src/runtime/x86-darwin-os.c

   1
   2
   3 #ifdef LISP_FEATURE_SB_THREAD
   4 #include <architecture/i386/table.h>
   5 #include <i386/user_ldt.h>
   6 #include <mach/mach_init.h>
   7 #endif
   8
   9 #include "thread.h"
  10 #include "validate.h"
  11 #include "runtime.h"
  12 #include "interrupt.h"
  13 #include "x86-darwin-os.h"
  14 #include "genesis/fdefn.h"
  15
  16 #include <mach/mach.h>
  17 #include <mach/mach_error.h>
  18 #include <mach/mach_types.h>
  19 #include <mach/sync_policy.h>
  20 #include <mach/vm_region.h>
  21 #include <mach/machine/thread_state.h>
  22 #include <mach/machine/thread_status.h>
  23 #include <sys/_types.h>
  24 #include <sys/ucontext.h>
  25 #include <pthread.h>
  26 #include <assert.h>
  27 #include <stdlib.h>
  28
  29 #ifdef LISP_FEATURE_SB_THREAD
  30
  31 pthread_mutex_t modify_ldt_lock = PTHREAD_MUTEX_INITIALIZER;
  32
  33 void set_data_desc_size(data_desc_t* desc, unsigned long size)
  34 {
  35     desc->limit00 = (size - 1) & 0xffff;
  36     desc->limit16 = ((size - 1) >> 16) &0xf;
  37 }
  38
  39 void set_data_desc_addr(data_desc_t* desc, void* addr)
  40 {
  41     desc->base00 = (unsigned int)addr & 0xffff;
  42     desc->base16 = ((unsigned int)addr & 0xff0000) >> 16;
  43     desc->base24 = ((unsigned int)addr & 0xff000000) >> 24;
  44 }
  45
  46 #endif
  47
  48 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
  49 kern_return_t mach_thread_init(mach_port_t thread_exception_port);
  50 #endif
  51
  52 int arch_os_thread_init(struct thread *thread) {
  53 #ifdef LISP_FEATURE_SB_THREAD
  54     int n;
  55     sel_t sel;
  56
  57     data_desc_t ldt_entry = { 0, 0, 0, DESC_DATA_WRITE,
  58                               3, 1, 0, DESC_DATA_32B, DESC_GRAN_BYTE, 0 };
  59
  60     set_data_desc_addr(&ldt_entry, thread);
  61     set_data_desc_size(&ldt_entry, dynamic_values_bytes);
  62
  63     thread_mutex_lock(&modify_ldt_lock);
  64     n = i386_set_ldt(LDT_AUTO_ALLOC, (union ldt_entry*) &ldt_entry, 1);
  65
  66     if (n < 0) {
  67         perror("i386_set_ldt");
  68         lose("unexpected i386_set_ldt(..) failure\n");
  69     }
  70     thread_mutex_unlock(&modify_ldt_lock);
  71
  72     FSHOW_SIGNAL((stderr, "/ TLS: Allocated LDT %x\n", n));
  73     sel.index = n;
  74     sel.rpl = USER_PRIV;
  75     sel.ti = SEL_LDT;
  76
  77     __asm__ __volatile__ ("mov %0, %%fs" : : "r"(sel));
  78
  79     thread->tls_cookie=n;
  80     pthread_setspecific(specials,thread);
  81 #endif
  82 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
  83     mach_thread_init(THREAD_STRUCT_TO_EXCEPTION_PORT(thread));
  84 #endif
  85
  86 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
  87     stack_t sigstack;
  88
  89     /* Signal handlers are run on the control stack, so if it is exhausted
  90      * we had better use an alternate stack for whatever signal tells us
  91      * we've exhausted it */
  92     sigstack.ss_sp=((void *) thread)+dynamic_values_bytes;
  93     sigstack.ss_flags=0;
  94     sigstack.ss_size = 32*SIGSTKSZ;
  95     sigaltstack(&sigstack,0);
  96 #endif
  97     return 1;                  /* success */
  98 }
  99
 100 int arch_os_thread_cleanup(struct thread *thread) {
 101 #if defined(LISP_FEATURE_SB_THREAD)
 102     int n = thread->tls_cookie;
 103
 104     /* Set the %%fs register back to 0 and free the ldt by setting it
 105      * to NULL.
 106      */
 107     FSHOW_SIGNAL((stderr, "/ TLS: Freeing LDT %x\n", n));
 108
 109     __asm__ __volatile__ ("mov %0, %%fs" : : "r"(0));
 110     thread_mutex_lock(&modify_ldt_lock);
 111     i386_set_ldt(n, NULL, 1);
 112     thread_mutex_unlock(&modify_ldt_lock);
 113 #endif
 114     return 1;                  /* success */
 115 }
 116
 117 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
 118
 119 void sigill_handler(int signal, siginfo_t *siginfo, void *void_context);
 120 void sigtrap_handler(int signal, siginfo_t *siginfo, void *void_context);
 121 void memory_fault_handler(int signal, siginfo_t *siginfo, void *void_context);
 122
 123 /* exc_server handles mach exception messages from the kernel and
 124  * calls catch exception raise. We use the system-provided
 125  * mach_msg_server, which, I assume, calls exc_server in a loop.
 126  *
 127  */
 128 extern boolean_t exc_server();
 129
 130 /* This executes in the faulting thread as part of the signal
 131  * emulation.  It is passed a context with the uc_mcontext field
 132  * pointing to a valid block of memory. */
 133 void build_fake_signal_context(os_context_t *context,
 134                                x86_thread_state32_t *thread_state,
 135                                x86_float_state32_t *float_state) {
 136     pthread_sigmask(0, NULL, &context->uc_sigmask);
 137     context->uc_mcontext->SS = *thread_state;
 138     context->uc_mcontext->FS = *float_state;
 139 }
 140
 141 /* This executes in the faulting thread as part of the signal
 142  * emulation.  It is effectively the inverse operation from above. */
 143 void update_thread_state_from_context(x86_thread_state32_t *thread_state,
 144                                       x86_float_state32_t *float_state,
 145                                       os_context_t *context) {
 146     *thread_state = context->uc_mcontext->SS;
 147     *float_state = context->uc_mcontext->FS;
 148     pthread_sigmask(SIG_SETMASK, &context->uc_sigmask, NULL);
 149 }
 150
 151 /* Modify a context to push new data on its stack. */
 152 void push_context(u32 data, x86_thread_state32_t *thread_state)
 153 {
 154     u32 *stack_pointer;
 155
 156     stack_pointer = (u32*) thread_state->ESP;
 157     *(--stack_pointer) = data;
 158     thread_state->ESP = (unsigned int) stack_pointer;
 159 }
 160
 161 void align_context_stack(x86_thread_state32_t *thread_state)
 162 {
 163     /* 16byte align the stack (provided that the stack is, as it
 164      * should be, 4byte aligned. */
 165     while (thread_state->ESP & 15) push_context(0, thread_state);
 166 }
 167
 168 /* Stack allocation starts with a context that has a mod-4 ESP value
 169  * and needs to leave a context with a mod-16 ESP that will restore
 170  * the old ESP value and other register state when activated.  The
 171  * first part of this is the recovery trampoline, which loads ESP from
 172  * EBP, pops EBP, and returns. */
 173 asm("_stack_allocation_recover: movl %ebp, %esp; popl %ebp; ret;");
 174
 175 void open_stack_allocation(x86_thread_state32_t *thread_state)
 176 {
 177     void stack_allocation_recover(void);
 178
 179     push_context(thread_state->EIP, thread_state);
 180     push_context(thread_state->EBP, thread_state);
 181     thread_state->EBP = thread_state->ESP;
 182     thread_state->EIP = (unsigned int) stack_allocation_recover;
 183
 184     align_context_stack(thread_state);
 185 }
 186
 187 /* Stack allocation of data starts with a context with a mod-16 ESP
 188  * value and reserves some space on it by manipulating the ESP
 189  * register. */
 190 void *stack_allocate(x86_thread_state32_t *thread_state, size_t size)
 191 {
 192     /* round up size to 16byte multiple */
 193     size = (size + 15) & -16;
 194
 195     thread_state->ESP = ((u32)thread_state->ESP) - size;
 196
 197     return (void *)thread_state->ESP;
 198 }
 199
 200 /* Arranging to invoke a C function is tricky, as we have to assume
 201  * cdecl calling conventions (caller removes args) and x86/darwin
 202  * alignment requirements.  The simplest way to arrange this,
 203  * actually, is to open a new stack allocation.
 204  * WARNING!!! THIS DOES NOT PRESERVE REGISTERS! */
 205 void call_c_function_in_context(x86_thread_state32_t *thread_state,
 206                                 void *function,
 207                                 int nargs,
 208                                 ...)
 209 {
 210     va_list ap;
 211     int i;
 212     u32 *stack_pointer;
 213
 214     /* Set up to restore stack on exit. */
 215     open_stack_allocation(thread_state);
 216
 217     /* Have to keep stack 16byte aligned on x86/darwin. */
 218     for (i = (3 & -nargs); i; i--) {
 219         push_context(0, thread_state);
 220     }
 221
 222     thread_state->ESP = ((u32)thread_state->ESP) - nargs * 4;
 223     stack_pointer = (u32 *)thread_state->ESP;
 224
 225     va_start(ap, nargs);
 226     for (i = 0; i < nargs; i++) {
 227         //push_context(va_arg(ap, u32), thread_state);
 228         stack_pointer[i] = va_arg(ap, u32);
 229     }
 230     va_end(ap);
 231
 232     push_context(thread_state->EIP, thread_state);
 233     thread_state->EIP = (unsigned int) function;
 234 }
 235
 236 void signal_emulation_wrapper(x86_thread_state32_t *thread_state,
 237                               x86_float_state32_t *float_state,
 238                               int signal,
 239                               siginfo_t *siginfo,
 240                               void (*handler)(int, siginfo_t *, void *))
 241 {
 242
 243     /* CLH: FIXME **NOTE: HACK ALERT!** Ideally, we would allocate
 244      * context and regs on the stack as local variables, but this
 245      * causes problems for the lisp debugger. When it walks the stack
 246      * for a back trace, it sees the 1) address of the local variable
 247      * on the stack and thinks that is a frame pointer to a lisp
 248      * frame, and, 2) the address of the sap that we alloc'ed in
 249      * dynamic space and thinks that is a return address, so it,
 250      * heuristicly (and wrongly), chooses that this should be
 251      * interpreted as a lisp frame instead of as a C frame.
 252      * We can work around this in this case by os_validating the
 253      * context (and regs just for symmetry).
 254      */
 255
 256     os_context_t *context;
 257 #if MAC_OS_X_VERSION_10_5
 258     struct __darwin_mcontext32 *regs;
 259 #else
 260     struct mcontext *regs;
 261 #endif
 262
 263     context = (os_context_t*) os_validate(0, sizeof(os_context_t));
 264 #if MAC_OS_X_VERSION_10_5
 265     regs = (struct __darwin_mcontext32*) os_validate(0, sizeof(struct __darwin_mcontext32));
 266 #else
 267     regs = (struct mcontext*) os_validate(0, sizeof(struct mcontext));
 268 #endif
 269     context->uc_mcontext = regs;
 270
 271     /* when BSD signals are fired, they mask they signals in sa_mask
 272        which always seem to be the blockable_sigset, for us, so we
 273        need to:
 274        1) save the current sigmask
 275        2) block blockable signals
 276        3) call the signal handler
 277        4) restore the sigmask */
 278
 279     build_fake_signal_context(context, thread_state, float_state);
 280
 281     block_blockable_signals();
 282
 283     handler(signal, siginfo, context);
 284
 285     update_thread_state_from_context(thread_state, float_state, context);
 286
 287     os_invalidate((os_vm_address_t)context, sizeof(os_context_t));
 288 #if MAC_OS_X_VERSION_10_5
 289     os_invalidate((os_vm_address_t)regs, sizeof(struct __darwin_mcontext32));
 290 #else
 291     os_invalidate((os_vm_address_t)regs, sizeof(struct mcontext));
 292 #endif
 293
 294     /* Trap to restore the signal context. */
 295     asm volatile ("movl %0, %%eax; movl %1, %%ebx; .long 0xffff0b0f"
 296                   : : "r" (thread_state), "r" (float_state));
 297 }
 298
 299 /* Convenience wrapper for the above */
 300 void call_handler_on_thread(mach_port_t thread,
 301                             x86_thread_state32_t *thread_state,
 302                             int signal,
 303                             siginfo_t *siginfo,
 304                             void (*handler)(int, siginfo_t *, void *))
 305 {
 306     x86_thread_state32_t new_state;
 307     x86_thread_state32_t *save_thread_state;
 308     x86_float_state32_t *save_float_state;
 309     mach_msg_type_number_t state_count;
 310     siginfo_t *save_siginfo;
 311     kern_return_t ret;
 312     /* Initialize the new state */
 313     new_state = *thread_state;
 314     open_stack_allocation(&new_state);
 315     /* Save old state */
 316     save_thread_state = (x86_thread_state32_t *)stack_allocate(&new_state, sizeof(*save_thread_state));
 317     *save_thread_state = *thread_state;
 318     /* Save float state */
 319     save_float_state = (x86_float_state32_t *)stack_allocate(&new_state, sizeof(*save_float_state));
 320     state_count = x86_FLOAT_STATE32_COUNT;
 321     if ((ret = thread_get_state(thread,
 322                                 x86_FLOAT_STATE32,
 323                                 (thread_state_t)save_float_state,
 324                                 &state_count)) != KERN_SUCCESS)
 325         lose("thread_get_state (x86_THREAD_STATE32) failed %d\n", ret);
 326     /* Set up siginfo */
 327     save_siginfo = stack_allocate(&new_state, sizeof(*siginfo));
 328     if (siginfo == NULL)
 329         save_siginfo = siginfo;
 330     else
 331         *save_siginfo = *siginfo;
 332     /* Prepare to call */
 333     call_c_function_in_context(&new_state,
 334                                signal_emulation_wrapper,
 335                                5,
 336                                save_thread_state,
 337                                save_float_state,
 338                                signal,
 339                                save_siginfo,
 340                                handler);
 341     /* Update the thread state */
 342     state_count = x86_THREAD_STATE32_COUNT;
 343     if ((ret = thread_set_state(thread,
 344                                 x86_THREAD_STATE32,
 345                                 (thread_state_t)&new_state,
 346                                 state_count)) != KERN_SUCCESS)
 347         lose("thread_set_state (x86_FLOAT_STATE32) failed %d\n", ret);
 348
 349 }
 350
 351 #if defined DUMP_CONTEXT
 352 void dump_context(x86_thread_state32_t *thread_state)
 353 {
 354     int i;
 355     u32 *stack_pointer;
 356
 357     printf("eax: %08lx  ecx: %08lx  edx: %08lx  ebx: %08lx\n",
 358            thread_state->EAX, thread_state->ECX, thread_state->EDX, thread_state->EAX);
 359     printf("esp: %08lx  ebp: %08lx  esi: %08lx  edi: %08lx\n",
 360            thread_state->ESP, thread_state->EBP, thread_state->ESI, thread_state->EDI);
 361     printf("eip: %08lx  eflags: %08lx\n",
 362            thread_state->EIP, thread_state->EFLAGS);
 363     printf("cs: %04hx  ds: %04hx  es: %04hx  "
 364            "ss: %04hx  fs: %04hx  gs: %04hx\n",
 365            thread_state->CS,
 366            thread_state->DS,
 367            thread_state->ES,
 368            thread_state->SS,
 369            thread_state->FS,
 370            thread_state->GS);
 371
 372     stack_pointer = (u32 *)thread_state->ESP;
 373     for (i = 0; i < 48; i+=4) {
 374         printf("%08x:  %08x %08x %08x %08x\n",
 375                thread_state->ESP + (i * 4),
 376                stack_pointer[i],
 377                stack_pointer[i+1],
 378                stack_pointer[i+2],
 379                stack_pointer[i+3]);
 380     }
 381 }
 382 #endif
 383
 384 void
 385 control_stack_exhausted_handler(int signal, siginfo_t *siginfo, void *void_context) {
 386     os_context_t *context = arch_os_get_context(&void_context);
 387
 388     arrange_return_to_lisp_function
 389         (context, StaticSymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
 390 }
 391
 392 void
 393 undefined_alien_handler(int signal, siginfo_t *siginfo, void *void_context) {
 394     os_context_t *context = arch_os_get_context(&void_context);
 395
 396     arrange_return_to_lisp_function
 397         (context, StaticSymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
 398 }
 399
 400 kern_return_t
 401 catch_exception_raise(mach_port_t exception_port,
 402                       mach_port_t thread,
 403                       mach_port_t task,
 404                       exception_type_t exception,
 405                       exception_data_t code_vector,
 406                       mach_msg_type_number_t code_count)
 407 {
 408     struct thread *th = (struct thread*) exception_port;
 409     x86_thread_state32_t thread_state;
 410     mach_msg_type_number_t state_count;
 411     vm_address_t region_addr;
 412     vm_size_t region_size;
 413     vm_region_basic_info_data_t region_info;
 414     mach_msg_type_number_t info_count;
 415     mach_port_t region_name;
 416     void *addr = NULL;
 417     int signal = 0;
 418     void (*handler)(int, siginfo_t *, void *) = NULL;
 419     siginfo_t siginfo;
 420     kern_return_t ret;
 421
 422     /* Get state and info */
 423     state_count = x86_THREAD_STATE32_COUNT;
 424     if ((ret = thread_get_state(thread,
 425                                 x86_THREAD_STATE32,
 426                                 (thread_state_t)&thread_state,
 427                                 &state_count)) != KERN_SUCCESS)
 428         lose("thread_get_state (x86_THREAD_STATE32) failed %d\n", ret);
 429     switch (exception) {
 430     case EXC_BAD_ACCESS:
 431         signal = SIGBUS;
 432         /* Check if write protection fault */
 433         if ((code_vector[0] & OS_VM_PROT_ALL) == 0) {
 434             ret = KERN_INVALID_RIGHT;
 435             break;
 436         }
 437         addr = (void*)code_vector[1];
 438         /* Undefined alien */
 439         if (os_trunc_to_page(addr) == undefined_alien_address) {
 440             handler = undefined_alien_handler;
 441             break;
 442         }
 443         /* At stack guard */
 444         if (os_trunc_to_page(addr) == CONTROL_STACK_GUARD_PAGE(th)) {
 445             protect_control_stack_guard_page_thread(0, th);
 446             protect_control_stack_return_guard_page_thread(1, th);
 447             handler = control_stack_exhausted_handler;
 448             break;
 449         }
 450         /* Return from stack guard */
 451         if (os_trunc_to_page(addr) == CONTROL_STACK_RETURN_GUARD_PAGE(th)) {
 452             protect_control_stack_guard_page_thread(1, th);
 453             protect_control_stack_return_guard_page_thread(0, th);
 454             break;
 455         }
 456         /* Get vm_region info */
 457         region_addr = (vm_address_t)code_vector[1];
 458         info_count = VM_REGION_BASIC_INFO_COUNT;
 459         if ((ret = vm_region(mach_task_self(),
 460                              &region_addr,
 461                              &region_size,
 462                              VM_REGION_BASIC_INFO,
 463                              (vm_region_info_t)&region_info,
 464                              &info_count,
 465                              &region_name)))
 466             lose("vm_region (VM_REGION_BASIC_INFO) failed failed %d\n", ret);
 467         /* Check if still protected */
 468         if ((region_info.protection & OS_VM_PROT_ALL) == 0) {
 469           /* KLUDGE:
 470            * If two threads fault on the same page, the protection
 471            * is cleared as the first thread runs memory_fault_handler.
 472            * Grep for "not marked as write-protected" in gencgc.c
 473            */
 474             ret = KERN_SUCCESS;
 475             break;
 476         }
 477         /* Regular memory fault */
 478         handler = memory_fault_handler;
 479         break;
 480     case EXC_BAD_INSTRUCTION:
 481         signal = SIGTRAP;
 482         /* Check if illegal instruction trap */
 483         if (code_vector[0] != EXC_I386_INVOP) {
 484             ret = KERN_INVALID_RIGHT;
 485             break;
 486         }
 487         /* Check if UD2 instruction */
 488         if (*(unsigned short *)thread_state.EIP != 0x0b0f) {
 489             /* KLUDGE: There are two ways we could get here:
 490              * 1) We're executing data and we've hit some truly
 491              *    illegal opcode, of which there are a few, see
 492              *    Intel 64 and IA-32 Architectures
 493              *    Sofware Developer's Manual
 494              *    Volume 3A page 5-34)
 495              * 2) The kernel started an unrelated signal handler
 496              *    before we got a chance to run. The context that
 497              *    caused the exception is saved in a stack frame
 498              *    somewhere down below.
 499              * In either case we rely on the exception to retrigger,
 500              * eventually bailing out if we're spinning on case 2).
 501              */
 502             static mach_port_t last_thread;
 503             static unsigned int last_eip;
 504             if (last_thread == thread && last_eip == thread_state.EIP)
 505                 ret = KERN_INVALID_RIGHT;
 506             else
 507                 ret = KERN_SUCCESS;
 508             last_thread = thread;
 509             last_eip = thread_state.EIP;
 510             break;
 511         }
 512         /* Skip the trap code */
 513         thread_state.EIP += 2;
 514         /* Return from handler? */
 515         if (*(unsigned short *)thread_state.EIP == 0xffff) {
 516             if ((ret = thread_set_state(thread,
 517                                         x86_THREAD_STATE32,
 518                                         (thread_state_t)thread_state.EAX,
 519                                         x86_THREAD_STATE32_COUNT)) != KERN_SUCCESS)
 520                 lose("thread_set_state (x86_THREAD_STATE32) failed %d\n", ret);
 521             if ((ret = thread_set_state(thread,
 522                                         x86_FLOAT_STATE32,
 523                                         (thread_state_t)thread_state.EBX,
 524                                         x86_FLOAT_STATE32_COUNT)) != KERN_SUCCESS)
 525                 lose("thread_set_state (x86_FLOAT_STATE32) failed %d\n", ret);
 526             break;
 527         }
 528         /* Trap call */
 529         handler = sigtrap_handler;
 530         break;
 531     default:
 532         ret = KERN_INVALID_RIGHT;
 533     }
 534     /* Call handler */
 535     if (handler != 0) {
 536       siginfo.si_signo = signal;
 537       siginfo.si_addr = addr;
 538       call_handler_on_thread(thread, &thread_state, signal, &siginfo, handler);
 539     }
 540     return ret;
 541 }
 542
 543 void *
 544 mach_exception_handler(void *port)
 545 {
 546   mach_msg_server(exc_server, 2048, (mach_port_t) port, 0);
 547   /* mach_msg_server should never return, but it should dispatch mach
 548    * exceptions to our catch_exception_raise function
 549    */
 550   abort();
 551 }
 552
 553 #endif
 554
 555 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
 556
 557 /* Sets up the thread that will listen for mach exceptions. note that
 558    the exception handlers will be run on this thread. This is
 559    different from the BSD-style signal handling situation in which the
 560    signal handlers run in the relevant thread directly. */
 561
 562 mach_port_t mach_exception_handler_port_set = MACH_PORT_NULL;
 563
 564 pthread_t
 565 setup_mach_exception_handling_thread()
 566 {
 567     kern_return_t ret;
 568     pthread_t mach_exception_handling_thread = NULL;
 569     pthread_attr_t attr;
 570
 571     /* allocate a mach_port for this process */
 572     ret = mach_port_allocate(mach_task_self(),
 573                              MACH_PORT_RIGHT_PORT_SET,
 574                              &mach_exception_handler_port_set);
 575
 576     /* create the thread that will receive the mach exceptions */
 577
 578     FSHOW((stderr, "Creating mach_exception_handler thread!\n"));
 579
 580     pthread_attr_init(&attr);
 581     pthread_create(&mach_exception_handling_thread,
 582                    &attr,
 583                    mach_exception_handler,
 584                    (void*) mach_exception_handler_port_set);
 585     pthread_attr_destroy(&attr);
 586
 587     return mach_exception_handling_thread;
 588 }
 589
 590 /* tell the kernel that we want EXC_BAD_ACCESS exceptions sent to the
 591    exception port (which is being listened to do by the mach
 592    exception handling thread). */
 593 kern_return_t
 594 mach_thread_init(mach_port_t thread_exception_port)
 595 {
 596     kern_return_t ret;
 597     /* allocate a named port for the thread */
 598
 599     FSHOW((stderr, "Allocating mach port %x\n", thread_exception_port));
 600
 601     ret = mach_port_allocate_name(mach_task_self(),
 602                                   MACH_PORT_RIGHT_RECEIVE,
 603                                   thread_exception_port);
 604     if (ret) {
 605         lose("mach_port_allocate_name failed with return_code %d\n", ret);
 606     }
 607
 608     /* establish the right for the thread_exception_port to send messages */
 609     ret = mach_port_insert_right(mach_task_self(),
 610                                  thread_exception_port,
 611                                  thread_exception_port,
 612                                  MACH_MSG_TYPE_MAKE_SEND);
 613     if (ret) {
 614         lose("mach_port_insert_right failed with return_code %d\n", ret);
 615     }
 616
 617     ret = thread_set_exception_ports(mach_thread_self(),
 618                                      EXC_MASK_BAD_ACCESS | EXC_MASK_BAD_INSTRUCTION,
 619                                      thread_exception_port,
 620                                      EXCEPTION_DEFAULT,
 621                                      THREAD_STATE_NONE);
 622     if (ret) {
 623         lose("thread_set_exception_port failed with return_code %d\n", ret);
 624     }
 625
 626     ret = mach_port_move_member(mach_task_self(),
 627                                 thread_exception_port,
 628                                 mach_exception_handler_port_set);
 629     if (ret) {
 630         lose("mach_port_ failed with return_code %d\n", ret);
 631     }
 632
 633     return ret;
 634 }
 635
 636 void
 637 setup_mach_exceptions() {
 638     setup_mach_exception_handling_thread();
 639     mach_thread_init(THREAD_STRUCT_TO_EXCEPTION_PORT(all_threads));
 640 }
 641
 642 pid_t
 643 mach_fork() {
 644     pid_t pid = fork();
 645     if (pid == 0) {
 646         setup_mach_exceptions();
 647         return pid;
 648     } else {
 649         return pid;
 650     }
 651 }
 652
 653 #endif