1
2
3
4
5
6#include <linux/percpu.h>
7#include <linux/sched.h>
8#include <linux/syscalls.h>
9#include <asm/uaccess.h>
10#include <os.h>
11#include <skas.h>
12#include <sysdep/tls.h>
13
14
15
16
17
18
19static int host_supports_tls = -1;
20int host_gdt_entry_tls_min;
21
22int do_set_thread_area(struct user_desc *info)
23{
24 int ret;
25 u32 cpu;
26
27 cpu = get_cpu();
28 ret = os_set_thread_area(info, userspace_pid[cpu]);
29 put_cpu();
30
31 if (ret)
32 printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, "
33 "index = %d\n", ret, info->entry_number);
34
35 return ret;
36}
37
38int do_get_thread_area(struct user_desc *info)
39{
40 int ret;
41 u32 cpu;
42
43 cpu = get_cpu();
44 ret = os_get_thread_area(info, userspace_pid[cpu]);
45 put_cpu();
46
47 if (ret)
48 printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, "
49 "index = %d\n", ret, info->entry_number);
50
51 return ret;
52}
53
54
55
56
57
58
59
60
61
62static int get_free_idx(struct task_struct* task)
63{
64 struct thread_struct *t = &task->thread;
65 int idx;
66
67 if (!t->arch.tls_array)
68 return GDT_ENTRY_TLS_MIN;
69
70 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
71 if (!t->arch.tls_array[idx].present)
72 return idx + GDT_ENTRY_TLS_MIN;
73 return -ESRCH;
74}
75
76static inline void clear_user_desc(struct user_desc* info)
77{
78
79 memset(info, 0, sizeof(*info));
80
81
82
83
84
85 info->read_exec_only = 1;
86 info->seg_not_present = 1;
87}
88
89#define O_FORCE 1
90
91static int load_TLS(int flags, struct task_struct *to)
92{
93 int ret = 0;
94 int idx;
95
96 for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
97 struct uml_tls_struct* curr =
98 &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
99
100
101
102
103
104 if (!curr->present) {
105 if (!curr->flushed) {
106 clear_user_desc(&curr->tls);
107 curr->tls.entry_number = idx;
108 } else {
109 WARN_ON(!LDT_empty(&curr->tls));
110 continue;
111 }
112 }
113
114 if (!(flags & O_FORCE) && curr->flushed)
115 continue;
116
117 ret = do_set_thread_area(&curr->tls);
118 if (ret)
119 goto out;
120
121 curr->flushed = 1;
122 }
123out:
124 return ret;
125}
126
127
128
129
130
131static inline int needs_TLS_update(struct task_struct *task)
132{
133 int i;
134 int ret = 0;
135
136 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
137 struct uml_tls_struct* curr =
138 &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
139
140
141
142
143
144 if (curr->flushed)
145 continue;
146 ret = 1;
147 break;
148 }
149 return ret;
150}
151
152
153
154
155
156void clear_flushed_tls(struct task_struct *task)
157{
158 int i;
159
160 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
161 struct uml_tls_struct* curr =
162 &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
163
164
165
166
167
168 if (!curr->present)
169 continue;
170
171 curr->flushed = 0;
172 }
173}
174
175
176
177
178
179
180
181
182
183
184
185
186int arch_switch_tls(struct task_struct *to)
187{
188 if (!host_supports_tls)
189 return 0;
190
191
192
193
194
195
196 if (likely(to->mm))
197 return load_TLS(O_FORCE, to);
198
199 return 0;
200}
201
202static int set_tls_entry(struct task_struct* task, struct user_desc *info,
203 int idx, int flushed)
204{
205 struct thread_struct *t = &task->thread;
206
207 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
208 return -EINVAL;
209
210 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
211 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
212 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;
213
214 return 0;
215}
216
217int arch_copy_tls(struct task_struct *new)
218{
219 struct user_desc info;
220 int idx, ret = -EFAULT;
221
222 if (copy_from_user(&info,
223 (void __user *) UPT_SI(&new->thread.regs.regs),
224 sizeof(info)))
225 goto out;
226
227 ret = -EINVAL;
228 if (LDT_empty(&info))
229 goto out;
230
231 idx = info.entry_number;
232
233 ret = set_tls_entry(new, &info, idx, 0);
234out:
235 return ret;
236}
237
238
239static int get_tls_entry(struct task_struct *task, struct user_desc *info,
240 int idx)
241{
242 struct thread_struct *t = &task->thread;
243
244 if (!t->arch.tls_array)
245 goto clear;
246
247 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
248 return -EINVAL;
249
250 if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present)
251 goto clear;
252
253 *info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls;
254
255out:
256
257
258
259
260 if (unlikely(task == current &&
261 !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) {
262 printk(KERN_ERR "get_tls_entry: task with pid %d got here "
263 "without flushed TLS.", current->pid);
264 }
265
266 return 0;
267clear:
268
269
270
271
272
273 clear_user_desc(info);
274 info->entry_number = idx;
275 goto out;
276}
277
278SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc)
279{
280 struct user_desc info;
281 int idx, ret;
282
283 if (!host_supports_tls)
284 return -ENOSYS;
285
286 if (copy_from_user(&info, user_desc, sizeof(info)))
287 return -EFAULT;
288
289 idx = info.entry_number;
290
291 if (idx == -1) {
292 idx = get_free_idx(current);
293 if (idx < 0)
294 return idx;
295 info.entry_number = idx;
296
297 if (put_user(idx, &user_desc->entry_number))
298 return -EFAULT;
299 }
300
301 ret = do_set_thread_area(&info);
302 if (ret)
303 return ret;
304 return set_tls_entry(current, &info, idx, 1);
305}
306
307
308
309
310
311
312int ptrace_set_thread_area(struct task_struct *child, int idx,
313 struct user_desc __user *user_desc)
314{
315 struct user_desc info;
316
317 if (!host_supports_tls)
318 return -EIO;
319
320 if (copy_from_user(&info, user_desc, sizeof(info)))
321 return -EFAULT;
322
323 return set_tls_entry(child, &info, idx, 0);
324}
325
326SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc)
327{
328 struct user_desc info;
329 int idx, ret;
330
331 if (!host_supports_tls)
332 return -ENOSYS;
333
334 if (get_user(idx, &user_desc->entry_number))
335 return -EFAULT;
336
337 ret = get_tls_entry(current, &info, idx);
338 if (ret < 0)
339 goto out;
340
341 if (copy_to_user(user_desc, &info, sizeof(info)))
342 ret = -EFAULT;
343
344out:
345 return ret;
346}
347
348
349
350
351int ptrace_get_thread_area(struct task_struct *child, int idx,
352 struct user_desc __user *user_desc)
353{
354 struct user_desc info;
355 int ret;
356
357 if (!host_supports_tls)
358 return -EIO;
359
360 ret = get_tls_entry(child, &info, idx);
361 if (ret < 0)
362 goto out;
363
364 if (copy_to_user(user_desc, &info, sizeof(info)))
365 ret = -EFAULT;
366out:
367 return ret;
368}
369
370
371
372
373
374static int __init __setup_host_supports_tls(void)
375{
376 check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min);
377 if (host_supports_tls) {
378 printk(KERN_INFO "Host TLS support detected\n");
379 printk(KERN_INFO "Detected host type: ");
380 switch (host_gdt_entry_tls_min) {
381 case GDT_ENTRY_TLS_MIN_I386:
382 printk(KERN_CONT "i386");
383 break;
384 case GDT_ENTRY_TLS_MIN_X86_64:
385 printk(KERN_CONT "x86_64");
386 break;
387 }
388 printk(KERN_CONT " (GDT indexes %d to %d)\n",
389 host_gdt_entry_tls_min,
390 host_gdt_entry_tls_min + GDT_ENTRY_TLS_ENTRIES);
391 } else
392 printk(KERN_ERR " Host TLS support NOT detected! "
393 "TLS support inside UML will not work\n");
394 return 0;
395}
396
397__initcall(__setup_host_supports_tls);
398