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5
6#include "linux/percpu.h"
7#include "linux/sched.h"
8#include "asm/uaccess.h"
9#include "os.h"
10#include "skas.h"
11#include "sysdep/tls.h"
12
13
14
15
16
17
18static int host_supports_tls = -1;
19int host_gdt_entry_tls_min;
20
21int do_set_thread_area(struct user_desc *info)
22{
23 int ret;
24 u32 cpu;
25
26 cpu = get_cpu();
27 ret = os_set_thread_area(info, userspace_pid[cpu]);
28 put_cpu();
29
30 if (ret)
31 printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, "
32 "index = %d\n", ret, info->entry_number);
33
34 return ret;
35}
36
37int do_get_thread_area(struct user_desc *info)
38{
39 int ret;
40 u32 cpu;
41
42 cpu = get_cpu();
43 ret = os_get_thread_area(info, userspace_pid[cpu]);
44 put_cpu();
45
46 if (ret)
47 printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, "
48 "index = %d\n", ret, info->entry_number);
49
50 return ret;
51}
52
53
54
55
56
57
58
59
60
61static int get_free_idx(struct task_struct* task)
62{
63 struct thread_struct *t = &task->thread;
64 int idx;
65
66 if (!t->arch.tls_array)
67 return GDT_ENTRY_TLS_MIN;
68
69 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
70 if (!t->arch.tls_array[idx].present)
71 return idx + GDT_ENTRY_TLS_MIN;
72 return -ESRCH;
73}
74
75static inline void clear_user_desc(struct user_desc* info)
76{
77
78 memset(info, 0, sizeof(*info));
79
80
81
82
83
84 info->read_exec_only = 1;
85 info->seg_not_present = 1;
86}
87
88#define O_FORCE 1
89
90static int load_TLS(int flags, struct task_struct *to)
91{
92 int ret = 0;
93 int idx;
94
95 for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
96 struct uml_tls_struct* curr =
97 &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
98
99
100
101
102
103 if (!curr->present) {
104 if (!curr->flushed) {
105 clear_user_desc(&curr->tls);
106 curr->tls.entry_number = idx;
107 } else {
108 WARN_ON(!LDT_empty(&curr->tls));
109 continue;
110 }
111 }
112
113 if (!(flags & O_FORCE) && curr->flushed)
114 continue;
115
116 ret = do_set_thread_area(&curr->tls);
117 if (ret)
118 goto out;
119
120 curr->flushed = 1;
121 }
122out:
123 return ret;
124}
125
126
127
128
129
130static inline int needs_TLS_update(struct task_struct *task)
131{
132 int i;
133 int ret = 0;
134
135 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
136 struct uml_tls_struct* curr =
137 &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
138
139
140
141
142
143 if (curr->flushed)
144 continue;
145 ret = 1;
146 break;
147 }
148 return ret;
149}
150
151
152
153
154
155void clear_flushed_tls(struct task_struct *task)
156{
157 int i;
158
159 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
160 struct uml_tls_struct* curr =
161 &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
162
163
164
165
166
167 if (!curr->present)
168 continue;
169
170 curr->flushed = 0;
171 }
172}
173
174
175
176
177
178
179
180
181
182
183
184
185int arch_switch_tls(struct task_struct *to)
186{
187 if (!host_supports_tls)
188 return 0;
189
190
191
192
193
194
195 if (likely(to->mm))
196 return load_TLS(O_FORCE, to);
197
198 return 0;
199}
200
201static int set_tls_entry(struct task_struct* task, struct user_desc *info,
202 int idx, int flushed)
203{
204 struct thread_struct *t = &task->thread;
205
206 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
207 return -EINVAL;
208
209 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
210 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
211 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;
212
213 return 0;
214}
215
216int arch_copy_tls(struct task_struct *new)
217{
218 struct user_desc info;
219 int idx, ret = -EFAULT;
220
221 if (copy_from_user(&info,
222 (void __user *) UPT_ESI(&new->thread.regs.regs),
223 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
277int sys_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
325int sys_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