1 /* Fault handler information. MacOSX version.
2 Copyright (C) 1993-1999, 2002-2003 Bruno Haible <clisp.org at bruno>
4 Copyright (C) 2003 Paolo Bonzini <gnu.org at bonzini>
6 Used under BSD license with permission from Paolo Bonzini and Bruno Haible,
9 http://sourceforge.net/mailarchive/message.php?msg_name=200503102200.32002.bruno%40clisp.org
11 Modified for Factor by Slava Pestov */
18 /* The exception port on which our thread listens. */
19 mach_port_t our_exception_port;
21 /* The following sources were used as a *reference* for this exception handling
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 */
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 static void call_fault_handler(
32 exception_type_t exception,
33 exception_data_type_t code,
34 MACH_EXC_STATE_TYPE *exc_state,
35 MACH_THREAD_STATE_TYPE *thread_state)
37 /* There is a race condition here, but in practice an exception
38 delivered during stack frame setup/teardown or while transitioning
39 from Factor to C is a sign of things seriously gone wrong, not just
40 a divide by zero or stack underflow in the listener */
42 /* Are we in compiled Factor code? Then use the current stack pointer */
43 if(in_code_heap_p(MACH_PROGRAM_COUNTER(thread_state)))
44 signal_callstack_top = (stack_frame *)MACH_STACK_POINTER(thread_state);
45 /* Are we in C? Then use the saved callstack top */
47 signal_callstack_top = NULL;
49 MACH_STACK_POINTER(thread_state) = fix_stack_pointer(MACH_STACK_POINTER(thread_state));
51 /* Now we point the program counter at the right handler function. */
52 if(exception == EXC_BAD_ACCESS)
54 signal_fault_addr = MACH_EXC_STATE_FAULT(exc_state);
55 MACH_PROGRAM_COUNTER(thread_state) = (cell)memory_signal_handler_impl;
57 else if(exception == EXC_ARITHMETIC && code != MACH_EXC_INTEGER_DIV)
59 MACH_PROGRAM_COUNTER(thread_state) = (cell)fp_signal_handler_impl;
63 signal_number = (exception == EXC_ARITHMETIC ? SIGFPE : SIGABRT);
64 MACH_PROGRAM_COUNTER(thread_state) = (cell)misc_signal_handler_impl;
68 /* Handle an exception by invoking the user's fault handler and/or forwarding
69 the duty to the previously installed handlers. */
72 catch_exception_raise (mach_port_t exception_port,
75 exception_type_t exception,
76 exception_data_t code,
77 mach_msg_type_number_t code_count)
79 MACH_EXC_STATE_TYPE exc_state;
80 MACH_THREAD_STATE_TYPE thread_state;
81 mach_msg_type_number_t state_count;
83 /* Get fault information and the faulting thread's register contents..
85 See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/thread_get_state.html. */
86 state_count = MACH_EXC_STATE_COUNT;
87 if (thread_get_state (thread, MACH_EXC_STATE_FLAVOR,
88 (natural_t *)&exc_state, &state_count)
91 /* The thread is supposed to be suspended while the exception
92 handler is called. This shouldn't fail. */
96 state_count = MACH_THREAD_STATE_COUNT;
97 if (thread_get_state (thread, MACH_THREAD_STATE_FLAVOR,
98 (natural_t *)&thread_state, &state_count)
101 /* The thread is supposed to be suspended while the exception
102 handler is called. This shouldn't fail. */
106 /* Modify registers so to have the thread resume executing the
108 call_fault_handler(exception,code[0],&exc_state,&thread_state);
110 /* Set the faulting thread's register contents..
112 See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/thread_set_state.html. */
113 if (thread_set_state (thread, MACH_THREAD_STATE_FLAVOR,
114 (natural_t *)&thread_state, state_count)
124 /* The main function of the thread listening for exceptions. */
126 mach_exception_thread (void *arg)
130 /* These two structures contain some private kernel data. We don't need
131 to access any of it so we don't bother defining a proper struct. The
132 correct definitions are in the xnu source code. */
133 /* Buffer for a message to be received. */
136 mach_msg_header_t head;
137 mach_msg_body_t msgh_body;
141 /* Buffer for a reply message. */
144 mach_msg_header_t head;
149 mach_msg_return_t retval;
151 /* Wait for a message on the exception port. */
152 retval = mach_msg (&msg.head, MACH_RCV_MSG | MACH_RCV_LARGE, 0,
153 sizeof (msg), our_exception_port,
154 MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
155 if (retval != MACH_MSG_SUCCESS)
160 /* Handle the message: Call exc_server, which will call
161 catch_exception_raise and produce a reply message. */
162 exc_server (&msg.head, &reply.head);
164 /* Send the reply. */
165 if (mach_msg (&reply.head, MACH_SEND_MSG, reply.head.msgh_size,
166 0, MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL)
174 /* Initialize the Mach exception handler thread. */
175 void mach_initialize ()
178 exception_mask_t mask;
180 self = mach_task_self ();
182 /* Allocate a port on which the thread shall listen for exceptions. */
183 if (mach_port_allocate (self, MACH_PORT_RIGHT_RECEIVE, &our_exception_port)
185 fatal_error("mach_port_allocate() failed",0);
187 /* See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/mach_port_insert_right.html. */
188 if (mach_port_insert_right (self, our_exception_port, our_exception_port,
189 MACH_MSG_TYPE_MAKE_SEND)
191 fatal_error("mach_port_insert_right() failed",0);
193 /* The exceptions we want to catch. */
194 mask = EXC_MASK_BAD_ACCESS | EXC_MASK_ARITHMETIC;
196 /* Create the thread listening on the exception port. */
197 start_thread(mach_exception_thread);
199 /* Replace the exception port info for these exceptions with our own.
200 Note that we replace the exception port for the entire task, not only
201 for a particular thread. This has the effect that when our exception
202 port gets the message, the thread specific exception port has already
203 been asked, and we don't need to bother about it.
204 See http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/task_set_exception_ports.html. */
205 if (task_set_exception_ports (self, mask, our_exception_port,
206 EXCEPTION_DEFAULT, MACHINE_THREAD_STATE)
208 fatal_error("task_set_exception_ports() failed",0);