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