186
187int arch_switch_tls(struct task_struct *to)
188{
189 if (!host_supports_tls)
190 return 0;
191
192
193
194
195
196
197 if (likely(to->mm))
198 return load_TLS(O_FORCE, to);
199
200 return 0;
201}
202
203static int set_tls_entry(struct task_struct* task, struct user_desc *info,
204 int idx, int flushed)
205{
206 struct thread_struct *t = &task->thread;
207
208 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
209 return -EINVAL;
210
211 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
212 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
213 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;
214
215 return 0;
216}
217
218int arch_set_tls(struct task_struct *new, unsigned long tls)
219{
220 struct user_desc info;
221 int idx, ret = -EFAULT;
222
223 if (copy_from_user(&info, (void __user *) tls, sizeof(info)))
224 goto out;
225
226 ret = -EINVAL;
227 if (LDT_empty(&info))
228 goto out;
229
230 idx = info.entry_number;
231
232 ret = set_tls_entry(new, &info, idx, 0);
233out:
234 return ret;
235}
236
237
238static int get_tls_entry(struct task_struct *task, struct user_desc *info,
239 int idx)
240{
241 struct thread_struct *t = &task->thread;
242
243 if (!t->arch.tls_array)
244 goto clear;
245
246 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
247 return -EINVAL;
248
249 if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present)
250 goto clear;
251
252 *info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls;
253
254out:
255
256
257
258
259 if (unlikely(task == current &&
260 !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) {
261 printk(KERN_ERR "get_tls_entry: task with pid %d got here "
262 "without flushed TLS.", current->pid);
263 }
264
265 return 0;
266clear:
267
268
269
270
271
272 clear_user_desc(info);
273 info->entry_number = idx;
274 goto out;
275}
276
277SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
278{
279 struct user_desc info;
280 int idx, ret;
281
282 if (!host_supports_tls)
283 return -ENOSYS;
284
285 if (copy_from_user(&info, user_desc, sizeof(info)))
286 return -EFAULT;
287
288 idx = info.entry_number;
289
290 if (idx == -1) {
291 idx = get_free_idx(current);
292 if (idx < 0)
293 return idx;
294 info.entry_number = idx;
295
296 if (put_user(idx, &user_desc->entry_number))
297 return -EFAULT;
298 }
299
300 ret = do_set_thread_area(&info);
301 if (ret)
302 return ret;
303 return set_tls_entry(current, &info, idx, 1);
304}
305
306
307
308
309
310
311int ptrace_set_thread_area(struct task_struct *child, int idx,
312 struct user_desc __user *user_desc)
313{
314 struct user_desc info;
315
316 if (!host_supports_tls)
317 return -EIO;
318
319 if (copy_from_user(&info, user_desc, sizeof(info)))
320 return -EFAULT;
321
322 return set_tls_entry(child, &info, idx, 0);
323}
324
325SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
326{
327 struct user_desc info;
328 int idx, ret;
329
330 if (!host_supports_tls)
331 return -ENOSYS;
332
333 if (get_user(idx, &user_desc->entry_number))
334 return -EFAULT;
335
336 ret = get_tls_entry(current, &info, idx);
337 if (ret < 0)
338 goto out;
339
340 if (copy_to_user(user_desc, &info, sizeof(info)))
341 ret = -EFAULT;
342
343out:
344 return ret;
345}
346
347
348
349
350int ptrace_get_thread_area(struct task_struct *child, int idx,
351 struct user_desc __user *user_desc)
352{
353 struct user_desc info;
354 int ret;
355
356 if (!host_supports_tls)
357 return -EIO;
358
359 ret = get_tls_entry(child, &info, idx);
360 if (ret < 0)
361 goto out;
362
363 if (copy_to_user(user_desc, &info, sizeof(info)))
364 ret = -EFAULT;
365out:
366 return ret;
367}
368
369
370
371
372
373static int __init __setup_host_supports_tls(void)
374{
375 check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min);
376 if (host_supports_tls) {
377 printk(KERN_INFO "Host TLS support detected\n");
378 printk(KERN_INFO "Detected host type: ");
379 switch (host_gdt_entry_tls_min) {
380 case GDT_ENTRY_TLS_MIN_I386:
381 printk(KERN_CONT "i386");
382 break;
383 case GDT_ENTRY_TLS_MIN_X86_64:
384 printk(KERN_CONT "x86_64");
385 break;
386 }
387 printk(KERN_CONT " (GDT indexes %d to %d)\n",
388 host_gdt_entry_tls_min,
389 host_gdt_entry_tls_min + GDT_ENTRY_TLS_ENTRIES);
390 } else
391 printk(KERN_ERR " Host TLS support NOT detected! "
392 "TLS support inside UML will not work\n");
393 return 0;
394}
395
396__initcall(__setup_host_supports_tls);
397