1 | /* |
2 | * Emulation of Linux signals |
3 | * |
4 | * Copyright (c) 2003 Fabrice Bellard |
5 | * |
6 | * This program is free software; you can redistribute it and/or modify |
7 | * it under the terms of the GNU General Public License as published by |
8 | * the Free Software Foundation; either version 2 of the License, or |
9 | * (at your option) any later version. |
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 | #include "qemu/osdep.h" |
20 | #include "qemu/bitops.h" |
21 | #include <sys/ucontext.h> |
22 | #include <sys/resource.h> |
23 | |
24 | #include "qemu.h" |
25 | #include "trace.h" |
26 | #include "signal-common.h" |
27 | |
28 | static struct target_sigaction sigact_table[TARGET_NSIG]; |
29 | |
30 | static void host_signal_handler(int host_signum, siginfo_t *info, |
31 | void *puc); |
32 | |
33 | static uint8_t host_to_target_signal_table[_NSIG] = { |
34 | [SIGHUP] = TARGET_SIGHUP, |
35 | [SIGINT] = TARGET_SIGINT, |
36 | [SIGQUIT] = TARGET_SIGQUIT, |
37 | [SIGILL] = TARGET_SIGILL, |
38 | [SIGTRAP] = TARGET_SIGTRAP, |
39 | [SIGABRT] = TARGET_SIGABRT, |
40 | /* [SIGIOT] = TARGET_SIGIOT,*/ |
41 | [SIGBUS] = TARGET_SIGBUS, |
42 | [SIGFPE] = TARGET_SIGFPE, |
43 | [SIGKILL] = TARGET_SIGKILL, |
44 | [SIGUSR1] = TARGET_SIGUSR1, |
45 | [SIGSEGV] = TARGET_SIGSEGV, |
46 | [SIGUSR2] = TARGET_SIGUSR2, |
47 | [SIGPIPE] = TARGET_SIGPIPE, |
48 | [SIGALRM] = TARGET_SIGALRM, |
49 | [SIGTERM] = TARGET_SIGTERM, |
50 | #ifdef SIGSTKFLT |
51 | [SIGSTKFLT] = TARGET_SIGSTKFLT, |
52 | #endif |
53 | [SIGCHLD] = TARGET_SIGCHLD, |
54 | [SIGCONT] = TARGET_SIGCONT, |
55 | [SIGSTOP] = TARGET_SIGSTOP, |
56 | [SIGTSTP] = TARGET_SIGTSTP, |
57 | [SIGTTIN] = TARGET_SIGTTIN, |
58 | [SIGTTOU] = TARGET_SIGTTOU, |
59 | [SIGURG] = TARGET_SIGURG, |
60 | [SIGXCPU] = TARGET_SIGXCPU, |
61 | [SIGXFSZ] = TARGET_SIGXFSZ, |
62 | [SIGVTALRM] = TARGET_SIGVTALRM, |
63 | [SIGPROF] = TARGET_SIGPROF, |
64 | [SIGWINCH] = TARGET_SIGWINCH, |
65 | [SIGIO] = TARGET_SIGIO, |
66 | [SIGPWR] = TARGET_SIGPWR, |
67 | [SIGSYS] = TARGET_SIGSYS, |
68 | /* next signals stay the same */ |
69 | /* Nasty hack: Reverse SIGRTMIN and SIGRTMAX to avoid overlap with |
70 | host libpthread signals. This assumes no one actually uses SIGRTMAX :-/ |
71 | To fix this properly we need to do manual signal delivery multiplexed |
72 | over a single host signal. */ |
73 | [__SIGRTMIN] = __SIGRTMAX, |
74 | [__SIGRTMAX] = __SIGRTMIN, |
75 | }; |
76 | static uint8_t target_to_host_signal_table[_NSIG]; |
77 | |
78 | int host_to_target_signal(int sig) |
79 | { |
80 | if (sig < 0 || sig >= _NSIG) |
81 | return sig; |
82 | return host_to_target_signal_table[sig]; |
83 | } |
84 | |
85 | int target_to_host_signal(int sig) |
86 | { |
87 | if (sig < 0 || sig >= _NSIG) |
88 | return sig; |
89 | return target_to_host_signal_table[sig]; |
90 | } |
91 | |
92 | static inline void target_sigaddset(target_sigset_t *set, int signum) |
93 | { |
94 | signum--; |
95 | abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW); |
96 | set->sig[signum / TARGET_NSIG_BPW] |= mask; |
97 | } |
98 | |
99 | static inline int target_sigismember(const target_sigset_t *set, int signum) |
100 | { |
101 | signum--; |
102 | abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW); |
103 | return ((set->sig[signum / TARGET_NSIG_BPW] & mask) != 0); |
104 | } |
105 | |
106 | void host_to_target_sigset_internal(target_sigset_t *d, |
107 | const sigset_t *s) |
108 | { |
109 | int i; |
110 | target_sigemptyset(d); |
111 | for (i = 1; i <= TARGET_NSIG; i++) { |
112 | if (sigismember(s, i)) { |
113 | target_sigaddset(d, host_to_target_signal(i)); |
114 | } |
115 | } |
116 | } |
117 | |
118 | void host_to_target_sigset(target_sigset_t *d, const sigset_t *s) |
119 | { |
120 | target_sigset_t d1; |
121 | int i; |
122 | |
123 | host_to_target_sigset_internal(&d1, s); |
124 | for(i = 0;i < TARGET_NSIG_WORDS; i++) |
125 | d->sig[i] = tswapal(d1.sig[i]); |
126 | } |
127 | |
128 | void target_to_host_sigset_internal(sigset_t *d, |
129 | const target_sigset_t *s) |
130 | { |
131 | int i; |
132 | sigemptyset(d); |
133 | for (i = 1; i <= TARGET_NSIG; i++) { |
134 | if (target_sigismember(s, i)) { |
135 | sigaddset(d, target_to_host_signal(i)); |
136 | } |
137 | } |
138 | } |
139 | |
140 | void target_to_host_sigset(sigset_t *d, const target_sigset_t *s) |
141 | { |
142 | target_sigset_t s1; |
143 | int i; |
144 | |
145 | for(i = 0;i < TARGET_NSIG_WORDS; i++) |
146 | s1.sig[i] = tswapal(s->sig[i]); |
147 | target_to_host_sigset_internal(d, &s1); |
148 | } |
149 | |
150 | void host_to_target_old_sigset(abi_ulong *old_sigset, |
151 | const sigset_t *sigset) |
152 | { |
153 | target_sigset_t d; |
154 | host_to_target_sigset(&d, sigset); |
155 | *old_sigset = d.sig[0]; |
156 | } |
157 | |
158 | void target_to_host_old_sigset(sigset_t *sigset, |
159 | const abi_ulong *old_sigset) |
160 | { |
161 | target_sigset_t d; |
162 | int i; |
163 | |
164 | d.sig[0] = *old_sigset; |
165 | for(i = 1;i < TARGET_NSIG_WORDS; i++) |
166 | d.sig[i] = 0; |
167 | target_to_host_sigset(sigset, &d); |
168 | } |
169 | |
170 | int block_signals(void) |
171 | { |
172 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
173 | sigset_t set; |
174 | |
175 | /* It's OK to block everything including SIGSEGV, because we won't |
176 | * run any further guest code before unblocking signals in |
177 | * process_pending_signals(). |
178 | */ |
179 | sigfillset(&set); |
180 | sigprocmask(SIG_SETMASK, &set, 0); |
181 | |
182 | return atomic_xchg(&ts->signal_pending, 1); |
183 | } |
184 | |
185 | /* Wrapper for sigprocmask function |
186 | * Emulates a sigprocmask in a safe way for the guest. Note that set and oldset |
187 | * are host signal set, not guest ones. Returns -TARGET_ERESTARTSYS if |
188 | * a signal was already pending and the syscall must be restarted, or |
189 | * 0 on success. |
190 | * If set is NULL, this is guaranteed not to fail. |
191 | */ |
192 | int do_sigprocmask(int how, const sigset_t *set, sigset_t *oldset) |
193 | { |
194 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
195 | |
196 | if (oldset) { |
197 | *oldset = ts->signal_mask; |
198 | } |
199 | |
200 | if (set) { |
201 | int i; |
202 | |
203 | if (block_signals()) { |
204 | return -TARGET_ERESTARTSYS; |
205 | } |
206 | |
207 | switch (how) { |
208 | case SIG_BLOCK: |
209 | sigorset(&ts->signal_mask, &ts->signal_mask, set); |
210 | break; |
211 | case SIG_UNBLOCK: |
212 | for (i = 1; i <= NSIG; ++i) { |
213 | if (sigismember(set, i)) { |
214 | sigdelset(&ts->signal_mask, i); |
215 | } |
216 | } |
217 | break; |
218 | case SIG_SETMASK: |
219 | ts->signal_mask = *set; |
220 | break; |
221 | default: |
222 | g_assert_not_reached(); |
223 | } |
224 | |
225 | /* Silently ignore attempts to change blocking status of KILL or STOP */ |
226 | sigdelset(&ts->signal_mask, SIGKILL); |
227 | sigdelset(&ts->signal_mask, SIGSTOP); |
228 | } |
229 | return 0; |
230 | } |
231 | |
232 | #if !defined(TARGET_NIOS2) |
233 | /* Just set the guest's signal mask to the specified value; the |
234 | * caller is assumed to have called block_signals() already. |
235 | */ |
236 | void set_sigmask(const sigset_t *set) |
237 | { |
238 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
239 | |
240 | ts->signal_mask = *set; |
241 | } |
242 | #endif |
243 | |
244 | /* sigaltstack management */ |
245 | |
246 | int on_sig_stack(unsigned long sp) |
247 | { |
248 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
249 | |
250 | return (sp - ts->sigaltstack_used.ss_sp |
251 | < ts->sigaltstack_used.ss_size); |
252 | } |
253 | |
254 | int sas_ss_flags(unsigned long sp) |
255 | { |
256 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
257 | |
258 | return (ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE |
259 | : on_sig_stack(sp) ? SS_ONSTACK : 0); |
260 | } |
261 | |
262 | abi_ulong target_sigsp(abi_ulong sp, struct target_sigaction *ka) |
263 | { |
264 | /* |
265 | * This is the X/Open sanctioned signal stack switching. |
266 | */ |
267 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
268 | |
269 | if ((ka->sa_flags & TARGET_SA_ONSTACK) && !sas_ss_flags(sp)) { |
270 | return ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size; |
271 | } |
272 | return sp; |
273 | } |
274 | |
275 | void target_save_altstack(target_stack_t *uss, CPUArchState *env) |
276 | { |
277 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
278 | |
279 | __put_user(ts->sigaltstack_used.ss_sp, &uss->ss_sp); |
280 | __put_user(sas_ss_flags(get_sp_from_cpustate(env)), &uss->ss_flags); |
281 | __put_user(ts->sigaltstack_used.ss_size, &uss->ss_size); |
282 | } |
283 | |
284 | /* siginfo conversion */ |
285 | |
286 | static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo, |
287 | const siginfo_t *info) |
288 | { |
289 | int sig = host_to_target_signal(info->si_signo); |
290 | int si_code = info->si_code; |
291 | int si_type; |
292 | tinfo->si_signo = sig; |
293 | tinfo->si_errno = 0; |
294 | tinfo->si_code = info->si_code; |
295 | |
296 | /* This memset serves two purposes: |
297 | * (1) ensure we don't leak random junk to the guest later |
298 | * (2) placate false positives from gcc about fields |
299 | * being used uninitialized if it chooses to inline both this |
300 | * function and tswap_siginfo() into host_to_target_siginfo(). |
301 | */ |
302 | memset(tinfo->_sifields._pad, 0, sizeof(tinfo->_sifields._pad)); |
303 | |
304 | /* This is awkward, because we have to use a combination of |
305 | * the si_code and si_signo to figure out which of the union's |
306 | * members are valid. (Within the host kernel it is always possible |
307 | * to tell, but the kernel carefully avoids giving userspace the |
308 | * high 16 bits of si_code, so we don't have the information to |
309 | * do this the easy way...) We therefore make our best guess, |
310 | * bearing in mind that a guest can spoof most of the si_codes |
311 | * via rt_sigqueueinfo() if it likes. |
312 | * |
313 | * Once we have made our guess, we record it in the top 16 bits of |
314 | * the si_code, so that tswap_siginfo() later can use it. |
315 | * tswap_siginfo() will strip these top bits out before writing |
316 | * si_code to the guest (sign-extending the lower bits). |
317 | */ |
318 | |
319 | switch (si_code) { |
320 | case SI_USER: |
321 | case SI_TKILL: |
322 | case SI_KERNEL: |
323 | /* Sent via kill(), tkill() or tgkill(), or direct from the kernel. |
324 | * These are the only unspoofable si_code values. |
325 | */ |
326 | tinfo->_sifields._kill._pid = info->si_pid; |
327 | tinfo->_sifields._kill._uid = info->si_uid; |
328 | si_type = QEMU_SI_KILL; |
329 | break; |
330 | default: |
331 | /* Everything else is spoofable. Make best guess based on signal */ |
332 | switch (sig) { |
333 | case TARGET_SIGCHLD: |
334 | tinfo->_sifields._sigchld._pid = info->si_pid; |
335 | tinfo->_sifields._sigchld._uid = info->si_uid; |
336 | tinfo->_sifields._sigchld._status |
337 | = host_to_target_waitstatus(info->si_status); |
338 | tinfo->_sifields._sigchld._utime = info->si_utime; |
339 | tinfo->_sifields._sigchld._stime = info->si_stime; |
340 | si_type = QEMU_SI_CHLD; |
341 | break; |
342 | case TARGET_SIGIO: |
343 | tinfo->_sifields._sigpoll._band = info->si_band; |
344 | tinfo->_sifields._sigpoll._fd = info->si_fd; |
345 | si_type = QEMU_SI_POLL; |
346 | break; |
347 | default: |
348 | /* Assume a sigqueue()/mq_notify()/rt_sigqueueinfo() source. */ |
349 | tinfo->_sifields._rt._pid = info->si_pid; |
350 | tinfo->_sifields._rt._uid = info->si_uid; |
351 | /* XXX: potential problem if 64 bit */ |
352 | tinfo->_sifields._rt._sigval.sival_ptr |
353 | = (abi_ulong)(unsigned long)info->si_value.sival_ptr; |
354 | si_type = QEMU_SI_RT; |
355 | break; |
356 | } |
357 | break; |
358 | } |
359 | |
360 | tinfo->si_code = deposit32(si_code, 16, 16, si_type); |
361 | } |
362 | |
363 | void tswap_siginfo(target_siginfo_t *tinfo, |
364 | const target_siginfo_t *info) |
365 | { |
366 | int si_type = extract32(info->si_code, 16, 16); |
367 | int si_code = sextract32(info->si_code, 0, 16); |
368 | |
369 | __put_user(info->si_signo, &tinfo->si_signo); |
370 | __put_user(info->si_errno, &tinfo->si_errno); |
371 | __put_user(si_code, &tinfo->si_code); |
372 | |
373 | /* We can use our internal marker of which fields in the structure |
374 | * are valid, rather than duplicating the guesswork of |
375 | * host_to_target_siginfo_noswap() here. |
376 | */ |
377 | switch (si_type) { |
378 | case QEMU_SI_KILL: |
379 | __put_user(info->_sifields._kill._pid, &tinfo->_sifields._kill._pid); |
380 | __put_user(info->_sifields._kill._uid, &tinfo->_sifields._kill._uid); |
381 | break; |
382 | case QEMU_SI_TIMER: |
383 | __put_user(info->_sifields._timer._timer1, |
384 | &tinfo->_sifields._timer._timer1); |
385 | __put_user(info->_sifields._timer._timer2, |
386 | &tinfo->_sifields._timer._timer2); |
387 | break; |
388 | case QEMU_SI_POLL: |
389 | __put_user(info->_sifields._sigpoll._band, |
390 | &tinfo->_sifields._sigpoll._band); |
391 | __put_user(info->_sifields._sigpoll._fd, |
392 | &tinfo->_sifields._sigpoll._fd); |
393 | break; |
394 | case QEMU_SI_FAULT: |
395 | __put_user(info->_sifields._sigfault._addr, |
396 | &tinfo->_sifields._sigfault._addr); |
397 | break; |
398 | case QEMU_SI_CHLD: |
399 | __put_user(info->_sifields._sigchld._pid, |
400 | &tinfo->_sifields._sigchld._pid); |
401 | __put_user(info->_sifields._sigchld._uid, |
402 | &tinfo->_sifields._sigchld._uid); |
403 | __put_user(info->_sifields._sigchld._status, |
404 | &tinfo->_sifields._sigchld._status); |
405 | __put_user(info->_sifields._sigchld._utime, |
406 | &tinfo->_sifields._sigchld._utime); |
407 | __put_user(info->_sifields._sigchld._stime, |
408 | &tinfo->_sifields._sigchld._stime); |
409 | break; |
410 | case QEMU_SI_RT: |
411 | __put_user(info->_sifields._rt._pid, &tinfo->_sifields._rt._pid); |
412 | __put_user(info->_sifields._rt._uid, &tinfo->_sifields._rt._uid); |
413 | __put_user(info->_sifields._rt._sigval.sival_ptr, |
414 | &tinfo->_sifields._rt._sigval.sival_ptr); |
415 | break; |
416 | default: |
417 | g_assert_not_reached(); |
418 | } |
419 | } |
420 | |
421 | void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info) |
422 | { |
423 | target_siginfo_t tgt_tmp; |
424 | host_to_target_siginfo_noswap(&tgt_tmp, info); |
425 | tswap_siginfo(tinfo, &tgt_tmp); |
426 | } |
427 | |
428 | /* XXX: we support only POSIX RT signals are used. */ |
429 | /* XXX: find a solution for 64 bit (additional malloced data is needed) */ |
430 | void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo) |
431 | { |
432 | /* This conversion is used only for the rt_sigqueueinfo syscall, |
433 | * and so we know that the _rt fields are the valid ones. |
434 | */ |
435 | abi_ulong sival_ptr; |
436 | |
437 | __get_user(info->si_signo, &tinfo->si_signo); |
438 | __get_user(info->si_errno, &tinfo->si_errno); |
439 | __get_user(info->si_code, &tinfo->si_code); |
440 | __get_user(info->si_pid, &tinfo->_sifields._rt._pid); |
441 | __get_user(info->si_uid, &tinfo->_sifields._rt._uid); |
442 | __get_user(sival_ptr, &tinfo->_sifields._rt._sigval.sival_ptr); |
443 | info->si_value.sival_ptr = (void *)(long)sival_ptr; |
444 | } |
445 | |
446 | static int fatal_signal (int sig) |
447 | { |
448 | switch (sig) { |
449 | case TARGET_SIGCHLD: |
450 | case TARGET_SIGURG: |
451 | case TARGET_SIGWINCH: |
452 | /* Ignored by default. */ |
453 | return 0; |
454 | case TARGET_SIGCONT: |
455 | case TARGET_SIGSTOP: |
456 | case TARGET_SIGTSTP: |
457 | case TARGET_SIGTTIN: |
458 | case TARGET_SIGTTOU: |
459 | /* Job control signals. */ |
460 | return 0; |
461 | default: |
462 | return 1; |
463 | } |
464 | } |
465 | |
466 | /* returns 1 if given signal should dump core if not handled */ |
467 | static int core_dump_signal(int sig) |
468 | { |
469 | switch (sig) { |
470 | case TARGET_SIGABRT: |
471 | case TARGET_SIGFPE: |
472 | case TARGET_SIGILL: |
473 | case TARGET_SIGQUIT: |
474 | case TARGET_SIGSEGV: |
475 | case TARGET_SIGTRAP: |
476 | case TARGET_SIGBUS: |
477 | return (1); |
478 | default: |
479 | return (0); |
480 | } |
481 | } |
482 | |
483 | void signal_init(void) |
484 | { |
485 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
486 | struct sigaction act; |
487 | struct sigaction oact; |
488 | int i, j; |
489 | int host_sig; |
490 | |
491 | /* generate signal conversion tables */ |
492 | for(i = 1; i < _NSIG; i++) { |
493 | if (host_to_target_signal_table[i] == 0) |
494 | host_to_target_signal_table[i] = i; |
495 | } |
496 | for(i = 1; i < _NSIG; i++) { |
497 | j = host_to_target_signal_table[i]; |
498 | target_to_host_signal_table[j] = i; |
499 | } |
500 | |
501 | /* Set the signal mask from the host mask. */ |
502 | sigprocmask(0, 0, &ts->signal_mask); |
503 | |
504 | /* set all host signal handlers. ALL signals are blocked during |
505 | the handlers to serialize them. */ |
506 | memset(sigact_table, 0, sizeof(sigact_table)); |
507 | |
508 | sigfillset(&act.sa_mask); |
509 | act.sa_flags = SA_SIGINFO; |
510 | act.sa_sigaction = host_signal_handler; |
511 | for(i = 1; i <= TARGET_NSIG; i++) { |
512 | #ifdef TARGET_GPROF |
513 | if (i == SIGPROF) { |
514 | continue; |
515 | } |
516 | #endif |
517 | host_sig = target_to_host_signal(i); |
518 | sigaction(host_sig, NULL, &oact); |
519 | if (oact.sa_sigaction == (void *)SIG_IGN) { |
520 | sigact_table[i - 1]._sa_handler = TARGET_SIG_IGN; |
521 | } else if (oact.sa_sigaction == (void *)SIG_DFL) { |
522 | sigact_table[i - 1]._sa_handler = TARGET_SIG_DFL; |
523 | } |
524 | /* If there's already a handler installed then something has |
525 | gone horribly wrong, so don't even try to handle that case. */ |
526 | /* Install some handlers for our own use. We need at least |
527 | SIGSEGV and SIGBUS, to detect exceptions. We can not just |
528 | trap all signals because it affects syscall interrupt |
529 | behavior. But do trap all default-fatal signals. */ |
530 | if (fatal_signal (i)) |
531 | sigaction(host_sig, &act, NULL); |
532 | } |
533 | } |
534 | |
535 | /* Force a synchronously taken signal. The kernel force_sig() function |
536 | * also forces the signal to "not blocked, not ignored", but for QEMU |
537 | * that work is done in process_pending_signals(). |
538 | */ |
539 | void force_sig(int sig) |
540 | { |
541 | CPUState *cpu = thread_cpu; |
542 | CPUArchState *env = cpu->env_ptr; |
543 | target_siginfo_t info; |
544 | |
545 | info.si_signo = sig; |
546 | info.si_errno = 0; |
547 | info.si_code = TARGET_SI_KERNEL; |
548 | info._sifields._kill._pid = 0; |
549 | info._sifields._kill._uid = 0; |
550 | queue_signal(env, info.si_signo, QEMU_SI_KILL, &info); |
551 | } |
552 | |
553 | /* Force a SIGSEGV if we couldn't write to memory trying to set |
554 | * up the signal frame. oldsig is the signal we were trying to handle |
555 | * at the point of failure. |
556 | */ |
557 | #if !defined(TARGET_RISCV) |
558 | void force_sigsegv(int oldsig) |
559 | { |
560 | if (oldsig == SIGSEGV) { |
561 | /* Make sure we don't try to deliver the signal again; this will |
562 | * end up with handle_pending_signal() calling dump_core_and_abort(). |
563 | */ |
564 | sigact_table[oldsig - 1]._sa_handler = TARGET_SIG_DFL; |
565 | } |
566 | force_sig(TARGET_SIGSEGV); |
567 | } |
568 | |
569 | #endif |
570 | |
571 | /* abort execution with signal */ |
572 | static void QEMU_NORETURN dump_core_and_abort(int target_sig) |
573 | { |
574 | CPUState *cpu = thread_cpu; |
575 | CPUArchState *env = cpu->env_ptr; |
576 | TaskState *ts = (TaskState *)cpu->opaque; |
577 | int host_sig, core_dumped = 0; |
578 | struct sigaction act; |
579 | |
580 | host_sig = target_to_host_signal(target_sig); |
581 | trace_user_force_sig(env, target_sig, host_sig); |
582 | gdb_signalled(env, target_sig); |
583 | |
584 | /* dump core if supported by target binary format */ |
585 | if (core_dump_signal(target_sig) && (ts->bprm->core_dump != NULL)) { |
586 | stop_all_tasks(); |
587 | core_dumped = |
588 | ((*ts->bprm->core_dump)(target_sig, env) == 0); |
589 | } |
590 | if (core_dumped) { |
591 | /* we already dumped the core of target process, we don't want |
592 | * a coredump of qemu itself */ |
593 | struct rlimit nodump; |
594 | getrlimit(RLIMIT_CORE, &nodump); |
595 | nodump.rlim_cur=0; |
596 | setrlimit(RLIMIT_CORE, &nodump); |
597 | (void) fprintf(stderr, "qemu: uncaught target signal %d (%s) - %s\n" , |
598 | target_sig, strsignal(host_sig), "core dumped" ); |
599 | } |
600 | |
601 | /* The proper exit code for dying from an uncaught signal is |
602 | * -<signal>. The kernel doesn't allow exit() or _exit() to pass |
603 | * a negative value. To get the proper exit code we need to |
604 | * actually die from an uncaught signal. Here the default signal |
605 | * handler is installed, we send ourself a signal and we wait for |
606 | * it to arrive. */ |
607 | sigfillset(&act.sa_mask); |
608 | act.sa_handler = SIG_DFL; |
609 | act.sa_flags = 0; |
610 | sigaction(host_sig, &act, NULL); |
611 | |
612 | /* For some reason raise(host_sig) doesn't send the signal when |
613 | * statically linked on x86-64. */ |
614 | kill(getpid(), host_sig); |
615 | |
616 | /* Make sure the signal isn't masked (just reuse the mask inside |
617 | of act) */ |
618 | sigdelset(&act.sa_mask, host_sig); |
619 | sigsuspend(&act.sa_mask); |
620 | |
621 | /* unreachable */ |
622 | abort(); |
623 | } |
624 | |
625 | /* queue a signal so that it will be send to the virtual CPU as soon |
626 | as possible */ |
627 | int queue_signal(CPUArchState *env, int sig, int si_type, |
628 | target_siginfo_t *info) |
629 | { |
630 | CPUState *cpu = env_cpu(env); |
631 | TaskState *ts = cpu->opaque; |
632 | |
633 | trace_user_queue_signal(env, sig); |
634 | |
635 | info->si_code = deposit32(info->si_code, 16, 16, si_type); |
636 | |
637 | ts->sync_signal.info = *info; |
638 | ts->sync_signal.pending = sig; |
639 | /* signal that a new signal is pending */ |
640 | atomic_set(&ts->signal_pending, 1); |
641 | return 1; /* indicates that the signal was queued */ |
642 | } |
643 | |
644 | #ifndef HAVE_SAFE_SYSCALL |
645 | static inline void rewind_if_in_safe_syscall(void *puc) |
646 | { |
647 | /* Default version: never rewind */ |
648 | } |
649 | #endif |
650 | |
651 | static void host_signal_handler(int host_signum, siginfo_t *info, |
652 | void *puc) |
653 | { |
654 | CPUArchState *env = thread_cpu->env_ptr; |
655 | CPUState *cpu = env_cpu(env); |
656 | TaskState *ts = cpu->opaque; |
657 | |
658 | int sig; |
659 | target_siginfo_t tinfo; |
660 | ucontext_t *uc = puc; |
661 | struct emulated_sigtable *k; |
662 | |
663 | /* the CPU emulator uses some host signals to detect exceptions, |
664 | we forward to it some signals */ |
665 | if ((host_signum == SIGSEGV || host_signum == SIGBUS) |
666 | && info->si_code > 0) { |
667 | if (cpu_signal_handler(host_signum, info, puc)) |
668 | return; |
669 | } |
670 | |
671 | /* get target signal number */ |
672 | sig = host_to_target_signal(host_signum); |
673 | if (sig < 1 || sig > TARGET_NSIG) |
674 | return; |
675 | trace_user_host_signal(env, host_signum, sig); |
676 | |
677 | rewind_if_in_safe_syscall(puc); |
678 | |
679 | host_to_target_siginfo_noswap(&tinfo, info); |
680 | k = &ts->sigtab[sig - 1]; |
681 | k->info = tinfo; |
682 | k->pending = sig; |
683 | ts->signal_pending = 1; |
684 | |
685 | /* Block host signals until target signal handler entered. We |
686 | * can't block SIGSEGV or SIGBUS while we're executing guest |
687 | * code in case the guest code provokes one in the window between |
688 | * now and it getting out to the main loop. Signals will be |
689 | * unblocked again in process_pending_signals(). |
690 | * |
691 | * WARNING: we cannot use sigfillset() here because the uc_sigmask |
692 | * field is a kernel sigset_t, which is much smaller than the |
693 | * libc sigset_t which sigfillset() operates on. Using sigfillset() |
694 | * would write 0xff bytes off the end of the structure and trash |
695 | * data on the struct. |
696 | * We can't use sizeof(uc->uc_sigmask) either, because the libc |
697 | * headers define the struct field with the wrong (too large) type. |
698 | */ |
699 | memset(&uc->uc_sigmask, 0xff, SIGSET_T_SIZE); |
700 | sigdelset(&uc->uc_sigmask, SIGSEGV); |
701 | sigdelset(&uc->uc_sigmask, SIGBUS); |
702 | |
703 | /* interrupt the virtual CPU as soon as possible */ |
704 | cpu_exit(thread_cpu); |
705 | } |
706 | |
707 | /* do_sigaltstack() returns target values and errnos. */ |
708 | /* compare linux/kernel/signal.c:do_sigaltstack() */ |
709 | abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp) |
710 | { |
711 | int ret; |
712 | struct target_sigaltstack oss; |
713 | TaskState *ts = (TaskState *)thread_cpu->opaque; |
714 | |
715 | /* XXX: test errors */ |
716 | if(uoss_addr) |
717 | { |
718 | __put_user(ts->sigaltstack_used.ss_sp, &oss.ss_sp); |
719 | __put_user(ts->sigaltstack_used.ss_size, &oss.ss_size); |
720 | __put_user(sas_ss_flags(sp), &oss.ss_flags); |
721 | } |
722 | |
723 | if(uss_addr) |
724 | { |
725 | struct target_sigaltstack *uss; |
726 | struct target_sigaltstack ss; |
727 | size_t minstacksize = TARGET_MINSIGSTKSZ; |
728 | |
729 | #if defined(TARGET_PPC64) |
730 | /* ELF V2 for PPC64 has a 4K minimum stack size for signal handlers */ |
731 | struct image_info *image = ((TaskState *)thread_cpu->opaque)->info; |
732 | if (get_ppc64_abi(image) > 1) { |
733 | minstacksize = 4096; |
734 | } |
735 | #endif |
736 | |
737 | ret = -TARGET_EFAULT; |
738 | if (!lock_user_struct(VERIFY_READ, uss, uss_addr, 1)) { |
739 | goto out; |
740 | } |
741 | __get_user(ss.ss_sp, &uss->ss_sp); |
742 | __get_user(ss.ss_size, &uss->ss_size); |
743 | __get_user(ss.ss_flags, &uss->ss_flags); |
744 | unlock_user_struct(uss, uss_addr, 0); |
745 | |
746 | ret = -TARGET_EPERM; |
747 | if (on_sig_stack(sp)) |
748 | goto out; |
749 | |
750 | ret = -TARGET_EINVAL; |
751 | if (ss.ss_flags != TARGET_SS_DISABLE |
752 | && ss.ss_flags != TARGET_SS_ONSTACK |
753 | && ss.ss_flags != 0) |
754 | goto out; |
755 | |
756 | if (ss.ss_flags == TARGET_SS_DISABLE) { |
757 | ss.ss_size = 0; |
758 | ss.ss_sp = 0; |
759 | } else { |
760 | ret = -TARGET_ENOMEM; |
761 | if (ss.ss_size < minstacksize) { |
762 | goto out; |
763 | } |
764 | } |
765 | |
766 | ts->sigaltstack_used.ss_sp = ss.ss_sp; |
767 | ts->sigaltstack_used.ss_size = ss.ss_size; |
768 | } |
769 | |
770 | if (uoss_addr) { |
771 | ret = -TARGET_EFAULT; |
772 | if (copy_to_user(uoss_addr, &oss, sizeof(oss))) |
773 | goto out; |
774 | } |
775 | |
776 | ret = 0; |
777 | out: |
778 | return ret; |
779 | } |
780 | |
781 | /* do_sigaction() return target values and host errnos */ |
782 | int do_sigaction(int sig, const struct target_sigaction *act, |
783 | struct target_sigaction *oact) |
784 | { |
785 | struct target_sigaction *k; |
786 | struct sigaction act1; |
787 | int host_sig; |
788 | int ret = 0; |
789 | |
790 | if (sig < 1 || sig > TARGET_NSIG || sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) { |
791 | return -TARGET_EINVAL; |
792 | } |
793 | |
794 | if (block_signals()) { |
795 | return -TARGET_ERESTARTSYS; |
796 | } |
797 | |
798 | k = &sigact_table[sig - 1]; |
799 | if (oact) { |
800 | __put_user(k->_sa_handler, &oact->_sa_handler); |
801 | __put_user(k->sa_flags, &oact->sa_flags); |
802 | #ifdef TARGET_ARCH_HAS_SA_RESTORER |
803 | __put_user(k->sa_restorer, &oact->sa_restorer); |
804 | #endif |
805 | /* Not swapped. */ |
806 | oact->sa_mask = k->sa_mask; |
807 | } |
808 | if (act) { |
809 | /* FIXME: This is not threadsafe. */ |
810 | __get_user(k->_sa_handler, &act->_sa_handler); |
811 | __get_user(k->sa_flags, &act->sa_flags); |
812 | #ifdef TARGET_ARCH_HAS_SA_RESTORER |
813 | __get_user(k->sa_restorer, &act->sa_restorer); |
814 | #endif |
815 | /* To be swapped in target_to_host_sigset. */ |
816 | k->sa_mask = act->sa_mask; |
817 | |
818 | /* we update the host linux signal state */ |
819 | host_sig = target_to_host_signal(sig); |
820 | if (host_sig != SIGSEGV && host_sig != SIGBUS) { |
821 | sigfillset(&act1.sa_mask); |
822 | act1.sa_flags = SA_SIGINFO; |
823 | if (k->sa_flags & TARGET_SA_RESTART) |
824 | act1.sa_flags |= SA_RESTART; |
825 | /* NOTE: it is important to update the host kernel signal |
826 | ignore state to avoid getting unexpected interrupted |
827 | syscalls */ |
828 | if (k->_sa_handler == TARGET_SIG_IGN) { |
829 | act1.sa_sigaction = (void *)SIG_IGN; |
830 | } else if (k->_sa_handler == TARGET_SIG_DFL) { |
831 | if (fatal_signal (sig)) |
832 | act1.sa_sigaction = host_signal_handler; |
833 | else |
834 | act1.sa_sigaction = (void *)SIG_DFL; |
835 | } else { |
836 | act1.sa_sigaction = host_signal_handler; |
837 | } |
838 | ret = sigaction(host_sig, &act1, NULL); |
839 | } |
840 | } |
841 | return ret; |
842 | } |
843 | |
844 | static void handle_pending_signal(CPUArchState *cpu_env, int sig, |
845 | struct emulated_sigtable *k) |
846 | { |
847 | CPUState *cpu = env_cpu(cpu_env); |
848 | abi_ulong handler; |
849 | sigset_t set; |
850 | target_sigset_t target_old_set; |
851 | struct target_sigaction *sa; |
852 | TaskState *ts = cpu->opaque; |
853 | |
854 | trace_user_handle_signal(cpu_env, sig); |
855 | /* dequeue signal */ |
856 | k->pending = 0; |
857 | |
858 | sig = gdb_handlesig(cpu, sig); |
859 | if (!sig) { |
860 | sa = NULL; |
861 | handler = TARGET_SIG_IGN; |
862 | } else { |
863 | sa = &sigact_table[sig - 1]; |
864 | handler = sa->_sa_handler; |
865 | } |
866 | |
867 | if (do_strace) { |
868 | print_taken_signal(sig, &k->info); |
869 | } |
870 | |
871 | if (handler == TARGET_SIG_DFL) { |
872 | /* default handler : ignore some signal. The other are job control or fatal */ |
873 | if (sig == TARGET_SIGTSTP || sig == TARGET_SIGTTIN || sig == TARGET_SIGTTOU) { |
874 | kill(getpid(),SIGSTOP); |
875 | } else if (sig != TARGET_SIGCHLD && |
876 | sig != TARGET_SIGURG && |
877 | sig != TARGET_SIGWINCH && |
878 | sig != TARGET_SIGCONT) { |
879 | dump_core_and_abort(sig); |
880 | } |
881 | } else if (handler == TARGET_SIG_IGN) { |
882 | /* ignore sig */ |
883 | } else if (handler == TARGET_SIG_ERR) { |
884 | dump_core_and_abort(sig); |
885 | } else { |
886 | /* compute the blocked signals during the handler execution */ |
887 | sigset_t *blocked_set; |
888 | |
889 | target_to_host_sigset(&set, &sa->sa_mask); |
890 | /* SA_NODEFER indicates that the current signal should not be |
891 | blocked during the handler */ |
892 | if (!(sa->sa_flags & TARGET_SA_NODEFER)) |
893 | sigaddset(&set, target_to_host_signal(sig)); |
894 | |
895 | /* save the previous blocked signal state to restore it at the |
896 | end of the signal execution (see do_sigreturn) */ |
897 | host_to_target_sigset_internal(&target_old_set, &ts->signal_mask); |
898 | |
899 | /* block signals in the handler */ |
900 | blocked_set = ts->in_sigsuspend ? |
901 | &ts->sigsuspend_mask : &ts->signal_mask; |
902 | sigorset(&ts->signal_mask, blocked_set, &set); |
903 | ts->in_sigsuspend = 0; |
904 | |
905 | /* if the CPU is in VM86 mode, we restore the 32 bit values */ |
906 | #if defined(TARGET_I386) && !defined(TARGET_X86_64) |
907 | { |
908 | CPUX86State *env = cpu_env; |
909 | if (env->eflags & VM_MASK) |
910 | save_v86_state(env); |
911 | } |
912 | #endif |
913 | /* prepare the stack frame of the virtual CPU */ |
914 | #if defined(TARGET_ARCH_HAS_SETUP_FRAME) |
915 | if (sa->sa_flags & TARGET_SA_SIGINFO) { |
916 | setup_rt_frame(sig, sa, &k->info, &target_old_set, cpu_env); |
917 | } else { |
918 | setup_frame(sig, sa, &target_old_set, cpu_env); |
919 | } |
920 | #else |
921 | /* These targets do not have traditional signals. */ |
922 | setup_rt_frame(sig, sa, &k->info, &target_old_set, cpu_env); |
923 | #endif |
924 | if (sa->sa_flags & TARGET_SA_RESETHAND) { |
925 | sa->_sa_handler = TARGET_SIG_DFL; |
926 | } |
927 | } |
928 | } |
929 | |
930 | void process_pending_signals(CPUArchState *cpu_env) |
931 | { |
932 | CPUState *cpu = env_cpu(cpu_env); |
933 | int sig; |
934 | TaskState *ts = cpu->opaque; |
935 | sigset_t set; |
936 | sigset_t *blocked_set; |
937 | |
938 | while (atomic_read(&ts->signal_pending)) { |
939 | /* FIXME: This is not threadsafe. */ |
940 | sigfillset(&set); |
941 | sigprocmask(SIG_SETMASK, &set, 0); |
942 | |
943 | restart_scan: |
944 | sig = ts->sync_signal.pending; |
945 | if (sig) { |
946 | /* Synchronous signals are forced, |
947 | * see force_sig_info() and callers in Linux |
948 | * Note that not all of our queue_signal() calls in QEMU correspond |
949 | * to force_sig_info() calls in Linux (some are send_sig_info()). |
950 | * However it seems like a kernel bug to me to allow the process |
951 | * to block a synchronous signal since it could then just end up |
952 | * looping round and round indefinitely. |
953 | */ |
954 | if (sigismember(&ts->signal_mask, target_to_host_signal_table[sig]) |
955 | || sigact_table[sig - 1]._sa_handler == TARGET_SIG_IGN) { |
956 | sigdelset(&ts->signal_mask, target_to_host_signal_table[sig]); |
957 | sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL; |
958 | } |
959 | |
960 | handle_pending_signal(cpu_env, sig, &ts->sync_signal); |
961 | } |
962 | |
963 | for (sig = 1; sig <= TARGET_NSIG; sig++) { |
964 | blocked_set = ts->in_sigsuspend ? |
965 | &ts->sigsuspend_mask : &ts->signal_mask; |
966 | |
967 | if (ts->sigtab[sig - 1].pending && |
968 | (!sigismember(blocked_set, |
969 | target_to_host_signal_table[sig]))) { |
970 | handle_pending_signal(cpu_env, sig, &ts->sigtab[sig - 1]); |
971 | /* Restart scan from the beginning, as handle_pending_signal |
972 | * might have resulted in a new synchronous signal (eg SIGSEGV). |
973 | */ |
974 | goto restart_scan; |
975 | } |
976 | } |
977 | |
978 | /* if no signal is pending, unblock signals and recheck (the act |
979 | * of unblocking might cause us to take another host signal which |
980 | * will set signal_pending again). |
981 | */ |
982 | atomic_set(&ts->signal_pending, 0); |
983 | ts->in_sigsuspend = 0; |
984 | set = ts->signal_mask; |
985 | sigdelset(&set, SIGSEGV); |
986 | sigdelset(&set, SIGBUS); |
987 | sigprocmask(SIG_SETMASK, &set, 0); |
988 | } |
989 | ts->in_sigsuspend = 0; |
990 | } |
991 | |