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2c020ed8 CM |
1 | /* |
2 | * Based on arch/arm/kernel/signal.c | |
3 | * | |
4 | * Copyright (C) 1995-2009 Russell King | |
5 | * Copyright (C) 2012 ARM Ltd. | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
18 | */ | |
19 | ||
6fa3eb70 | 20 | #include <linux/compat.h> |
2c020ed8 CM |
21 | #include <linux/errno.h> |
22 | #include <linux/signal.h> | |
23 | #include <linux/personality.h> | |
24 | #include <linux/freezer.h> | |
25 | #include <linux/uaccess.h> | |
26 | #include <linux/tracehook.h> | |
27 | #include <linux/ratelimit.h> | |
28 | ||
2c020ed8 CM |
29 | #include <asm/debug-monitors.h> |
30 | #include <asm/elf.h> | |
31 | #include <asm/cacheflush.h> | |
32 | #include <asm/ucontext.h> | |
33 | #include <asm/unistd.h> | |
34 | #include <asm/fpsimd.h> | |
35 | #include <asm/signal32.h> | |
36 | #include <asm/vdso.h> | |
37 | ||
38 | /* | |
39 | * Do a signal return; undo the signal stack. These are aligned to 128-bit. | |
40 | */ | |
41 | struct rt_sigframe { | |
42 | struct siginfo info; | |
43 | struct ucontext uc; | |
304ef4e8 WD |
44 | u64 fp; |
45 | u64 lr; | |
2c020ed8 CM |
46 | }; |
47 | ||
48 | static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) | |
49 | { | |
50 | struct fpsimd_state *fpsimd = ¤t->thread.fpsimd_state; | |
51 | int err; | |
52 | ||
53 | /* dump the hardware registers to the fpsimd_state structure */ | |
6fa3eb70 | 54 | fpsimd_preserve_current_state(); |
2c020ed8 CM |
55 | |
56 | /* copy the FP and status/control registers */ | |
57 | err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs)); | |
58 | __put_user_error(fpsimd->fpsr, &ctx->fpsr, err); | |
59 | __put_user_error(fpsimd->fpcr, &ctx->fpcr, err); | |
60 | ||
61 | /* copy the magic/size information */ | |
62 | __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err); | |
63 | __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err); | |
64 | ||
65 | return err ? -EFAULT : 0; | |
66 | } | |
67 | ||
68 | static int restore_fpsimd_context(struct fpsimd_context __user *ctx) | |
69 | { | |
70 | struct fpsimd_state fpsimd; | |
71 | __u32 magic, size; | |
72 | int err = 0; | |
73 | ||
74 | /* check the magic/size information */ | |
75 | __get_user_error(magic, &ctx->head.magic, err); | |
76 | __get_user_error(size, &ctx->head.size, err); | |
77 | if (err) | |
78 | return -EFAULT; | |
79 | if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context)) | |
80 | return -EINVAL; | |
81 | ||
82 | /* copy the FP and status/control registers */ | |
83 | err = __copy_from_user(fpsimd.vregs, ctx->vregs, | |
84 | sizeof(fpsimd.vregs)); | |
85 | __get_user_error(fpsimd.fpsr, &ctx->fpsr, err); | |
86 | __get_user_error(fpsimd.fpcr, &ctx->fpcr, err); | |
87 | ||
88 | /* load the hardware registers from the fpsimd_state structure */ | |
6fa3eb70 S |
89 | if (!err) |
90 | fpsimd_update_current_state(&fpsimd); | |
2c020ed8 CM |
91 | |
92 | return err ? -EFAULT : 0; | |
93 | } | |
94 | ||
95 | static int restore_sigframe(struct pt_regs *regs, | |
96 | struct rt_sigframe __user *sf) | |
97 | { | |
98 | sigset_t set; | |
99 | int i, err; | |
100 | struct aux_context __user *aux = | |
101 | (struct aux_context __user *)sf->uc.uc_mcontext.__reserved; | |
102 | ||
103 | err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); | |
104 | if (err == 0) | |
105 | set_current_blocked(&set); | |
106 | ||
107 | for (i = 0; i < 31; i++) | |
108 | __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], | |
109 | err); | |
110 | __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); | |
111 | __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); | |
112 | __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); | |
113 | ||
114 | /* | |
115 | * Avoid sys_rt_sigreturn() restarting. | |
116 | */ | |
117 | regs->syscallno = ~0UL; | |
118 | ||
119 | err |= !valid_user_regs(®s->user_regs); | |
120 | ||
121 | if (err == 0) | |
122 | err |= restore_fpsimd_context(&aux->fpsimd); | |
123 | ||
124 | return err; | |
125 | } | |
126 | ||
127 | asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) | |
128 | { | |
129 | struct rt_sigframe __user *frame; | |
130 | ||
131 | /* Always make any pending restarted system calls return -EINTR */ | |
132 | current_thread_info()->restart_block.fn = do_no_restart_syscall; | |
133 | ||
134 | /* | |
135 | * Since we stacked the signal on a 128-bit boundary, then 'sp' should | |
136 | * be word aligned here. | |
137 | */ | |
138 | if (regs->sp & 15) | |
139 | goto badframe; | |
140 | ||
141 | frame = (struct rt_sigframe __user *)regs->sp; | |
142 | ||
143 | if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) | |
144 | goto badframe; | |
145 | ||
146 | if (restore_sigframe(regs, frame)) | |
147 | goto badframe; | |
148 | ||
207bdae4 | 149 | if (restore_altstack(&frame->uc.uc_stack)) |
2c020ed8 CM |
150 | goto badframe; |
151 | ||
152 | return regs->regs[0]; | |
153 | ||
154 | badframe: | |
155 | if (show_unhandled_signals) | |
156 | pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n", | |
157 | current->comm, task_pid_nr(current), __func__, | |
158 | regs->pc, regs->sp); | |
159 | force_sig(SIGSEGV, current); | |
160 | return 0; | |
161 | } | |
162 | ||
2c020ed8 CM |
163 | static int setup_sigframe(struct rt_sigframe __user *sf, |
164 | struct pt_regs *regs, sigset_t *set) | |
165 | { | |
166 | int i, err = 0; | |
167 | struct aux_context __user *aux = | |
168 | (struct aux_context __user *)sf->uc.uc_mcontext.__reserved; | |
169 | ||
304ef4e8 WD |
170 | /* set up the stack frame for unwinding */ |
171 | __put_user_error(regs->regs[29], &sf->fp, err); | |
172 | __put_user_error(regs->regs[30], &sf->lr, err); | |
173 | ||
2c020ed8 CM |
174 | for (i = 0; i < 31; i++) |
175 | __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], | |
176 | err); | |
177 | __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); | |
178 | __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); | |
179 | __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); | |
180 | ||
181 | __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err); | |
182 | ||
183 | err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); | |
184 | ||
185 | if (err == 0) | |
186 | err |= preserve_fpsimd_context(&aux->fpsimd); | |
187 | ||
188 | /* set the "end" magic */ | |
189 | __put_user_error(0, &aux->end.magic, err); | |
190 | __put_user_error(0, &aux->end.size, err); | |
191 | ||
192 | return err; | |
193 | } | |
194 | ||
b64e1c61 WD |
195 | static struct rt_sigframe __user *get_sigframe(struct k_sigaction *ka, |
196 | struct pt_regs *regs) | |
2c020ed8 CM |
197 | { |
198 | unsigned long sp, sp_top; | |
b64e1c61 | 199 | struct rt_sigframe __user *frame; |
2c020ed8 CM |
200 | |
201 | sp = sp_top = regs->sp; | |
202 | ||
203 | /* | |
204 | * This is the X/Open sanctioned signal stack switching. | |
205 | */ | |
206 | if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp)) | |
207 | sp = sp_top = current->sas_ss_sp + current->sas_ss_size; | |
208 | ||
b64e1c61 WD |
209 | sp = (sp - sizeof(struct rt_sigframe)) & ~15; |
210 | frame = (struct rt_sigframe __user *)sp; | |
2c020ed8 CM |
211 | |
212 | /* | |
213 | * Check that we can actually write to the signal frame. | |
214 | */ | |
215 | if (!access_ok(VERIFY_WRITE, frame, sp_top - sp)) | |
216 | frame = NULL; | |
217 | ||
218 | return frame; | |
219 | } | |
220 | ||
304ef4e8 WD |
221 | static void setup_return(struct pt_regs *regs, struct k_sigaction *ka, |
222 | void __user *frame, int usig) | |
2c020ed8 | 223 | { |
2c020ed8 | 224 | __sigrestore_t sigtramp; |
2c020ed8 CM |
225 | |
226 | regs->regs[0] = usig; | |
2c020ed8 | 227 | regs->sp = (unsigned long)frame; |
304ef4e8 | 228 | regs->regs[29] = regs->sp + offsetof(struct rt_sigframe, fp); |
2c020ed8 CM |
229 | regs->pc = (unsigned long)ka->sa.sa_handler; |
230 | ||
231 | if (ka->sa.sa_flags & SA_RESTORER) | |
232 | sigtramp = ka->sa.sa_restorer; | |
233 | else | |
234 | sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp); | |
235 | ||
236 | regs->regs[30] = (unsigned long)sigtramp; | |
2c020ed8 CM |
237 | } |
238 | ||
239 | static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info, | |
240 | sigset_t *set, struct pt_regs *regs) | |
241 | { | |
242 | struct rt_sigframe __user *frame; | |
2c020ed8 CM |
243 | int err = 0; |
244 | ||
b64e1c61 | 245 | frame = get_sigframe(ka, regs); |
2c020ed8 CM |
246 | if (!frame) |
247 | return 1; | |
248 | ||
249 | __put_user_error(0, &frame->uc.uc_flags, err); | |
250 | __put_user_error(NULL, &frame->uc.uc_link, err); | |
251 | ||
207bdae4 | 252 | err |= __save_altstack(&frame->uc.uc_stack, regs->sp); |
2c020ed8 | 253 | err |= setup_sigframe(frame, regs, set); |
304ef4e8 WD |
254 | if (err == 0) { |
255 | setup_return(regs, ka, frame, usig); | |
256 | if (ka->sa.sa_flags & SA_SIGINFO) { | |
257 | err |= copy_siginfo_to_user(&frame->info, info); | |
258 | regs->regs[1] = (unsigned long)&frame->info; | |
259 | regs->regs[2] = (unsigned long)&frame->uc; | |
260 | } | |
2c020ed8 CM |
261 | } |
262 | ||
263 | return err; | |
264 | } | |
265 | ||
266 | static void setup_restart_syscall(struct pt_regs *regs) | |
267 | { | |
268 | if (is_compat_task()) | |
269 | compat_setup_restart_syscall(regs); | |
270 | else | |
271 | regs->regs[8] = __NR_restart_syscall; | |
272 | } | |
273 | ||
274 | /* | |
275 | * OK, we're invoking a handler | |
276 | */ | |
277 | static void handle_signal(unsigned long sig, struct k_sigaction *ka, | |
278 | siginfo_t *info, struct pt_regs *regs) | |
279 | { | |
280 | struct thread_info *thread = current_thread_info(); | |
281 | struct task_struct *tsk = current; | |
282 | sigset_t *oldset = sigmask_to_save(); | |
283 | int usig = sig; | |
284 | int ret; | |
285 | ||
286 | /* | |
287 | * translate the signal | |
288 | */ | |
289 | if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap) | |
290 | usig = thread->exec_domain->signal_invmap[usig]; | |
291 | ||
292 | /* | |
293 | * Set up the stack frame | |
294 | */ | |
295 | if (is_compat_task()) { | |
296 | if (ka->sa.sa_flags & SA_SIGINFO) | |
297 | ret = compat_setup_rt_frame(usig, ka, info, oldset, | |
298 | regs); | |
299 | else | |
300 | ret = compat_setup_frame(usig, ka, oldset, regs); | |
301 | } else { | |
302 | ret = setup_rt_frame(usig, ka, info, oldset, regs); | |
303 | } | |
304 | ||
305 | /* | |
306 | * Check that the resulting registers are actually sane. | |
307 | */ | |
308 | ret |= !valid_user_regs(®s->user_regs); | |
309 | ||
310 | if (ret != 0) { | |
311 | force_sigsegv(sig, tsk); | |
312 | return; | |
313 | } | |
314 | ||
315 | /* | |
316 | * Fast forward the stepping logic so we step into the signal | |
317 | * handler. | |
318 | */ | |
319 | user_fastforward_single_step(tsk); | |
320 | ||
321 | signal_delivered(sig, info, ka, regs, 0); | |
322 | } | |
323 | ||
324 | /* | |
325 | * Note that 'init' is a special process: it doesn't get signals it doesn't | |
326 | * want to handle. Thus you cannot kill init even with a SIGKILL even by | |
327 | * mistake. | |
328 | * | |
329 | * Note that we go through the signals twice: once to check the signals that | |
330 | * the kernel can handle, and then we build all the user-level signal handling | |
331 | * stack-frames in one go after that. | |
332 | */ | |
333 | static void do_signal(struct pt_regs *regs) | |
334 | { | |
335 | unsigned long continue_addr = 0, restart_addr = 0; | |
336 | struct k_sigaction ka; | |
337 | siginfo_t info; | |
338 | int signr, retval = 0; | |
339 | int syscall = (int)regs->syscallno; | |
340 | ||
341 | /* | |
342 | * If we were from a system call, check for system call restarting... | |
343 | */ | |
344 | if (syscall >= 0) { | |
345 | continue_addr = regs->pc; | |
346 | restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4); | |
347 | retval = regs->regs[0]; | |
348 | ||
349 | /* | |
350 | * Avoid additional syscall restarting via ret_to_user. | |
351 | */ | |
352 | regs->syscallno = ~0UL; | |
353 | ||
354 | /* | |
355 | * Prepare for system call restart. We do this here so that a | |
356 | * debugger will see the already changed PC. | |
357 | */ | |
358 | switch (retval) { | |
359 | case -ERESTARTNOHAND: | |
360 | case -ERESTARTSYS: | |
361 | case -ERESTARTNOINTR: | |
362 | case -ERESTART_RESTARTBLOCK: | |
363 | regs->regs[0] = regs->orig_x0; | |
364 | regs->pc = restart_addr; | |
365 | break; | |
366 | } | |
367 | } | |
368 | ||
369 | /* | |
370 | * Get the signal to deliver. When running under ptrace, at this point | |
371 | * the debugger may change all of our registers. | |
372 | */ | |
373 | signr = get_signal_to_deliver(&info, &ka, regs, NULL); | |
374 | if (signr > 0) { | |
375 | /* | |
376 | * Depending on the signal settings, we may need to revert the | |
377 | * decision to restart the system call, but skip this if a | |
378 | * debugger has chosen to restart at a different PC. | |
379 | */ | |
380 | if (regs->pc == restart_addr && | |
381 | (retval == -ERESTARTNOHAND || | |
382 | retval == -ERESTART_RESTARTBLOCK || | |
383 | (retval == -ERESTARTSYS && | |
384 | !(ka.sa.sa_flags & SA_RESTART)))) { | |
385 | regs->regs[0] = -EINTR; | |
386 | regs->pc = continue_addr; | |
387 | } | |
388 | ||
389 | handle_signal(signr, &ka, &info, regs); | |
390 | return; | |
391 | } | |
392 | ||
393 | /* | |
394 | * Handle restarting a different system call. As above, if a debugger | |
395 | * has chosen to restart at a different PC, ignore the restart. | |
396 | */ | |
397 | if (syscall >= 0 && regs->pc == restart_addr) { | |
398 | if (retval == -ERESTART_RESTARTBLOCK) | |
399 | setup_restart_syscall(regs); | |
400 | user_rewind_single_step(current); | |
401 | } | |
402 | ||
403 | restore_saved_sigmask(); | |
404 | } | |
405 | ||
406 | asmlinkage void do_notify_resume(struct pt_regs *regs, | |
407 | unsigned int thread_flags) | |
408 | { | |
409 | if (thread_flags & _TIF_SIGPENDING) | |
410 | do_signal(regs); | |
411 | ||
412 | if (thread_flags & _TIF_NOTIFY_RESUME) { | |
413 | clear_thread_flag(TIF_NOTIFY_RESUME); | |
414 | tracehook_notify_resume(regs); | |
415 | } | |
6fa3eb70 S |
416 | |
417 | if (thread_flags & _TIF_FOREIGN_FPSTATE) | |
418 | fpsimd_restore_current_state(); | |
419 | ||
2c020ed8 | 420 | } |