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Commit | Line | Data |
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aa6758d4 PBG |
1 | /* |
2 | * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> | |
3 | * Licensed under the GPL | |
4 | */ | |
5 | ||
37185b33 AV |
6 | #include <linux/percpu.h> |
7 | #include <linux/sched.h> | |
2cf09666 | 8 | #include <linux/syscalls.h> |
37185b33 AV |
9 | #include <asm/uaccess.h> |
10 | #include <os.h> | |
11 | #include <skas.h> | |
12 | #include <sysdep/tls.h> | |
aa6758d4 | 13 | |
65a58ab0 JD |
14 | /* |
15 | * If needed we can detect when it's uninitialized. | |
16 | * | |
17 | * These are initialized in an initcall and unchanged thereafter. | |
18 | */ | |
3feb8856 | 19 | static int host_supports_tls = -1; |
65a58ab0 | 20 | int host_gdt_entry_tls_min; |
3feb8856 | 21 | |
6aa802ce | 22 | int do_set_thread_area(struct user_desc *info) |
aa6758d4 PBG |
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(); | |
b8bec829 JD |
30 | |
31 | if (ret) | |
32 | printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, " | |
33 | "index = %d\n", ret, info->entry_number); | |
34 | ||
aa6758d4 PBG |
35 | return ret; |
36 | } | |
37 | ||
6aa802ce | 38 | int do_get_thread_area(struct user_desc *info) |
aa6758d4 PBG |
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(); | |
b8bec829 JD |
46 | |
47 | if (ret) | |
48 | printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, " | |
49 | "index = %d\n", ret, info->entry_number); | |
50 | ||
aa6758d4 PBG |
51 | return ret; |
52 | } | |
aa6758d4 PBG |
53 | |
54 | /* | |
55 | * sys_get_thread_area: get a yet unused TLS descriptor index. | |
56 | * XXX: Consider leaving one free slot for glibc usage at first place. This must | |
57 | * be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else. | |
58 | * | |
b60745b9 | 59 | * Also, this must be tested when compiling in SKAS mode with dynamic linking |
aa6758d4 PBG |
60 | * and running against NPTL. |
61 | */ | |
62 | static 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 | ||
aa6758d4 PBG |
76 | static inline void clear_user_desc(struct user_desc* info) |
77 | { | |
78 | /* Postcondition: LDT_empty(info) returns true. */ | |
79 | memset(info, 0, sizeof(*info)); | |
80 | ||
ba180fd4 JD |
81 | /* |
82 | * Check the LDT_empty or the i386 sys_get_thread_area code - we obtain | |
aa6758d4 PBG |
83 | * indeed an empty user_desc. |
84 | */ | |
85 | info->read_exec_only = 1; | |
86 | info->seg_not_present = 1; | |
87 | } | |
88 | ||
54d8d3b5 PBG |
89 | #define O_FORCE 1 |
90 | ||
aa6758d4 PBG |
91 | static 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++) { | |
ba180fd4 JD |
97 | struct uml_tls_struct* curr = |
98 | &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN]; | |
aa6758d4 | 99 | |
ba180fd4 JD |
100 | /* |
101 | * Actually, now if it wasn't flushed it gets cleared and | |
102 | * flushed to the host, which will clear it. | |
103 | */ | |
aa6758d4 PBG |
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 | } | |
123 | out: | |
124 | return ret; | |
125 | } | |
126 | ||
ba180fd4 JD |
127 | /* |
128 | * Verify if we need to do a flush for the new process, i.e. if there are any | |
aa6758d4 PBG |
129 | * present desc's, only if they haven't been flushed. |
130 | */ | |
131 | static 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++) { | |
ba180fd4 JD |
137 | struct uml_tls_struct* curr = |
138 | &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; | |
aa6758d4 | 139 | |
ba180fd4 JD |
140 | /* |
141 | * Can't test curr->present, we may need to clear a descriptor | |
142 | * which had a value. | |
143 | */ | |
aa6758d4 PBG |
144 | if (curr->flushed) |
145 | continue; | |
146 | ret = 1; | |
147 | break; | |
148 | } | |
149 | return ret; | |
150 | } | |
151 | ||
ba180fd4 JD |
152 | /* |
153 | * On a newly forked process, the TLS descriptors haven't yet been flushed. So | |
aa6758d4 PBG |
154 | * we mark them as such and the first switch_to will do the job. |
155 | */ | |
156 | void 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++) { | |
ba180fd4 JD |
161 | struct uml_tls_struct* curr = |
162 | &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; | |
aa6758d4 | 163 | |
ba180fd4 JD |
164 | /* |
165 | * Still correct to do this, if it wasn't present on the host it | |
166 | * will remain as flushed as it was. | |
167 | */ | |
aa6758d4 PBG |
168 | if (!curr->present) |
169 | continue; | |
170 | ||
171 | curr->flushed = 0; | |
172 | } | |
173 | } | |
174 | ||
ba180fd4 JD |
175 | /* |
176 | * In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a | |
3feb8856 PBG |
177 | * common host process. So this is needed in SKAS0 too. |
178 | * | |
179 | * However, if each thread had a different host process (and this was discussed | |
180 | * for SMP support) this won't be needed. | |
181 | * | |
182 | * And this will not need be used when (and if) we'll add support to the host | |
ba180fd4 JD |
183 | * SKAS patch. |
184 | */ | |
3feb8856 | 185 | |
291248fd | 186 | int arch_switch_tls(struct task_struct *to) |
aa6758d4 | 187 | { |
3feb8856 PBG |
188 | if (!host_supports_tls) |
189 | return 0; | |
190 | ||
ba180fd4 JD |
191 | /* |
192 | * We have no need whatsoever to switch TLS for kernel threads; beyond | |
54d8d3b5 | 193 | * that, that would also result in us calling os_set_thread_area with |
ba180fd4 JD |
194 | * userspace_pid[cpu] == 0, which gives an error. |
195 | */ | |
54d8d3b5 PBG |
196 | if (likely(to->mm)) |
197 | return load_TLS(O_FORCE, to); | |
198 | ||
199 | return 0; | |
aa6758d4 PBG |
200 | } |
201 | ||
aa6758d4 PBG |
202 | static 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 | ||
217 | int 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, | |
243412be | 223 | (void __user *) UPT_SI(&new->thread.regs.regs), |
aa6758d4 PBG |
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); | |
234 | out: | |
235 | return ret; | |
236 | } | |
237 | ||
238 | /* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */ | |
b2cf7707 JD |
239 | static int get_tls_entry(struct task_struct *task, struct user_desc *info, |
240 | int idx) | |
aa6758d4 PBG |
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 | ||
255 | out: | |
ba180fd4 JD |
256 | /* |
257 | * Temporary debugging check, to make sure that things have been | |
aa6758d4 PBG |
258 | * flushed. This could be triggered if load_TLS() failed. |
259 | */ | |
ba180fd4 JD |
260 | if (unlikely(task == current && |
261 | !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) { | |
aa6758d4 PBG |
262 | printk(KERN_ERR "get_tls_entry: task with pid %d got here " |
263 | "without flushed TLS.", current->pid); | |
264 | } | |
265 | ||
266 | return 0; | |
267 | clear: | |
ba180fd4 JD |
268 | /* |
269 | * When the TLS entry has not been set, the values read to user in the | |
aa6758d4 PBG |
270 | * tls_array are 0 (because it's cleared at boot, see |
271 | * arch/i386/kernel/head.S:cpu_gdt_table). Emulate that. | |
272 | */ | |
273 | clear_user_desc(info); | |
274 | info->entry_number = idx; | |
275 | goto out; | |
276 | } | |
277 | ||
2cf09666 | 278 | SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc) |
aa6758d4 PBG |
279 | { |
280 | struct user_desc info; | |
281 | int idx, ret; | |
282 | ||
3feb8856 PBG |
283 | if (!host_supports_tls) |
284 | return -ENOSYS; | |
285 | ||
aa6758d4 PBG |
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 | /* Tell the user which slot we chose for him.*/ | |
297 | if (put_user(idx, &user_desc->entry_number)) | |
298 | return -EFAULT; | |
299 | } | |
300 | ||
6aa802ce | 301 | ret = do_set_thread_area(&info); |
aa6758d4 PBG |
302 | if (ret) |
303 | return ret; | |
304 | return set_tls_entry(current, &info, idx, 1); | |
305 | } | |
306 | ||
307 | /* | |
308 | * Perform set_thread_area on behalf of the traced child. | |
309 | * Note: error handling is not done on the deferred load, and this differ from | |
310 | * i386. However the only possible error are caused by bugs. | |
311 | */ | |
312 | int ptrace_set_thread_area(struct task_struct *child, int idx, | |
b2cf7707 | 313 | struct user_desc __user *user_desc) |
aa6758d4 PBG |
314 | { |
315 | struct user_desc info; | |
316 | ||
3feb8856 PBG |
317 | if (!host_supports_tls) |
318 | return -EIO; | |
319 | ||
aa6758d4 PBG |
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 | ||
2cf09666 | 326 | SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc) |
aa6758d4 PBG |
327 | { |
328 | struct user_desc info; | |
329 | int idx, ret; | |
330 | ||
3feb8856 PBG |
331 | if (!host_supports_tls) |
332 | return -ENOSYS; | |
333 | ||
aa6758d4 PBG |
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 | ||
344 | out: | |
345 | return ret; | |
346 | } | |
347 | ||
348 | /* | |
349 | * Perform get_thread_area on behalf of the traced child. | |
350 | */ | |
351 | int 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 | ||
3feb8856 PBG |
357 | if (!host_supports_tls) |
358 | return -EIO; | |
359 | ||
aa6758d4 PBG |
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; | |
366 | out: | |
367 | return ret; | |
368 | } | |
54d8d3b5 | 369 | |
ba180fd4 | 370 | /* |
b8bec829 JD |
371 | * This code is really i386-only, but it detects and logs x86_64 GDT indexes |
372 | * if a 32-bit UML is running on a 64-bit host. | |
ba180fd4 | 373 | */ |
65a58ab0 JD |
374 | static int __init __setup_host_supports_tls(void) |
375 | { | |
3feb8856 PBG |
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) { | |
b8bec829 JD |
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; | |
3feb8856 | 387 | } |
b8bec829 JD |
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); | |
3feb8856 PBG |
391 | } else |
392 | printk(KERN_ERR " Host TLS support NOT detected! " | |
393 | "TLS support inside UML will not work\n"); | |
a5d2f46a | 394 | return 0; |
3feb8856 PBG |
395 | } |
396 | ||
397 | __initcall(__setup_host_supports_tls); |