src/runtime/x86-64-darwin-os.c

   1 #ifdef LISP_FEATURE_SB_THREAD
   2 #include <architecture/i386/table.h>
   3 #include <i386/user_ldt.h>
   4 #include <mach/mach_init.h>
   5 #endif
   6
   7 #include "thread.h"
   8 #include "validate.h"
   9 #include "runtime.h"
  10 #include "interrupt.h"
  11 #include "x86-64-darwin-os.h"
  12 #include "genesis/fdefn.h"
  13
  14 #include <mach/mach.h>
  15 #include <mach/mach_error.h>
  16 #include <mach/mach_types.h>
  17 #include <mach/sync_policy.h>
  18 #include <mach/machine/thread_state.h>
  19 #include <mach/machine/thread_status.h>
  20 #include <sys/_types.h>
  21 #include <sys/ucontext.h>
  22 #include <pthread.h>
  23 #include <assert.h>
  24 #include <stdlib.h>
  25 #include <stdio.h>
  26
  27 #if __DARWIN_UNIX03
  28 #include <sys/_structs.h>
  29 #endif
  30
  31 #if __DARWIN_UNIX03
  32
  33 typedef struct __darwin_ucontext darwin_ucontext;
  34 typedef struct __darwin_mcontext64 darwin_mcontext;
  35
  36 #define rip __rip
  37 #define rsp __rsp
  38 #define rbp __rbp
  39 #define rax __rax
  40 #define rbx __rbx
  41 #define rcx __rcx
  42 #define rdx __rdx
  43 #define rsi __rsi
  44 #define rdi __rdi
  45 #define r8 __r8
  46 #define r9 __r9
  47 #define faultvaddr __faultvaddr
  48 #define ss __ss
  49 #define es __es
  50 #define fs __fs
  51
  52 #else
  53
  54 typedef struct ucontext darwin_ucontext;
  55 typedef struct mcontext darwin_mcontext;
  56
  57 #endif
  58
  59 #ifdef LISP_FEATURE_SB_THREAD
  60 pthread_mutex_t mach_exception_lock = PTHREAD_MUTEX_INITIALIZER;
  61 #endif
  62
  63 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
  64
  65 kern_return_t mach_thread_init(mach_port_t thread_exception_port);
  66
  67 void sigill_handler(int signal, siginfo_t *siginfo, os_context_t *context);
  68 void sigtrap_handler(int signal, siginfo_t *siginfo, os_context_t *context);
  69 void memory_fault_handler(int signal, siginfo_t *siginfo,
  70                           os_context_t *context);
  71
  72 /* exc_server handles mach exception messages from the kernel and
  73  * calls catch exception raise. We use the system-provided
  74  * mach_msg_server, which, I assume, calls exc_server in a loop.
  75  *
  76  */
  77 extern boolean_t exc_server();
  78
  79 /* This executes in the faulting thread as part of the signal
  80  * emulation.  It is passed a context with the uc_mcontext field
  81  * pointing to a valid block of memory. */
  82 void build_fake_signal_context(darwin_ucontext *context,
  83                                x86_thread_state64_t *thread_state,
  84                                x86_float_state64_t *float_state) {
  85     pthread_sigmask(0, NULL, &context->uc_sigmask);
  86     context->uc_mcontext->ss = *thread_state;
  87     context->uc_mcontext->fs = *float_state;
  88 }
  89
  90 /* This executes in the faulting thread as part of the signal
  91  * emulation.  It is effectively the inverse operation from above. */
  92 void update_thread_state_from_context(x86_thread_state64_t *thread_state,
  93                                       x86_float_state64_t *float_state,
  94                                       darwin_ucontext  *context) {
  95     *thread_state = context->uc_mcontext->ss;
  96     *float_state = context->uc_mcontext->fs;
  97     pthread_sigmask(SIG_SETMASK, &context->uc_sigmask, NULL);
  98 }
  99
 100 /* Modify a context to push new data on its stack. */
 101 void push_context(u64 data, x86_thread_state64_t *context)
 102 {
 103     u64 *stack_pointer;
 104
 105     stack_pointer = (u64*) context->rsp;
 106     *(--stack_pointer) = data;
 107     context->rsp = (u64) stack_pointer;
 108 }
 109
 110 void align_context_stack(x86_thread_state64_t *context)
 111 {
 112     /* 16byte align the stack (provided that the stack is, as it
 113      * should be, 8byte aligned. */
 114     while (context->rsp & 15) push_context(0, context);
 115 }
 116
 117 /* Stack allocation starts with a context that has a mod-4 ESP value
 118  * and needs to leave a context with a mod-16 ESP that will restore
 119  * the old ESP value and other register state when activated.  The
 120  * first part of this is the recovery trampoline, which loads ESP from
 121  * EBP, pops EBP, and returns. */
 122 asm(".globl _stack_allocation_recover; .align 4; _stack_allocation_recover: mov %rbp, %rsp; pop %rsi; pop %rdi; pop \
 123 %rdx; pop %rcx; pop %r8; pop %r9; pop %rbp; ret;");
 124
 125 void open_stack_allocation(x86_thread_state64_t *context)
 126 {
 127     void stack_allocation_recover(void);
 128
 129     push_context(context->rip, context);
 130     push_context(context->rbp, context);
 131
 132     push_context(context->r9, context);
 133     push_context(context->r8, context);
 134     push_context(context->rcx, context);
 135     push_context(context->rdx, context);
 136     push_context(context->rsi, context);
 137     push_context(context->rdi, context);
 138
 139     context->rbp = context->rsp;
 140     context->rip = (u64) stack_allocation_recover;
 141
 142     align_context_stack(context);
 143 }
 144
 145 /* Stack allocation of data starts with a context with a mod-16 ESP
 146  * value and reserves some space on it by manipulating the ESP
 147  * register. */
 148 void *stack_allocate(x86_thread_state64_t *context, size_t size)
 149 {
 150     /* round up size to 16byte multiple */
 151     size = (size + 15) & -16;
 152
 153     context->rsp = ((u64)context->rsp) - size;
 154
 155     return (void *)context->rsp;
 156 }
 157
 158 /* Arranging to invoke a C function is tricky, as we have to assume
 159  * cdecl calling conventions (caller removes args) and x86/darwin
 160  * alignment requirements.  The simplest way to arrange this,
 161  * actually, is to open a new stack allocation.
 162  * WARNING!!! THIS DOES NOT PRESERVE REGISTERS! */
 163 void call_c_function_in_context(x86_thread_state64_t *context,
 164                                 void *function,
 165                                 int nargs,
 166                                 ...)
 167 {
 168     va_list ap;
 169     int i;
 170     u64 *stack_pointer;
 171
 172     /* Set up to restore stack on exit. */
 173     open_stack_allocation(context);
 174
 175     /* Have to keep stack 16byte aligned on x86/darwin. */
 176     for (i = (1 & -nargs); i; i--) {
 177         push_context(0, context);
 178     }
 179
 180     context->rsp = ((u64)context->rsp) - nargs * 8;
 181     stack_pointer = (u64 *)context->rsp;
 182
 183     va_start(ap, nargs);
 184     if (nargs > 0) context->rdi = va_arg(ap, u64);
 185     if (nargs > 1) context->rsi = va_arg(ap, u64);
 186     if (nargs > 2) context->rdx = va_arg(ap, u64);
 187     if (nargs > 3) context->rcx = va_arg(ap, u64);
 188     if (nargs > 4) context->r8 = va_arg(ap, u64);
 189     if (nargs > 5) context->r9 = va_arg(ap, u64);
 190     for (i = 6; i < nargs; i++) {
 191         stack_pointer[i] = va_arg(ap, u64);
 192     }
 193     va_end(ap);
 194
 195     push_context(context->rip, context);
 196     context->rip = (u64) function;
 197 }
 198
 199 void signal_emulation_wrapper(x86_thread_state64_t *thread_state,
 200                               x86_float_state64_t *float_state,
 201                               int signal,
 202                               siginfo_t *siginfo,
 203                               void (*handler)(int, siginfo_t *, void *))
 204 {
 205
 206     /* CLH: FIXME **NOTE: HACK ALERT!** Ideally, we would allocate
 207      * context and regs on the stack as local variables, but this
 208      * causes problems for the lisp debugger. When it walks the stack
 209      * for a back trace, it sees the 1) address of the local variable
 210      * on the stack and thinks that is a frame pointer to a lisp
 211      * frame, and, 2) the address of the sap that we alloc'ed in
 212      * dynamic space and thinks that is a return address, so it,
 213      * heuristicly (and wrongly), chooses that this should be
 214      * interpreted as a lisp frame instead of as a C frame.
 215      * We can work around this in this case by os_validating the
 216      * context (and regs just for symmetry).
 217      */
 218
 219     darwin_ucontext  *context;
 220     darwin_mcontext *regs;
 221
 222     context = (darwin_ucontext *) os_validate(0, sizeof(darwin_ucontext));
 223     regs = (darwin_mcontext*) os_validate(0, sizeof(darwin_mcontext));
 224     context->uc_mcontext = regs;
 225
 226     /* when BSD signals are fired, they mask they signals in sa_mask
 227        which always seem to be the blockable_sigset, for us, so we
 228        need to:
 229        1) save the current sigmask
 230        2) block blockable signals
 231        3) call the signal handler
 232        4) restore the sigmask */
 233
 234     build_fake_signal_context(context, thread_state, float_state);
 235
 236     block_blockable_signals(0, 0);
 237
 238     handler(signal, siginfo, context);
 239
 240     update_thread_state_from_context(thread_state, float_state, context);
 241
 242     os_invalidate((os_vm_address_t)context, sizeof(darwin_ucontext));
 243     os_invalidate((os_vm_address_t)regs, sizeof(darwin_mcontext));
 244
 245     /* Trap to restore the signal context. */
 246     asm volatile ("mov %0, %%rax; mov %1, %%rbx; .quad 0xffffffffffff0b0f"
 247                   : : "r" (thread_state), "r" (float_state));
 248 }
 249
 250 #if defined DUMP_CONTEXT
 251 void dump_context(x86_thread_state64_t *context)
 252 {
 253     int i;
 254     u64 *stack_pointer;
 255
 256     printf("rax: %08lx  rcx: %08lx  rdx: %08lx  rbx: %08lx\n",
 257            context->rax, context->rcx, context->rdx, context->rbx);
 258     printf("rsp: %08lx  rbp: %08lx  rsi: %08lx  rdi: %08lx\n",
 259            context->rsp, context->rbp, context->rsi, context->rdi);
 260     printf("rip: %08lx  eflags: %08lx\n",
 261            context->rip, context->rflags);
 262     printf("cs: %04hx  ds: %04hx  es: %04hx  "
 263            "ss: %04hx  fs: %04hx  gs: %04hx\n",
 264            context->cs, context->ds, context->rs,
 265            context->ss, context->fs, context->gs);
 266
 267     stack_pointer = (u64 *)context->rsp;
 268     for (i = 0; i < 48; i+=4) {
 269         printf("%08x:  %08x %08x %08x %08x\n",
 270                context->rsp + (i * 4),
 271                stack_pointer[i],
 272                stack_pointer[i+1],
 273                stack_pointer[i+2],
 274                stack_pointer[i+3]);
 275     }
 276 }
 277 #endif
 278
 279 void
 280 control_stack_exhausted_handler(int signal, siginfo_t *siginfo,
 281                                 os_context_t *context) {
 282     unblock_signals_in_context_and_maybe_warn(context);
 283     arrange_return_to_lisp_function
 284         (context, StaticSymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
 285 }
 286
 287 void
 288 undefined_alien_handler(int signal, siginfo_t *siginfo, os_context_t *context) {
 289     arrange_return_to_lisp_function
 290         (context, StaticSymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
 291 }
 292
 293 kern_return_t
 294 catch_exception_raise(mach_port_t exception_port,
 295                       mach_port_t thread,
 296                       mach_port_t task,
 297                       exception_type_t exception,
 298                       exception_data_t code_vector,
 299                       mach_msg_type_number_t code_count)
 300 {
 301     kern_return_t ret;
 302     int signal;
 303     siginfo_t* siginfo;
 304
 305 #ifdef LISP_FEATURE_SB_THREAD
 306     thread_mutex_lock(&mach_exception_lock);
 307 #endif
 308
 309     x86_thread_state64_t thread_state;
 310     mach_msg_type_number_t thread_state_count = x86_THREAD_STATE64_COUNT;
 311
 312     x86_float_state64_t float_state;
 313     mach_msg_type_number_t float_state_count = x86_FLOAT_STATE64_COUNT;
 314
 315     x86_exception_state64_t exception_state;
 316     mach_msg_type_number_t exception_state_count = x86_EXCEPTION_STATE64_COUNT;
 317
 318     x86_thread_state64_t backup_thread_state;
 319     x86_thread_state64_t *target_thread_state;
 320     x86_float_state64_t *target_float_state;
 321
 322     os_vm_address_t addr;
 323
 324     struct thread *th = (struct thread*) exception_port;
 325
 326     FSHOW((stderr,"/entering catch_exception_raise with exception: %d\n", exception));
 327
 328     switch (exception) {
 329
 330     case EXC_BAD_ACCESS:
 331         signal = SIGBUS;
 332         ret = thread_get_state(thread,
 333                                x86_THREAD_STATE64,
 334                                (thread_state_t)&thread_state,
 335                                &thread_state_count);
 336         ret = thread_get_state(thread,
 337                                x86_FLOAT_STATE64,
 338                                (thread_state_t)&float_state,
 339                                &float_state_count);
 340         ret = thread_get_state(thread,
 341                                x86_EXCEPTION_STATE64,
 342                                (thread_state_t)&exception_state,
 343                                &exception_state_count);
 344         addr = (void*)exception_state.faultvaddr;
 345
 346
 347         /* note the os_context hackery here.  When the signal handler returns,
 348          * it won't go back to what it was doing ... */
 349         if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
 350            addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
 351             /* We hit the end of the control stack: disable guard page
 352              * protection so the error handler has some headroom, protect the
 353              * previous page so that we can catch returns from the guard page
 354              * and restore it. */
 355             lower_thread_control_stack_guard_page(th);
 356
 357             backup_thread_state = thread_state;
 358             open_stack_allocation(&thread_state);
 359             /* Reserve a 256 byte zone for signal handlers
 360              * to use on the interrupted thread stack.
 361              */
 362             stack_allocate(&thread_state, 256);
 363
 364             /* Save thread state */
 365             target_thread_state =
 366                 stack_allocate(&thread_state, sizeof(*target_thread_state));
 367             (*target_thread_state) = backup_thread_state;
 368
 369             /* Save float state */
 370             target_float_state =
 371                 stack_allocate(&thread_state, sizeof(*target_float_state));
 372             (*target_float_state) = float_state;
 373
 374             /* Set up siginfo */
 375             siginfo = stack_allocate(&thread_state, sizeof(*siginfo));
 376             /* what do we need to put in our fake siginfo?  It looks like
 377              * the x86 code only uses si_signo and si_adrr. */
 378             siginfo->si_signo = signal;
 379             siginfo->si_addr = (void*)exception_state.faultvaddr;
 380
 381             call_c_function_in_context(&thread_state,
 382                                        signal_emulation_wrapper,
 383                                        5,
 384                                        target_thread_state,
 385                                        target_float_state,
 386                                        signal,
 387                                        siginfo,
 388                                        control_stack_exhausted_handler);
 389         }
 390         else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
 391                 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
 392             /* We're returning from the guard page: reprotect it, and
 393              * unprotect this one. This works even if we somehow missed
 394              * the return-guard-page, and hit it on our way to new
 395              * exhaustion instead. */
 396             reset_thread_control_stack_guard_page(th);
 397         }
 398         else if (addr >= undefined_alien_address &&
 399                  addr < undefined_alien_address + os_vm_page_size) {
 400             backup_thread_state = thread_state;
 401             open_stack_allocation(&thread_state);
 402             stack_allocate(&thread_state, 256);
 403
 404             /* Save thread state */
 405             target_thread_state =
 406                 stack_allocate(&thread_state, sizeof(*target_thread_state));
 407             (*target_thread_state) = backup_thread_state;
 408
 409             target_float_state =
 410                 stack_allocate(&thread_state, sizeof(*target_float_state));
 411             (*target_float_state) = float_state;
 412
 413             /* Set up siginfo */
 414             siginfo = stack_allocate(&thread_state, sizeof(*siginfo));
 415             /* what do we need to put in our fake siginfo?  It looks like
 416              * the x86 code only uses si_signo and si_adrr. */
 417             siginfo->si_signo = signal;
 418             siginfo->si_addr = (void*)exception_state.faultvaddr;
 419
 420             call_c_function_in_context(&thread_state,
 421                                        signal_emulation_wrapper,
 422                                        5,
 423                                        target_thread_state,
 424                                        target_float_state,
 425                                        signal,
 426                                        siginfo,
 427                                        undefined_alien_handler);
 428         } else {
 429
 430             backup_thread_state = thread_state;
 431             open_stack_allocation(&thread_state);
 432             stack_allocate(&thread_state, 256);
 433
 434             /* Save thread state */
 435             target_thread_state =
 436                 stack_allocate(&thread_state, sizeof(*target_thread_state));
 437             (*target_thread_state) = backup_thread_state;
 438
 439             target_float_state =
 440                 stack_allocate(&thread_state, sizeof(*target_float_state));
 441             (*target_float_state) = float_state;
 442
 443             /* Set up siginfo */
 444             siginfo = stack_allocate(&thread_state, sizeof(*siginfo));
 445             /* what do we need to put in our fake siginfo?  It looks like
 446              * the x86 code only uses si_signo and si_adrr. */
 447             siginfo->si_signo = signal;
 448             siginfo->si_addr = (void*)exception_state.faultvaddr;
 449
 450             call_c_function_in_context(&thread_state,
 451                                        signal_emulation_wrapper,
 452                                        5,
 453                                        target_thread_state,
 454                                        target_float_state,
 455                                        signal,
 456                                        siginfo,
 457                                        memory_fault_handler);
 458         }
 459         ret = thread_set_state(thread,
 460                                x86_THREAD_STATE64,
 461                                (thread_state_t)&thread_state,
 462                                thread_state_count);
 463
 464         ret = thread_set_state(thread,
 465                                x86_FLOAT_STATE64,
 466                                (thread_state_t)&float_state,
 467                                float_state_count);
 468 #ifdef LISP_FEATURE_SB_THREAD
 469         thread_mutex_unlock(&mach_exception_lock);
 470 #endif
 471         return KERN_SUCCESS;
 472
 473     case EXC_BAD_INSTRUCTION:
 474
 475         ret = thread_get_state(thread,
 476                                x86_THREAD_STATE64,
 477                                (thread_state_t)&thread_state,
 478                                &thread_state_count);
 479         ret = thread_get_state(thread,
 480                                x86_FLOAT_STATE64,
 481                                (thread_state_t)&float_state,
 482                                &float_state_count);
 483         ret = thread_get_state(thread,
 484                                x86_EXCEPTION_STATE64,
 485                                (thread_state_t)&exception_state,
 486                                &exception_state_count);
 487         if (0xffffffffffff0b0f == *((u64 *)thread_state.rip)) {
 488             /* fake sigreturn. */
 489
 490             /* When we get here, thread_state.rax is a pointer to a
 491              * thread_state to restore. */
 492             /* thread_state = *((thread_state_t *)thread_state.rax); */
 493
 494             ret = thread_set_state(thread,
 495                                    x86_THREAD_STATE64,
 496                                    (thread_state_t) thread_state.rax,
 497                                    /* &thread_state, */
 498                                    thread_state_count);
 499
 500             ret = thread_set_state(thread,
 501                                    x86_FLOAT_STATE64,
 502                                    (thread_state_t) thread_state.rbx,
 503                                    /* &thread_state, */
 504                                    float_state_count);
 505         } else {
 506
 507             backup_thread_state = thread_state;
 508             open_stack_allocation(&thread_state);
 509             stack_allocate(&thread_state, 256);
 510
 511             /* Save thread state */
 512             target_thread_state =
 513                 stack_allocate(&thread_state, sizeof(*target_thread_state));
 514             (*target_thread_state) = backup_thread_state;
 515
 516             target_float_state =
 517                 stack_allocate(&thread_state, sizeof(*target_float_state));
 518             (*target_float_state) = float_state;
 519
 520             /* Set up siginfo */
 521             siginfo = stack_allocate(&thread_state, sizeof(*siginfo));
 522             /* what do we need to put in our fake siginfo?  It looks like
 523              * the x86 code only uses si_signo and si_adrr. */
 524             if (*((unsigned short *)target_thread_state->rip) == 0x0b0f) {
 525                 signal = SIGTRAP;
 526                 siginfo->si_signo = signal;
 527                 siginfo->si_addr = (void*)exception_state.faultvaddr;
 528                 target_thread_state->rip += 2;
 529                 call_c_function_in_context(&thread_state,
 530                                            signal_emulation_wrapper,
 531                                            5,
 532                                            target_thread_state,
 533                                            target_float_state,
 534                                            signal,
 535                                            siginfo,
 536                                            sigtrap_handler);
 537             } else {
 538                 signal = SIGILL;
 539                 siginfo->si_signo = signal;
 540                 siginfo->si_addr = (void*)exception_state.faultvaddr;
 541
 542                 call_c_function_in_context(&thread_state,
 543                                            signal_emulation_wrapper,
 544                                            5,
 545                                            target_thread_state,
 546                                            target_float_state,
 547                                            signal,
 548                                            siginfo,
 549                                            sigill_handler);
 550             }
 551             ret = thread_set_state(thread,
 552                                    x86_THREAD_STATE64,
 553                                    (thread_state_t)&thread_state,
 554                                    thread_state_count);
 555             ret = thread_set_state(thread,
 556                                    x86_FLOAT_STATE64,
 557                                    (thread_state_t)&float_state,
 558                                    float_state_count);
 559         }
 560 #ifdef LISP_FEATURE_SB_THREAD
 561         thread_mutex_unlock(&mach_exception_lock);
 562 #endif
 563         return KERN_SUCCESS;
 564
 565     default:
 566 #ifdef LISP_FEATURE_SB_THREAD
 567         thread_mutex_unlock(&mach_exception_lock);
 568 #endif
 569         return KERN_INVALID_RIGHT;
 570     }
 571 }
 572
 573 void *
 574 mach_exception_handler(void *port)
 575 {
 576   mach_msg_server(exc_server, 2048, (mach_port_t) port, 0);
 577   /* mach_msg_server should never return, but it should dispatch mach
 578    * exceptions to our catch_exception_raise function
 579    */
 580   lose("mach_msg_server returned");
 581 }
 582
 583 /* Sets up the thread that will listen for mach exceptions. note that
 584    the exception handlers will be run on this thread. This is
 585    different from the BSD-style signal handling situation in which the
 586    signal handlers run in the relevant thread directly. */
 587
 588 mach_port_t mach_exception_handler_port_set = MACH_PORT_NULL;
 589
 590 pthread_t
 591 setup_mach_exception_handling_thread()
 592 {
 593     kern_return_t ret;
 594     pthread_t mach_exception_handling_thread = NULL;
 595     pthread_attr_t attr;
 596
 597     /* allocate a mach_port for this process */
 598     ret = mach_port_allocate(mach_task_self(),
 599                              MACH_PORT_RIGHT_PORT_SET,
 600                              &mach_exception_handler_port_set);
 601
 602     /* create the thread that will receive the mach exceptions */
 603
 604     FSHOW((stderr, "Creating mach_exception_handler thread!\n"));
 605
 606     pthread_attr_init(&attr);
 607     pthread_create(&mach_exception_handling_thread,
 608                    &attr,
 609                    mach_exception_handler,
 610                    (void*) mach_exception_handler_port_set);
 611     pthread_attr_destroy(&attr);
 612
 613     return mach_exception_handling_thread;
 614 }
 615
 616 /* tell the kernel that we want EXC_BAD_ACCESS exceptions sent to the
 617    exception port (which is being listened to do by the mach
 618    exception handling thread). */
 619 kern_return_t
 620 mach_thread_init(mach_port_t thread_exception_port)
 621 {
 622     kern_return_t ret;
 623     /* allocate a named port for the thread */
 624
 625     FSHOW((stderr, "Allocating mach port %x\n", thread_exception_port));
 626
 627     ret = mach_port_allocate_name(mach_task_self(),
 628                                   MACH_PORT_RIGHT_RECEIVE,
 629                                   thread_exception_port);
 630     if (ret) {
 631         lose("mach_port_allocate_name failed with return_code %d\n", ret);
 632     }
 633
 634     /* establish the right for the thread_exception_port to send messages */
 635     ret = mach_port_insert_right(mach_task_self(),
 636                                  thread_exception_port,
 637                                  thread_exception_port,
 638                                  MACH_MSG_TYPE_MAKE_SEND);
 639     if (ret) {
 640         lose("mach_port_insert_right failed with return_code %d\n", ret);
 641     }
 642
 643     ret = thread_set_exception_ports(mach_thread_self(),
 644                                      EXC_MASK_BAD_ACCESS | EXC_MASK_BAD_INSTRUCTION,
 645                                      thread_exception_port,
 646                                      EXCEPTION_DEFAULT,
 647                                      THREAD_STATE_NONE);
 648     if (ret) {
 649         lose("thread_set_exception_port failed with return_code %d\n", ret);
 650     }
 651
 652     ret = mach_port_move_member(mach_task_self(),
 653                                 thread_exception_port,
 654                                 mach_exception_handler_port_set);
 655     if (ret) {
 656         lose("mach_port_ failed with return_code %d\n", ret);
 657     }
 658
 659     return ret;
 660 }
 661
 662 void
 663 setup_mach_exceptions() {
 664     setup_mach_exception_handling_thread();
 665     mach_thread_init(THREAD_STRUCT_TO_EXCEPTION_PORT(all_threads));
 666 }
 667
 668 pid_t
 669 mach_fork() {
 670     pid_t pid = fork();
 671     if (pid == 0) {
 672         setup_mach_exceptions();
 673         return pid;
 674     } else {
 675         return pid;
 676     }
 677 }
 678
 679 #endif