vm/mach_signal.cpp

   1 // Fault handler information.  MacOSX version.
   2 // Copyright (C) 1993-1999, 2002-2003  Bruno Haible <clisp.org at bruno>
   3
   4 // Copyright (C) 2003  Paolo Bonzini <gnu.org at bonzini>
   5
   6 // Used under BSD license with permission from Paolo Bonzini and Bruno Haible,
   7 // 2005-03-10:
   8
   9 // http://sourceforge.net/mailarchive/message.php?msg_name=200503102200.32002.bruno%40clisp.org
  10
  11 // Modified for Factor by Slava Pestov
  12
  13 #include "master.hpp"
  14
  15 namespace factor {
  16
  17 // The exception port on which our thread listens.
  18 mach_port_t our_exception_port;
  19
  20 // The following sources were used as a *reference* for this exception handling
  21 // code:
  22
  23 // 1. Apple's mach/xnu documentation
  24 // 2. Timothy J. Wood's "Mach Exception Handlers 101" post to the
  25 //    omnigroup's macosx-dev list.
  26 //    http://www.wodeveloper.com/omniLists/macosx-dev/2000/June/msg00137.html
  27
  28 // Modify a suspended thread's thread_state so that when the thread resumes
  29 // executing, the call frame of the current C primitive (if any) is rewound, and
  30 // the appropriate Factor error is thrown from the top-most Factor frame.
  31 void factor_vm::call_fault_handler(exception_type_t exception,
  32                                    exception_data_type_t code,
  33                                    MACH_EXC_STATE_TYPE* exc_state,
  34                                    MACH_THREAD_STATE_TYPE* thread_state,
  35                                    MACH_FLOAT_STATE_TYPE* float_state) {
  36   cell handler = 0;
  37
  38   if (exception == EXC_BAD_ACCESS) {
  39     set_memory_protection_error(MACH_EXC_STATE_FAULT(exc_state),
  40                                 (cell)MACH_PROGRAM_COUNTER(thread_state));
  41     handler = (cell)factor::memory_signal_handler_impl;
  42   } else if (exception == EXC_ARITHMETIC && code != MACH_EXC_INTEGER_DIV) {
  43     signal_fpu_status = fpu_status(mach_fpu_status(float_state));
  44     mach_clear_fpu_status(float_state);
  45     handler = (cell)factor::fp_signal_handler_impl;
  46   } else {
  47     switch (exception) {
  48       case EXC_ARITHMETIC:
  49         signal_number = SIGFPE;
  50         break;
  51       case EXC_BAD_INSTRUCTION:
  52         signal_number = SIGILL;
  53         break;
  54       default:
  55         signal_number = SIGABRT;
  56         break;
  57     }
  58
  59     handler = (cell)factor::synchronous_signal_handler_impl;
  60   }
  61
  62   FACTOR_ASSERT(handler != 0);
  63
  64   dispatch_signal_handler((cell*)&MACH_STACK_POINTER(thread_state),
  65                           (cell*)&MACH_PROGRAM_COUNTER(thread_state),
  66                           (cell)handler);
  67 }
  68
  69 static void call_fault_handler(mach_port_t thread, exception_type_t exception,
  70                                exception_data_type_t code,
  71                                MACH_EXC_STATE_TYPE* exc_state,
  72                                MACH_THREAD_STATE_TYPE* thread_state,
  73                                MACH_FLOAT_STATE_TYPE* float_state) {
  74   // Look up the VM instance involved
  75   THREADHANDLE thread_id = pthread_from_mach_thread_np(thread);
  76   FACTOR_ASSERT(thread_id);
  77   std::map<THREADHANDLE, factor_vm*>::const_iterator vm =
  78       thread_vms.find(thread_id);
  79
  80   // Handle the exception
  81   if (vm != thread_vms.end())
  82     vm->second->call_fault_handler(exception, code, exc_state, thread_state,
  83                                    float_state);
  84 }
  85
  86 // Handle an exception by invoking the user's fault handler and/or forwarding
  87 // the duty to the previously installed handlers.
  88 extern "C" kern_return_t catch_exception_raise(
  89     mach_port_t exception_port, mach_port_t thread, mach_port_t task,
  90     exception_type_t exception, exception_data_t code,
  91     mach_msg_type_number_t code_count) {
  92   (void) exception_port;
  93   (void) code_count;
  94   // 10.6 likes to report exceptions from child processes too. Ignore those
  95   if (task != mach_task_self())
  96     return KERN_FAILURE;
  97
  98   // Get fault information and the faulting thread's register contents..
  99   // See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/thread_get_state.html.
 100   MACH_EXC_STATE_TYPE exc_state;
 101   mach_msg_type_number_t exc_state_count = MACH_EXC_STATE_COUNT;
 102   if (thread_get_state(thread, MACH_EXC_STATE_FLAVOR, (natural_t*)&exc_state,
 103                        &exc_state_count) !=
 104       KERN_SUCCESS) {
 105     // The thread is supposed to be suspended while the exception
 106     // handler is called. This shouldn't fail.
 107     return KERN_FAILURE;
 108   }
 109
 110   MACH_THREAD_STATE_TYPE thread_state;
 111   mach_msg_type_number_t thread_state_count = MACH_THREAD_STATE_COUNT;
 112   if (thread_get_state(thread, MACH_THREAD_STATE_FLAVOR,
 113                        (natural_t*)&thread_state, &thread_state_count) !=
 114       KERN_SUCCESS) {
 115     // The thread is supposed to be suspended while the exception
 116     // handler is called. This shouldn't fail.
 117     return KERN_FAILURE;
 118   }
 119
 120   MACH_FLOAT_STATE_TYPE float_state;
 121   mach_msg_type_number_t float_state_count = MACH_FLOAT_STATE_COUNT;
 122   if (thread_get_state(thread, MACH_FLOAT_STATE_FLAVOR,
 123                        (natural_t*)&float_state, &float_state_count) !=
 124       KERN_SUCCESS) {
 125     // The thread is supposed to be suspended while the exception
 126     // handler is called. This shouldn't fail.
 127     return KERN_FAILURE;
 128   }
 129
 130   // Modify registers so to have the thread resume executing the
 131   // fault handler
 132   call_fault_handler(thread, exception, code[0], &exc_state, &thread_state,
 133                      &float_state);
 134
 135   // Set the faulting thread's register contents..
 136   // See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/thread_set_state.html.
 137   if (thread_set_state(thread, MACH_FLOAT_STATE_FLAVOR,
 138                        (natural_t*)&float_state, float_state_count) !=
 139       KERN_SUCCESS) {
 140     return KERN_FAILURE;
 141   }
 142
 143   if (thread_set_state(thread, MACH_THREAD_STATE_FLAVOR,
 144                        (natural_t*)&thread_state, thread_state_count) !=
 145       KERN_SUCCESS) {
 146     return KERN_FAILURE;
 147   }
 148
 149   return KERN_SUCCESS;
 150 }
 151
 152 // The main function of the thread listening for exceptions.
 153 static void* mach_exception_thread(void* arg) {
 154   (void) arg;
 155   for (;;) {
 156     // These two structures contain some private kernel data. We don't need
 157     // to access any of it so we don't bother defining a proper struct. The
 158     // correct definitions are in the xnu source code.
 159     // Buffer for a message to be received.
 160     struct {
 161       mach_msg_header_t head;
 162       mach_msg_body_t msgh_body;
 163       char data[1024];
 164     } msg;
 165     // Buffer for a reply message.
 166     struct {
 167       mach_msg_header_t head;
 168       char data[1024];
 169     } reply;
 170
 171     // Wait for a message on the exception port.
 172     if (mach_msg(&msg.head, MACH_RCV_MSG | MACH_RCV_LARGE, 0, sizeof(msg),
 173                  our_exception_port, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL) !=
 174         MACH_MSG_SUCCESS) {
 175       abort();
 176     }
 177
 178     // Handle the message: Call exc_server, which will call
 179     // catch_exception_raise and produce a reply message.
 180     exc_server(&msg.head, &reply.head);
 181
 182     // Send the reply.
 183     if (mach_msg(&reply.head, MACH_SEND_MSG, reply.head.msgh_size, 0,
 184                  MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL) !=
 185         MACH_MSG_SUCCESS) {
 186       abort();
 187     }
 188   }
 189   return NULL;  // quiet warning
 190 }
 191
 192 // Initialize the Mach exception handler thread.
 193 void mach_initialize() {
 194   mach_port_t self;
 195   exception_mask_t mask;
 196
 197   self = mach_task_self();
 198
 199   // Allocate a port on which the thread shall listen for exceptions.
 200   if (mach_port_allocate(self, MACH_PORT_RIGHT_RECEIVE, &our_exception_port) !=
 201       KERN_SUCCESS)
 202     fatal_error("mach_port_allocate() failed", 0);
 203
 204   // See
 205   // http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/mach_port_insert_right.html.
 206
 207   if (mach_port_insert_right(self, our_exception_port, our_exception_port,
 208                              MACH_MSG_TYPE_MAKE_SEND) !=
 209       KERN_SUCCESS)
 210     fatal_error("mach_port_insert_right() failed", 0);
 211
 212   // The exceptions we want to catch.
 213   mask = EXC_MASK_BAD_ACCESS | EXC_MASK_BAD_INSTRUCTION | EXC_MASK_ARITHMETIC;
 214
 215   // Create the thread listening on the exception port.
 216   start_thread(mach_exception_thread, NULL);
 217
 218   // Replace the exception port info for these exceptions with our own.
 219   // Note that we replace the exception port for the entire task, not only
 220   // for a particular thread. This has the effect that when our exception
 221   // port gets the message, the thread specific exception port has already
 222   // been asked, and we don't need to bother about it. See
 223   // http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/task_set_exception_ports.html.
 224   if (task_set_exception_ports(self, mask, our_exception_port,
 225                                EXCEPTION_DEFAULT, MACHINE_THREAD_STATE) !=
 226       KERN_SUCCESS)
 227     fatal_error("task_set_exception_ports() failed", 0);
 228 }
 229
 230 }