1 /* 2 * Emulation of BSD signals 3 * 4 * Copyright (c) 2003 - 2008 Fabrice Bellard 5 * Copyright (c) 2013 Stacey Son 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 as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, see <http://www.gnu.org/licenses/>. 19 */ 20 21 #include "qemu/osdep.h" 22 #include "qemu/log.h" 23 #include "qemu.h" 24 #include "gdbstub/user.h" 25 #include "signal-common.h" 26 #include "trace.h" 27 #include "hw/core/tcg-cpu-ops.h" 28 #include "host-signal.h" 29 30 static struct target_sigaction sigact_table[TARGET_NSIG]; 31 static void host_signal_handler(int host_sig, siginfo_t *info, void *puc); 32 static void target_to_host_sigset_internal(sigset_t *d, 33 const target_sigset_t *s); 34 35 static inline int on_sig_stack(TaskState *ts, unsigned long sp) 36 { 37 return sp - ts->sigaltstack_used.ss_sp < ts->sigaltstack_used.ss_size; 38 } 39 40 static inline int sas_ss_flags(TaskState *ts, unsigned long sp) 41 { 42 return ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE : 43 on_sig_stack(ts, sp) ? SS_ONSTACK : 0; 44 } 45 46 /* 47 * The BSD ABIs use the same signal numbers across all the CPU architectures, so 48 * (unlike Linux) these functions are just the identity mapping. This might not 49 * be true for XyzBSD running on AbcBSD, which doesn't currently work. 50 */ 51 int host_to_target_signal(int sig) 52 { 53 return sig; 54 } 55 56 int target_to_host_signal(int sig) 57 { 58 return sig; 59 } 60 61 static inline void target_sigemptyset(target_sigset_t *set) 62 { 63 memset(set, 0, sizeof(*set)); 64 } 65 66 static inline void target_sigaddset(target_sigset_t *set, int signum) 67 { 68 signum--; 69 uint32_t mask = (uint32_t)1 << (signum % TARGET_NSIG_BPW); 70 set->__bits[signum / TARGET_NSIG_BPW] |= mask; 71 } 72 73 static inline int target_sigismember(const target_sigset_t *set, int signum) 74 { 75 signum--; 76 abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW); 77 return (set->__bits[signum / TARGET_NSIG_BPW] & mask) != 0; 78 } 79 80 /* Adjust the signal context to rewind out of safe-syscall if we're in it */ 81 static inline void rewind_if_in_safe_syscall(void *puc) 82 { 83 ucontext_t *uc = (ucontext_t *)puc; 84 uintptr_t pcreg = host_signal_pc(uc); 85 86 if (pcreg > (uintptr_t)safe_syscall_start 87 && pcreg < (uintptr_t)safe_syscall_end) { 88 host_signal_set_pc(uc, (uintptr_t)safe_syscall_start); 89 } 90 } 91 92 /* 93 * Note: The following take advantage of the BSD signal property that all 94 * signals are available on all architectures. 95 */ 96 static void host_to_target_sigset_internal(target_sigset_t *d, 97 const sigset_t *s) 98 { 99 int i; 100 101 target_sigemptyset(d); 102 for (i = 1; i <= NSIG; i++) { 103 if (sigismember(s, i)) { 104 target_sigaddset(d, host_to_target_signal(i)); 105 } 106 } 107 } 108 109 void host_to_target_sigset(target_sigset_t *d, const sigset_t *s) 110 { 111 target_sigset_t d1; 112 int i; 113 114 host_to_target_sigset_internal(&d1, s); 115 for (i = 0; i < _SIG_WORDS; i++) { 116 d->__bits[i] = tswap32(d1.__bits[i]); 117 } 118 } 119 120 static void target_to_host_sigset_internal(sigset_t *d, 121 const target_sigset_t *s) 122 { 123 int i; 124 125 sigemptyset(d); 126 for (i = 1; i <= TARGET_NSIG; i++) { 127 if (target_sigismember(s, i)) { 128 sigaddset(d, target_to_host_signal(i)); 129 } 130 } 131 } 132 133 void target_to_host_sigset(sigset_t *d, const target_sigset_t *s) 134 { 135 target_sigset_t s1; 136 int i; 137 138 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 139 s1.__bits[i] = tswap32(s->__bits[i]); 140 } 141 target_to_host_sigset_internal(d, &s1); 142 } 143 144 static bool has_trapno(int tsig) 145 { 146 return tsig == TARGET_SIGILL || 147 tsig == TARGET_SIGFPE || 148 tsig == TARGET_SIGSEGV || 149 tsig == TARGET_SIGBUS || 150 tsig == TARGET_SIGTRAP; 151 } 152 153 /* Siginfo conversion. */ 154 155 /* 156 * Populate tinfo w/o swapping based on guessing which fields are valid. 157 */ 158 static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo, 159 const siginfo_t *info) 160 { 161 int sig = host_to_target_signal(info->si_signo); 162 int si_code = info->si_code; 163 int si_type; 164 165 /* 166 * Make sure we that the variable portion of the target siginfo is zeroed 167 * out so we don't leak anything into that. 168 */ 169 memset(&tinfo->_reason, 0, sizeof(tinfo->_reason)); 170 171 /* 172 * This is awkward, because we have to use a combination of the si_code and 173 * si_signo to figure out which of the union's members are valid.o We 174 * therefore make our best guess. 175 * 176 * Once we have made our guess, we record it in the top 16 bits of 177 * the si_code, so that tswap_siginfo() later can use it. 178 * tswap_siginfo() will strip these top bits out before writing 179 * si_code to the guest (sign-extending the lower bits). 180 */ 181 tinfo->si_signo = sig; 182 tinfo->si_errno = info->si_errno; 183 tinfo->si_code = info->si_code; 184 tinfo->si_pid = info->si_pid; 185 tinfo->si_uid = info->si_uid; 186 tinfo->si_status = info->si_status; 187 tinfo->si_addr = (abi_ulong)(unsigned long)info->si_addr; 188 /* 189 * si_value is opaque to kernel. On all FreeBSD platforms, 190 * sizeof(sival_ptr) >= sizeof(sival_int) so the following 191 * always will copy the larger element. 192 */ 193 tinfo->si_value.sival_ptr = 194 (abi_ulong)(unsigned long)info->si_value.sival_ptr; 195 196 switch (si_code) { 197 /* 198 * All the SI_xxx codes that are defined here are global to 199 * all the signals (they have values that none of the other, 200 * more specific signal info will set). 201 */ 202 case SI_USER: 203 case SI_LWP: 204 case SI_KERNEL: 205 case SI_QUEUE: 206 case SI_ASYNCIO: 207 /* 208 * Only the fixed parts are valid (though FreeBSD doesn't always 209 * set all the fields to non-zero values. 210 */ 211 si_type = QEMU_SI_NOINFO; 212 break; 213 case SI_TIMER: 214 tinfo->_reason._timer._timerid = info->_reason._timer._timerid; 215 tinfo->_reason._timer._overrun = info->_reason._timer._overrun; 216 si_type = QEMU_SI_TIMER; 217 break; 218 case SI_MESGQ: 219 tinfo->_reason._mesgq._mqd = info->_reason._mesgq._mqd; 220 si_type = QEMU_SI_MESGQ; 221 break; 222 default: 223 /* 224 * We have to go based on the signal number now to figure out 225 * what's valid. 226 */ 227 si_type = QEMU_SI_NOINFO; 228 if (has_trapno(sig)) { 229 tinfo->_reason._fault._trapno = info->_reason._fault._trapno; 230 si_type = QEMU_SI_FAULT; 231 } 232 #ifdef TARGET_SIGPOLL 233 /* 234 * FreeBSD never had SIGPOLL, but emulates it for Linux so there's 235 * a chance it may popup in the future. 236 */ 237 if (sig == TARGET_SIGPOLL) { 238 tinfo->_reason._poll._band = info->_reason._poll._band; 239 si_type = QEMU_SI_POLL; 240 } 241 #endif 242 /* 243 * Unsure that this can actually be generated, and our support for 244 * capsicum is somewhere between weak and non-existent, but if we get 245 * one, then we know what to save. 246 */ 247 #ifdef QEMU_SI_CAPSICUM 248 if (sig == TARGET_SIGTRAP) { 249 tinfo->_reason._capsicum._syscall = 250 info->_reason._capsicum._syscall; 251 si_type = QEMU_SI_CAPSICUM; 252 } 253 #endif 254 break; 255 } 256 tinfo->si_code = deposit32(si_code, 24, 8, si_type); 257 } 258 259 static void tswap_siginfo(target_siginfo_t *tinfo, const target_siginfo_t *info) 260 { 261 int si_type = extract32(info->si_code, 24, 8); 262 int si_code = sextract32(info->si_code, 0, 24); 263 264 __put_user(info->si_signo, &tinfo->si_signo); 265 __put_user(info->si_errno, &tinfo->si_errno); 266 __put_user(si_code, &tinfo->si_code); /* Zero out si_type, it's internal */ 267 __put_user(info->si_pid, &tinfo->si_pid); 268 __put_user(info->si_uid, &tinfo->si_uid); 269 __put_user(info->si_status, &tinfo->si_status); 270 __put_user(info->si_addr, &tinfo->si_addr); 271 /* 272 * Unswapped, because we passed it through mostly untouched. si_value is 273 * opaque to the kernel, so we didn't bother with potentially wasting cycles 274 * to swap it into host byte order. 275 */ 276 tinfo->si_value.sival_ptr = info->si_value.sival_ptr; 277 278 /* 279 * We can use our internal marker of which fields in the structure 280 * are valid, rather than duplicating the guesswork of 281 * host_to_target_siginfo_noswap() here. 282 */ 283 switch (si_type) { 284 case QEMU_SI_NOINFO: /* No additional info */ 285 break; 286 case QEMU_SI_FAULT: 287 __put_user(info->_reason._fault._trapno, 288 &tinfo->_reason._fault._trapno); 289 break; 290 case QEMU_SI_TIMER: 291 __put_user(info->_reason._timer._timerid, 292 &tinfo->_reason._timer._timerid); 293 __put_user(info->_reason._timer._overrun, 294 &tinfo->_reason._timer._overrun); 295 break; 296 case QEMU_SI_MESGQ: 297 __put_user(info->_reason._mesgq._mqd, &tinfo->_reason._mesgq._mqd); 298 break; 299 case QEMU_SI_POLL: 300 /* Note: Not generated on FreeBSD */ 301 __put_user(info->_reason._poll._band, &tinfo->_reason._poll._band); 302 break; 303 #ifdef QEMU_SI_CAPSICUM 304 case QEMU_SI_CAPSICUM: 305 __put_user(info->_reason._capsicum._syscall, 306 &tinfo->_reason._capsicum._syscall); 307 break; 308 #endif 309 default: 310 g_assert_not_reached(); 311 } 312 } 313 314 int block_signals(void) 315 { 316 TaskState *ts = (TaskState *)thread_cpu->opaque; 317 sigset_t set; 318 319 /* 320 * It's OK to block everything including SIGSEGV, because we won't run any 321 * further guest code before unblocking signals in 322 * process_pending_signals(). We depend on the FreeBSD behavior here where 323 * this will only affect this thread's signal mask. We don't use 324 * pthread_sigmask which might seem more correct because that routine also 325 * does odd things with SIGCANCEL to implement pthread_cancel(). 326 */ 327 sigfillset(&set); 328 sigprocmask(SIG_SETMASK, &set, 0); 329 330 return qatomic_xchg(&ts->signal_pending, 1); 331 } 332 333 /* Returns 1 if given signal should dump core if not handled. */ 334 static int core_dump_signal(int sig) 335 { 336 switch (sig) { 337 case TARGET_SIGABRT: 338 case TARGET_SIGFPE: 339 case TARGET_SIGILL: 340 case TARGET_SIGQUIT: 341 case TARGET_SIGSEGV: 342 case TARGET_SIGTRAP: 343 case TARGET_SIGBUS: 344 return 1; 345 default: 346 return 0; 347 } 348 } 349 350 /* Abort execution with signal. */ 351 static G_NORETURN 352 void dump_core_and_abort(int target_sig) 353 { 354 CPUState *cpu = thread_cpu; 355 CPUArchState *env = cpu_env(cpu); 356 TaskState *ts = cpu->opaque; 357 int core_dumped = 0; 358 int host_sig; 359 struct sigaction act; 360 361 host_sig = target_to_host_signal(target_sig); 362 gdb_signalled(env, target_sig); 363 364 /* Dump core if supported by target binary format */ 365 if (core_dump_signal(target_sig) && (ts->bprm->core_dump != NULL)) { 366 stop_all_tasks(); 367 core_dumped = 368 ((*ts->bprm->core_dump)(target_sig, env) == 0); 369 } 370 if (core_dumped) { 371 struct rlimit nodump; 372 373 /* 374 * We already dumped the core of target process, we don't want 375 * a coredump of qemu itself. 376 */ 377 getrlimit(RLIMIT_CORE, &nodump); 378 nodump.rlim_cur = 0; 379 setrlimit(RLIMIT_CORE, &nodump); 380 (void) fprintf(stderr, "qemu: uncaught target signal %d (%s) " 381 "- %s\n", target_sig, strsignal(host_sig), "core dumped"); 382 } 383 384 /* 385 * The proper exit code for dying from an uncaught signal is 386 * -<signal>. The kernel doesn't allow exit() or _exit() to pass 387 * a negative value. To get the proper exit code we need to 388 * actually die from an uncaught signal. Here the default signal 389 * handler is installed, we send ourself a signal and we wait for 390 * it to arrive. 391 */ 392 memset(&act, 0, sizeof(act)); 393 sigfillset(&act.sa_mask); 394 act.sa_handler = SIG_DFL; 395 sigaction(host_sig, &act, NULL); 396 397 kill(getpid(), host_sig); 398 399 /* 400 * Make sure the signal isn't masked (just reuse the mask inside 401 * of act). 402 */ 403 sigdelset(&act.sa_mask, host_sig); 404 sigsuspend(&act.sa_mask); 405 406 /* unreachable */ 407 abort(); 408 } 409 410 /* 411 * Queue a signal so that it will be send to the virtual CPU as soon as 412 * possible. 413 */ 414 void queue_signal(CPUArchState *env, int sig, int si_type, 415 target_siginfo_t *info) 416 { 417 CPUState *cpu = env_cpu(env); 418 TaskState *ts = cpu->opaque; 419 420 trace_user_queue_signal(env, sig); 421 422 info->si_code = deposit32(info->si_code, 24, 8, si_type); 423 424 ts->sync_signal.info = *info; 425 ts->sync_signal.pending = sig; 426 /* Signal that a new signal is pending. */ 427 qatomic_set(&ts->signal_pending, 1); 428 return; 429 } 430 431 static int fatal_signal(int sig) 432 { 433 434 switch (sig) { 435 case TARGET_SIGCHLD: 436 case TARGET_SIGURG: 437 case TARGET_SIGWINCH: 438 case TARGET_SIGINFO: 439 /* Ignored by default. */ 440 return 0; 441 case TARGET_SIGCONT: 442 case TARGET_SIGSTOP: 443 case TARGET_SIGTSTP: 444 case TARGET_SIGTTIN: 445 case TARGET_SIGTTOU: 446 /* Job control signals. */ 447 return 0; 448 default: 449 return 1; 450 } 451 } 452 453 /* 454 * Force a synchronously taken QEMU_SI_FAULT signal. For QEMU the 455 * 'force' part is handled in process_pending_signals(). 456 */ 457 void force_sig_fault(int sig, int code, abi_ulong addr) 458 { 459 CPUState *cpu = thread_cpu; 460 CPUArchState *env = cpu_env(cpu); 461 target_siginfo_t info = {}; 462 463 info.si_signo = sig; 464 info.si_errno = 0; 465 info.si_code = code; 466 info.si_addr = addr; 467 queue_signal(env, sig, QEMU_SI_FAULT, &info); 468 } 469 470 static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) 471 { 472 CPUState *cpu = thread_cpu; 473 TaskState *ts = cpu->opaque; 474 target_siginfo_t tinfo; 475 ucontext_t *uc = puc; 476 struct emulated_sigtable *k; 477 int guest_sig; 478 uintptr_t pc = 0; 479 bool sync_sig = false; 480 481 /* 482 * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special 483 * handling wrt signal blocking and unwinding. 484 */ 485 if ((host_sig == SIGSEGV || host_sig == SIGBUS) && info->si_code > 0) { 486 MMUAccessType access_type; 487 uintptr_t host_addr; 488 abi_ptr guest_addr; 489 bool is_write; 490 491 host_addr = (uintptr_t)info->si_addr; 492 493 /* 494 * Convert forcefully to guest address space: addresses outside 495 * reserved_va are still valid to report via SEGV_MAPERR. 496 */ 497 guest_addr = h2g_nocheck(host_addr); 498 499 pc = host_signal_pc(uc); 500 is_write = host_signal_write(info, uc); 501 access_type = adjust_signal_pc(&pc, is_write); 502 503 if (host_sig == SIGSEGV) { 504 bool maperr = true; 505 506 if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) { 507 /* If this was a write to a TB protected page, restart. */ 508 if (is_write && 509 handle_sigsegv_accerr_write(cpu, &uc->uc_sigmask, 510 pc, guest_addr)) { 511 return; 512 } 513 514 /* 515 * With reserved_va, the whole address space is PROT_NONE, 516 * which means that we may get ACCERR when we want MAPERR. 517 */ 518 if (page_get_flags(guest_addr) & PAGE_VALID) { 519 maperr = false; 520 } else { 521 info->si_code = SEGV_MAPERR; 522 } 523 } 524 525 sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL); 526 cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc); 527 } else { 528 sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL); 529 if (info->si_code == BUS_ADRALN) { 530 cpu_loop_exit_sigbus(cpu, guest_addr, access_type, pc); 531 } 532 } 533 534 sync_sig = true; 535 } 536 537 /* Get the target signal number. */ 538 guest_sig = host_to_target_signal(host_sig); 539 if (guest_sig < 1 || guest_sig > TARGET_NSIG) { 540 return; 541 } 542 trace_user_host_signal(cpu, host_sig, guest_sig); 543 544 host_to_target_siginfo_noswap(&tinfo, info); 545 546 k = &ts->sigtab[guest_sig - 1]; 547 k->info = tinfo; 548 k->pending = guest_sig; 549 ts->signal_pending = 1; 550 551 /* 552 * For synchronous signals, unwind the cpu state to the faulting 553 * insn and then exit back to the main loop so that the signal 554 * is delivered immediately. 555 */ 556 if (sync_sig) { 557 cpu->exception_index = EXCP_INTERRUPT; 558 cpu_loop_exit_restore(cpu, pc); 559 } 560 561 rewind_if_in_safe_syscall(puc); 562 563 /* 564 * Block host signals until target signal handler entered. We 565 * can't block SIGSEGV or SIGBUS while we're executing guest 566 * code in case the guest code provokes one in the window between 567 * now and it getting out to the main loop. Signals will be 568 * unblocked again in process_pending_signals(). 569 */ 570 sigfillset(&uc->uc_sigmask); 571 sigdelset(&uc->uc_sigmask, SIGSEGV); 572 sigdelset(&uc->uc_sigmask, SIGBUS); 573 574 /* Interrupt the virtual CPU as soon as possible. */ 575 cpu_exit(thread_cpu); 576 } 577 578 /* do_sigaltstack() returns target values and errnos. */ 579 /* compare to kern/kern_sig.c sys_sigaltstack() and kern_sigaltstack() */ 580 abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp) 581 { 582 TaskState *ts = (TaskState *)thread_cpu->opaque; 583 int ret; 584 target_stack_t oss; 585 586 if (uoss_addr) { 587 /* Save current signal stack params */ 588 oss.ss_sp = tswapl(ts->sigaltstack_used.ss_sp); 589 oss.ss_size = tswapl(ts->sigaltstack_used.ss_size); 590 oss.ss_flags = tswapl(sas_ss_flags(ts, sp)); 591 } 592 593 if (uss_addr) { 594 target_stack_t *uss; 595 target_stack_t ss; 596 size_t minstacksize = TARGET_MINSIGSTKSZ; 597 598 ret = -TARGET_EFAULT; 599 if (!lock_user_struct(VERIFY_READ, uss, uss_addr, 1)) { 600 goto out; 601 } 602 __get_user(ss.ss_sp, &uss->ss_sp); 603 __get_user(ss.ss_size, &uss->ss_size); 604 __get_user(ss.ss_flags, &uss->ss_flags); 605 unlock_user_struct(uss, uss_addr, 0); 606 607 ret = -TARGET_EPERM; 608 if (on_sig_stack(ts, sp)) { 609 goto out; 610 } 611 612 ret = -TARGET_EINVAL; 613 if (ss.ss_flags != TARGET_SS_DISABLE 614 && ss.ss_flags != TARGET_SS_ONSTACK 615 && ss.ss_flags != 0) { 616 goto out; 617 } 618 619 if (ss.ss_flags == TARGET_SS_DISABLE) { 620 ss.ss_size = 0; 621 ss.ss_sp = 0; 622 } else { 623 ret = -TARGET_ENOMEM; 624 if (ss.ss_size < minstacksize) { 625 goto out; 626 } 627 } 628 629 ts->sigaltstack_used.ss_sp = ss.ss_sp; 630 ts->sigaltstack_used.ss_size = ss.ss_size; 631 } 632 633 if (uoss_addr) { 634 ret = -TARGET_EFAULT; 635 if (copy_to_user(uoss_addr, &oss, sizeof(oss))) { 636 goto out; 637 } 638 } 639 640 ret = 0; 641 out: 642 return ret; 643 } 644 645 /* do_sigaction() return host values and errnos */ 646 int do_sigaction(int sig, const struct target_sigaction *act, 647 struct target_sigaction *oact) 648 { 649 struct target_sigaction *k; 650 struct sigaction act1; 651 int host_sig; 652 int ret = 0; 653 654 if (sig < 1 || sig > TARGET_NSIG) { 655 return -TARGET_EINVAL; 656 } 657 658 if ((sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) && 659 act != NULL && act->_sa_handler != TARGET_SIG_DFL) { 660 return -TARGET_EINVAL; 661 } 662 663 if (block_signals()) { 664 return -TARGET_ERESTART; 665 } 666 667 k = &sigact_table[sig - 1]; 668 if (oact) { 669 oact->_sa_handler = tswapal(k->_sa_handler); 670 oact->sa_flags = tswap32(k->sa_flags); 671 oact->sa_mask = k->sa_mask; 672 } 673 if (act) { 674 k->_sa_handler = tswapal(act->_sa_handler); 675 k->sa_flags = tswap32(act->sa_flags); 676 k->sa_mask = act->sa_mask; 677 678 /* Update the host signal state. */ 679 host_sig = target_to_host_signal(sig); 680 if (host_sig != SIGSEGV && host_sig != SIGBUS) { 681 memset(&act1, 0, sizeof(struct sigaction)); 682 sigfillset(&act1.sa_mask); 683 act1.sa_flags = SA_SIGINFO; 684 if (k->sa_flags & TARGET_SA_RESTART) { 685 act1.sa_flags |= SA_RESTART; 686 } 687 /* 688 * Note: It is important to update the host kernel signal mask to 689 * avoid getting unexpected interrupted system calls. 690 */ 691 if (k->_sa_handler == TARGET_SIG_IGN) { 692 act1.sa_sigaction = (void *)SIG_IGN; 693 } else if (k->_sa_handler == TARGET_SIG_DFL) { 694 if (fatal_signal(sig)) { 695 act1.sa_sigaction = host_signal_handler; 696 } else { 697 act1.sa_sigaction = (void *)SIG_DFL; 698 } 699 } else { 700 act1.sa_sigaction = host_signal_handler; 701 } 702 ret = sigaction(host_sig, &act1, NULL); 703 } 704 } 705 return ret; 706 } 707 708 static inline abi_ulong get_sigframe(struct target_sigaction *ka, 709 CPUArchState *env, size_t frame_size) 710 { 711 TaskState *ts = (TaskState *)thread_cpu->opaque; 712 abi_ulong sp; 713 714 /* Use default user stack */ 715 sp = get_sp_from_cpustate(env); 716 717 if ((ka->sa_flags & TARGET_SA_ONSTACK) && sas_ss_flags(ts, sp) == 0) { 718 sp = ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size; 719 } 720 721 /* TODO: make this a target_arch function / define */ 722 #if defined(TARGET_ARM) 723 return (sp - frame_size) & ~7; 724 #elif defined(TARGET_AARCH64) 725 return (sp - frame_size) & ~15; 726 #else 727 return sp - frame_size; 728 #endif 729 } 730 731 /* compare to $M/$M/exec_machdep.c sendsig and sys/kern/kern_sig.c sigexit */ 732 733 static void setup_frame(int sig, int code, struct target_sigaction *ka, 734 target_sigset_t *set, target_siginfo_t *tinfo, CPUArchState *env) 735 { 736 struct target_sigframe *frame; 737 abi_ulong frame_addr; 738 int i; 739 740 frame_addr = get_sigframe(ka, env, sizeof(*frame)); 741 trace_user_setup_frame(env, frame_addr); 742 if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { 743 unlock_user_struct(frame, frame_addr, 1); 744 dump_core_and_abort(TARGET_SIGILL); 745 return; 746 } 747 748 memset(frame, 0, sizeof(*frame)); 749 setup_sigframe_arch(env, frame_addr, frame, 0); 750 751 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 752 __put_user(set->__bits[i], &frame->sf_uc.uc_sigmask.__bits[i]); 753 } 754 755 if (tinfo) { 756 frame->sf_si.si_signo = tinfo->si_signo; 757 frame->sf_si.si_errno = tinfo->si_errno; 758 frame->sf_si.si_code = tinfo->si_code; 759 frame->sf_si.si_pid = tinfo->si_pid; 760 frame->sf_si.si_uid = tinfo->si_uid; 761 frame->sf_si.si_status = tinfo->si_status; 762 frame->sf_si.si_addr = tinfo->si_addr; 763 /* see host_to_target_siginfo_noswap() for more details */ 764 frame->sf_si.si_value.sival_ptr = tinfo->si_value.sival_ptr; 765 /* 766 * At this point, whatever is in the _reason union is complete 767 * and in target order, so just copy the whole thing over, even 768 * if it's too large for this specific signal. 769 * host_to_target_siginfo_noswap() and tswap_siginfo() have ensured 770 * that's so. 771 */ 772 memcpy(&frame->sf_si._reason, &tinfo->_reason, 773 sizeof(tinfo->_reason)); 774 } 775 776 set_sigtramp_args(env, sig, frame, frame_addr, ka); 777 778 unlock_user_struct(frame, frame_addr, 1); 779 } 780 781 static int reset_signal_mask(target_ucontext_t *ucontext) 782 { 783 int i; 784 sigset_t blocked; 785 target_sigset_t target_set; 786 TaskState *ts = (TaskState *)thread_cpu->opaque; 787 788 for (i = 0; i < TARGET_NSIG_WORDS; i++) { 789 __get_user(target_set.__bits[i], &ucontext->uc_sigmask.__bits[i]); 790 } 791 target_to_host_sigset_internal(&blocked, &target_set); 792 ts->signal_mask = blocked; 793 794 return 0; 795 } 796 797 /* See sys/$M/$M/exec_machdep.c sigreturn() */ 798 long do_sigreturn(CPUArchState *env, abi_ulong addr) 799 { 800 long ret; 801 abi_ulong target_ucontext; 802 target_ucontext_t *ucontext = NULL; 803 804 /* Get the target ucontext address from the stack frame */ 805 ret = get_ucontext_sigreturn(env, addr, &target_ucontext); 806 if (is_error(ret)) { 807 return ret; 808 } 809 trace_user_do_sigreturn(env, addr); 810 if (!lock_user_struct(VERIFY_READ, ucontext, target_ucontext, 0)) { 811 goto badframe; 812 } 813 814 /* Set the register state back to before the signal. */ 815 if (set_mcontext(env, &ucontext->uc_mcontext, 1)) { 816 goto badframe; 817 } 818 819 /* And reset the signal mask. */ 820 if (reset_signal_mask(ucontext)) { 821 goto badframe; 822 } 823 824 unlock_user_struct(ucontext, target_ucontext, 0); 825 return -TARGET_EJUSTRETURN; 826 827 badframe: 828 if (ucontext != NULL) { 829 unlock_user_struct(ucontext, target_ucontext, 0); 830 } 831 return -TARGET_EFAULT; 832 } 833 834 void signal_init(void) 835 { 836 TaskState *ts = (TaskState *)thread_cpu->opaque; 837 struct sigaction act; 838 struct sigaction oact; 839 int i; 840 int host_sig; 841 842 /* Set the signal mask from the host mask. */ 843 sigprocmask(0, 0, &ts->signal_mask); 844 845 sigfillset(&act.sa_mask); 846 act.sa_sigaction = host_signal_handler; 847 act.sa_flags = SA_SIGINFO; 848 849 for (i = 1; i <= TARGET_NSIG; i++) { 850 #ifdef CONFIG_GPROF 851 if (i == TARGET_SIGPROF) { 852 continue; 853 } 854 #endif 855 host_sig = target_to_host_signal(i); 856 sigaction(host_sig, NULL, &oact); 857 if (oact.sa_sigaction == (void *)SIG_IGN) { 858 sigact_table[i - 1]._sa_handler = TARGET_SIG_IGN; 859 } else if (oact.sa_sigaction == (void *)SIG_DFL) { 860 sigact_table[i - 1]._sa_handler = TARGET_SIG_DFL; 861 } 862 /* 863 * If there's already a handler installed then something has 864 * gone horribly wrong, so don't even try to handle that case. 865 * Install some handlers for our own use. We need at least 866 * SIGSEGV and SIGBUS, to detect exceptions. We can not just 867 * trap all signals because it affects syscall interrupt 868 * behavior. But do trap all default-fatal signals. 869 */ 870 if (fatal_signal(i)) { 871 sigaction(host_sig, &act, NULL); 872 } 873 } 874 } 875 876 static void handle_pending_signal(CPUArchState *env, int sig, 877 struct emulated_sigtable *k) 878 { 879 CPUState *cpu = env_cpu(env); 880 TaskState *ts = cpu->opaque; 881 struct target_sigaction *sa; 882 int code; 883 sigset_t set; 884 abi_ulong handler; 885 target_siginfo_t tinfo; 886 target_sigset_t target_old_set; 887 888 trace_user_handle_signal(env, sig); 889 890 k->pending = 0; 891 892 sig = gdb_handlesig(cpu, sig); 893 if (!sig) { 894 sa = NULL; 895 handler = TARGET_SIG_IGN; 896 } else { 897 sa = &sigact_table[sig - 1]; 898 handler = sa->_sa_handler; 899 } 900 901 if (do_strace) { 902 print_taken_signal(sig, &k->info); 903 } 904 905 if (handler == TARGET_SIG_DFL) { 906 /* 907 * default handler : ignore some signal. The other are job 908 * control or fatal. 909 */ 910 if (sig == TARGET_SIGTSTP || sig == TARGET_SIGTTIN || 911 sig == TARGET_SIGTTOU) { 912 kill(getpid(), SIGSTOP); 913 } else if (sig != TARGET_SIGCHLD && sig != TARGET_SIGURG && 914 sig != TARGET_SIGINFO && sig != TARGET_SIGWINCH && 915 sig != TARGET_SIGCONT) { 916 dump_core_and_abort(sig); 917 } 918 } else if (handler == TARGET_SIG_IGN) { 919 /* ignore sig */ 920 } else if (handler == TARGET_SIG_ERR) { 921 dump_core_and_abort(sig); 922 } else { 923 /* compute the blocked signals during the handler execution */ 924 sigset_t *blocked_set; 925 926 target_to_host_sigset(&set, &sa->sa_mask); 927 /* 928 * SA_NODEFER indicates that the current signal should not be 929 * blocked during the handler. 930 */ 931 if (!(sa->sa_flags & TARGET_SA_NODEFER)) { 932 sigaddset(&set, target_to_host_signal(sig)); 933 } 934 935 /* 936 * Save the previous blocked signal state to restore it at the 937 * end of the signal execution (see do_sigreturn). 938 */ 939 host_to_target_sigset_internal(&target_old_set, &ts->signal_mask); 940 941 blocked_set = ts->in_sigsuspend ? 942 &ts->sigsuspend_mask : &ts->signal_mask; 943 sigorset(&ts->signal_mask, blocked_set, &set); 944 ts->in_sigsuspend = false; 945 sigprocmask(SIG_SETMASK, &ts->signal_mask, NULL); 946 947 /* XXX VM86 on x86 ??? */ 948 949 code = k->info.si_code; /* From host, so no si_type */ 950 /* prepare the stack frame of the virtual CPU */ 951 if (sa->sa_flags & TARGET_SA_SIGINFO) { 952 tswap_siginfo(&tinfo, &k->info); 953 setup_frame(sig, code, sa, &target_old_set, &tinfo, env); 954 } else { 955 setup_frame(sig, code, sa, &target_old_set, NULL, env); 956 } 957 if (sa->sa_flags & TARGET_SA_RESETHAND) { 958 sa->_sa_handler = TARGET_SIG_DFL; 959 } 960 } 961 } 962 963 void process_pending_signals(CPUArchState *env) 964 { 965 CPUState *cpu = env_cpu(env); 966 int sig; 967 sigset_t *blocked_set, set; 968 struct emulated_sigtable *k; 969 TaskState *ts = cpu->opaque; 970 971 while (qatomic_read(&ts->signal_pending)) { 972 sigfillset(&set); 973 sigprocmask(SIG_SETMASK, &set, 0); 974 975 restart_scan: 976 sig = ts->sync_signal.pending; 977 if (sig) { 978 /* 979 * Synchronous signals are forced by the emulated CPU in some way. 980 * If they are set to ignore, restore the default handler (see 981 * sys/kern_sig.c trapsignal() and execsigs() for this behavior) 982 * though maybe this is done only when forcing exit for non SIGCHLD. 983 */ 984 if (sigismember(&ts->signal_mask, target_to_host_signal(sig)) || 985 sigact_table[sig - 1]._sa_handler == TARGET_SIG_IGN) { 986 sigdelset(&ts->signal_mask, target_to_host_signal(sig)); 987 sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL; 988 } 989 handle_pending_signal(env, sig, &ts->sync_signal); 990 } 991 992 k = ts->sigtab; 993 for (sig = 1; sig <= TARGET_NSIG; sig++, k++) { 994 blocked_set = ts->in_sigsuspend ? 995 &ts->sigsuspend_mask : &ts->signal_mask; 996 if (k->pending && 997 !sigismember(blocked_set, target_to_host_signal(sig))) { 998 handle_pending_signal(env, sig, k); 999 /* 1000 * Restart scan from the beginning, as handle_pending_signal 1001 * might have resulted in a new synchronous signal (eg SIGSEGV). 1002 */ 1003 goto restart_scan; 1004 } 1005 } 1006 1007 /* 1008 * Unblock signals and check one more time. Unblocking signals may cause 1009 * us to take another host signal, which will set signal_pending again. 1010 */ 1011 qatomic_set(&ts->signal_pending, 0); 1012 ts->in_sigsuspend = false; 1013 set = ts->signal_mask; 1014 sigdelset(&set, SIGSEGV); 1015 sigdelset(&set, SIGBUS); 1016 sigprocmask(SIG_SETMASK, &set, 0); 1017 } 1018 ts->in_sigsuspend = false; 1019 } 1020 1021 void cpu_loop_exit_sigsegv(CPUState *cpu, target_ulong addr, 1022 MMUAccessType access_type, bool maperr, uintptr_t ra) 1023 { 1024 const struct TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops; 1025 1026 if (tcg_ops->record_sigsegv) { 1027 tcg_ops->record_sigsegv(cpu, addr, access_type, maperr, ra); 1028 } 1029 1030 force_sig_fault(TARGET_SIGSEGV, 1031 maperr ? TARGET_SEGV_MAPERR : TARGET_SEGV_ACCERR, 1032 addr); 1033 cpu->exception_index = EXCP_INTERRUPT; 1034 cpu_loop_exit_restore(cpu, ra); 1035 } 1036 1037 void cpu_loop_exit_sigbus(CPUState *cpu, target_ulong addr, 1038 MMUAccessType access_type, uintptr_t ra) 1039 { 1040 const struct TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops; 1041 1042 if (tcg_ops->record_sigbus) { 1043 tcg_ops->record_sigbus(cpu, addr, access_type, ra); 1044 } 1045 1046 force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN, addr); 1047 cpu->exception_index = EXCP_INTERRUPT; 1048 cpu_loop_exit_restore(cpu, ra); 1049 } 1050