darwin-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, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  19  *  MA 02110-1301, USA.
  20  */
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <stdarg.h>
  25 #include <unistd.h>
  26 #include <signal.h>
  27 #include <errno.h>
  28 #include <sys/ucontext.h>
  29
  30 #ifdef __ia64__
  31 #undef uc_mcontext
  32 #undef uc_sigmask
  33 #undef uc_stack
  34 #undef uc_link
  35 #endif
  36
  37 #include <signal.h>
  38
  39 #include "qemu.h"
  40 #include "qemu-common.h"
  41
  42 #define DEBUG_SIGNAL
  43
  44 #define MAX_SIGQUEUE_SIZE 1024
  45
  46 struct sigqueue {
  47     struct sigqueue *next;
  48     target_siginfo_t info;
  49 };
  50
  51 struct emulated_sigaction {
  52     struct target_sigaction sa;
  53     int pending; /* true if signal is pending */
  54     struct sigqueue *first;
  55     struct sigqueue info; /* in order to always have memory for the
  56                              first signal, we put it here */
  57 };
  58
  59 static struct sigaltstack target_sigaltstack_used = {
  60     0, 0, SA_DISABLE
  61 };
  62
  63 static struct emulated_sigaction sigact_table[NSIG];
  64 static struct sigqueue sigqueue_table[MAX_SIGQUEUE_SIZE]; /* siginfo queue */
  65 static struct sigqueue *first_free; /* first free siginfo queue entry */
  66 static int signal_pending; /* non zero if a signal may be pending */
  67
  68 static void host_signal_handler(int host_signum, siginfo_t *info,
  69                                 void *puc);
  70
  71
  72 static inline int host_to_target_signal(int sig)
  73 {
  74     return sig;
  75 }
  76
  77 static inline int target_to_host_signal(int sig)
  78 {
  79     return sig;
  80 }
  81
  82 /* siginfo conversion */
  83
  84
  85
  86 void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info)
  87 {
  88
  89 }
  90
  91 void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo)
  92 {
  93
  94 }
  95
  96 void signal_init(void)
  97 {
  98     struct sigaction act;
  99     int i;
 100
 101     /* set all host signal handlers. ALL signals are blocked during
 102        the handlers to serialize them. */
 103     sigfillset(&act.sa_mask);
 104     act.sa_flags = SA_SIGINFO;
 105     act.sa_sigaction = host_signal_handler;
 106     for(i = 1; i < NSIG; i++) {
 107         sigaction(i, &act, NULL);
 108     }
 109
 110     memset(sigact_table, 0, sizeof(sigact_table));
 111
 112     first_free = &sigqueue_table[0];
 113     for(i = 0; i < MAX_SIGQUEUE_SIZE - 1; i++)
 114         sigqueue_table[i].next = &sigqueue_table[i + 1];
 115     sigqueue_table[MAX_SIGQUEUE_SIZE - 1].next = NULL;
 116 }
 117
 118 /* signal queue handling */
 119
 120 static inline struct sigqueue *alloc_sigqueue(void)
 121 {
 122     struct sigqueue *q = first_free;
 123     if (!q)
 124         return NULL;
 125     first_free = q->next;
 126     return q;
 127 }
 128
 129 static inline void free_sigqueue(struct sigqueue *q)
 130 {
 131     q->next = first_free;
 132     first_free = q;
 133 }
 134
 135 /* abort execution with signal */
 136 void QEMU_NORETURN force_sig(int sig)
 137 {
 138     int host_sig;
 139     host_sig = target_to_host_signal(sig);
 140     fprintf(stderr, "qemu: uncaught target signal %d (%s) - exiting\n",
 141             sig, strsignal(host_sig));
 142     _exit(-host_sig);
 143 }
 144
 145 /* queue a signal so that it will be send to the virtual CPU as soon
 146    as possible */
 147 int queue_signal(int sig, target_siginfo_t *info)
 148 {
 149     struct emulated_sigaction *k;
 150     struct sigqueue *q, **pq;
 151     target_ulong handler;
 152
 153 #if defined(DEBUG_SIGNAL)
 154     fprintf(stderr, "queue_signal: sig=%d\n",
 155             sig);
 156 #endif
 157     k = &sigact_table[sig - 1];
 158     handler = (target_ulong)k->sa.sa_handler;
 159     if (handler == SIG_DFL) {
 160         /* default handler : ignore some signal. The other are fatal */
 161         if (sig != SIGCHLD &&
 162             sig != SIGURG &&
 163             sig != SIGWINCH) {
 164             force_sig(sig);
 165         } else {
 166             return 0; /* indicate ignored */
 167         }
 168     } else if (handler == host_to_target_signal(SIG_IGN)) {
 169         /* ignore signal */
 170         return 0;
 171     } else if (handler == host_to_target_signal(SIG_ERR)) {
 172         force_sig(sig);
 173     } else {
 174         pq = &k->first;
 175         if (!k->pending) {
 176             /* first signal */
 177             q = &k->info;
 178         } else {
 179             q = alloc_sigqueue();
 180             if (!q)
 181                 return -EAGAIN;
 182             while (*pq != NULL)
 183                 pq = &(*pq)->next;
 184         }
 185         *pq = q;
 186         q->info = *info;
 187         q->next = NULL;
 188         k->pending = 1;
 189         /* signal that a new signal is pending */
 190         signal_pending = 1;
 191         return 1; /* indicates that the signal was queued */
 192     }
 193 }
 194
 195 static void host_signal_handler(int host_signum, siginfo_t *info,
 196                                 void *puc)
 197 {
 198     int sig;
 199     target_siginfo_t tinfo;
 200
 201     /* the CPU emulator uses some host signals to detect exceptions,
 202        we we forward to it some signals */
 203     if (host_signum == SIGSEGV || host_signum == SIGBUS) {
 204         if (cpu_signal_handler(host_signum, (void*)info, puc))
 205             return;
 206     }
 207
 208     /* get target signal number */
 209     sig = host_to_target_signal(host_signum);
 210     if (sig < 1 || sig > NSIG)
 211         return;
 212
 213 #if defined(DEBUG_SIGNAL)
 214         fprintf(stderr, "qemu: got signal %d\n", sig);
 215 #endif
 216     if (queue_signal(sig, &tinfo) == 1) {
 217         /* interrupt the virtual CPU as soon as possible */
 218         cpu_exit(global_env);
 219     }
 220 }
 221
 222 int do_sigaltstack(const struct sigaltstack *ss, struct sigaltstack *oss)
 223 {
 224     /* XXX: test errors */
 225     if(oss)
 226     {
 227         oss->ss_sp = tswap32(target_sigaltstack_used.ss_sp);
 228         oss->ss_size = tswap32(target_sigaltstack_used.ss_size);
 229         oss->ss_flags = tswap32(target_sigaltstack_used.ss_flags);
 230     }
 231     if(ss)
 232     {
 233         target_sigaltstack_used.ss_sp = tswap32(ss->ss_sp);
 234         target_sigaltstack_used.ss_size = tswap32(ss->ss_size);
 235         target_sigaltstack_used.ss_flags = tswap32(ss->ss_flags);
 236     }
 237     return 0;
 238 }
 239
 240 int do_sigaction(int sig, const struct sigaction *act,
 241                  struct sigaction *oact)
 242 {
 243     struct emulated_sigaction *k;
 244     struct sigaction act1;
 245     int host_sig;
 246
 247     if (sig < 1 || sig > NSIG)
 248         return -EINVAL;
 249
 250     k = &sigact_table[sig - 1];
 251 #if defined(DEBUG_SIGNAL)
 252     fprintf(stderr, "sigaction 1 sig=%d act=0x%08x, oact=0x%08x\n",
 253             sig, (int)act, (int)oact);
 254 #endif
 255     if (oact) {
 256 #if defined(DEBUG_SIGNAL)
 257     fprintf(stderr, "sigaction 1 sig=%d act=0x%08x, oact=0x%08x\n",
 258             sig, (int)act, (int)oact);
 259 #endif
 260
 261         oact->sa_handler = tswapl(k->sa.sa_handler);
 262         oact->sa_flags = tswapl(k->sa.sa_flags);
 263         oact->sa_mask = tswapl(k->sa.sa_mask);
 264     }
 265     if (act) {
 266 #if defined(DEBUG_SIGNAL)
 267     fprintf(stderr, "sigaction handler 0x%x flag 0x%x mask 0x%x\n",
 268             act->sa_handler, act->sa_flags, act->sa_mask);
 269 #endif
 270
 271         k->sa.sa_handler = tswapl(act->sa_handler);
 272         k->sa.sa_flags = tswapl(act->sa_flags);
 273         k->sa.sa_mask = tswapl(act->sa_mask);
 274         /* we update the host signal state */
 275         host_sig = target_to_host_signal(sig);
 276         if (host_sig != SIGSEGV && host_sig != SIGBUS) {
 277 #if defined(DEBUG_SIGNAL)
 278     fprintf(stderr, "sigaction handler going to call sigaction\n",
 279             act->sa_handler, act->sa_flags, act->sa_mask);
 280 #endif
 281
 282             sigfillset(&act1.sa_mask);
 283             act1.sa_flags = SA_SIGINFO;
 284             if (k->sa.sa_flags & SA_RESTART)
 285                 act1.sa_flags |= SA_RESTART;
 286             /* NOTE: it is important to update the host kernel signal
 287                ignore state to avoid getting unexpected interrupted
 288                syscalls */
 289             if (k->sa.sa_handler == SIG_IGN) {
 290                 act1.sa_sigaction = (void *)SIG_IGN;
 291             } else if (k->sa.sa_handler == SIG_DFL) {
 292                 act1.sa_sigaction = (void *)SIG_DFL;
 293             } else {
 294                 act1.sa_sigaction = host_signal_handler;
 295             }
 296             sigaction(host_sig, &act1, NULL);
 297         }
 298     }
 299     return 0;
 300 }
 301
 302
 303 #ifdef TARGET_I386
 304
 305 static inline void *
 306 get_sigframe(struct emulated_sigaction *ka, CPUX86State *env, size_t frame_size)
 307 {
 308     /* XXX Fix that */
 309     if(target_sigaltstack_used.ss_flags & SA_DISABLE)
 310     {
 311         int esp;
 312         /* Default to using normal stack */
 313         esp = env->regs[R_ESP];
 314
 315         return (void *)((esp - frame_size) & -8ul);
 316     }
 317     else
 318     {
 319         return target_sigaltstack_used.ss_sp;
 320     }
 321 }
 322
 323 static void setup_frame(int sig, struct emulated_sigaction *ka,
 324                         void *set, CPUState *env)
 325 {
 326         void *frame;
 327         int i, err = 0;
 328
 329     fprintf(stderr, "setup_frame %d\n", sig);
 330         frame = get_sigframe(ka, env, sizeof(*frame));
 331
 332         /* Set up registers for signal handler */
 333         env->regs[R_ESP] = (unsigned long) frame;
 334         env->eip = (unsigned long) ka->sa.sa_handler;
 335
 336         env->eflags &= ~TF_MASK;
 337
 338         return;
 339
 340 give_sigsegv:
 341         if (sig == SIGSEGV)
 342                 ka->sa.sa_handler = SIG_DFL;
 343         force_sig(SIGSEGV /* , current */);
 344 }
 345
 346 long do_sigreturn(CPUState *env, int num)
 347 {
 348     int i = 0;
 349     struct target_sigcontext *scp = get_int_arg(&i, env);
 350     /* XXX Get current signal number */
 351     /* XXX Adjust accordin to sc_onstack, sc_mask */
 352     if(tswapl(scp->sc_onstack) & 0x1)
 353         target_sigaltstack_used.ss_flags |= ~SA_DISABLE;
 354     else
 355         target_sigaltstack_used.ss_flags &=  SA_DISABLE;
 356     int set = tswapl(scp->sc_eax);
 357     sigprocmask(SIG_SETMASK, &set, NULL);
 358
 359     fprintf(stderr, "do_sigreturn: partially implemented %x EAX:%x EBX:%x\n", scp->sc_mask, tswapl(scp->sc_eax), tswapl(scp->sc_ebx));
 360     fprintf(stderr, "ECX:%x EDX:%x EDI:%x\n", scp->sc_ecx, tswapl(scp->sc_edx), tswapl(scp->sc_edi));
 361     fprintf(stderr, "EIP:%x\n", tswapl(scp->sc_eip));
 362
 363     env->regs[R_EAX] = tswapl(scp->sc_eax);
 364     env->regs[R_EBX] = tswapl(scp->sc_ebx);
 365     env->regs[R_ECX] = tswapl(scp->sc_ecx);
 366     env->regs[R_EDX] = tswapl(scp->sc_edx);
 367     env->regs[R_EDI] = tswapl(scp->sc_edi);
 368     env->regs[R_ESI] = tswapl(scp->sc_esi);
 369     env->regs[R_EBP] = tswapl(scp->sc_ebp);
 370     env->regs[R_ESP] = tswapl(scp->sc_esp);
 371     env->segs[R_SS].selector = (void*)tswapl(scp->sc_ss);
 372     env->eflags = tswapl(scp->sc_eflags);
 373     env->eip = tswapl(scp->sc_eip);
 374     env->segs[R_CS].selector = (void*)tswapl(scp->sc_cs);
 375     env->segs[R_DS].selector = (void*)tswapl(scp->sc_ds);
 376     env->segs[R_ES].selector = (void*)tswapl(scp->sc_es);
 377     env->segs[R_FS].selector = (void*)tswapl(scp->sc_fs);
 378     env->segs[R_GS].selector = (void*)tswapl(scp->sc_gs);
 379
 380     /* Again, because our caller's caller will reset EAX */
 381     return env->regs[R_EAX];
 382 }
 383
 384 #else
 385
 386 static void setup_frame(int sig, struct emulated_sigaction *ka,
 387                         void *set, CPUState *env)
 388 {
 389     fprintf(stderr, "setup_frame: not implemented\n");
 390 }
 391
 392 long do_sigreturn(CPUState *env, int num)
 393 {
 394     int i = 0;
 395     struct target_sigcontext *scp = get_int_arg(&i, env);
 396     fprintf(stderr, "do_sigreturn: not implemented\n");
 397     return -ENOSYS;
 398 }
 399
 400 #endif
 401
 402 void process_pending_signals(void *cpu_env)
 403 {
 404     struct emulated_sigaction *k;
 405     struct sigqueue *q;
 406     target_ulong handler;
 407     int sig;
 408
 409     if (!signal_pending)
 410         return;
 411
 412     k = sigact_table;
 413
 414     for(sig = 1; sig <= NSIG; sig++) {
 415         if (k->pending)
 416             goto handle_signal;
 417         k++;
 418     }
 419
 420     /* if no signal is pending, just return */
 421     signal_pending = 0;
 422     return;
 423 handle_signal:
 424     #ifdef DEBUG_SIGNAL
 425     fprintf(stderr, "qemu: process signal %d\n", sig);
 426     #endif
 427     /* dequeue signal */
 428     q = k->first;
 429     k->first = q->next;
 430     if (!k->first)
 431         k->pending = 0;
 432
 433     sig = gdb_handlesig (cpu_env, sig);
 434     if (!sig) {
 435         fprintf (stderr, "Lost signal\n");
 436         abort();
 437     }
 438
 439     handler = k->sa.sa_handler;
 440     if (handler == SIG_DFL) {
 441         /* default handler : ignore some signal. The other are fatal */
 442         if (sig != SIGCHLD &&
 443             sig != SIGURG &&
 444             sig != SIGWINCH) {
 445             force_sig(sig);
 446         }
 447     } else if (handler == SIG_IGN) {
 448         /* ignore sig */
 449     } else if (handler == SIG_ERR) {
 450         force_sig(sig);
 451     } else {
 452
 453         setup_frame(sig, k, 0, cpu_env);
 454         if (k->sa.sa_flags & SA_RESETHAND)
 455             k->sa.sa_handler = SIG_DFL;
 456     }
 457     if (q != &k->info)
 458         free_sigqueue(q);
 459 }