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aa6758d4 PBG |
1 | /* |
2 | * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> | |
3 | * Licensed under the GPL | |
4 | */ | |
5 | ||
6 | #include "linux/config.h" | |
7 | #include "linux/kernel.h" | |
8 | #include "linux/sched.h" | |
9 | #include "linux/slab.h" | |
10 | #include "linux/types.h" | |
11 | #include "asm/uaccess.h" | |
12 | #include "asm/ptrace.h" | |
13 | #include "asm/segment.h" | |
14 | #include "asm/smp.h" | |
15 | #include "asm/desc.h" | |
16 | #include "choose-mode.h" | |
17 | #include "kern.h" | |
18 | #include "kern_util.h" | |
19 | #include "mode_kern.h" | |
20 | #include "os.h" | |
21 | #include "mode.h" | |
22 | ||
23 | #ifdef CONFIG_MODE_SKAS | |
24 | #include "skas.h" | |
25 | #endif | |
26 | ||
27 | #ifdef CONFIG_MODE_SKAS | |
28 | int do_set_thread_area_skas(struct user_desc *info) | |
29 | { | |
30 | int ret; | |
31 | u32 cpu; | |
32 | ||
33 | cpu = get_cpu(); | |
34 | ret = os_set_thread_area(info, userspace_pid[cpu]); | |
35 | put_cpu(); | |
36 | return ret; | |
37 | } | |
38 | ||
39 | int do_get_thread_area_skas(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 | return ret; | |
48 | } | |
49 | #endif | |
50 | ||
51 | /* | |
52 | * sys_get_thread_area: get a yet unused TLS descriptor index. | |
53 | * XXX: Consider leaving one free slot for glibc usage at first place. This must | |
54 | * be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else. | |
55 | * | |
56 | * Also, this must be tested when compiling in SKAS mode with dinamic linking | |
57 | * and running against NPTL. | |
58 | */ | |
59 | static int get_free_idx(struct task_struct* task) | |
60 | { | |
61 | struct thread_struct *t = &task->thread; | |
62 | int idx; | |
63 | ||
64 | if (!t->arch.tls_array) | |
65 | return GDT_ENTRY_TLS_MIN; | |
66 | ||
67 | for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) | |
68 | if (!t->arch.tls_array[idx].present) | |
69 | return idx + GDT_ENTRY_TLS_MIN; | |
70 | return -ESRCH; | |
71 | } | |
72 | ||
73 | #define O_FORCE 1 | |
74 | ||
75 | static inline void clear_user_desc(struct user_desc* info) | |
76 | { | |
77 | /* Postcondition: LDT_empty(info) returns true. */ | |
78 | memset(info, 0, sizeof(*info)); | |
79 | ||
80 | /* Check the LDT_empty or the i386 sys_get_thread_area code - we obtain | |
81 | * indeed an empty user_desc. | |
82 | */ | |
83 | info->read_exec_only = 1; | |
84 | info->seg_not_present = 1; | |
85 | } | |
86 | ||
87 | static int load_TLS(int flags, struct task_struct *to) | |
88 | { | |
89 | int ret = 0; | |
90 | int idx; | |
91 | ||
92 | for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) { | |
93 | struct uml_tls_struct* curr = &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN]; | |
94 | ||
95 | /* Actually, now if it wasn't flushed it gets cleared and | |
96 | * flushed to the host, which will clear it.*/ | |
97 | if (!curr->present) { | |
98 | if (!curr->flushed) { | |
99 | clear_user_desc(&curr->tls); | |
100 | curr->tls.entry_number = idx; | |
101 | } else { | |
102 | WARN_ON(!LDT_empty(&curr->tls)); | |
103 | continue; | |
104 | } | |
105 | } | |
106 | ||
107 | if (!(flags & O_FORCE) && curr->flushed) | |
108 | continue; | |
109 | ||
110 | ret = do_set_thread_area(&curr->tls); | |
111 | if (ret) | |
112 | goto out; | |
113 | ||
114 | curr->flushed = 1; | |
115 | } | |
116 | out: | |
117 | return ret; | |
118 | } | |
119 | ||
120 | /* Verify if we need to do a flush for the new process, i.e. if there are any | |
121 | * present desc's, only if they haven't been flushed. | |
122 | */ | |
123 | static inline int needs_TLS_update(struct task_struct *task) | |
124 | { | |
125 | int i; | |
126 | int ret = 0; | |
127 | ||
128 | for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) { | |
129 | struct uml_tls_struct* curr = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; | |
130 | ||
131 | /* Can't test curr->present, we may need to clear a descriptor | |
132 | * which had a value. */ | |
133 | if (curr->flushed) | |
134 | continue; | |
135 | ret = 1; | |
136 | break; | |
137 | } | |
138 | return ret; | |
139 | } | |
140 | ||
141 | /* On a newly forked process, the TLS descriptors haven't yet been flushed. So | |
142 | * we mark them as such and the first switch_to will do the job. | |
143 | */ | |
144 | void clear_flushed_tls(struct task_struct *task) | |
145 | { | |
146 | int i; | |
147 | ||
148 | for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) { | |
149 | struct uml_tls_struct* curr = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN]; | |
150 | ||
151 | /* Still correct to do this, if it wasn't present on the host it | |
152 | * will remain as flushed as it was. */ | |
153 | if (!curr->present) | |
154 | continue; | |
155 | ||
156 | curr->flushed = 0; | |
157 | } | |
158 | } | |
159 | ||
160 | /* This in SKAS0 does not need to be used, since we have different host | |
161 | * processes. Nor will this need to be used when we'll add support to the host | |
162 | * SKAS patch. */ | |
163 | int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to) | |
164 | { | |
165 | return load_TLS(O_FORCE, to); | |
166 | } | |
167 | ||
168 | int arch_switch_tls_tt(struct task_struct *from, struct task_struct *to) | |
169 | { | |
170 | if (needs_TLS_update(to)) | |
171 | return load_TLS(0, to); | |
172 | ||
173 | return 0; | |
174 | } | |
175 | ||
176 | static int set_tls_entry(struct task_struct* task, struct user_desc *info, | |
177 | int idx, int flushed) | |
178 | { | |
179 | struct thread_struct *t = &task->thread; | |
180 | ||
181 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
182 | return -EINVAL; | |
183 | ||
184 | t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info; | |
185 | t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1; | |
186 | t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed; | |
187 | ||
188 | return 0; | |
189 | } | |
190 | ||
191 | int arch_copy_tls(struct task_struct *new) | |
192 | { | |
193 | struct user_desc info; | |
194 | int idx, ret = -EFAULT; | |
195 | ||
196 | if (copy_from_user(&info, | |
197 | (void __user *) UPT_ESI(&new->thread.regs.regs), | |
198 | sizeof(info))) | |
199 | goto out; | |
200 | ||
201 | ret = -EINVAL; | |
202 | if (LDT_empty(&info)) | |
203 | goto out; | |
204 | ||
205 | idx = info.entry_number; | |
206 | ||
207 | ret = set_tls_entry(new, &info, idx, 0); | |
208 | out: | |
209 | return ret; | |
210 | } | |
211 | ||
212 | /* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */ | |
213 | static int get_tls_entry(struct task_struct* task, struct user_desc *info, int idx) | |
214 | { | |
215 | struct thread_struct *t = &task->thread; | |
216 | ||
217 | if (!t->arch.tls_array) | |
218 | goto clear; | |
219 | ||
220 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
221 | return -EINVAL; | |
222 | ||
223 | if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present) | |
224 | goto clear; | |
225 | ||
226 | *info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls; | |
227 | ||
228 | out: | |
229 | /* Temporary debugging check, to make sure that things have been | |
230 | * flushed. This could be triggered if load_TLS() failed. | |
231 | */ | |
232 | if (unlikely(task == current && !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) { | |
233 | printk(KERN_ERR "get_tls_entry: task with pid %d got here " | |
234 | "without flushed TLS.", current->pid); | |
235 | } | |
236 | ||
237 | return 0; | |
238 | clear: | |
239 | /* When the TLS entry has not been set, the values read to user in the | |
240 | * tls_array are 0 (because it's cleared at boot, see | |
241 | * arch/i386/kernel/head.S:cpu_gdt_table). Emulate that. | |
242 | */ | |
243 | clear_user_desc(info); | |
244 | info->entry_number = idx; | |
245 | goto out; | |
246 | } | |
247 | ||
248 | asmlinkage int sys_set_thread_area(struct user_desc __user *user_desc) | |
249 | { | |
250 | struct user_desc info; | |
251 | int idx, ret; | |
252 | ||
253 | if (copy_from_user(&info, user_desc, sizeof(info))) | |
254 | return -EFAULT; | |
255 | ||
256 | idx = info.entry_number; | |
257 | ||
258 | if (idx == -1) { | |
259 | idx = get_free_idx(current); | |
260 | if (idx < 0) | |
261 | return idx; | |
262 | info.entry_number = idx; | |
263 | /* Tell the user which slot we chose for him.*/ | |
264 | if (put_user(idx, &user_desc->entry_number)) | |
265 | return -EFAULT; | |
266 | } | |
267 | ||
268 | ret = CHOOSE_MODE_PROC(do_set_thread_area_tt, do_set_thread_area_skas, &info); | |
269 | if (ret) | |
270 | return ret; | |
271 | return set_tls_entry(current, &info, idx, 1); | |
272 | } | |
273 | ||
274 | /* | |
275 | * Perform set_thread_area on behalf of the traced child. | |
276 | * Note: error handling is not done on the deferred load, and this differ from | |
277 | * i386. However the only possible error are caused by bugs. | |
278 | */ | |
279 | int ptrace_set_thread_area(struct task_struct *child, int idx, | |
280 | struct user_desc __user *user_desc) | |
281 | { | |
282 | struct user_desc info; | |
283 | ||
284 | if (copy_from_user(&info, user_desc, sizeof(info))) | |
285 | return -EFAULT; | |
286 | ||
287 | return set_tls_entry(child, &info, idx, 0); | |
288 | } | |
289 | ||
290 | asmlinkage int sys_get_thread_area(struct user_desc __user *user_desc) | |
291 | { | |
292 | struct user_desc info; | |
293 | int idx, ret; | |
294 | ||
295 | if (get_user(idx, &user_desc->entry_number)) | |
296 | return -EFAULT; | |
297 | ||
298 | ret = get_tls_entry(current, &info, idx); | |
299 | if (ret < 0) | |
300 | goto out; | |
301 | ||
302 | if (copy_to_user(user_desc, &info, sizeof(info))) | |
303 | ret = -EFAULT; | |
304 | ||
305 | out: | |
306 | return ret; | |
307 | } | |
308 | ||
309 | /* | |
310 | * Perform get_thread_area on behalf of the traced child. | |
311 | */ | |
312 | int ptrace_get_thread_area(struct task_struct *child, int idx, | |
313 | struct user_desc __user *user_desc) | |
314 | { | |
315 | struct user_desc info; | |
316 | int ret; | |
317 | ||
318 | ret = get_tls_entry(child, &info, idx); | |
319 | if (ret < 0) | |
320 | goto out; | |
321 | ||
322 | if (copy_to_user(user_desc, &info, sizeof(info))) | |
323 | ret = -EFAULT; | |
324 | out: | |
325 | return ret; | |
326 | } |