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 "exec/page-protection.h"
  25 #include "user/tswap-target.h"
  26 #include "gdbstub/user.h"
  27 #include "signal-common.h"
  28 #include "trace.h"
  29 #include "hw/core/tcg-cpu-ops.h"
  30 #include "host-signal.h"
  31
  32 /* target_siginfo_t must fit in gdbstub's siginfo save area. */
  33 QEMU_BUILD_BUG_ON(sizeof(target_siginfo_t) > MAX_SIGINFO_LENGTH);
  34
  35 static struct target_sigaction sigact_table[TARGET_NSIG];
  36 static void host_signal_handler(int host_sig, siginfo_t *info, void *puc);
  37 static void target_to_host_sigset_internal(sigset_t *d,
  38         const target_sigset_t *s);
  39
  40 static inline int on_sig_stack(TaskState *ts, unsigned long sp)
  41 {
  42     return sp - ts->sigaltstack_used.ss_sp < ts->sigaltstack_used.ss_size;
  43 }
  44
  45 static inline int sas_ss_flags(TaskState *ts, unsigned long sp)
  46 {
  47     return ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE :
  48         on_sig_stack(ts, sp) ? SS_ONSTACK : 0;
  49 }
  50
  51 /*
  52  * The BSD ABIs use the same signal numbers across all the CPU architectures, so
  53  * (unlike Linux) these functions are just the identity mapping. This might not
  54  * be true for XyzBSD running on AbcBSD, which doesn't currently work.
  55  */
  56 int host_to_target_signal(int sig)
  57 {
  58     return sig;
  59 }
  60
  61 int target_to_host_signal(int sig)
  62 {
  63     return sig;
  64 }
  65
  66 static inline void target_sigemptyset(target_sigset_t *set)
  67 {
  68     memset(set, 0, sizeof(*set));
  69 }
  70
  71 static inline void target_sigaddset(target_sigset_t *set, int signum)
  72 {
  73     signum--;
  74     uint32_t mask = (uint32_t)1 << (signum % TARGET_NSIG_BPW);
  75     set->__bits[signum / TARGET_NSIG_BPW] |= mask;
  76 }
  77
  78 static inline int target_sigismember(const target_sigset_t *set, int signum)
  79 {
  80     signum--;
  81     abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW);
  82     return (set->__bits[signum / TARGET_NSIG_BPW] & mask) != 0;
  83 }
  84
  85 /* Adjust the signal context to rewind out of safe-syscall if we're in it */
  86 static inline void rewind_if_in_safe_syscall(void *puc)
  87 {
  88     ucontext_t *uc = (ucontext_t *)puc;
  89     uintptr_t pcreg = host_signal_pc(uc);
  90
  91     if (pcreg > (uintptr_t)safe_syscall_start
  92         && pcreg < (uintptr_t)safe_syscall_end) {
  93         host_signal_set_pc(uc, (uintptr_t)safe_syscall_start);
  94     }
  95 }
  96
  97 /*
  98  * Note: The following take advantage of the BSD signal property that all
  99  * signals are available on all architectures.
 100  */
 101 static void host_to_target_sigset_internal(target_sigset_t *d,
 102         const sigset_t *s)
 103 {
 104     int i;
 105
 106     target_sigemptyset(d);
 107     for (i = 1; i <= NSIG; i++) {
 108         if (sigismember(s, i)) {
 109             target_sigaddset(d, host_to_target_signal(i));
 110         }
 111     }
 112 }
 113
 114 void host_to_target_sigset(target_sigset_t *d, const sigset_t *s)
 115 {
 116     target_sigset_t d1;
 117     int i;
 118
 119     host_to_target_sigset_internal(&d1, s);
 120     for (i = 0; i < _SIG_WORDS; i++) {
 121         d->__bits[i] = tswap32(d1.__bits[i]);
 122     }
 123 }
 124
 125 static void target_to_host_sigset_internal(sigset_t *d,
 126         const target_sigset_t *s)
 127 {
 128     int i;
 129
 130     sigemptyset(d);
 131     for (i = 1; i <= TARGET_NSIG; i++) {
 132         if (target_sigismember(s, i)) {
 133             sigaddset(d, target_to_host_signal(i));
 134         }
 135     }
 136 }
 137
 138 void target_to_host_sigset(sigset_t *d, const target_sigset_t *s)
 139 {
 140     target_sigset_t s1;
 141     int i;
 142
 143     for (i = 0; i < TARGET_NSIG_WORDS; i++) {
 144         s1.__bits[i] = tswap32(s->__bits[i]);
 145     }
 146     target_to_host_sigset_internal(d, &s1);
 147 }
 148
 149 static bool has_trapno(int tsig)
 150 {
 151     return tsig == TARGET_SIGILL ||
 152         tsig == TARGET_SIGFPE ||
 153         tsig == TARGET_SIGSEGV ||
 154         tsig == TARGET_SIGBUS ||
 155         tsig == TARGET_SIGTRAP;
 156 }
 157
 158 /* Siginfo conversion. */
 159
 160 /*
 161  * Populate tinfo w/o swapping based on guessing which fields are valid.
 162  */
 163 static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo,
 164         const siginfo_t *info)
 165 {
 166     int sig = host_to_target_signal(info->si_signo);
 167     int si_code = info->si_code;
 168     int si_type;
 169
 170     /*
 171      * Make sure we that the variable portion of the target siginfo is zeroed
 172      * out so we don't leak anything into that.
 173      */
 174     memset(&tinfo->_reason, 0, sizeof(tinfo->_reason));
 175
 176     /*
 177      * This is awkward, because we have to use a combination of the si_code and
 178      * si_signo to figure out which of the union's members are valid.o We
 179      * therefore make our best guess.
 180      *
 181      * Once we have made our guess, we record it in the top 16 bits of
 182      * the si_code, so that tswap_siginfo() later can use it.
 183      * tswap_siginfo() will strip these top bits out before writing
 184      * si_code to the guest (sign-extending the lower bits).
 185      */
 186     tinfo->si_signo = sig;
 187     tinfo->si_errno = info->si_errno;
 188     tinfo->si_code = info->si_code;
 189     tinfo->si_pid = info->si_pid;
 190     tinfo->si_uid = info->si_uid;
 191     tinfo->si_status = info->si_status;
 192     tinfo->si_addr = (abi_ulong)(unsigned long)info->si_addr;
 193     /*
 194      * si_value is opaque to kernel. On all FreeBSD platforms,
 195      * sizeof(sival_ptr) >= sizeof(sival_int) so the following
 196      * always will copy the larger element.
 197      */
 198     tinfo->si_value.sival_ptr =
 199         (abi_ulong)(unsigned long)info->si_value.sival_ptr;
 200
 201     switch (si_code) {
 202         /*
 203          * All the SI_xxx codes that are defined here are global to
 204          * all the signals (they have values that none of the other,
 205          * more specific signal info will set).
 206          */
 207     case SI_USER:
 208     case SI_LWP:
 209     case SI_KERNEL:
 210     case SI_QUEUE:
 211     case SI_ASYNCIO:
 212         /*
 213          * Only the fixed parts are valid (though FreeBSD doesn't always
 214          * set all the fields to non-zero values.
 215          */
 216         si_type = QEMU_SI_NOINFO;
 217         break;
 218     case SI_TIMER:
 219         tinfo->_reason._timer._timerid = info->_reason._timer._timerid;
 220         tinfo->_reason._timer._overrun = info->_reason._timer._overrun;
 221         si_type = QEMU_SI_TIMER;
 222         break;
 223     case SI_MESGQ:
 224         tinfo->_reason._mesgq._mqd = info->_reason._mesgq._mqd;
 225         si_type = QEMU_SI_MESGQ;
 226         break;
 227     default:
 228         /*
 229          * We have to go based on the signal number now to figure out
 230          * what's valid.
 231          */
 232         si_type = QEMU_SI_NOINFO;
 233         if (has_trapno(sig)) {
 234             tinfo->_reason._fault._trapno = info->_reason._fault._trapno;
 235             si_type = QEMU_SI_FAULT;
 236         }
 237 #ifdef TARGET_SIGPOLL
 238         /*
 239          * FreeBSD never had SIGPOLL, but emulates it for Linux so there's
 240          * a chance it may popup in the future.
 241          */
 242         if (sig == TARGET_SIGPOLL) {
 243             tinfo->_reason._poll._band = info->_reason._poll._band;
 244             si_type = QEMU_SI_POLL;
 245         }
 246 #endif
 247         /*
 248          * Unsure that this can actually be generated, and our support for
 249          * capsicum is somewhere between weak and non-existent, but if we get
 250          * one, then we know what to save.
 251          */
 252 #ifdef QEMU_SI_CAPSICUM
 253         if (sig == TARGET_SIGTRAP) {
 254             tinfo->_reason._capsicum._syscall =
 255                 info->_reason._capsicum._syscall;
 256             si_type = QEMU_SI_CAPSICUM;
 257         }
 258 #endif
 259         break;
 260     }
 261     tinfo->si_code = deposit32(si_code, 24, 8, si_type);
 262 }
 263
 264 static void tswap_siginfo(target_siginfo_t *tinfo, const target_siginfo_t *info)
 265 {
 266     int si_type = extract32(info->si_code, 24, 8);
 267     int si_code = sextract32(info->si_code, 0, 24);
 268
 269     __put_user(info->si_signo, &tinfo->si_signo);
 270     __put_user(info->si_errno, &tinfo->si_errno);
 271     __put_user(si_code, &tinfo->si_code); /* Zero out si_type, it's internal */
 272     __put_user(info->si_pid, &tinfo->si_pid);
 273     __put_user(info->si_uid, &tinfo->si_uid);
 274     __put_user(info->si_status, &tinfo->si_status);
 275     __put_user(info->si_addr, &tinfo->si_addr);
 276     /*
 277      * Unswapped, because we passed it through mostly untouched.  si_value is
 278      * opaque to the kernel, so we didn't bother with potentially wasting cycles
 279      * to swap it into host byte order.
 280      */
 281     tinfo->si_value.sival_ptr = info->si_value.sival_ptr;
 282
 283     /*
 284      * We can use our internal marker of which fields in the structure
 285      * are valid, rather than duplicating the guesswork of
 286      * host_to_target_siginfo_noswap() here.
 287      */
 288     switch (si_type) {
 289     case QEMU_SI_NOINFO:        /* No additional info */
 290         break;
 291     case QEMU_SI_FAULT:
 292         __put_user(info->_reason._fault._trapno,
 293                    &tinfo->_reason._fault._trapno);
 294         break;
 295     case QEMU_SI_TIMER:
 296         __put_user(info->_reason._timer._timerid,
 297                    &tinfo->_reason._timer._timerid);
 298         __put_user(info->_reason._timer._overrun,
 299                    &tinfo->_reason._timer._overrun);
 300         break;
 301     case QEMU_SI_MESGQ:
 302         __put_user(info->_reason._mesgq._mqd, &tinfo->_reason._mesgq._mqd);
 303         break;
 304     case QEMU_SI_POLL:
 305         /* Note: Not generated on FreeBSD */
 306         __put_user(info->_reason._poll._band, &tinfo->_reason._poll._band);
 307         break;
 308 #ifdef QEMU_SI_CAPSICUM
 309     case QEMU_SI_CAPSICUM:
 310         __put_user(info->_reason._capsicum._syscall,
 311                    &tinfo->_reason._capsicum._syscall);
 312         break;
 313 #endif
 314     default:
 315         g_assert_not_reached();
 316     }
 317 }
 318
 319 void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info)
 320 {
 321     host_to_target_siginfo_noswap(tinfo, info);
 322     tswap_siginfo(tinfo, tinfo);
 323 }
 324
 325 int block_signals(void)
 326 {
 327     TaskState *ts = get_task_state(thread_cpu);
 328     sigset_t set;
 329
 330     /*
 331      * It's OK to block everything including SIGSEGV, because we won't run any
 332      * further guest code before unblocking signals in
 333      * process_pending_signals(). We depend on the FreeBSD behavior here where
 334      * this will only affect this thread's signal mask. We don't use
 335      * pthread_sigmask which might seem more correct because that routine also
 336      * does odd things with SIGCANCEL to implement pthread_cancel().
 337      */
 338     sigfillset(&set);
 339     sigprocmask(SIG_SETMASK, &set, 0);
 340
 341     return qatomic_xchg(&ts->signal_pending, 1);
 342 }
 343
 344 /* Returns 1 if given signal should dump core if not handled. */
 345 static int core_dump_signal(int sig)
 346 {
 347     switch (sig) {
 348     case TARGET_SIGABRT:
 349     case TARGET_SIGFPE:
 350     case TARGET_SIGILL:
 351     case TARGET_SIGQUIT:
 352     case TARGET_SIGSEGV:
 353     case TARGET_SIGTRAP:
 354     case TARGET_SIGBUS:
 355         return 1;
 356     default:
 357         return 0;
 358     }
 359 }
 360
 361 /* Abort execution with signal. */
 362 static G_NORETURN
 363 void dump_core_and_abort(int target_sig)
 364 {
 365     CPUState *cpu = thread_cpu;
 366     CPUArchState *env = cpu_env(cpu);
 367     TaskState *ts = get_task_state(cpu);
 368     int core_dumped = 0;
 369     int host_sig;
 370     struct sigaction act;
 371
 372     host_sig = target_to_host_signal(target_sig);
 373     gdb_signalled(env, target_sig);
 374
 375     /* Dump core if supported by target binary format */
 376     if (core_dump_signal(target_sig) && (ts->bprm->core_dump != NULL)) {
 377         stop_all_tasks();
 378         core_dumped =
 379             ((*ts->bprm->core_dump)(target_sig, env) == 0);
 380     }
 381     if (core_dumped) {
 382         struct rlimit nodump;
 383
 384         /*
 385          * We already dumped the core of target process, we don't want
 386          * a coredump of qemu itself.
 387          */
 388          getrlimit(RLIMIT_CORE, &nodump);
 389          nodump.rlim_cur = 0;
 390          setrlimit(RLIMIT_CORE, &nodump);
 391          (void) fprintf(stderr, "qemu: uncaught target signal %d (%s) "
 392              "- %s\n", target_sig, strsignal(host_sig), "core dumped");
 393     }
 394
 395     /*
 396      * The proper exit code for dying from an uncaught signal is
 397      * -<signal>.  The kernel doesn't allow exit() or _exit() to pass
 398      * a negative value.  To get the proper exit code we need to
 399      * actually die from an uncaught signal.  Here the default signal
 400      * handler is installed, we send ourself a signal and we wait for
 401      * it to arrive.
 402      */
 403     memset(&act, 0, sizeof(act));
 404     sigfillset(&act.sa_mask);
 405     act.sa_handler = SIG_DFL;
 406     sigaction(host_sig, &act, NULL);
 407
 408     kill(getpid(), host_sig);
 409
 410     /*
 411      * Make sure the signal isn't masked (just reuse the mask inside
 412      * of act).
 413      */
 414     sigdelset(&act.sa_mask, host_sig);
 415     sigsuspend(&act.sa_mask);
 416
 417     /* unreachable */
 418     abort();
 419 }
 420
 421 /*
 422  * Queue a signal so that it will be send to the virtual CPU as soon as
 423  * possible.
 424  */
 425 void queue_signal(CPUArchState *env, int sig, int si_type,
 426                   target_siginfo_t *info)
 427 {
 428     CPUState *cpu = env_cpu(env);
 429     TaskState *ts = get_task_state(cpu);
 430
 431     trace_user_queue_signal(env, sig);
 432
 433     info->si_code = deposit32(info->si_code, 24, 8, si_type);
 434
 435     ts->sync_signal.info = *info;
 436     ts->sync_signal.pending = sig;
 437     /* Signal that a new signal is pending. */
 438     qatomic_set(&ts->signal_pending, 1);
 439     return;
 440 }
 441
 442 static int fatal_signal(int sig)
 443 {
 444
 445     switch (sig) {
 446     case TARGET_SIGCHLD:
 447     case TARGET_SIGURG:
 448     case TARGET_SIGWINCH:
 449     case TARGET_SIGINFO:
 450         /* Ignored by default. */
 451         return 0;
 452     case TARGET_SIGCONT:
 453     case TARGET_SIGSTOP:
 454     case TARGET_SIGTSTP:
 455     case TARGET_SIGTTIN:
 456     case TARGET_SIGTTOU:
 457         /* Job control signals.  */
 458         return 0;
 459     default:
 460         return 1;
 461     }
 462 }
 463
 464 /*
 465  * Force a synchronously taken QEMU_SI_FAULT signal. For QEMU the
 466  * 'force' part is handled in process_pending_signals().
 467  */
 468 void force_sig_fault(int sig, int code, abi_ulong addr)
 469 {
 470     CPUState *cpu = thread_cpu;
 471     target_siginfo_t info = {};
 472
 473     info.si_signo = sig;
 474     info.si_errno = 0;
 475     info.si_code = code;
 476     info.si_addr = addr;
 477     queue_signal(cpu_env(cpu), sig, QEMU_SI_FAULT, &info);
 478 }
 479
 480 static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
 481 {
 482     CPUState *cpu = thread_cpu;
 483     TaskState *ts = get_task_state(cpu);
 484     target_siginfo_t tinfo;
 485     ucontext_t *uc = puc;
 486     struct emulated_sigtable *k;
 487     int guest_sig;
 488     uintptr_t pc = 0;
 489     bool sync_sig = false;
 490
 491     /*
 492      * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special
 493      * handling wrt signal blocking and unwinding.
 494      */
 495     if ((host_sig == SIGSEGV || host_sig == SIGBUS) && info->si_code > 0) {
 496         MMUAccessType access_type;
 497         uintptr_t host_addr;
 498         abi_ptr guest_addr;
 499         bool is_write;
 500
 501         host_addr = (uintptr_t)info->si_addr;
 502
 503         /*
 504          * Convert forcefully to guest address space: addresses outside
 505          * reserved_va are still valid to report via SEGV_MAPERR.
 506          */
 507         guest_addr = h2g_nocheck(host_addr);
 508
 509         pc = host_signal_pc(uc);
 510         is_write = host_signal_write(info, uc);
 511         access_type = adjust_signal_pc(&pc, is_write);
 512
 513         if (host_sig == SIGSEGV) {
 514             bool maperr = true;
 515
 516             if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) {
 517                 /* If this was a write to a TB protected page, restart. */
 518                 if (is_write &&
 519                     handle_sigsegv_accerr_write(cpu, &uc->uc_sigmask,
 520                                                 pc, guest_addr)) {
 521                     return;
 522                 }
 523
 524                 /*
 525                  * With reserved_va, the whole address space is PROT_NONE,
 526                  * which means that we may get ACCERR when we want MAPERR.
 527                  */
 528                 if (page_get_flags(guest_addr) & PAGE_VALID) {
 529                     maperr = false;
 530                 } else {
 531                     info->si_code = SEGV_MAPERR;
 532                 }
 533             }
 534
 535             sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
 536             cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc);
 537         } else {
 538             sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
 539             if (info->si_code == BUS_ADRALN) {
 540                 cpu_loop_exit_sigbus(cpu, guest_addr, access_type, pc);
 541             }
 542         }
 543
 544         sync_sig = true;
 545     }
 546
 547     /* Get the target signal number. */
 548     guest_sig = host_to_target_signal(host_sig);
 549     if (guest_sig < 1 || guest_sig > TARGET_NSIG) {
 550         return;
 551     }
 552     trace_user_host_signal(cpu, host_sig, guest_sig);
 553
 554     host_to_target_siginfo_noswap(&tinfo, info);
 555
 556     k = &ts->sigtab[guest_sig - 1];
 557     k->info = tinfo;
 558     k->pending = guest_sig;
 559     ts->signal_pending = 1;
 560
 561     /*
 562      * For synchronous signals, unwind the cpu state to the faulting
 563      * insn and then exit back to the main loop so that the signal
 564      * is delivered immediately.
 565      */
 566     if (sync_sig) {
 567         cpu->exception_index = EXCP_INTERRUPT;
 568         cpu_loop_exit_restore(cpu, pc);
 569     }
 570
 571     rewind_if_in_safe_syscall(puc);
 572
 573     /*
 574      * Block host signals until target signal handler entered. We
 575      * can't block SIGSEGV or SIGBUS while we're executing guest
 576      * code in case the guest code provokes one in the window between
 577      * now and it getting out to the main loop. Signals will be
 578      * unblocked again in process_pending_signals().
 579      */
 580     sigfillset(&uc->uc_sigmask);
 581     sigdelset(&uc->uc_sigmask, SIGSEGV);
 582     sigdelset(&uc->uc_sigmask, SIGBUS);
 583
 584     /* Interrupt the virtual CPU as soon as possible. */
 585     cpu_exit(thread_cpu);
 586 }
 587
 588 /* do_sigaltstack() returns target values and errnos. */
 589 /* compare to kern/kern_sig.c sys_sigaltstack() and kern_sigaltstack() */
 590 abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp)
 591 {
 592     TaskState *ts = get_task_state(thread_cpu);
 593     int ret;
 594     target_stack_t oss;
 595
 596     if (uoss_addr) {
 597         /* Save current signal stack params */
 598         oss.ss_sp = tswapl(ts->sigaltstack_used.ss_sp);
 599         oss.ss_size = tswapl(ts->sigaltstack_used.ss_size);
 600         oss.ss_flags = tswapl(sas_ss_flags(ts, sp));
 601     }
 602
 603     if (uss_addr) {
 604         target_stack_t *uss;
 605         target_stack_t ss;
 606         size_t minstacksize = TARGET_MINSIGSTKSZ;
 607
 608         ret = -TARGET_EFAULT;
 609         if (!lock_user_struct(VERIFY_READ, uss, uss_addr, 1)) {
 610             goto out;
 611         }
 612         __get_user(ss.ss_sp, &uss->ss_sp);
 613         __get_user(ss.ss_size, &uss->ss_size);
 614         __get_user(ss.ss_flags, &uss->ss_flags);
 615         unlock_user_struct(uss, uss_addr, 0);
 616
 617         ret = -TARGET_EPERM;
 618         if (on_sig_stack(ts, sp)) {
 619             goto out;
 620         }
 621
 622         ret = -TARGET_EINVAL;
 623         if (ss.ss_flags != TARGET_SS_DISABLE
 624             && ss.ss_flags != TARGET_SS_ONSTACK
 625             && ss.ss_flags != 0) {
 626             goto out;
 627         }
 628
 629         if (ss.ss_flags == TARGET_SS_DISABLE) {
 630             ss.ss_size = 0;
 631             ss.ss_sp = 0;
 632         } else {
 633             ret = -TARGET_ENOMEM;
 634             if (ss.ss_size < minstacksize) {
 635                 goto out;
 636             }
 637         }
 638
 639         ts->sigaltstack_used.ss_sp = ss.ss_sp;
 640         ts->sigaltstack_used.ss_size = ss.ss_size;
 641     }
 642
 643     if (uoss_addr) {
 644         ret = -TARGET_EFAULT;
 645         if (copy_to_user(uoss_addr, &oss, sizeof(oss))) {
 646             goto out;
 647         }
 648     }
 649
 650     ret = 0;
 651 out:
 652     return ret;
 653 }
 654
 655 /* do_sigaction() return host values and errnos */
 656 int do_sigaction(int sig, const struct target_sigaction *act,
 657         struct target_sigaction *oact)
 658 {
 659     struct target_sigaction *k;
 660     struct sigaction act1;
 661     int host_sig;
 662     int ret = 0;
 663
 664     if (sig < 1 || sig > TARGET_NSIG) {
 665         return -TARGET_EINVAL;
 666     }
 667
 668     if ((sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) &&
 669         act != NULL && act->_sa_handler != TARGET_SIG_DFL) {
 670         return -TARGET_EINVAL;
 671     }
 672
 673     if (block_signals()) {
 674         return -TARGET_ERESTART;
 675     }
 676
 677     k = &sigact_table[sig - 1];
 678     if (oact) {
 679         oact->_sa_handler = tswapal(k->_sa_handler);
 680         oact->sa_flags = tswap32(k->sa_flags);
 681         oact->sa_mask = k->sa_mask;
 682     }
 683     if (act) {
 684         k->_sa_handler = tswapal(act->_sa_handler);
 685         k->sa_flags = tswap32(act->sa_flags);
 686         k->sa_mask = act->sa_mask;
 687
 688         /* Update the host signal state. */
 689         host_sig = target_to_host_signal(sig);
 690         if (host_sig != SIGSEGV && host_sig != SIGBUS) {
 691             memset(&act1, 0, sizeof(struct sigaction));
 692             sigfillset(&act1.sa_mask);
 693             act1.sa_flags = SA_SIGINFO;
 694             if (k->sa_flags & TARGET_SA_RESTART) {
 695                 act1.sa_flags |= SA_RESTART;
 696             }
 697             /*
 698              *  Note: It is important to update the host kernel signal mask to
 699              *  avoid getting unexpected interrupted system calls.
 700              */
 701             if (k->_sa_handler == TARGET_SIG_IGN) {
 702                 act1.sa_sigaction = (void *)SIG_IGN;
 703             } else if (k->_sa_handler == TARGET_SIG_DFL) {
 704                 if (fatal_signal(sig)) {
 705                     act1.sa_sigaction = host_signal_handler;
 706                 } else {
 707                     act1.sa_sigaction = (void *)SIG_DFL;
 708                 }
 709             } else {
 710                 act1.sa_sigaction = host_signal_handler;
 711             }
 712             ret = sigaction(host_sig, &act1, NULL);
 713         }
 714     }
 715     return ret;
 716 }
 717
 718 static inline abi_ulong get_sigframe(struct target_sigaction *ka,
 719         CPUArchState *env, size_t frame_size)
 720 {
 721     TaskState *ts = get_task_state(thread_cpu);
 722     abi_ulong sp;
 723
 724     /* Use default user stack */
 725     sp = get_sp_from_cpustate(env);
 726
 727     if ((ka->sa_flags & TARGET_SA_ONSTACK) && sas_ss_flags(ts, sp) == 0) {
 728         sp = ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size;
 729     }
 730
 731 /* TODO: make this a target_arch function / define */
 732 #if defined(TARGET_ARM)
 733     return (sp - frame_size) & ~7;
 734 #elif defined(TARGET_AARCH64)
 735     return (sp - frame_size) & ~15;
 736 #else
 737     return sp - frame_size;
 738 #endif
 739 }
 740
 741 /* compare to $M/$M/exec_machdep.c sendsig and sys/kern/kern_sig.c sigexit */
 742
 743 static void setup_frame(int sig, int code, struct target_sigaction *ka,
 744     target_sigset_t *set, target_siginfo_t *tinfo, CPUArchState *env)
 745 {
 746     struct target_sigframe *frame;
 747     abi_ulong frame_addr;
 748     int i;
 749
 750     frame_addr = get_sigframe(ka, env, sizeof(*frame));
 751     trace_user_setup_frame(env, frame_addr);
 752     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
 753         unlock_user_struct(frame, frame_addr, 1);
 754         dump_core_and_abort(TARGET_SIGILL);
 755         return;
 756     }
 757
 758     memset(frame, 0, sizeof(*frame));
 759     setup_sigframe_arch(env, frame_addr, frame, 0);
 760
 761     for (i = 0; i < TARGET_NSIG_WORDS; i++) {
 762         __put_user(set->__bits[i], &frame->sf_uc.uc_sigmask.__bits[i]);
 763     }
 764
 765     if (tinfo) {
 766         frame->sf_si.si_signo = tinfo->si_signo;
 767         frame->sf_si.si_errno = tinfo->si_errno;
 768         frame->sf_si.si_code = tinfo->si_code;
 769         frame->sf_si.si_pid = tinfo->si_pid;
 770         frame->sf_si.si_uid = tinfo->si_uid;
 771         frame->sf_si.si_status = tinfo->si_status;
 772         frame->sf_si.si_addr = tinfo->si_addr;
 773         /* see host_to_target_siginfo_noswap() for more details */
 774         frame->sf_si.si_value.sival_ptr = tinfo->si_value.sival_ptr;
 775         /*
 776          * At this point, whatever is in the _reason union is complete
 777          * and in target order, so just copy the whole thing over, even
 778          * if it's too large for this specific signal.
 779          * host_to_target_siginfo_noswap() and tswap_siginfo() have ensured
 780          * that's so.
 781          */
 782         memcpy(&frame->sf_si._reason, &tinfo->_reason,
 783                sizeof(tinfo->_reason));
 784     }
 785
 786     set_sigtramp_args(env, sig, frame, frame_addr, ka);
 787
 788     unlock_user_struct(frame, frame_addr, 1);
 789 }
 790
 791 static int reset_signal_mask(target_ucontext_t *ucontext)
 792 {
 793     int i;
 794     sigset_t blocked;
 795     target_sigset_t target_set;
 796     TaskState *ts = get_task_state(thread_cpu);
 797
 798     for (i = 0; i < TARGET_NSIG_WORDS; i++) {
 799         __get_user(target_set.__bits[i], &ucontext->uc_sigmask.__bits[i]);
 800     }
 801     target_to_host_sigset_internal(&blocked, &target_set);
 802     ts->signal_mask = blocked;
 803
 804     return 0;
 805 }
 806
 807 /* See sys/$M/$M/exec_machdep.c sigreturn() */
 808 long do_sigreturn(CPUArchState *env, abi_ulong addr)
 809 {
 810     long ret;
 811     abi_ulong target_ucontext;
 812     target_ucontext_t *ucontext = NULL;
 813
 814     /* Get the target ucontext address from the stack frame */
 815     ret = get_ucontext_sigreturn(env, addr, &target_ucontext);
 816     if (is_error(ret)) {
 817         return ret;
 818     }
 819     trace_user_do_sigreturn(env, addr);
 820     if (!lock_user_struct(VERIFY_READ, ucontext, target_ucontext, 0)) {
 821         goto badframe;
 822     }
 823
 824     /* Set the register state back to before the signal. */
 825     if (set_mcontext(env, &ucontext->uc_mcontext, 1)) {
 826         goto badframe;
 827     }
 828
 829     /* And reset the signal mask. */
 830     if (reset_signal_mask(ucontext)) {
 831         goto badframe;
 832     }
 833
 834     unlock_user_struct(ucontext, target_ucontext, 0);
 835     return -TARGET_EJUSTRETURN;
 836
 837 badframe:
 838     if (ucontext != NULL) {
 839         unlock_user_struct(ucontext, target_ucontext, 0);
 840     }
 841     return -TARGET_EFAULT;
 842 }
 843
 844 void signal_init(void)
 845 {
 846     TaskState *ts = get_task_state(thread_cpu);
 847     struct sigaction act;
 848     struct sigaction oact;
 849     int i;
 850     int host_sig;
 851
 852     /* Set the signal mask from the host mask. */
 853     sigprocmask(0, 0, &ts->signal_mask);
 854
 855     sigfillset(&act.sa_mask);
 856     act.sa_sigaction = host_signal_handler;
 857     act.sa_flags = SA_SIGINFO;
 858
 859     for (i = 1; i <= TARGET_NSIG; i++) {
 860         host_sig = target_to_host_signal(i);
 861         sigaction(host_sig, NULL, &oact);
 862         if (oact.sa_sigaction == (void *)SIG_IGN) {
 863             sigact_table[i - 1]._sa_handler = TARGET_SIG_IGN;
 864         } else if (oact.sa_sigaction == (void *)SIG_DFL) {
 865             sigact_table[i - 1]._sa_handler = TARGET_SIG_DFL;
 866         }
 867         /*
 868          * If there's already a handler installed then something has
 869          * gone horribly wrong, so don't even try to handle that case.
 870          * Install some handlers for our own use.  We need at least
 871          * SIGSEGV and SIGBUS, to detect exceptions.  We can not just
 872          * trap all signals because it affects syscall interrupt
 873          * behavior.  But do trap all default-fatal signals.
 874          */
 875         if (fatal_signal(i)) {
 876             sigaction(host_sig, &act, NULL);
 877         }
 878     }
 879 }
 880
 881 static void handle_pending_signal(CPUArchState *env, int sig,
 882                                   struct emulated_sigtable *k)
 883 {
 884     CPUState *cpu = env_cpu(env);
 885     TaskState *ts = get_task_state(cpu);
 886     struct target_sigaction *sa;
 887     int code;
 888     sigset_t set;
 889     abi_ulong handler;
 890     target_siginfo_t tinfo;
 891     target_sigset_t target_old_set;
 892
 893     trace_user_handle_signal(env, sig);
 894
 895     k->pending = 0;
 896
 897     sig = gdb_handlesig(cpu, sig, NULL, &k->info, sizeof(k->info));
 898     if (!sig) {
 899         sa = NULL;
 900         handler = TARGET_SIG_IGN;
 901     } else {
 902         sa = &sigact_table[sig - 1];
 903         handler = sa->_sa_handler;
 904     }
 905
 906     if (do_strace) {
 907         print_taken_signal(sig, &k->info);
 908     }
 909
 910     if (handler == TARGET_SIG_DFL) {
 911         /*
 912          * default handler : ignore some signal. The other are job
 913          * control or fatal.
 914          */
 915         if (sig == TARGET_SIGTSTP || sig == TARGET_SIGTTIN ||
 916             sig == TARGET_SIGTTOU) {
 917             kill(getpid(), SIGSTOP);
 918         } else if (sig != TARGET_SIGCHLD && sig != TARGET_SIGURG &&
 919                    sig != TARGET_SIGINFO && sig != TARGET_SIGWINCH &&
 920                    sig != TARGET_SIGCONT) {
 921             dump_core_and_abort(sig);
 922         }
 923     } else if (handler == TARGET_SIG_IGN) {
 924         /* ignore sig */
 925     } else if (handler == TARGET_SIG_ERR) {
 926         dump_core_and_abort(sig);
 927     } else {
 928         /* compute the blocked signals during the handler execution */
 929         sigset_t *blocked_set;
 930
 931         target_to_host_sigset(&set, &sa->sa_mask);
 932         /*
 933          * SA_NODEFER indicates that the current signal should not be
 934          * blocked during the handler.
 935          */
 936         if (!(sa->sa_flags & TARGET_SA_NODEFER)) {
 937             sigaddset(&set, target_to_host_signal(sig));
 938         }
 939
 940         /*
 941          * Save the previous blocked signal state to restore it at the
 942          * end of the signal execution (see do_sigreturn).
 943          */
 944         host_to_target_sigset_internal(&target_old_set, &ts->signal_mask);
 945
 946         blocked_set = ts->in_sigsuspend ?
 947             &ts->sigsuspend_mask : &ts->signal_mask;
 948         sigorset(&ts->signal_mask, blocked_set, &set);
 949         ts->in_sigsuspend = false;
 950         sigprocmask(SIG_SETMASK, &ts->signal_mask, NULL);
 951
 952         /* XXX VM86 on x86 ??? */
 953
 954         code = k->info.si_code; /* From host, so no si_type */
 955         /* prepare the stack frame of the virtual CPU */
 956         if (sa->sa_flags & TARGET_SA_SIGINFO) {
 957             tswap_siginfo(&tinfo, &k->info);
 958             setup_frame(sig, code, sa, &target_old_set, &tinfo, env);
 959         } else {
 960             setup_frame(sig, code, sa, &target_old_set, NULL, env);
 961         }
 962         if (sa->sa_flags & TARGET_SA_RESETHAND) {
 963             sa->_sa_handler = TARGET_SIG_DFL;
 964         }
 965     }
 966 }
 967
 968 void process_pending_signals(CPUArchState *env)
 969 {
 970     CPUState *cpu = env_cpu(env);
 971     int sig;
 972     sigset_t *blocked_set, set;
 973     struct emulated_sigtable *k;
 974     TaskState *ts = get_task_state(cpu);
 975
 976     while (qatomic_read(&ts->signal_pending)) {
 977         sigfillset(&set);
 978         sigprocmask(SIG_SETMASK, &set, 0);
 979
 980     restart_scan:
 981         sig = ts->sync_signal.pending;
 982         if (sig) {
 983             /*
 984              * Synchronous signals are forced by the emulated CPU in some way.
 985              * If they are set to ignore, restore the default handler (see
 986              * sys/kern_sig.c trapsignal() and execsigs() for this behavior)
 987              * though maybe this is done only when forcing exit for non SIGCHLD.
 988              */
 989             if (sigismember(&ts->signal_mask, target_to_host_signal(sig)) ||
 990                 sigact_table[sig - 1]._sa_handler == TARGET_SIG_IGN) {
 991                 sigdelset(&ts->signal_mask, target_to_host_signal(sig));
 992                 sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL;
 993             }
 994             handle_pending_signal(env, sig, &ts->sync_signal);
 995         }
 996
 997         k = ts->sigtab;
 998         for (sig = 1; sig <= TARGET_NSIG; sig++, k++) {
 999             blocked_set = ts->in_sigsuspend ?
1000                 &ts->sigsuspend_mask : &ts->signal_mask;
1001             if (k->pending &&
1002                 !sigismember(blocked_set, target_to_host_signal(sig))) {
1003                 handle_pending_signal(env, sig, k);
1004                 /*
1005                  * Restart scan from the beginning, as handle_pending_signal
1006                  * might have resulted in a new synchronous signal (eg SIGSEGV).
1007                  */
1008                 goto restart_scan;
1009             }
1010         }
1011
1012         /*
1013          * Unblock signals and check one more time. Unblocking signals may cause
1014          * us to take another host signal, which will set signal_pending again.
1015          */
1016         qatomic_set(&ts->signal_pending, 0);
1017         ts->in_sigsuspend = false;
1018         set = ts->signal_mask;
1019         sigdelset(&set, SIGSEGV);
1020         sigdelset(&set, SIGBUS);
1021         sigprocmask(SIG_SETMASK, &set, 0);
1022     }
1023     ts->in_sigsuspend = false;
1024 }
1025
1026 void cpu_loop_exit_sigsegv(CPUState *cpu, target_ulong addr,
1027                            MMUAccessType access_type, bool maperr, uintptr_t ra)
1028 {
1029     const TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops;
1030
1031     if (tcg_ops->record_sigsegv) {
1032         tcg_ops->record_sigsegv(cpu, addr, access_type, maperr, ra);
1033     }
1034
1035     force_sig_fault(TARGET_SIGSEGV,
1036                     maperr ? TARGET_SEGV_MAPERR : TARGET_SEGV_ACCERR,
1037                     addr);
1038     cpu->exception_index = EXCP_INTERRUPT;
1039     cpu_loop_exit_restore(cpu, ra);
1040 }
1041
1042 void cpu_loop_exit_sigbus(CPUState *cpu, target_ulong addr,
1043                           MMUAccessType access_type, uintptr_t ra)
1044 {
1045     const TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops;
1046
1047     if (tcg_ops->record_sigbus) {
1048         tcg_ops->record_sigbus(cpu, addr, access_type, ra);
1049     }
1050
1051     force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN, addr);
1052     cpu->exception_index = EXCP_INTERRUPT;
1053     cpu_loop_exit_restore(cpu, ra);
1054 }