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> |
7c0f6ba6 | 9 | #include <linux/uaccess.h> |
da028d5e | 10 | #include <asm/ptrace-abi.h> |
37185b33 AV |
11 | #include <os.h> |
12 | #include <skas.h> | |
13 | #include <sysdep/tls.h> | |
aa6758d4 | 14 | |
65a58ab0 JD |
15 | /* |
16 | * If needed we can detect when it's uninitialized. | |
17 | * | |
18 | * These are initialized in an initcall and unchanged thereafter. | |
19 | */ | |
3feb8856 | 20 | static int host_supports_tls = -1; |
65a58ab0 | 21 | int host_gdt_entry_tls_min; |
3feb8856 | 22 | |
6aa802ce | 23 | int do_set_thread_area(struct user_desc *info) |
aa6758d4 PBG |
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(); | |
b8bec829 JD |
31 | |
32 | if (ret) | |
33 | printk(KERN_ERR "PTRACE_SET_THREAD_AREA failed, err = %d, " | |
34 | "index = %d\n", ret, info->entry_number); | |
35 | ||
aa6758d4 PBG |
36 | return ret; |
37 | } | |
38 | ||
6aa802ce | 39 | int do_get_thread_area(struct user_desc *info) |
aa6758d4 PBG |
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(); | |
b8bec829 JD |
47 | |
48 | if (ret) | |
49 | printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, " | |
50 | "index = %d\n", ret, info->entry_number); | |
51 | ||
aa6758d4 PBG |
52 | return ret; |
53 | } | |
aa6758d4 PBG |
54 | |
55 | /* | |
56 | * sys_get_thread_area: get a yet unused TLS descriptor index. | |
57 | * XXX: Consider leaving one free slot for glibc usage at first place. This must | |
58 | * be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else. | |
59 | * | |
b60745b9 | 60 | * Also, this must be tested when compiling in SKAS mode with dynamic linking |
aa6758d4 PBG |
61 | * and running against NPTL. |
62 | */ | |
63 | static int get_free_idx(struct task_struct* task) | |
64 | { | |
65 | struct thread_struct *t = &task->thread; | |
66 | int idx; | |
67 | ||
aa6758d4 PBG |
68 | for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) |
69 | if (!t->arch.tls_array[idx].present) | |
70 | return idx + GDT_ENTRY_TLS_MIN; | |
71 | return -ESRCH; | |
72 | } | |
73 | ||
aa6758d4 PBG |
74 | static inline void clear_user_desc(struct user_desc* info) |
75 | { | |
76 | /* Postcondition: LDT_empty(info) returns true. */ | |
77 | memset(info, 0, sizeof(*info)); | |
78 | ||
ba180fd4 JD |
79 | /* |
80 | * Check the LDT_empty or the i386 sys_get_thread_area code - we obtain | |
aa6758d4 PBG |
81 | * indeed an empty user_desc. |
82 | */ | |
83 | info->read_exec_only = 1; | |
84 | info->seg_not_present = 1; | |
85 | } | |
86 | ||
54d8d3b5 PBG |
87 | #define O_FORCE 1 |
88 | ||
aa6758d4 PBG |
89 | static int load_TLS(int flags, struct task_struct *to) |
90 | { | |
91 | int ret = 0; | |
92 | int idx; | |
93 | ||
94 | for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) { | |
ba180fd4 JD |
95 | struct uml_tls_struct* curr = |
96 | &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN]; | |
aa6758d4 | 97 | |
ba180fd4 JD |
98 | /* |
99 | * Actually, now if it wasn't flushed it gets cleared and | |
100 | * flushed to the host, which will clear it. | |
101 | */ | |
aa6758d4 PBG |
102 | if (!curr->present) { |
103 | if (!curr->flushed) { | |
104 | clear_user_desc(&curr->tls); | |
105 | curr->tls.entry_number = idx; | |
106 | } else { | |
107 | WARN_ON(!LDT_empty(&curr->tls)); | |
108 | continue; | |
109 | } | |
110 | } | |
111 | ||
112 | if (!(flags & O_FORCE) && curr->flushed) | |
113 | continue; | |
114 | ||
115 | ret = do_set_thread_area(&curr->tls); | |
116 | if (ret) | |
117 | goto out; | |
118 | ||
119 | curr->flushed = 1; | |
120 | } | |
121 | out: | |
122 | return ret; | |
123 | } | |
124 | ||
ba180fd4 JD |
125 | /* |
126 | * Verify if we need to do a flush for the new process, i.e. if there are any | |
aa6758d4 PBG |
127 | * present desc's, only if they haven't been flushed. |
128 | */ | |
129 | static inline int needs_TLS_update(struct task_struct *task) | |
130 | { | |
131 | int i; | |
132 | int ret = 0; | |
133 | ||
134 | for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) { | |
ba180fd4 JD |
135 | struct uml_tls_struct* curr = |
136 | &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; | |
aa6758d4 | 137 | |
ba180fd4 JD |
138 | /* |
139 | * Can't test curr->present, we may need to clear a descriptor | |
140 | * which had a value. | |
141 | */ | |
aa6758d4 PBG |
142 | if (curr->flushed) |
143 | continue; | |
144 | ret = 1; | |
145 | break; | |
146 | } | |
147 | return ret; | |
148 | } | |
149 | ||
ba180fd4 JD |
150 | /* |
151 | * On a newly forked process, the TLS descriptors haven't yet been flushed. So | |
aa6758d4 PBG |
152 | * we mark them as such and the first switch_to will do the job. |
153 | */ | |
154 | void clear_flushed_tls(struct task_struct *task) | |
155 | { | |
156 | int i; | |
157 | ||
158 | for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) { | |
ba180fd4 JD |
159 | struct uml_tls_struct* curr = |
160 | &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; | |
aa6758d4 | 161 | |
ba180fd4 JD |
162 | /* |
163 | * Still correct to do this, if it wasn't present on the host it | |
164 | * will remain as flushed as it was. | |
165 | */ | |
aa6758d4 PBG |
166 | if (!curr->present) |
167 | continue; | |
168 | ||
169 | curr->flushed = 0; | |
170 | } | |
171 | } | |
172 | ||
ba180fd4 JD |
173 | /* |
174 | * In SKAS0 mode, currently, multiple guest threads sharing the same ->mm have a | |
3feb8856 PBG |
175 | * common host process. So this is needed in SKAS0 too. |
176 | * | |
177 | * However, if each thread had a different host process (and this was discussed | |
178 | * for SMP support) this won't be needed. | |
179 | * | |
180 | * And this will not need be used when (and if) we'll add support to the host | |
ba180fd4 JD |
181 | * SKAS patch. |
182 | */ | |
3feb8856 | 183 | |
291248fd | 184 | int arch_switch_tls(struct task_struct *to) |
aa6758d4 | 185 | { |
3feb8856 PBG |
186 | if (!host_supports_tls) |
187 | return 0; | |
188 | ||
ba180fd4 JD |
189 | /* |
190 | * We have no need whatsoever to switch TLS for kernel threads; beyond | |
54d8d3b5 | 191 | * that, that would also result in us calling os_set_thread_area with |
ba180fd4 JD |
192 | * userspace_pid[cpu] == 0, which gives an error. |
193 | */ | |
54d8d3b5 PBG |
194 | if (likely(to->mm)) |
195 | return load_TLS(O_FORCE, to); | |
196 | ||
197 | return 0; | |
aa6758d4 PBG |
198 | } |
199 | ||
aa6758d4 PBG |
200 | static int set_tls_entry(struct task_struct* task, struct user_desc *info, |
201 | int idx, int flushed) | |
202 | { | |
203 | struct thread_struct *t = &task->thread; | |
204 | ||
205 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
206 | return -EINVAL; | |
207 | ||
208 | t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info; | |
209 | t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1; | |
210 | t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed; | |
211 | ||
212 | return 0; | |
213 | } | |
214 | ||
457677c7 | 215 | int arch_set_tls(struct task_struct *new, unsigned long tls) |
aa6758d4 PBG |
216 | { |
217 | struct user_desc info; | |
218 | int idx, ret = -EFAULT; | |
219 | ||
457677c7 | 220 | if (copy_from_user(&info, (void __user *) tls, sizeof(info))) |
aa6758d4 PBG |
221 | goto out; |
222 | ||
223 | ret = -EINVAL; | |
224 | if (LDT_empty(&info)) | |
225 | goto out; | |
226 | ||
227 | idx = info.entry_number; | |
228 | ||
229 | ret = set_tls_entry(new, &info, idx, 0); | |
230 | out: | |
231 | return ret; | |
232 | } | |
233 | ||
234 | /* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */ | |
b2cf7707 JD |
235 | static int get_tls_entry(struct task_struct *task, struct user_desc *info, |
236 | int idx) | |
aa6758d4 PBG |
237 | { |
238 | struct thread_struct *t = &task->thread; | |
239 | ||
aa6758d4 PBG |
240 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) |
241 | return -EINVAL; | |
242 | ||
243 | if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present) | |
244 | goto clear; | |
245 | ||
246 | *info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls; | |
247 | ||
248 | out: | |
ba180fd4 JD |
249 | /* |
250 | * Temporary debugging check, to make sure that things have been | |
aa6758d4 PBG |
251 | * flushed. This could be triggered if load_TLS() failed. |
252 | */ | |
ba180fd4 JD |
253 | if (unlikely(task == current && |
254 | !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) { | |
aa6758d4 PBG |
255 | printk(KERN_ERR "get_tls_entry: task with pid %d got here " |
256 | "without flushed TLS.", current->pid); | |
257 | } | |
258 | ||
259 | return 0; | |
260 | clear: | |
ba180fd4 JD |
261 | /* |
262 | * When the TLS entry has not been set, the values read to user in the | |
aa6758d4 PBG |
263 | * tls_array are 0 (because it's cleared at boot, see |
264 | * arch/i386/kernel/head.S:cpu_gdt_table). Emulate that. | |
265 | */ | |
266 | clear_user_desc(info); | |
267 | info->entry_number = idx; | |
268 | goto out; | |
269 | } | |
270 | ||
2cf09666 | 271 | SYSCALL_DEFINE1(set_thread_area, struct user_desc __user *, user_desc) |
aa6758d4 PBG |
272 | { |
273 | struct user_desc info; | |
274 | int idx, ret; | |
275 | ||
3feb8856 PBG |
276 | if (!host_supports_tls) |
277 | return -ENOSYS; | |
278 | ||
aa6758d4 PBG |
279 | if (copy_from_user(&info, user_desc, sizeof(info))) |
280 | return -EFAULT; | |
281 | ||
282 | idx = info.entry_number; | |
283 | ||
284 | if (idx == -1) { | |
285 | idx = get_free_idx(current); | |
286 | if (idx < 0) | |
287 | return idx; | |
288 | info.entry_number = idx; | |
289 | /* Tell the user which slot we chose for him.*/ | |
290 | if (put_user(idx, &user_desc->entry_number)) | |
291 | return -EFAULT; | |
292 | } | |
293 | ||
6aa802ce | 294 | ret = do_set_thread_area(&info); |
aa6758d4 PBG |
295 | if (ret) |
296 | return ret; | |
297 | return set_tls_entry(current, &info, idx, 1); | |
298 | } | |
299 | ||
300 | /* | |
301 | * Perform set_thread_area on behalf of the traced child. | |
302 | * Note: error handling is not done on the deferred load, and this differ from | |
303 | * i386. However the only possible error are caused by bugs. | |
304 | */ | |
305 | int ptrace_set_thread_area(struct task_struct *child, int idx, | |
b2cf7707 | 306 | struct user_desc __user *user_desc) |
aa6758d4 PBG |
307 | { |
308 | struct user_desc info; | |
309 | ||
3feb8856 PBG |
310 | if (!host_supports_tls) |
311 | return -EIO; | |
312 | ||
aa6758d4 PBG |
313 | if (copy_from_user(&info, user_desc, sizeof(info))) |
314 | return -EFAULT; | |
315 | ||
316 | return set_tls_entry(child, &info, idx, 0); | |
317 | } | |
318 | ||
2cf09666 | 319 | SYSCALL_DEFINE1(get_thread_area, struct user_desc __user *, user_desc) |
aa6758d4 PBG |
320 | { |
321 | struct user_desc info; | |
322 | int idx, ret; | |
323 | ||
3feb8856 PBG |
324 | if (!host_supports_tls) |
325 | return -ENOSYS; | |
326 | ||
aa6758d4 PBG |
327 | if (get_user(idx, &user_desc->entry_number)) |
328 | return -EFAULT; | |
329 | ||
330 | ret = get_tls_entry(current, &info, idx); | |
331 | if (ret < 0) | |
332 | goto out; | |
333 | ||
334 | if (copy_to_user(user_desc, &info, sizeof(info))) | |
335 | ret = -EFAULT; | |
336 | ||
337 | out: | |
338 | return ret; | |
339 | } | |
340 | ||
341 | /* | |
342 | * Perform get_thread_area on behalf of the traced child. | |
343 | */ | |
344 | int ptrace_get_thread_area(struct task_struct *child, int idx, | |
345 | struct user_desc __user *user_desc) | |
346 | { | |
347 | struct user_desc info; | |
348 | int ret; | |
349 | ||
3feb8856 PBG |
350 | if (!host_supports_tls) |
351 | return -EIO; | |
352 | ||
aa6758d4 PBG |
353 | ret = get_tls_entry(child, &info, idx); |
354 | if (ret < 0) | |
355 | goto out; | |
356 | ||
357 | if (copy_to_user(user_desc, &info, sizeof(info))) | |
358 | ret = -EFAULT; | |
359 | out: | |
360 | return ret; | |
361 | } | |
54d8d3b5 | 362 | |
ba180fd4 | 363 | /* |
b8bec829 JD |
364 | * This code is really i386-only, but it detects and logs x86_64 GDT indexes |
365 | * if a 32-bit UML is running on a 64-bit host. | |
ba180fd4 | 366 | */ |
65a58ab0 JD |
367 | static int __init __setup_host_supports_tls(void) |
368 | { | |
3feb8856 PBG |
369 | check_host_supports_tls(&host_supports_tls, &host_gdt_entry_tls_min); |
370 | if (host_supports_tls) { | |
371 | printk(KERN_INFO "Host TLS support detected\n"); | |
372 | printk(KERN_INFO "Detected host type: "); | |
373 | switch (host_gdt_entry_tls_min) { | |
b8bec829 JD |
374 | case GDT_ENTRY_TLS_MIN_I386: |
375 | printk(KERN_CONT "i386"); | |
376 | break; | |
377 | case GDT_ENTRY_TLS_MIN_X86_64: | |
378 | printk(KERN_CONT "x86_64"); | |
379 | break; | |
3feb8856 | 380 | } |
b8bec829 JD |
381 | printk(KERN_CONT " (GDT indexes %d to %d)\n", |
382 | host_gdt_entry_tls_min, | |
383 | host_gdt_entry_tls_min + GDT_ENTRY_TLS_ENTRIES); | |
3feb8856 PBG |
384 | } else |
385 | printk(KERN_ERR " Host TLS support NOT detected! " | |
386 | "TLS support inside UML will not work\n"); | |
a5d2f46a | 387 | return 0; |
3feb8856 PBG |
388 | } |
389 | ||
390 | __initcall(__setup_host_supports_tls); |