bsd-user/signal.c

   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 /* target_siginfo_t must fit in gdbstub's siginfo save area. */
  31 QEMU_BUILD_BUG_ON(sizeof(target_siginfo_t) > MAX_SIGINFO_LENGTH);
  32
  33 static struct target_sigaction sigact_table[TARGET_NSIG];
  34 static void host_signal_handler(int host_sig, siginfo_t *info, void *puc);
  35 static void target_to_host_sigset_internal(sigset_t *d,
  36         const target_sigset_t *s);
  37
  38 static inline int on_sig_stack(TaskState *ts, unsigned long sp)
  39 {
  40     return sp - ts->sigaltstack_used.ss_sp < ts->sigaltstack_used.ss_size;
  41 }
  42
  43 static inline int sas_ss_flags(TaskState *ts, unsigned long sp)
  44 {
  45     return ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE :
  46         on_sig_stack(ts, sp) ? SS_ONSTACK : 0;
  47 }
  48
  49 /*
  50  * The BSD ABIs use the same signal numbers across all the CPU architectures, so
  51  * (unlike Linux) these functions are just the identity mapping. This might not
  52  * be true for XyzBSD running on AbcBSD, which doesn't currently work.
  53  */
  54 int host_to_target_signal(int sig)
  55 {
  56     return sig;
  57 }
  58
  59 int target_to_host_signal(int sig)
  60 {
  61     return sig;
  62 }
  63
  64 static inline void target_sigemptyset(target_sigset_t *set)
  65 {
  66     memset(set, 0, sizeof(*set));
  67 }
  68
  69 static inline void target_sigaddset(target_sigset_t *set, int signum)
  70 {
  71     signum--;
  72     uint32_t mask = (uint32_t)1 << (signum % TARGET_NSIG_BPW);
  73     set->__bits[signum / TARGET_NSIG_BPW] |= mask;
  74 }
  75
  76 static inline int target_sigismember(const target_sigset_t *set, int signum)
  77 {
  78     signum--;
  79     abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW);
  80     return (set->__bits[signum / TARGET_NSIG_BPW] & mask) != 0;
  81 }
  82
  83 /* Adjust the signal context to rewind out of safe-syscall if we're in it */
  84 static inline void rewind_if_in_safe_syscall(void *puc)
  85 {
  86     ucontext_t *uc = (ucontext_t *)puc;
  87     uintptr_t pcreg = host_signal_pc(uc);
  88
  89     if (pcreg > (uintptr_t)safe_syscall_start
  90         && pcreg < (uintptr_t)safe_syscall_end) {
  91         host_signal_set_pc(uc, (uintptr_t)safe_syscall_start);
  92     }
  93 }
  94
  95 /*
  96  * Note: The following take advantage of the BSD signal property that all
  97  * signals are available on all architectures.
  98  */
  99 static void host_to_target_sigset_internal(target_sigset_t *d,
 100         const sigset_t *s)
 101 {
 102     int i;
 103
 104     target_sigemptyset(d);
 105     for (i = 1; i <= NSIG; i++) {
 106         if (sigismember(s, i)) {
 107             target_sigaddset(d, host_to_target_signal(i));
 108         }
 109     }
 110 }
 111
 112 void host_to_target_sigset(target_sigset_t *d, const sigset_t *s)
 113 {
 114     target_sigset_t d1;
 115     int i;
 116
 117     host_to_target_sigset_internal(&d1, s);
 118     for (i = 0; i < _SIG_WORDS; i++) {
 119         d->__bits[i] = tswap32(d1.__bits[i]);
 120     }
 121 }
 122
 123 static void target_to_host_sigset_internal(sigset_t *d,
 124         const target_sigset_t *s)
 125 {
 126     int i;
 127
 128     sigemptyset(d);
 129     for (i = 1; i <= TARGET_NSIG; i++) {
 130         if (target_sigismember(s, i)) {
 131             sigaddset(d, target_to_host_signal(i));
 132         }
 133     }
 134 }
 135
 136 void target_to_host_sigset(sigset_t *d, const target_sigset_t *s)
 137 {
 138     target_sigset_t s1;
 139     int i;
 140
 141     for (i = 0; i < TARGET_NSIG_WORDS; i++) {
 142         s1.__bits[i] = tswap32(s->__bits[i]);
 143     }
 144     target_to_host_sigset_internal(d, &s1);
 145 }
 146
 147 static bool has_trapno(int tsig)
 148 {
 149     return tsig == TARGET_SIGILL ||
 150         tsig == TARGET_SIGFPE ||
 151         tsig == TARGET_SIGSEGV ||
 152         tsig == TARGET_SIGBUS ||
 153         tsig == TARGET_SIGTRAP;
 154 }
 155
 156 /* Siginfo conversion. */
 157
 158 /*
 159  * Populate tinfo w/o swapping based on guessing which fields are valid.
 160  */
 161 static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo,
 162         const siginfo_t *info)
 163 {
 164     int sig = host_to_target_signal(info->si_signo);
 165     int si_code = info->si_code;
 166     int si_type;
 167
 168     /*
 169      * Make sure we that the variable portion of the target siginfo is zeroed
 170      * out so we don't leak anything into that.
 171      */
 172     memset(&tinfo->_reason, 0, sizeof(tinfo->_reason));
 173
 174     /*
 175      * This is awkward, because we have to use a combination of the si_code and
 176      * si_signo to figure out which of the union's members are valid.o We
 177      * therefore make our best guess.
 178      *
 179      * Once we have made our guess, we record it in the top 16 bits of
 180      * the si_code, so that tswap_siginfo() later can use it.
 181      * tswap_siginfo() will strip these top bits out before writing
 182      * si_code to the guest (sign-extending the lower bits).
 183      */
 184     tinfo->si_signo = sig;
 185     tinfo->si_errno = info->si_errno;
 186     tinfo->si_code = info->si_code;
 187     tinfo->si_pid = info->si_pid;
 188     tinfo->si_uid = info->si_uid;
 189     tinfo->si_status = info->si_status;
 190     tinfo->si_addr = (abi_ulong)(unsigned long)info->si_addr;
 191     /*
 192      * si_value is opaque to kernel. On all FreeBSD platforms,
 193      * sizeof(sival_ptr) >= sizeof(sival_int) so the following
 194      * always will copy the larger element.
 195      */
 196     tinfo->si_value.sival_ptr =
 197         (abi_ulong)(unsigned long)info->si_value.sival_ptr;
 198
 199     switch (si_code) {
 200         /*
 201          * All the SI_xxx codes that are defined here are global to
 202          * all the signals (they have values that none of the other,
 203          * more specific signal info will set).
 204          */
 205     case SI_USER:
 206     case SI_LWP:
 207     case SI_KERNEL:
 208     case SI_QUEUE:
 209     case SI_ASYNCIO:
 210         /*
 211          * Only the fixed parts are valid (though FreeBSD doesn't always
 212          * set all the fields to non-zero values.
 213          */
 214         si_type = QEMU_SI_NOINFO;
 215         break;
 216     case SI_TIMER:
 217         tinfo->_reason._timer._timerid = info->_reason._timer._timerid;
 218         tinfo->_reason._timer._overrun = info->_reason._timer._overrun;
 219         si_type = QEMU_SI_TIMER;
 220         break;
 221     case SI_MESGQ:
 222         tinfo->_reason._mesgq._mqd = info->_reason._mesgq._mqd;
 223         si_type = QEMU_SI_MESGQ;
 224         break;
 225     default:
 226         /*
 227          * We have to go based on the signal number now to figure out
 228          * what's valid.
 229          */
 230         si_type = QEMU_SI_NOINFO;
 231         if (has_trapno(sig)) {
 232             tinfo->_reason._fault._trapno = info->_reason._fault._trapno;
 233             si_type = QEMU_SI_FAULT;
 234         }
 235 #ifdef TARGET_SIGPOLL
 236         /*
 237          * FreeBSD never had SIGPOLL, but emulates it for Linux so there's
 238          * a chance it may popup in the future.
 239          */
 240         if (sig == TARGET_SIGPOLL) {
 241             tinfo->_reason._poll._band = info->_reason._poll._band;
 242             si_type = QEMU_SI_POLL;
 243         }
 244 #endif
 245         /*
 246          * Unsure that this can actually be generated, and our support for
 247          * capsicum is somewhere between weak and non-existent, but if we get
 248          * one, then we know what to save.
 249          */
 250 #ifdef QEMU_SI_CAPSICUM
 251         if (sig == TARGET_SIGTRAP) {
 252             tinfo->_reason._capsicum._syscall =
 253                 info->_reason._capsicum._syscall;
 254             si_type = QEMU_SI_CAPSICUM;
 255         }
 256 #endif
 257         break;
 258     }
 259     tinfo->si_code = deposit32(si_code, 24, 8, si_type);
 260 }
 261
 262 static void tswap_siginfo(target_siginfo_t *tinfo, const target_siginfo_t *info)
 263 {
 264     int si_type = extract32(info->si_code, 24, 8);
 265     int si_code = sextract32(info->si_code, 0, 24);
 266
 267     __put_user(info->si_signo, &tinfo->si_signo);
 268     __put_user(info->si_errno, &tinfo->si_errno);
 269     __put_user(si_code, &tinfo->si_code); /* Zero out si_type, it's internal */
 270     __put_user(info->si_pid, &tinfo->si_pid);
 271     __put_user(info->si_uid, &tinfo->si_uid);
 272     __put_user(info->si_status, &tinfo->si_status);
 273     __put_user(info->si_addr, &tinfo->si_addr);
 274     /*
 275      * Unswapped, because we passed it through mostly untouched.  si_value is
 276      * opaque to the kernel, so we didn't bother with potentially wasting cycles
 277      * to swap it into host byte order.
 278      */
 279     tinfo->si_value.sival_ptr = info->si_value.sival_ptr;
 280
 281     /*
 282      * We can use our internal marker of which fields in the structure
 283      * are valid, rather than duplicating the guesswork of
 284      * host_to_target_siginfo_noswap() here.
 285      */
 286     switch (si_type) {
 287     case QEMU_SI_NOINFO:        /* No additional info */
 288         break;
 289     case QEMU_SI_FAULT:
 290         __put_user(info->_reason._fault._trapno,
 291                    &tinfo->_reason._fault._trapno);
 292         break;
 293     case QEMU_SI_TIMER:
 294         __put_user(info->_reason._timer._timerid,
 295                    &tinfo->_reason._timer._timerid);
 296         __put_user(info->_reason._timer._overrun,
 297                    &tinfo->_reason._timer._overrun);
 298         break;
 299     case QEMU_SI_MESGQ:
 300         __put_user(info->_reason._mesgq._mqd, &tinfo->_reason._mesgq._mqd);
 301         break;
 302     case QEMU_SI_POLL:
 303         /* Note: Not generated on FreeBSD */
 304         __put_user(info->_reason._poll._band, &tinfo->_reason._poll._band);
 305         break;
 306 #ifdef QEMU_SI_CAPSICUM
 307     case QEMU_SI_CAPSICUM:
 308         __put_user(info->_reason._capsicum._syscall,
 309                    &tinfo->_reason._capsicum._syscall);
 310         break;
 311 #endif
 312     default:
 313         g_assert_not_reached();
 314     }
 315 }
 316
 317 void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info)
 318 {
 319     host_to_target_siginfo_noswap(tinfo, info);
 320     tswap_siginfo(tinfo, tinfo);
 321 }
 322
 323 int block_signals(void)
 324 {
 325     TaskState *ts = get_task_state(thread_cpu);
 326     sigset_t set;
 327
 328     /*
 329      * It's OK to block everything including SIGSEGV, because we won't run any
 330      * further guest code before unblocking signals in
 331      * process_pending_signals(). We depend on the FreeBSD behavior here where
 332      * this will only affect this thread's signal mask. We don't use
 333      * pthread_sigmask which might seem more correct because that routine also
 334      * does odd things with SIGCANCEL to implement pthread_cancel().
 335      */
 336     sigfillset(&set);
 337     sigprocmask(SIG_SETMASK, &set, 0);
 338
 339     return qatomic_xchg(&ts->signal_pending, 1);
 340 }
 341
 342 /* Returns 1 if given signal should dump core if not handled. */
 343 static int core_dump_signal(int sig)
 344 {
 345     switch (sig) {
 346     case TARGET_SIGABRT:
 347     case TARGET_SIGFPE:
 348     case TARGET_SIGILL:
 349     case TARGET_SIGQUIT:
 350     case TARGET_SIGSEGV:
 351     case TARGET_SIGTRAP:
 352     case TARGET_SIGBUS:
 353         return 1;
 354     default:
 355         return 0;
 356     }
 357 }
 358
 359 /* Abort execution with signal. */
 360 static G_NORETURN
 361 void dump_core_and_abort(int target_sig)
 362 {
 363     CPUState *cpu = thread_cpu;
 364     CPUArchState *env = cpu_env(cpu);
 365     TaskState *ts = get_task_state(cpu);
 366     int core_dumped = 0;
 367     int host_sig;
 368     struct sigaction act;
 369
 370     host_sig = target_to_host_signal(target_sig);
 371     gdb_signalled(env, target_sig);
 372
 373     /* Dump core if supported by target binary format */
 374     if (core_dump_signal(target_sig) && (ts->bprm->core_dump != NULL)) {
 375         stop_all_tasks();
 376         core_dumped =
 377             ((*ts->bprm->core_dump)(target_sig, env) == 0);
 378     }
 379     if (core_dumped) {
 380         struct rlimit nodump;
 381
 382         /*
 383          * We already dumped the core of target process, we don't want
 384          * a coredump of qemu itself.
 385          */
 386          getrlimit(RLIMIT_CORE, &nodump);
 387          nodump.rlim_cur = 0;
 388          setrlimit(RLIMIT_CORE, &nodump);
 389          (void) fprintf(stderr, "qemu: uncaught target signal %d (%s) "
 390              "- %s\n", target_sig, strsignal(host_sig), "core dumped");
 391     }
 392
 393     /*
 394      * The proper exit code for dying from an uncaught signal is
 395      * -<signal>.  The kernel doesn't allow exit() or _exit() to pass
 396      * a negative value.  To get the proper exit code we need to
 397      * actually die from an uncaught signal.  Here the default signal
 398      * handler is installed, we send ourself a signal and we wait for
 399      * it to arrive.
 400      */
 401     memset(&act, 0, sizeof(act));
 402     sigfillset(&act.sa_mask);
 403     act.sa_handler = SIG_DFL;
 404     sigaction(host_sig, &act, NULL);
 405
 406     kill(getpid(), host_sig);
 407
 408     /*
 409      * Make sure the signal isn't masked (just reuse the mask inside
 410      * of act).
 411      */
 412     sigdelset(&act.sa_mask, host_sig);
 413     sigsuspend(&act.sa_mask);
 414
 415     /* unreachable */
 416     abort();
 417 }
 418
 419 /*
 420  * Queue a signal so that it will be send to the virtual CPU as soon as
 421  * possible.
 422  */
 423 void queue_signal(CPUArchState *env, int sig, int si_type,
 424                   target_siginfo_t *info)
 425 {
 426     CPUState *cpu = env_cpu(env);
 427     TaskState *ts = get_task_state(cpu);
 428
 429     trace_user_queue_signal(env, sig);
 430
 431     info->si_code = deposit32(info->si_code, 24, 8, si_type);
 432
 433     ts->sync_signal.info = *info;
 434     ts->sync_signal.pending = sig;
 435     /* Signal that a new signal is pending. */
 436     qatomic_set(&ts->signal_pending, 1);
 437     return;
 438 }
 439
 440 static int fatal_signal(int sig)
 441 {
 442
 443     switch (sig) {
 444     case TARGET_SIGCHLD:
 445     case TARGET_SIGURG:
 446     case TARGET_SIGWINCH:
 447     case TARGET_SIGINFO:
 448         /* Ignored by default. */
 449         return 0;
 450     case TARGET_SIGCONT:
 451     case TARGET_SIGSTOP:
 452     case TARGET_SIGTSTP:
 453     case TARGET_SIGTTIN:
 454     case TARGET_SIGTTOU:
 455         /* Job control signals.  */
 456         return 0;
 457     default:
 458         return 1;
 459     }
 460 }
 461
 462 /*
 463  * Force a synchronously taken QEMU_SI_FAULT signal. For QEMU the
 464  * 'force' part is handled in process_pending_signals().
 465  */
 466 void force_sig_fault(int sig, int code, abi_ulong addr)
 467 {
 468     CPUState *cpu = thread_cpu;
 469     target_siginfo_t info = {};
 470
 471     info.si_signo = sig;
 472     info.si_errno = 0;
 473     info.si_code = code;
 474     info.si_addr = addr;
 475     queue_signal(cpu_env(cpu), sig, QEMU_SI_FAULT, &info);
 476 }
 477
 478 static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
 479 {
 480     CPUState *cpu = thread_cpu;
 481     TaskState *ts = get_task_state(cpu);
 482     target_siginfo_t tinfo;
 483     ucontext_t *uc = puc;
 484     struct emulated_sigtable *k;
 485     int guest_sig;
 486     uintptr_t pc = 0;
 487     bool sync_sig = false;
 488
 489     /*
 490      * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special
 491      * handling wrt signal blocking and unwinding.
 492      */
 493     if ((host_sig == SIGSEGV || host_sig == SIGBUS) && info->si_code > 0) {
 494         MMUAccessType access_type;
 495         uintptr_t host_addr;
 496         abi_ptr guest_addr;
 497         bool is_write;
 498
 499         host_addr = (uintptr_t)info->si_addr;
 500
 501         /*
 502          * Convert forcefully to guest address space: addresses outside
 503          * reserved_va are still valid to report via SEGV_MAPERR.
 504          */
 505         guest_addr = h2g_nocheck(host_addr);
 506
 507         pc = host_signal_pc(uc);
 508         is_write = host_signal_write(info, uc);
 509         access_type = adjust_signal_pc(&pc, is_write);
 510
 511         if (host_sig == SIGSEGV) {
 512             bool maperr = true;
 513
 514             if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) {
 515                 /* If this was a write to a TB protected page, restart. */
 516                 if (is_write &&
 517                     handle_sigsegv_accerr_write(cpu, &uc->uc_sigmask,
 518                                                 pc, guest_addr)) {
 519                     return;
 520                 }
 521
 522                 /*
 523                  * With reserved_va, the whole address space is PROT_NONE,
 524                  * which means that we may get ACCERR when we want MAPERR.
 525                  */
 526                 if (page_get_flags(guest_addr) & PAGE_VALID) {
 527                     maperr = false;
 528                 } else {
 529                     info->si_code = SEGV_MAPERR;
 530                 }
 531             }
 532
 533             sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
 534             cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc);
 535         } else {
 536             sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
 537             if (info->si_code == BUS_ADRALN) {
 538                 cpu_loop_exit_sigbus(cpu, guest_addr, access_type, pc);
 539             }
 540         }
 541
 542         sync_sig = true;
 543     }
 544
 545     /* Get the target signal number. */
 546     guest_sig = host_to_target_signal(host_sig);
 547     if (guest_sig < 1 || guest_sig > TARGET_NSIG) {
 548         return;
 549     }
 550     trace_user_host_signal(cpu, host_sig, guest_sig);
 551
 552     host_to_target_siginfo_noswap(&tinfo, info);
 553
 554     k = &ts->sigtab[guest_sig - 1];
 555     k->info = tinfo;
 556     k->pending = guest_sig;
 557     ts->signal_pending = 1;
 558
 559     /*
 560      * For synchronous signals, unwind the cpu state to the faulting
 561      * insn and then exit back to the main loop so that the signal
 562      * is delivered immediately.
 563      */
 564     if (sync_sig) {
 565         cpu->exception_index = EXCP_INTERRUPT;
 566         cpu_loop_exit_restore(cpu, pc);
 567     }
 568
 569     rewind_if_in_safe_syscall(puc);
 570
 571     /*
 572      * Block host signals until target signal handler entered. We
 573      * can't block SIGSEGV or SIGBUS while we're executing guest
 574      * code in case the guest code provokes one in the window between
 575      * now and it getting out to the main loop. Signals will be
 576      * unblocked again in process_pending_signals().
 577      */
 578     sigfillset(&uc->uc_sigmask);
 579     sigdelset(&uc->uc_sigmask, SIGSEGV);
 580     sigdelset(&uc->uc_sigmask, SIGBUS);
 581
 582     /* Interrupt the virtual CPU as soon as possible. */
 583     cpu_exit(thread_cpu);
 584 }
 585
 586 /* do_sigaltstack() returns target values and errnos. */
 587 /* compare to kern/kern_sig.c sys_sigaltstack() and kern_sigaltstack() */
 588 abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp)
 589 {
 590     TaskState *ts = get_task_state(thread_cpu);
 591     int ret;
 592     target_stack_t oss;
 593
 594     if (uoss_addr) {
 595         /* Save current signal stack params */
 596         oss.ss_sp = tswapl(ts->sigaltstack_used.ss_sp);
 597         oss.ss_size = tswapl(ts->sigaltstack_used.ss_size);
 598         oss.ss_flags = tswapl(sas_ss_flags(ts, sp));
 599     }
 600
 601     if (uss_addr) {
 602         target_stack_t *uss;
 603         target_stack_t ss;
 604         size_t minstacksize = TARGET_MINSIGSTKSZ;
 605
 606         ret = -TARGET_EFAULT;
 607         if (!lock_user_struct(VERIFY_READ, uss, uss_addr, 1)) {
 608             goto out;
 609         }
 610         __get_user(ss.ss_sp, &uss->ss_sp);
 611         __get_user(ss.ss_size, &uss->ss_size);
 612         __get_user(ss.ss_flags, &uss->ss_flags);
 613         unlock_user_struct(uss, uss_addr, 0);
 614
 615         ret = -TARGET_EPERM;
 616         if (on_sig_stack(ts, sp)) {
 617             goto out;
 618         }
 619
 620         ret = -TARGET_EINVAL;
 621         if (ss.ss_flags != TARGET_SS_DISABLE
 622             && ss.ss_flags != TARGET_SS_ONSTACK
 623             && ss.ss_flags != 0) {
 624             goto out;
 625         }
 626
 627         if (ss.ss_flags == TARGET_SS_DISABLE) {
 628             ss.ss_size = 0;
 629             ss.ss_sp = 0;
 630         } else {
 631             ret = -TARGET_ENOMEM;
 632             if (ss.ss_size < minstacksize) {
 633                 goto out;
 634             }
 635         }
 636
 637         ts->sigaltstack_used.ss_sp = ss.ss_sp;
 638         ts->sigaltstack_used.ss_size = ss.ss_size;
 639     }
 640
 641     if (uoss_addr) {
 642         ret = -TARGET_EFAULT;
 643         if (copy_to_user(uoss_addr, &oss, sizeof(oss))) {
 644             goto out;
 645         }
 646     }
 647
 648     ret = 0;
 649 out:
 650     return ret;
 651 }
 652
 653 /* do_sigaction() return host values and errnos */
 654 int do_sigaction(int sig, const struct target_sigaction *act,
 655         struct target_sigaction *oact)
 656 {
 657     struct target_sigaction *k;
 658     struct sigaction act1;
 659     int host_sig;
 660     int ret = 0;
 661
 662     if (sig < 1 || sig > TARGET_NSIG) {
 663         return -TARGET_EINVAL;
 664     }
 665
 666     if ((sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) &&
 667         act != NULL && act->_sa_handler != TARGET_SIG_DFL) {
 668         return -TARGET_EINVAL;
 669     }
 670
 671     if (block_signals()) {
 672         return -TARGET_ERESTART;
 673     }
 674
 675     k = &sigact_table[sig - 1];
 676     if (oact) {
 677         oact->_sa_handler = tswapal(k->_sa_handler);
 678         oact->sa_flags = tswap32(k->sa_flags);
 679         oact->sa_mask = k->sa_mask;
 680     }
 681     if (act) {
 682         k->_sa_handler = tswapal(act->_sa_handler);
 683         k->sa_flags = tswap32(act->sa_flags);
 684         k->sa_mask = act->sa_mask;
 685
 686         /* Update the host signal state. */
 687         host_sig = target_to_host_signal(sig);
 688         if (host_sig != SIGSEGV && host_sig != SIGBUS) {
 689             memset(&act1, 0, sizeof(struct sigaction));
 690             sigfillset(&act1.sa_mask);
 691             act1.sa_flags = SA_SIGINFO;
 692             if (k->sa_flags & TARGET_SA_RESTART) {
 693                 act1.sa_flags |= SA_RESTART;
 694             }
 695             /*
 696              *  Note: It is important to update the host kernel signal mask to
 697              *  avoid getting unexpected interrupted system calls.
 698              */
 699             if (k->_sa_handler == TARGET_SIG_IGN) {
 700                 act1.sa_sigaction = (void *)SIG_IGN;
 701             } else if (k->_sa_handler == TARGET_SIG_DFL) {
 702                 if (fatal_signal(sig)) {
 703                     act1.sa_sigaction = host_signal_handler;
 704                 } else {
 705                     act1.sa_sigaction = (void *)SIG_DFL;
 706                 }
 707             } else {
 708                 act1.sa_sigaction = host_signal_handler;
 709             }
 710             ret = sigaction(host_sig, &act1, NULL);
 711         }
 712     }
 713     return ret;
 714 }
 715
 716 static inline abi_ulong get_sigframe(struct target_sigaction *ka,
 717         CPUArchState *env, size_t frame_size)
 718 {
 719     TaskState *ts = get_task_state(thread_cpu);
 720     abi_ulong sp;
 721
 722     /* Use default user stack */
 723     sp = get_sp_from_cpustate(env);
 724
 725     if ((ka->sa_flags & TARGET_SA_ONSTACK) && sas_ss_flags(ts, sp) == 0) {
 726         sp = ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size;
 727     }
 728
 729 /* TODO: make this a target_arch function / define */
 730 #if defined(TARGET_ARM)
 731     return (sp - frame_size) & ~7;
 732 #elif defined(TARGET_AARCH64)
 733     return (sp - frame_size) & ~15;
 734 #else
 735     return sp - frame_size;
 736 #endif
 737 }
 738
 739 /* compare to $M/$M/exec_machdep.c sendsig and sys/kern/kern_sig.c sigexit */
 740
 741 static void setup_frame(int sig, int code, struct target_sigaction *ka,
 742     target_sigset_t *set, target_siginfo_t *tinfo, CPUArchState *env)
 743 {
 744     struct target_sigframe *frame;
 745     abi_ulong frame_addr;
 746     int i;
 747
 748     frame_addr = get_sigframe(ka, env, sizeof(*frame));
 749     trace_user_setup_frame(env, frame_addr);
 750     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
 751         unlock_user_struct(frame, frame_addr, 1);
 752         dump_core_and_abort(TARGET_SIGILL);
 753         return;
 754     }
 755
 756     memset(frame, 0, sizeof(*frame));
 757     setup_sigframe_arch(env, frame_addr, frame, 0);
 758
 759     for (i = 0; i < TARGET_NSIG_WORDS; i++) {
 760         __put_user(set->__bits[i], &frame->sf_uc.uc_sigmask.__bits[i]);
 761     }
 762
 763     if (tinfo) {
 764         frame->sf_si.si_signo = tinfo->si_signo;
 765         frame->sf_si.si_errno = tinfo->si_errno;
 766         frame->sf_si.si_code = tinfo->si_code;
 767         frame->sf_si.si_pid = tinfo->si_pid;
 768         frame->sf_si.si_uid = tinfo->si_uid;
 769         frame->sf_si.si_status = tinfo->si_status;
 770         frame->sf_si.si_addr = tinfo->si_addr;
 771         /* see host_to_target_siginfo_noswap() for more details */
 772         frame->sf_si.si_value.sival_ptr = tinfo->si_value.sival_ptr;
 773         /*
 774          * At this point, whatever is in the _reason union is complete
 775          * and in target order, so just copy the whole thing over, even
 776          * if it's too large for this specific signal.
 777          * host_to_target_siginfo_noswap() and tswap_siginfo() have ensured
 778          * that's so.
 779          */
 780         memcpy(&frame->sf_si._reason, &tinfo->_reason,
 781                sizeof(tinfo->_reason));
 782     }
 783
 784     set_sigtramp_args(env, sig, frame, frame_addr, ka);
 785
 786     unlock_user_struct(frame, frame_addr, 1);
 787 }
 788
 789 static int reset_signal_mask(target_ucontext_t *ucontext)
 790 {
 791     int i;
 792     sigset_t blocked;
 793     target_sigset_t target_set;
 794     TaskState *ts = get_task_state(thread_cpu);
 795
 796     for (i = 0; i < TARGET_NSIG_WORDS; i++) {
 797         __get_user(target_set.__bits[i], &ucontext->uc_sigmask.__bits[i]);
 798     }
 799     target_to_host_sigset_internal(&blocked, &target_set);
 800     ts->signal_mask = blocked;
 801
 802     return 0;
 803 }
 804
 805 /* See sys/$M/$M/exec_machdep.c sigreturn() */
 806 long do_sigreturn(CPUArchState *env, abi_ulong addr)
 807 {
 808     long ret;
 809     abi_ulong target_ucontext;
 810     target_ucontext_t *ucontext = NULL;
 811
 812     /* Get the target ucontext address from the stack frame */
 813     ret = get_ucontext_sigreturn(env, addr, &target_ucontext);
 814     if (is_error(ret)) {
 815         return ret;
 816     }
 817     trace_user_do_sigreturn(env, addr);
 818     if (!lock_user_struct(VERIFY_READ, ucontext, target_ucontext, 0)) {
 819         goto badframe;
 820     }
 821
 822     /* Set the register state back to before the signal. */
 823     if (set_mcontext(env, &ucontext->uc_mcontext, 1)) {
 824         goto badframe;
 825     }
 826
 827     /* And reset the signal mask. */
 828     if (reset_signal_mask(ucontext)) {
 829         goto badframe;
 830     }
 831
 832     unlock_user_struct(ucontext, target_ucontext, 0);
 833     return -TARGET_EJUSTRETURN;
 834
 835 badframe:
 836     if (ucontext != NULL) {
 837         unlock_user_struct(ucontext, target_ucontext, 0);
 838     }
 839     return -TARGET_EFAULT;
 840 }
 841
 842 void signal_init(void)
 843 {
 844     TaskState *ts = get_task_state(thread_cpu);
 845     struct sigaction act;
 846     struct sigaction oact;
 847     int i;
 848     int host_sig;
 849
 850     /* Set the signal mask from the host mask. */
 851     sigprocmask(0, 0, &ts->signal_mask);
 852
 853     sigfillset(&act.sa_mask);
 854     act.sa_sigaction = host_signal_handler;
 855     act.sa_flags = SA_SIGINFO;
 856
 857     for (i = 1; i <= TARGET_NSIG; i++) {
 858         host_sig = target_to_host_signal(i);
 859         sigaction(host_sig, NULL, &oact);
 860         if (oact.sa_sigaction == (void *)SIG_IGN) {
 861             sigact_table[i - 1]._sa_handler = TARGET_SIG_IGN;
 862         } else if (oact.sa_sigaction == (void *)SIG_DFL) {
 863             sigact_table[i - 1]._sa_handler = TARGET_SIG_DFL;
 864         }
 865         /*
 866          * If there's already a handler installed then something has
 867          * gone horribly wrong, so don't even try to handle that case.
 868          * Install some handlers for our own use.  We need at least
 869          * SIGSEGV and SIGBUS, to detect exceptions.  We can not just
 870          * trap all signals because it affects syscall interrupt
 871          * behavior.  But do trap all default-fatal signals.
 872          */
 873         if (fatal_signal(i)) {
 874             sigaction(host_sig, &act, NULL);
 875         }
 876     }
 877 }
 878
 879 static void handle_pending_signal(CPUArchState *env, int sig,
 880                                   struct emulated_sigtable *k)
 881 {
 882     CPUState *cpu = env_cpu(env);
 883     TaskState *ts = get_task_state(cpu);
 884     struct target_sigaction *sa;
 885     int code;
 886     sigset_t set;
 887     abi_ulong handler;
 888     target_siginfo_t tinfo;
 889     target_sigset_t target_old_set;
 890
 891     trace_user_handle_signal(env, sig);
 892
 893     k->pending = 0;
 894
 895     sig = gdb_handlesig(cpu, sig, NULL, &k->info, sizeof(k->info));
 896     if (!sig) {
 897         sa = NULL;
 898         handler = TARGET_SIG_IGN;
 899     } else {
 900         sa = &sigact_table[sig - 1];
 901         handler = sa->_sa_handler;
 902     }
 903
 904     if (do_strace) {
 905         print_taken_signal(sig, &k->info);
 906     }
 907
 908     if (handler == TARGET_SIG_DFL) {
 909         /*
 910          * default handler : ignore some signal. The other are job
 911          * control or fatal.
 912          */
 913         if (sig == TARGET_SIGTSTP || sig == TARGET_SIGTTIN ||
 914             sig == TARGET_SIGTTOU) {
 915             kill(getpid(), SIGSTOP);
 916         } else if (sig != TARGET_SIGCHLD && sig != TARGET_SIGURG &&
 917                    sig != TARGET_SIGINFO && sig != TARGET_SIGWINCH &&
 918                    sig != TARGET_SIGCONT) {
 919             dump_core_and_abort(sig);
 920         }
 921     } else if (handler == TARGET_SIG_IGN) {
 922         /* ignore sig */
 923     } else if (handler == TARGET_SIG_ERR) {
 924         dump_core_and_abort(sig);
 925     } else {
 926         /* compute the blocked signals during the handler execution */
 927         sigset_t *blocked_set;
 928
 929         target_to_host_sigset(&set, &sa->sa_mask);
 930         /*
 931          * SA_NODEFER indicates that the current signal should not be
 932          * blocked during the handler.
 933          */
 934         if (!(sa->sa_flags & TARGET_SA_NODEFER)) {
 935             sigaddset(&set, target_to_host_signal(sig));
 936         }
 937
 938         /*
 939          * Save the previous blocked signal state to restore it at the
 940          * end of the signal execution (see do_sigreturn).
 941          */
 942         host_to_target_sigset_internal(&target_old_set, &ts->signal_mask);
 943
 944         blocked_set = ts->in_sigsuspend ?
 945             &ts->sigsuspend_mask : &ts->signal_mask;
 946         sigorset(&ts->signal_mask, blocked_set, &set);
 947         ts->in_sigsuspend = false;
 948         sigprocmask(SIG_SETMASK, &ts->signal_mask, NULL);
 949
 950         /* XXX VM86 on x86 ??? */
 951
 952         code = k->info.si_code; /* From host, so no si_type */
 953         /* prepare the stack frame of the virtual CPU */
 954         if (sa->sa_flags & TARGET_SA_SIGINFO) {
 955             tswap_siginfo(&tinfo, &k->info);
 956             setup_frame(sig, code, sa, &target_old_set, &tinfo, env);
 957         } else {
 958             setup_frame(sig, code, sa, &target_old_set, NULL, env);
 959         }
 960         if (sa->sa_flags & TARGET_SA_RESETHAND) {
 961             sa->_sa_handler = TARGET_SIG_DFL;
 962         }
 963     }
 964 }
 965
 966 void process_pending_signals(CPUArchState *env)
 967 {
 968     CPUState *cpu = env_cpu(env);
 969     int sig;
 970     sigset_t *blocked_set, set;
 971     struct emulated_sigtable *k;
 972     TaskState *ts = get_task_state(cpu);
 973
 974     while (qatomic_read(&ts->signal_pending)) {
 975         sigfillset(&set);
 976         sigprocmask(SIG_SETMASK, &set, 0);
 977
 978     restart_scan:
 979         sig = ts->sync_signal.pending;
 980         if (sig) {
 981             /*
 982              * Synchronous signals are forced by the emulated CPU in some way.
 983              * If they are set to ignore, restore the default handler (see
 984              * sys/kern_sig.c trapsignal() and execsigs() for this behavior)
 985              * though maybe this is done only when forcing exit for non SIGCHLD.
 986              */
 987             if (sigismember(&ts->signal_mask, target_to_host_signal(sig)) ||
 988                 sigact_table[sig - 1]._sa_handler == TARGET_SIG_IGN) {
 989                 sigdelset(&ts->signal_mask, target_to_host_signal(sig));
 990                 sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL;
 991             }
 992             handle_pending_signal(env, sig, &ts->sync_signal);
 993         }
 994
 995         k = ts->sigtab;
 996         for (sig = 1; sig <= TARGET_NSIG; sig++, k++) {
 997             blocked_set = ts->in_sigsuspend ?
 998                 &ts->sigsuspend_mask : &ts->signal_mask;
 999             if (k->pending &&
1000                 !sigismember(blocked_set, target_to_host_signal(sig))) {
1001                 handle_pending_signal(env, sig, k);
1002                 /*
1003                  * Restart scan from the beginning, as handle_pending_signal
1004                  * might have resulted in a new synchronous signal (eg SIGSEGV).
1005                  */
1006                 goto restart_scan;
1007             }
1008         }
1009
1010         /*
1011          * Unblock signals and check one more time. Unblocking signals may cause
1012          * us to take another host signal, which will set signal_pending again.
1013          */
1014         qatomic_set(&ts->signal_pending, 0);
1015         ts->in_sigsuspend = false;
1016         set = ts->signal_mask;
1017         sigdelset(&set, SIGSEGV);
1018         sigdelset(&set, SIGBUS);
1019         sigprocmask(SIG_SETMASK, &set, 0);
1020     }
1021     ts->in_sigsuspend = false;
1022 }
1023
1024 void cpu_loop_exit_sigsegv(CPUState *cpu, target_ulong addr,
1025                            MMUAccessType access_type, bool maperr, uintptr_t ra)
1026 {
1027     const TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops;
1028
1029     if (tcg_ops->record_sigsegv) {
1030         tcg_ops->record_sigsegv(cpu, addr, access_type, maperr, ra);
1031     }
1032
1033     force_sig_fault(TARGET_SIGSEGV,
1034                     maperr ? TARGET_SEGV_MAPERR : TARGET_SEGV_ACCERR,
1035                     addr);
1036     cpu->exception_index = EXCP_INTERRUPT;
1037     cpu_loop_exit_restore(cpu, ra);
1038 }
1039
1040 void cpu_loop_exit_sigbus(CPUState *cpu, target_ulong addr,
1041                           MMUAccessType access_type, uintptr_t ra)
1042 {
1043     const TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops;
1044
1045     if (tcg_ops->record_sigbus) {
1046         tcg_ops->record_sigbus(cpu, addr, access_type, ra);
1047     }
1048
1049     force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN, addr);
1050     cpu->exception_index = EXCP_INTERRUPT;
1051     cpu_loop_exit_restore(cpu, ra);
1052 }