linux-user/signal.c

   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
  34 /*
  35  * System includes define _NSIG as SIGRTMAX + 1,
  36  * but qemu (like the kernel) defines TARGET_NSIG as TARGET_SIGRTMAX
  37  * and the first signal is SIGHUP defined as 1
  38  * Signal number 0 is reserved for use as kill(pid, 0), to test whether
  39  * a process exists without sending it a signal.
  40  */
  41 QEMU_BUILD_BUG_ON(__SIGRTMAX + 1 != _NSIG);
  42 static uint8_t host_to_target_signal_table[_NSIG] = {
  43     [SIGHUP] = TARGET_SIGHUP,
  44     [SIGINT] = TARGET_SIGINT,
  45     [SIGQUIT] = TARGET_SIGQUIT,
  46     [SIGILL] = TARGET_SIGILL,
  47     [SIGTRAP] = TARGET_SIGTRAP,
  48     [SIGABRT] = TARGET_SIGABRT,
  49 /*    [SIGIOT] = TARGET_SIGIOT,*/
  50     [SIGBUS] = TARGET_SIGBUS,
  51     [SIGFPE] = TARGET_SIGFPE,
  52     [SIGKILL] = TARGET_SIGKILL,
  53     [SIGUSR1] = TARGET_SIGUSR1,
  54     [SIGSEGV] = TARGET_SIGSEGV,
  55     [SIGUSR2] = TARGET_SIGUSR2,
  56     [SIGPIPE] = TARGET_SIGPIPE,
  57     [SIGALRM] = TARGET_SIGALRM,
  58     [SIGTERM] = TARGET_SIGTERM,
  59 #ifdef SIGSTKFLT
  60     [SIGSTKFLT] = TARGET_SIGSTKFLT,
  61 #endif
  62     [SIGCHLD] = TARGET_SIGCHLD,
  63     [SIGCONT] = TARGET_SIGCONT,
  64     [SIGSTOP] = TARGET_SIGSTOP,
  65     [SIGTSTP] = TARGET_SIGTSTP,
  66     [SIGTTIN] = TARGET_SIGTTIN,
  67     [SIGTTOU] = TARGET_SIGTTOU,
  68     [SIGURG] = TARGET_SIGURG,
  69     [SIGXCPU] = TARGET_SIGXCPU,
  70     [SIGXFSZ] = TARGET_SIGXFSZ,
  71     [SIGVTALRM] = TARGET_SIGVTALRM,
  72     [SIGPROF] = TARGET_SIGPROF,
  73     [SIGWINCH] = TARGET_SIGWINCH,
  74     [SIGIO] = TARGET_SIGIO,
  75     [SIGPWR] = TARGET_SIGPWR,
  76     [SIGSYS] = TARGET_SIGSYS,
  77     /* next signals stay the same */
  78 };
  79
  80 static uint8_t target_to_host_signal_table[TARGET_NSIG + 1];
  81
  82 /* valid sig is between 1 and _NSIG - 1 */
  83 int host_to_target_signal(int sig)
  84 {
  85     if (sig < 1 || sig >= _NSIG) {
  86         return sig;
  87     }
  88     return host_to_target_signal_table[sig];
  89 }
  90
  91 /* valid sig is between 1 and TARGET_NSIG */
  92 int target_to_host_signal(int sig)
  93 {
  94     if (sig < 1 || sig > TARGET_NSIG) {
  95         return sig;
  96     }
  97     return target_to_host_signal_table[sig];
  98 }
  99
 100 static inline void target_sigaddset(target_sigset_t *set, int signum)
 101 {
 102     signum--;
 103     abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW);
 104     set->sig[signum / TARGET_NSIG_BPW] |= mask;
 105 }
 106
 107 static inline int target_sigismember(const target_sigset_t *set, int signum)
 108 {
 109     signum--;
 110     abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW);
 111     return ((set->sig[signum / TARGET_NSIG_BPW] & mask) != 0);
 112 }
 113
 114 void host_to_target_sigset_internal(target_sigset_t *d,
 115                                     const sigset_t *s)
 116 {
 117     int host_sig, target_sig;
 118     target_sigemptyset(d);
 119     for (host_sig = 1; host_sig < _NSIG; host_sig++) {
 120         target_sig = host_to_target_signal(host_sig);
 121         if (target_sig < 1 || target_sig > TARGET_NSIG) {
 122             continue;
 123         }
 124         if (sigismember(s, host_sig)) {
 125             target_sigaddset(d, target_sig);
 126         }
 127     }
 128 }
 129
 130 void host_to_target_sigset(target_sigset_t *d, const sigset_t *s)
 131 {
 132     target_sigset_t d1;
 133     int i;
 134
 135     host_to_target_sigset_internal(&d1, s);
 136     for(i = 0;i < TARGET_NSIG_WORDS; i++)
 137         d->sig[i] = tswapal(d1.sig[i]);
 138 }
 139
 140 void target_to_host_sigset_internal(sigset_t *d,
 141                                     const target_sigset_t *s)
 142 {
 143     int host_sig, target_sig;
 144     sigemptyset(d);
 145     for (target_sig = 1; target_sig <= TARGET_NSIG; target_sig++) {
 146         host_sig = target_to_host_signal(target_sig);
 147         if (host_sig < 1 || host_sig >= _NSIG) {
 148             continue;
 149         }
 150         if (target_sigismember(s, target_sig)) {
 151             sigaddset(d, host_sig);
 152         }
 153     }
 154 }
 155
 156 void target_to_host_sigset(sigset_t *d, const target_sigset_t *s)
 157 {
 158     target_sigset_t s1;
 159     int i;
 160
 161     for(i = 0;i < TARGET_NSIG_WORDS; i++)
 162         s1.sig[i] = tswapal(s->sig[i]);
 163     target_to_host_sigset_internal(d, &s1);
 164 }
 165
 166 void host_to_target_old_sigset(abi_ulong *old_sigset,
 167                                const sigset_t *sigset)
 168 {
 169     target_sigset_t d;
 170     host_to_target_sigset(&d, sigset);
 171     *old_sigset = d.sig[0];
 172 }
 173
 174 void target_to_host_old_sigset(sigset_t *sigset,
 175                                const abi_ulong *old_sigset)
 176 {
 177     target_sigset_t d;
 178     int i;
 179
 180     d.sig[0] = *old_sigset;
 181     for(i = 1;i < TARGET_NSIG_WORDS; i++)
 182         d.sig[i] = 0;
 183     target_to_host_sigset(sigset, &d);
 184 }
 185
 186 int block_signals(void)
 187 {
 188     TaskState *ts = (TaskState *)thread_cpu->opaque;
 189     sigset_t set;
 190
 191     /* It's OK to block everything including SIGSEGV, because we won't
 192      * run any further guest code before unblocking signals in
 193      * process_pending_signals().
 194      */
 195     sigfillset(&set);
 196     sigprocmask(SIG_SETMASK, &set, 0);
 197
 198     return qatomic_xchg(&ts->signal_pending, 1);
 199 }
 200
 201 /* Wrapper for sigprocmask function
 202  * Emulates a sigprocmask in a safe way for the guest. Note that set and oldset
 203  * are host signal set, not guest ones. Returns -TARGET_ERESTARTSYS if
 204  * a signal was already pending and the syscall must be restarted, or
 205  * 0 on success.
 206  * If set is NULL, this is guaranteed not to fail.
 207  */
 208 int do_sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
 209 {
 210     TaskState *ts = (TaskState *)thread_cpu->opaque;
 211
 212     if (oldset) {
 213         *oldset = ts->signal_mask;
 214     }
 215
 216     if (set) {
 217         int i;
 218
 219         if (block_signals()) {
 220             return -TARGET_ERESTARTSYS;
 221         }
 222
 223         switch (how) {
 224         case SIG_BLOCK:
 225             sigorset(&ts->signal_mask, &ts->signal_mask, set);
 226             break;
 227         case SIG_UNBLOCK:
 228             for (i = 1; i <= NSIG; ++i) {
 229                 if (sigismember(set, i)) {
 230                     sigdelset(&ts->signal_mask, i);
 231                 }
 232             }
 233             break;
 234         case SIG_SETMASK:
 235             ts->signal_mask = *set;
 236             break;
 237         default:
 238             g_assert_not_reached();
 239         }
 240
 241         /* Silently ignore attempts to change blocking status of KILL or STOP */
 242         sigdelset(&ts->signal_mask, SIGKILL);
 243         sigdelset(&ts->signal_mask, SIGSTOP);
 244     }
 245     return 0;
 246 }
 247
 248 #if !defined(TARGET_NIOS2)
 249 /* Just set the guest's signal mask to the specified value; the
 250  * caller is assumed to have called block_signals() already.
 251  */
 252 void set_sigmask(const sigset_t *set)
 253 {
 254     TaskState *ts = (TaskState *)thread_cpu->opaque;
 255
 256     ts->signal_mask = *set;
 257 }
 258 #endif
 259
 260 /* sigaltstack management */
 261
 262 int on_sig_stack(unsigned long sp)
 263 {
 264     TaskState *ts = (TaskState *)thread_cpu->opaque;
 265
 266     return (sp - ts->sigaltstack_used.ss_sp
 267             < ts->sigaltstack_used.ss_size);
 268 }
 269
 270 int sas_ss_flags(unsigned long sp)
 271 {
 272     TaskState *ts = (TaskState *)thread_cpu->opaque;
 273
 274     return (ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE
 275             : on_sig_stack(sp) ? SS_ONSTACK : 0);
 276 }
 277
 278 abi_ulong target_sigsp(abi_ulong sp, struct target_sigaction *ka)
 279 {
 280     /*
 281      * This is the X/Open sanctioned signal stack switching.
 282      */
 283     TaskState *ts = (TaskState *)thread_cpu->opaque;
 284
 285     if ((ka->sa_flags & TARGET_SA_ONSTACK) && !sas_ss_flags(sp)) {
 286         return ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size;
 287     }
 288     return sp;
 289 }
 290
 291 void target_save_altstack(target_stack_t *uss, CPUArchState *env)
 292 {
 293     TaskState *ts = (TaskState *)thread_cpu->opaque;
 294
 295     __put_user(ts->sigaltstack_used.ss_sp, &uss->ss_sp);
 296     __put_user(sas_ss_flags(get_sp_from_cpustate(env)), &uss->ss_flags);
 297     __put_user(ts->sigaltstack_used.ss_size, &uss->ss_size);
 298 }
 299
 300 /* siginfo conversion */
 301
 302 static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo,
 303                                                  const siginfo_t *info)
 304 {
 305     int sig = host_to_target_signal(info->si_signo);
 306     int si_code = info->si_code;
 307     int si_type;
 308     tinfo->si_signo = sig;
 309     tinfo->si_errno = 0;
 310     tinfo->si_code = info->si_code;
 311
 312     /* This memset serves two purposes:
 313      * (1) ensure we don't leak random junk to the guest later
 314      * (2) placate false positives from gcc about fields
 315      *     being used uninitialized if it chooses to inline both this
 316      *     function and tswap_siginfo() into host_to_target_siginfo().
 317      */
 318     memset(tinfo->_sifields._pad, 0, sizeof(tinfo->_sifields._pad));
 319
 320     /* This is awkward, because we have to use a combination of
 321      * the si_code and si_signo to figure out which of the union's
 322      * members are valid. (Within the host kernel it is always possible
 323      * to tell, but the kernel carefully avoids giving userspace the
 324      * high 16 bits of si_code, so we don't have the information to
 325      * do this the easy way...) We therefore make our best guess,
 326      * bearing in mind that a guest can spoof most of the si_codes
 327      * via rt_sigqueueinfo() if it likes.
 328      *
 329      * Once we have made our guess, we record it in the top 16 bits of
 330      * the si_code, so that tswap_siginfo() later can use it.
 331      * tswap_siginfo() will strip these top bits out before writing
 332      * si_code to the guest (sign-extending the lower bits).
 333      */
 334
 335     switch (si_code) {
 336     case SI_USER:
 337     case SI_TKILL:
 338     case SI_KERNEL:
 339         /* Sent via kill(), tkill() or tgkill(), or direct from the kernel.
 340          * These are the only unspoofable si_code values.
 341          */
 342         tinfo->_sifields._kill._pid = info->si_pid;
 343         tinfo->_sifields._kill._uid = info->si_uid;
 344         si_type = QEMU_SI_KILL;
 345         break;
 346     default:
 347         /* Everything else is spoofable. Make best guess based on signal */
 348         switch (sig) {
 349         case TARGET_SIGCHLD:
 350             tinfo->_sifields._sigchld._pid = info->si_pid;
 351             tinfo->_sifields._sigchld._uid = info->si_uid;
 352             tinfo->_sifields._sigchld._status
 353                 = host_to_target_waitstatus(info->si_status);
 354             tinfo->_sifields._sigchld._utime = info->si_utime;
 355             tinfo->_sifields._sigchld._stime = info->si_stime;
 356             si_type = QEMU_SI_CHLD;
 357             break;
 358         case TARGET_SIGIO:
 359             tinfo->_sifields._sigpoll._band = info->si_band;
 360             tinfo->_sifields._sigpoll._fd = info->si_fd;
 361             si_type = QEMU_SI_POLL;
 362             break;
 363         default:
 364             /* Assume a sigqueue()/mq_notify()/rt_sigqueueinfo() source. */
 365             tinfo->_sifields._rt._pid = info->si_pid;
 366             tinfo->_sifields._rt._uid = info->si_uid;
 367             /* XXX: potential problem if 64 bit */
 368             tinfo->_sifields._rt._sigval.sival_ptr
 369                 = (abi_ulong)(unsigned long)info->si_value.sival_ptr;
 370             si_type = QEMU_SI_RT;
 371             break;
 372         }
 373         break;
 374     }
 375
 376     tinfo->si_code = deposit32(si_code, 16, 16, si_type);
 377 }
 378
 379 void tswap_siginfo(target_siginfo_t *tinfo,
 380                    const target_siginfo_t *info)
 381 {
 382     int si_type = extract32(info->si_code, 16, 16);
 383     int si_code = sextract32(info->si_code, 0, 16);
 384
 385     __put_user(info->si_signo, &tinfo->si_signo);
 386     __put_user(info->si_errno, &tinfo->si_errno);
 387     __put_user(si_code, &tinfo->si_code);
 388
 389     /* We can use our internal marker of which fields in the structure
 390      * are valid, rather than duplicating the guesswork of
 391      * host_to_target_siginfo_noswap() here.
 392      */
 393     switch (si_type) {
 394     case QEMU_SI_KILL:
 395         __put_user(info->_sifields._kill._pid, &tinfo->_sifields._kill._pid);
 396         __put_user(info->_sifields._kill._uid, &tinfo->_sifields._kill._uid);
 397         break;
 398     case QEMU_SI_TIMER:
 399         __put_user(info->_sifields._timer._timer1,
 400                    &tinfo->_sifields._timer._timer1);
 401         __put_user(info->_sifields._timer._timer2,
 402                    &tinfo->_sifields._timer._timer2);
 403         break;
 404     case QEMU_SI_POLL:
 405         __put_user(info->_sifields._sigpoll._band,
 406                    &tinfo->_sifields._sigpoll._band);
 407         __put_user(info->_sifields._sigpoll._fd,
 408                    &tinfo->_sifields._sigpoll._fd);
 409         break;
 410     case QEMU_SI_FAULT:
 411         __put_user(info->_sifields._sigfault._addr,
 412                    &tinfo->_sifields._sigfault._addr);
 413         break;
 414     case QEMU_SI_CHLD:
 415         __put_user(info->_sifields._sigchld._pid,
 416                    &tinfo->_sifields._sigchld._pid);
 417         __put_user(info->_sifields._sigchld._uid,
 418                    &tinfo->_sifields._sigchld._uid);
 419         __put_user(info->_sifields._sigchld._status,
 420                    &tinfo->_sifields._sigchld._status);
 421         __put_user(info->_sifields._sigchld._utime,
 422                    &tinfo->_sifields._sigchld._utime);
 423         __put_user(info->_sifields._sigchld._stime,
 424                    &tinfo->_sifields._sigchld._stime);
 425         break;
 426     case QEMU_SI_RT:
 427         __put_user(info->_sifields._rt._pid, &tinfo->_sifields._rt._pid);
 428         __put_user(info->_sifields._rt._uid, &tinfo->_sifields._rt._uid);
 429         __put_user(info->_sifields._rt._sigval.sival_ptr,
 430                    &tinfo->_sifields._rt._sigval.sival_ptr);
 431         break;
 432     default:
 433         g_assert_not_reached();
 434     }
 435 }
 436
 437 void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info)
 438 {
 439     target_siginfo_t tgt_tmp;
 440     host_to_target_siginfo_noswap(&tgt_tmp, info);
 441     tswap_siginfo(tinfo, &tgt_tmp);
 442 }
 443
 444 /* XXX: we support only POSIX RT signals are used. */
 445 /* XXX: find a solution for 64 bit (additional malloced data is needed) */
 446 void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo)
 447 {
 448     /* This conversion is used only for the rt_sigqueueinfo syscall,
 449      * and so we know that the _rt fields are the valid ones.
 450      */
 451     abi_ulong sival_ptr;
 452
 453     __get_user(info->si_signo, &tinfo->si_signo);
 454     __get_user(info->si_errno, &tinfo->si_errno);
 455     __get_user(info->si_code, &tinfo->si_code);
 456     __get_user(info->si_pid, &tinfo->_sifields._rt._pid);
 457     __get_user(info->si_uid, &tinfo->_sifields._rt._uid);
 458     __get_user(sival_ptr, &tinfo->_sifields._rt._sigval.sival_ptr);
 459     info->si_value.sival_ptr = (void *)(long)sival_ptr;
 460 }
 461
 462 static int fatal_signal (int sig)
 463 {
 464     switch (sig) {
 465     case TARGET_SIGCHLD:
 466     case TARGET_SIGURG:
 467     case TARGET_SIGWINCH:
 468         /* Ignored by default.  */
 469         return 0;
 470     case TARGET_SIGCONT:
 471     case TARGET_SIGSTOP:
 472     case TARGET_SIGTSTP:
 473     case TARGET_SIGTTIN:
 474     case TARGET_SIGTTOU:
 475         /* Job control signals.  */
 476         return 0;
 477     default:
 478         return 1;
 479     }
 480 }
 481
 482 /* returns 1 if given signal should dump core if not handled */
 483 static int core_dump_signal(int sig)
 484 {
 485     switch (sig) {
 486     case TARGET_SIGABRT:
 487     case TARGET_SIGFPE:
 488     case TARGET_SIGILL:
 489     case TARGET_SIGQUIT:
 490     case TARGET_SIGSEGV:
 491     case TARGET_SIGTRAP:
 492     case TARGET_SIGBUS:
 493         return (1);
 494     default:
 495         return (0);
 496     }
 497 }
 498
 499 static void signal_table_init(void)
 500 {
 501     int host_sig, target_sig, count;
 502
 503     /*
 504      * Signals are supported starting from TARGET_SIGRTMIN and going up
 505      * until we run out of host realtime signals.
 506      * glibc at least uses only the lower 2 rt signals and probably
 507      * nobody's using the upper ones.
 508      * it's why SIGRTMIN (34) is generally greater than __SIGRTMIN (32)
 509      * To fix this properly we need to do manual signal delivery multiplexed
 510      * over a single host signal.
 511      * Attempts for configure "missing" signals via sigaction will be
 512      * silently ignored.
 513      */
 514     for (host_sig = SIGRTMIN; host_sig <= SIGRTMAX; host_sig++) {
 515         target_sig = host_sig - SIGRTMIN + TARGET_SIGRTMIN;
 516         if (target_sig <= TARGET_NSIG) {
 517             host_to_target_signal_table[host_sig] = target_sig;
 518         }
 519     }
 520
 521     /* generate signal conversion tables */
 522     for (target_sig = 1; target_sig <= TARGET_NSIG; target_sig++) {
 523         target_to_host_signal_table[target_sig] = _NSIG; /* poison */
 524     }
 525     for (host_sig = 1; host_sig < _NSIG; host_sig++) {
 526         if (host_to_target_signal_table[host_sig] == 0) {
 527             host_to_target_signal_table[host_sig] = host_sig;
 528         }
 529         target_sig = host_to_target_signal_table[host_sig];
 530         if (target_sig <= TARGET_NSIG) {
 531             target_to_host_signal_table[target_sig] = host_sig;
 532         }
 533     }
 534
 535     if (trace_event_get_state_backends(TRACE_SIGNAL_TABLE_INIT)) {
 536         for (target_sig = 1, count = 0; target_sig <= TARGET_NSIG; target_sig++) {
 537             if (target_to_host_signal_table[target_sig] == _NSIG) {
 538                 count++;
 539             }
 540         }
 541         trace_signal_table_init(count);
 542     }
 543 }
 544
 545 void signal_init(void)
 546 {
 547     TaskState *ts = (TaskState *)thread_cpu->opaque;
 548     struct sigaction act;
 549     struct sigaction oact;
 550     int i;
 551     int host_sig;
 552
 553     /* initialize signal conversion tables */
 554     signal_table_init();
 555
 556     /* Set the signal mask from the host mask. */
 557     sigprocmask(0, 0, &ts->signal_mask);
 558
 559     sigfillset(&act.sa_mask);
 560     act.sa_flags = SA_SIGINFO;
 561     act.sa_sigaction = host_signal_handler;
 562     for(i = 1; i <= TARGET_NSIG; i++) {
 563 #ifdef CONFIG_GPROF
 564         if (i == TARGET_SIGPROF) {
 565             continue;
 566         }
 567 #endif
 568         host_sig = target_to_host_signal(i);
 569         sigaction(host_sig, NULL, &oact);
 570         if (oact.sa_sigaction == (void *)SIG_IGN) {
 571             sigact_table[i - 1]._sa_handler = TARGET_SIG_IGN;
 572         } else if (oact.sa_sigaction == (void *)SIG_DFL) {
 573             sigact_table[i - 1]._sa_handler = TARGET_SIG_DFL;
 574         }
 575         /* If there's already a handler installed then something has
 576            gone horribly wrong, so don't even try to handle that case.  */
 577         /* Install some handlers for our own use.  We need at least
 578            SIGSEGV and SIGBUS, to detect exceptions.  We can not just
 579            trap all signals because it affects syscall interrupt
 580            behavior.  But do trap all default-fatal signals.  */
 581         if (fatal_signal (i))
 582             sigaction(host_sig, &act, NULL);
 583     }
 584 }
 585
 586 /* Force a synchronously taken signal. The kernel force_sig() function
 587  * also forces the signal to "not blocked, not ignored", but for QEMU
 588  * that work is done in process_pending_signals().
 589  */
 590 void force_sig(int sig)
 591 {
 592     CPUState *cpu = thread_cpu;
 593     CPUArchState *env = cpu->env_ptr;
 594     target_siginfo_t info;
 595
 596     info.si_signo = sig;
 597     info.si_errno = 0;
 598     info.si_code = TARGET_SI_KERNEL;
 599     info._sifields._kill._pid = 0;
 600     info._sifields._kill._uid = 0;
 601     queue_signal(env, info.si_signo, QEMU_SI_KILL, &info);
 602 }
 603
 604 /* Force a SIGSEGV if we couldn't write to memory trying to set
 605  * up the signal frame. oldsig is the signal we were trying to handle
 606  * at the point of failure.
 607  */
 608 #if !defined(TARGET_RISCV)
 609 void force_sigsegv(int oldsig)
 610 {
 611     if (oldsig == SIGSEGV) {
 612         /* Make sure we don't try to deliver the signal again; this will
 613          * end up with handle_pending_signal() calling dump_core_and_abort().
 614          */
 615         sigact_table[oldsig - 1]._sa_handler = TARGET_SIG_DFL;
 616     }
 617     force_sig(TARGET_SIGSEGV);
 618 }
 619
 620 #endif
 621
 622 /* abort execution with signal */
 623 static void QEMU_NORETURN dump_core_and_abort(int target_sig)
 624 {
 625     CPUState *cpu = thread_cpu;
 626     CPUArchState *env = cpu->env_ptr;
 627     TaskState *ts = (TaskState *)cpu->opaque;
 628     int host_sig, core_dumped = 0;
 629     struct sigaction act;
 630
 631     host_sig = target_to_host_signal(target_sig);
 632     trace_user_force_sig(env, target_sig, host_sig);
 633     gdb_signalled(env, target_sig);
 634
 635     /* dump core if supported by target binary format */
 636     if (core_dump_signal(target_sig) && (ts->bprm->core_dump != NULL)) {
 637         stop_all_tasks();
 638         core_dumped =
 639             ((*ts->bprm->core_dump)(target_sig, env) == 0);
 640     }
 641     if (core_dumped) {
 642         /* we already dumped the core of target process, we don't want
 643          * a coredump of qemu itself */
 644         struct rlimit nodump;
 645         getrlimit(RLIMIT_CORE, &nodump);
 646         nodump.rlim_cur=0;
 647         setrlimit(RLIMIT_CORE, &nodump);
 648         (void) fprintf(stderr, "qemu: uncaught target signal %d (%s) - %s\n",
 649             target_sig, strsignal(host_sig), "core dumped" );
 650     }
 651
 652     /* The proper exit code for dying from an uncaught signal is
 653      * -<signal>.  The kernel doesn't allow exit() or _exit() to pass
 654      * a negative value.  To get the proper exit code we need to
 655      * actually die from an uncaught signal.  Here the default signal
 656      * handler is installed, we send ourself a signal and we wait for
 657      * it to arrive. */
 658     sigfillset(&act.sa_mask);
 659     act.sa_handler = SIG_DFL;
 660     act.sa_flags = 0;
 661     sigaction(host_sig, &act, NULL);
 662
 663     /* For some reason raise(host_sig) doesn't send the signal when
 664      * statically linked on x86-64. */
 665     kill(getpid(), host_sig);
 666
 667     /* Make sure the signal isn't masked (just reuse the mask inside
 668     of act) */
 669     sigdelset(&act.sa_mask, host_sig);
 670     sigsuspend(&act.sa_mask);
 671
 672     /* unreachable */
 673     abort();
 674 }
 675
 676 /* queue a signal so that it will be send to the virtual CPU as soon
 677    as possible */
 678 int queue_signal(CPUArchState *env, int sig, int si_type,
 679                  target_siginfo_t *info)
 680 {
 681     CPUState *cpu = env_cpu(env);
 682     TaskState *ts = cpu->opaque;
 683
 684     trace_user_queue_signal(env, sig);
 685
 686     info->si_code = deposit32(info->si_code, 16, 16, si_type);
 687
 688     ts->sync_signal.info = *info;
 689     ts->sync_signal.pending = sig;
 690     /* signal that a new signal is pending */
 691     qatomic_set(&ts->signal_pending, 1);
 692     return 1; /* indicates that the signal was queued */
 693 }
 694
 695 #ifndef HAVE_SAFE_SYSCALL
 696 static inline void rewind_if_in_safe_syscall(void *puc)
 697 {
 698     /* Default version: never rewind */
 699 }
 700 #endif
 701
 702 static void host_signal_handler(int host_signum, siginfo_t *info,
 703                                 void *puc)
 704 {
 705     CPUArchState *env = thread_cpu->env_ptr;
 706     CPUState *cpu = env_cpu(env);
 707     TaskState *ts = cpu->opaque;
 708
 709     int sig;
 710     target_siginfo_t tinfo;
 711     ucontext_t *uc = puc;
 712     struct emulated_sigtable *k;
 713
 714     /* the CPU emulator uses some host signals to detect exceptions,
 715        we forward to it some signals */
 716     if ((host_signum == SIGSEGV || host_signum == SIGBUS)
 717         && info->si_code > 0) {
 718         if (cpu_signal_handler(host_signum, info, puc))
 719             return;
 720     }
 721
 722     /* get target signal number */
 723     sig = host_to_target_signal(host_signum);
 724     if (sig < 1 || sig > TARGET_NSIG)
 725         return;
 726     trace_user_host_signal(env, host_signum, sig);
 727
 728     rewind_if_in_safe_syscall(puc);
 729
 730     host_to_target_siginfo_noswap(&tinfo, info);
 731     k = &ts->sigtab[sig - 1];
 732     k->info = tinfo;
 733     k->pending = sig;
 734     ts->signal_pending = 1;
 735
 736     /* Block host signals until target signal handler entered. We
 737      * can't block SIGSEGV or SIGBUS while we're executing guest
 738      * code in case the guest code provokes one in the window between
 739      * now and it getting out to the main loop. Signals will be
 740      * unblocked again in process_pending_signals().
 741      *
 742      * WARNING: we cannot use sigfillset() here because the uc_sigmask
 743      * field is a kernel sigset_t, which is much smaller than the
 744      * libc sigset_t which sigfillset() operates on. Using sigfillset()
 745      * would write 0xff bytes off the end of the structure and trash
 746      * data on the struct.
 747      * We can't use sizeof(uc->uc_sigmask) either, because the libc
 748      * headers define the struct field with the wrong (too large) type.
 749      */
 750     memset(&uc->uc_sigmask, 0xff, SIGSET_T_SIZE);
 751     sigdelset(&uc->uc_sigmask, SIGSEGV);
 752     sigdelset(&uc->uc_sigmask, SIGBUS);
 753
 754     /* interrupt the virtual CPU as soon as possible */
 755     cpu_exit(thread_cpu);
 756 }
 757
 758 /* do_sigaltstack() returns target values and errnos. */
 759 /* compare linux/kernel/signal.c:do_sigaltstack() */
 760 abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp)
 761 {
 762     int ret;
 763     struct target_sigaltstack oss;
 764     TaskState *ts = (TaskState *)thread_cpu->opaque;
 765
 766     /* XXX: test errors */
 767     if(uoss_addr)
 768     {
 769         __put_user(ts->sigaltstack_used.ss_sp, &oss.ss_sp);
 770         __put_user(ts->sigaltstack_used.ss_size, &oss.ss_size);
 771         __put_user(sas_ss_flags(sp), &oss.ss_flags);
 772     }
 773
 774     if(uss_addr)
 775     {
 776         struct target_sigaltstack *uss;
 777         struct target_sigaltstack ss;
 778         size_t minstacksize = TARGET_MINSIGSTKSZ;
 779
 780 #if defined(TARGET_PPC64)
 781         /* ELF V2 for PPC64 has a 4K minimum stack size for signal handlers */
 782         struct image_info *image = ((TaskState *)thread_cpu->opaque)->info;
 783         if (get_ppc64_abi(image) > 1) {
 784             minstacksize = 4096;
 785         }
 786 #endif
 787
 788         ret = -TARGET_EFAULT;
 789         if (!lock_user_struct(VERIFY_READ, uss, uss_addr, 1)) {
 790             goto out;
 791         }
 792         __get_user(ss.ss_sp, &uss->ss_sp);
 793         __get_user(ss.ss_size, &uss->ss_size);
 794         __get_user(ss.ss_flags, &uss->ss_flags);
 795         unlock_user_struct(uss, uss_addr, 0);
 796
 797         ret = -TARGET_EPERM;
 798         if (on_sig_stack(sp))
 799             goto out;
 800
 801         ret = -TARGET_EINVAL;
 802         if (ss.ss_flags != TARGET_SS_DISABLE
 803             && ss.ss_flags != TARGET_SS_ONSTACK
 804             && ss.ss_flags != 0)
 805             goto out;
 806
 807         if (ss.ss_flags == TARGET_SS_DISABLE) {
 808             ss.ss_size = 0;
 809             ss.ss_sp = 0;
 810         } else {
 811             ret = -TARGET_ENOMEM;
 812             if (ss.ss_size < minstacksize) {
 813                 goto out;
 814             }
 815         }
 816
 817         ts->sigaltstack_used.ss_sp = ss.ss_sp;
 818         ts->sigaltstack_used.ss_size = ss.ss_size;
 819     }
 820
 821     if (uoss_addr) {
 822         ret = -TARGET_EFAULT;
 823         if (copy_to_user(uoss_addr, &oss, sizeof(oss)))
 824             goto out;
 825     }
 826
 827     ret = 0;
 828 out:
 829     return ret;
 830 }
 831
 832 /* do_sigaction() return target values and host errnos */
 833 int do_sigaction(int sig, const struct target_sigaction *act,
 834                  struct target_sigaction *oact)
 835 {
 836     struct target_sigaction *k;
 837     struct sigaction act1;
 838     int host_sig;
 839     int ret = 0;
 840
 841     trace_signal_do_sigaction_guest(sig, TARGET_NSIG);
 842
 843     if (sig < 1 || sig > TARGET_NSIG || sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) {
 844         return -TARGET_EINVAL;
 845     }
 846
 847     if (block_signals()) {
 848         return -TARGET_ERESTARTSYS;
 849     }
 850
 851     k = &sigact_table[sig - 1];
 852     if (oact) {
 853         __put_user(k->_sa_handler, &oact->_sa_handler);
 854         __put_user(k->sa_flags, &oact->sa_flags);
 855 #ifdef TARGET_ARCH_HAS_SA_RESTORER
 856         __put_user(k->sa_restorer, &oact->sa_restorer);
 857 #endif
 858         /* Not swapped.  */
 859         oact->sa_mask = k->sa_mask;
 860     }
 861     if (act) {
 862         /* FIXME: This is not threadsafe.  */
 863         __get_user(k->_sa_handler, &act->_sa_handler);
 864         __get_user(k->sa_flags, &act->sa_flags);
 865 #ifdef TARGET_ARCH_HAS_SA_RESTORER
 866         __get_user(k->sa_restorer, &act->sa_restorer);
 867 #endif
 868         /* To be swapped in target_to_host_sigset.  */
 869         k->sa_mask = act->sa_mask;
 870
 871         /* we update the host linux signal state */
 872         host_sig = target_to_host_signal(sig);
 873         trace_signal_do_sigaction_host(host_sig, TARGET_NSIG);
 874         if (host_sig > SIGRTMAX) {
 875             /* we don't have enough host signals to map all target signals */
 876             qemu_log_mask(LOG_UNIMP, "Unsupported target signal #%d, ignored\n",
 877                           sig);
 878             /*
 879              * we don't return an error here because some programs try to
 880              * register an handler for all possible rt signals even if they
 881              * don't need it.
 882              * An error here can abort them whereas there can be no problem
 883              * to not have the signal available later.
 884              * This is the case for golang,
 885              *   See https://github.com/golang/go/issues/33746
 886              * So we silently ignore the error.
 887              */
 888             return 0;
 889         }
 890         if (host_sig != SIGSEGV && host_sig != SIGBUS) {
 891             sigfillset(&act1.sa_mask);
 892             act1.sa_flags = SA_SIGINFO;
 893             if (k->sa_flags & TARGET_SA_RESTART)
 894                 act1.sa_flags |= SA_RESTART;
 895             /* NOTE: it is important to update the host kernel signal
 896                ignore state to avoid getting unexpected interrupted
 897                syscalls */
 898             if (k->_sa_handler == TARGET_SIG_IGN) {
 899                 act1.sa_sigaction = (void *)SIG_IGN;
 900             } else if (k->_sa_handler == TARGET_SIG_DFL) {
 901                 if (fatal_signal (sig))
 902                     act1.sa_sigaction = host_signal_handler;
 903                 else
 904                     act1.sa_sigaction = (void *)SIG_DFL;
 905             } else {
 906                 act1.sa_sigaction = host_signal_handler;
 907             }
 908             ret = sigaction(host_sig, &act1, NULL);
 909         }
 910     }
 911     return ret;
 912 }
 913
 914 static void handle_pending_signal(CPUArchState *cpu_env, int sig,
 915                                   struct emulated_sigtable *k)
 916 {
 917     CPUState *cpu = env_cpu(cpu_env);
 918     abi_ulong handler;
 919     sigset_t set;
 920     target_sigset_t target_old_set;
 921     struct target_sigaction *sa;
 922     TaskState *ts = cpu->opaque;
 923
 924     trace_user_handle_signal(cpu_env, sig);
 925     /* dequeue signal */
 926     k->pending = 0;
 927
 928     sig = gdb_handlesig(cpu, sig);
 929     if (!sig) {
 930         sa = NULL;
 931         handler = TARGET_SIG_IGN;
 932     } else {
 933         sa = &sigact_table[sig - 1];
 934         handler = sa->_sa_handler;
 935     }
 936
 937     if (unlikely(qemu_loglevel_mask(LOG_STRACE))) {
 938         print_taken_signal(sig, &k->info);
 939     }
 940
 941     if (handler == TARGET_SIG_DFL) {
 942         /* default handler : ignore some signal. The other are job control or fatal */
 943         if (sig == TARGET_SIGTSTP || sig == TARGET_SIGTTIN || sig == TARGET_SIGTTOU) {
 944             kill(getpid(),SIGSTOP);
 945         } else if (sig != TARGET_SIGCHLD &&
 946                    sig != TARGET_SIGURG &&
 947                    sig != TARGET_SIGWINCH &&
 948                    sig != TARGET_SIGCONT) {
 949             dump_core_and_abort(sig);
 950         }
 951     } else if (handler == TARGET_SIG_IGN) {
 952         /* ignore sig */
 953     } else if (handler == TARGET_SIG_ERR) {
 954         dump_core_and_abort(sig);
 955     } else {
 956         /* compute the blocked signals during the handler execution */
 957         sigset_t *blocked_set;
 958
 959         target_to_host_sigset(&set, &sa->sa_mask);
 960         /* SA_NODEFER indicates that the current signal should not be
 961            blocked during the handler */
 962         if (!(sa->sa_flags & TARGET_SA_NODEFER))
 963             sigaddset(&set, target_to_host_signal(sig));
 964
 965         /* save the previous blocked signal state to restore it at the
 966            end of the signal execution (see do_sigreturn) */
 967         host_to_target_sigset_internal(&target_old_set, &ts->signal_mask);
 968
 969         /* block signals in the handler */
 970         blocked_set = ts->in_sigsuspend ?
 971             &ts->sigsuspend_mask : &ts->signal_mask;
 972         sigorset(&ts->signal_mask, blocked_set, &set);
 973         ts->in_sigsuspend = 0;
 974
 975         /* if the CPU is in VM86 mode, we restore the 32 bit values */
 976 #if defined(TARGET_I386) && !defined(TARGET_X86_64)
 977         {
 978             CPUX86State *env = cpu_env;
 979             if (env->eflags & VM_MASK)
 980                 save_v86_state(env);
 981         }
 982 #endif
 983         /* prepare the stack frame of the virtual CPU */
 984 #if defined(TARGET_ARCH_HAS_SETUP_FRAME)
 985         if (sa->sa_flags & TARGET_SA_SIGINFO) {
 986             setup_rt_frame(sig, sa, &k->info, &target_old_set, cpu_env);
 987         } else {
 988             setup_frame(sig, sa, &target_old_set, cpu_env);
 989         }
 990 #else
 991         /* These targets do not have traditional signals.  */
 992         setup_rt_frame(sig, sa, &k->info, &target_old_set, cpu_env);
 993 #endif
 994         if (sa->sa_flags & TARGET_SA_RESETHAND) {
 995             sa->_sa_handler = TARGET_SIG_DFL;
 996         }
 997     }
 998 }
 999
1000 void process_pending_signals(CPUArchState *cpu_env)
1001 {
1002     CPUState *cpu = env_cpu(cpu_env);
1003     int sig;
1004     TaskState *ts = cpu->opaque;
1005     sigset_t set;
1006     sigset_t *blocked_set;
1007
1008     while (qatomic_read(&ts->signal_pending)) {
1009         /* FIXME: This is not threadsafe.  */
1010         sigfillset(&set);
1011         sigprocmask(SIG_SETMASK, &set, 0);
1012
1013     restart_scan:
1014         sig = ts->sync_signal.pending;
1015         if (sig) {
1016             /* Synchronous signals are forced,
1017              * see force_sig_info() and callers in Linux
1018              * Note that not all of our queue_signal() calls in QEMU correspond
1019              * to force_sig_info() calls in Linux (some are send_sig_info()).
1020              * However it seems like a kernel bug to me to allow the process
1021              * to block a synchronous signal since it could then just end up
1022              * looping round and round indefinitely.
1023              */
1024             if (sigismember(&ts->signal_mask, target_to_host_signal_table[sig])
1025                 || sigact_table[sig - 1]._sa_handler == TARGET_SIG_IGN) {
1026                 sigdelset(&ts->signal_mask, target_to_host_signal_table[sig]);
1027                 sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL;
1028             }
1029
1030             handle_pending_signal(cpu_env, sig, &ts->sync_signal);
1031         }
1032
1033         for (sig = 1; sig <= TARGET_NSIG; sig++) {
1034             blocked_set = ts->in_sigsuspend ?
1035                 &ts->sigsuspend_mask : &ts->signal_mask;
1036
1037             if (ts->sigtab[sig - 1].pending &&
1038                 (!sigismember(blocked_set,
1039                               target_to_host_signal_table[sig]))) {
1040                 handle_pending_signal(cpu_env, sig, &ts->sigtab[sig - 1]);
1041                 /* Restart scan from the beginning, as handle_pending_signal
1042                  * might have resulted in a new synchronous signal (eg SIGSEGV).
1043                  */
1044                 goto restart_scan;
1045             }
1046         }
1047
1048         /* if no signal is pending, unblock signals and recheck (the act
1049          * of unblocking might cause us to take another host signal which
1050          * will set signal_pending again).
1051          */
1052         qatomic_set(&ts->signal_pending, 0);
1053         ts->in_sigsuspend = 0;
1054         set = ts->signal_mask;
1055         sigdelset(&set, SIGSEGV);
1056         sigdelset(&set, SIGBUS);
1057         sigprocmask(SIG_SETMASK, &set, 0);
1058     }
1059     ts->in_sigsuspend = 0;
1060 }