exception.c   [plain text]

/*
 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */

#include <mach/mach_types.h>
#include <mach/boolean.h>
#include <mach/kern_return.h>
#include <mach/message.h>
#include <mach/port.h>
#include <mach/mig_errors.h>
#include <mach/task.h>
#include <mach/thread_status.h>
#include <mach/exception_types.h>
#include <mach/exc.h>
#include <mach/mach_exc.h>
#include <ipc/port.h>
#include <ipc/ipc_entry.h>
#include <ipc/ipc_object.h>
#include <ipc/ipc_notify.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_pset.h>
#include <ipc/ipc_machdep.h>
#include <kern/counters.h>
#include <kern/ipc_tt.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <kern/processor.h>
#include <kern/sched.h>
#include <kern/sched_prim.h>
#include <kern/host.h>
#include <kern/misc_protos.h>
#include <string.h>
#include <pexpert/pexpert.h>

extern int panic_on_exception_triage;

unsigned long c_thr_exc_raise = 0;
unsigned long c_thr_exc_raise_state = 0;
unsigned long c_thr_exc_raise_state_id = 0;
unsigned long c_tsk_exc_raise = 0;
unsigned long c_tsk_exc_raise_state = 0;
unsigned long c_tsk_exc_raise_state_id = 0;

/* forward declarations */
kern_return_t exception_deliver(
	thread_t 		thread,
	exception_type_t	exception,
	mach_exception_data_t	code,
	mach_msg_type_number_t  codeCnt,
	struct exception_action *excp,
	lck_mtx_t			*mutex);

static kern_return_t
check_exc_receiver_dependency(
	exception_type_t exception, 
	struct exception_action *excp, 
	lck_mtx_t *mutex);

#ifdef MACH_BSD
kern_return_t bsd_exception(
	exception_type_t	exception,
	mach_exception_data_t	code,
	mach_msg_type_number_t  codeCnt);
#endif /* MACH_BSD */

/*
 *	Routine:	exception_deliver
 *	Purpose:
 *		Make an upcall to the exception server provided.
 *	Conditions:
 *		Nothing locked and no resources held.
 *		Called from an exception context, so
 *		thread_exception_return and thread_kdb_return
 *		are possible.
 *	Returns:
 *		KERN_SUCCESS if the exception was handled
 */
kern_return_t 
exception_deliver(
	thread_t		thread,
	exception_type_t	exception,
	mach_exception_data_t	code,
	mach_msg_type_number_t  codeCnt,
	struct exception_action *excp,
	lck_mtx_t			*mutex)
{
	ipc_port_t		exc_port;
	exception_data_type_t	small_code[EXCEPTION_CODE_MAX];
	int			code64;
	int			behavior;
	int			flavor;
	kern_return_t		kr;

	/*
	 *  Save work if we are terminating.
	 *  Just go back to our AST handler.
	 */
	if (!thread->active && !thread->inspection)
		return KERN_SUCCESS;

	/*
	 * If there are no exception actions defined for this entity,
	 * we can't deliver here.
	 */
	if (excp == NULL)
		return KERN_FAILURE;

	assert(exception < EXC_TYPES_COUNT);
	if (exception >= EXC_TYPES_COUNT)
		return KERN_FAILURE;

	excp = &excp[exception];

	/*
	 * Snapshot the exception action data under lock for consistency.
	 * Hold a reference to the port over the exception_raise_* calls
	 * so it can't be destroyed.  This seems like overkill, but keeps
	 * the port from disappearing between now and when
	 * ipc_object_copyin_from_kernel is finally called.
	 */
	lck_mtx_lock(mutex);
	exc_port = excp->port;
	if (!IP_VALID(exc_port)) {
		lck_mtx_unlock(mutex);
		return KERN_FAILURE;
	}
	ip_lock(exc_port);
	if (!ip_active(exc_port)) {
		ip_unlock(exc_port);
		lck_mtx_unlock(mutex);
		return KERN_FAILURE;
	}
	ip_reference(exc_port);	
	exc_port->ip_srights++;
	ip_unlock(exc_port);

	flavor = excp->flavor;
	behavior = excp->behavior;
	lck_mtx_unlock(mutex);

	code64 = (behavior & MACH_EXCEPTION_CODES);
	behavior &= ~MACH_EXCEPTION_CODES;

	if (!code64) {
		small_code[0] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[0]);
		small_code[1] = CAST_DOWN_EXPLICIT(exception_data_type_t, code[1]);
	}


	switch (behavior) {
	case EXCEPTION_STATE: {
		mach_msg_type_number_t state_cnt;
		thread_state_data_t state;

		c_thr_exc_raise_state++;
		state_cnt = _MachineStateCount[flavor];
		kr = thread_getstatus(thread, flavor, 
				      (thread_state_t)state,
				      &state_cnt);
		if (kr == KERN_SUCCESS) {
			if (code64) {
				kr = mach_exception_raise_state(exc_port, 
						exception,
						code, 
						codeCnt,
						&flavor,
						state, state_cnt,
						state, &state_cnt);
			} else {
				kr = exception_raise_state(exc_port, exception,
						small_code, 
						codeCnt,
						&flavor,
						state, state_cnt,
						state, &state_cnt);
			}
			if (kr == MACH_MSG_SUCCESS && exception != EXC_CORPSE_NOTIFY)
				kr = thread_setstatus(thread, flavor, 
						(thread_state_t)state,
						state_cnt);
		}

		return kr;
	}

	case EXCEPTION_DEFAULT:
		c_thr_exc_raise++;
		if (code64) {
			kr = mach_exception_raise(exc_port,
					retrieve_thread_self_fast(thread),
					retrieve_task_self_fast(thread->task),
					exception,
					code, 
					codeCnt);
		} else {
			kr = exception_raise(exc_port,
					retrieve_thread_self_fast(thread),
					retrieve_task_self_fast(thread->task),
					exception,
					small_code, 
					codeCnt);
		}

		return kr;

	case EXCEPTION_STATE_IDENTITY: {
		mach_msg_type_number_t state_cnt;
		thread_state_data_t state;

		c_thr_exc_raise_state_id++;
		state_cnt = _MachineStateCount[flavor];
		kr = thread_getstatus(thread, flavor,
				      (thread_state_t)state,
				      &state_cnt);
		if (kr == KERN_SUCCESS) {
			if (code64) {
				kr = mach_exception_raise_state_identity(
						exc_port,
						retrieve_thread_self_fast(thread),
						retrieve_task_self_fast(thread->task),
						exception,
						code, 
						codeCnt,
						&flavor,
						state, state_cnt,
						state, &state_cnt);
			} else {
				kr = exception_raise_state_identity(exc_port,
						retrieve_thread_self_fast(thread),
						retrieve_task_self_fast(thread->task),
						exception,
						small_code, 
						codeCnt,
						&flavor,
						state, state_cnt,
						state, &state_cnt);
			}
			if (kr == MACH_MSG_SUCCESS && exception != EXC_CORPSE_NOTIFY)
				kr = thread_setstatus(thread, flavor,
						(thread_state_t)state,
						state_cnt);
		}

		return kr;
	}

	default:
	       panic ("bad exception behavior!");
	       return KERN_FAILURE; 
	}/* switch */
}

/*
 * Routine: check_exc_receiver_dependency
 * Purpose:
 *      Verify that the port destined for receiving this exception is not
 *      on the current task. This would cause hang in kernel for
 *      EXC_CRASH primarily. Note: If port is transferred
 *      between check and delivery then deadlock may happen.
 *
 * Conditions:
 *		Nothing locked and no resources held.
 *		Called from an exception context.
 * Returns:
 *      KERN_SUCCESS if its ok to send exception message.
 */
kern_return_t
check_exc_receiver_dependency(
	exception_type_t exception,
	struct exception_action *excp,
	lck_mtx_t *mutex)
{
	kern_return_t retval = KERN_SUCCESS;

	if (excp == NULL || exception != EXC_CRASH)
		return retval;

	task_t task = current_task();
	lck_mtx_lock(mutex);
	ipc_port_t xport = excp[exception].port;
	if ( IP_VALID(xport)
		     && ip_active(xport)
		     && task->itk_space == xport->ip_receiver)
		retval = KERN_FAILURE;
	lck_mtx_unlock(mutex);
	return retval;
}

/*
 *	Routine:	exception_triage
 *	Purpose:
 *		The current thread caught an exception.
 *		We make an up-call to the thread's exception server.
 *	Conditions:
 *		Nothing locked and no resources held.
 *		Called from an exception context, so
 *		thread_exception_return and thread_kdb_return
 *		are possible.
 *	Returns:
 *		KERN_SUCCESS if exception is handled by any of the handlers.
 */
kern_return_t
exception_triage(
	exception_type_t	exception,
	mach_exception_data_t	code,
	mach_msg_type_number_t  codeCnt)
{
	thread_t		thread;
	task_t			task;
	host_priv_t		host_priv;
	lck_mtx_t		*mutex;
	kern_return_t	kr = KERN_FAILURE;

	assert(exception != EXC_RPC_ALERT);

	/*
	 * If this behavior has been requested by the the kernel
	 * (due to the boot environment), we should panic if we
	 * enter this function.  This is intended as a debugging
	 * aid; it should allow us to debug why we caught an
	 * exception in environments where debugging is especially
	 * difficult.
	 */
	if (panic_on_exception_triage) {
		panic("called exception_triage when it was forbidden by the boot environment");
	}

	thread = current_thread();

	/*
	 * Try to raise the exception at the activation level.
	 */
	mutex = &thread->mutex;
	if (KERN_SUCCESS == check_exc_receiver_dependency(exception, thread->exc_actions, mutex))
	{
		kr = exception_deliver(thread, exception, code, codeCnt, thread->exc_actions, mutex);
		if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED)
			goto out;
	}

	/*
	 * Maybe the task level will handle it.
	 */
	task = current_task();
	mutex = &task->lock;
	if (KERN_SUCCESS == check_exc_receiver_dependency(exception, task->exc_actions, mutex))
	{
		kr = exception_deliver(thread, exception, code, codeCnt, task->exc_actions, mutex);
		if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED)
			goto out;
	}

	/*
	 * How about at the host level?
	 */
	host_priv = host_priv_self();
	mutex = &host_priv->lock;
	
	if (KERN_SUCCESS == check_exc_receiver_dependency(exception, host_priv->exc_actions, mutex))
	{
		kr = exception_deliver(thread, exception, code, codeCnt, host_priv->exc_actions, mutex);
		if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED)
			goto out;
	}

out:
	if ((exception != EXC_CRASH) && (exception != EXC_RESOURCE) &&
	    (exception != EXC_GUARD) && (exception != EXC_CORPSE_NOTIFY))
		thread_exception_return();
	return kr;
}

kern_return_t
bsd_exception(
	exception_type_t	exception,
	mach_exception_data_t	code,
	mach_msg_type_number_t  codeCnt)
{
	task_t			task;
	lck_mtx_t		*mutex;
	thread_t		self = current_thread();
	kern_return_t		kr;

	/*
	 * Maybe the task level will handle it.
	 */
	task = current_task();
	mutex = &task->lock;

	kr = exception_deliver(self, exception, code, codeCnt, task->exc_actions, mutex);

	if (kr == KERN_SUCCESS || kr == MACH_RCV_PORT_DIED)
		return(KERN_SUCCESS);
	return(KERN_FAILURE);
}


/*
 * Raise an exception on a task.
 * This should tell launchd to launch Crash Reporter for this task.
 */
kern_return_t task_exception_notify(exception_type_t exception,
	mach_exception_data_type_t exccode, mach_exception_data_type_t excsubcode)
{
	mach_exception_data_type_t	code[EXCEPTION_CODE_MAX];
	wait_interrupt_t		wsave;
	kern_return_t kr = KERN_SUCCESS;

	code[0] = exccode;
	code[1] = excsubcode;

	wsave = thread_interrupt_level(THREAD_UNINT);
	kr = exception_triage(exception, code, EXCEPTION_CODE_MAX);
	(void) thread_interrupt_level(wsave);
	return kr;
}


/*
 *	Handle interface for special performance monitoring
 *	This is a special case of the host exception handler
 */
kern_return_t sys_perf_notify(thread_t thread, int pid) 
{
	host_priv_t		hostp;
	ipc_port_t		xport;
	wait_interrupt_t	wsave;
	kern_return_t		ret;

	hostp = host_priv_self();	/* Get the host privileged ports */
	mach_exception_data_type_t	code[EXCEPTION_CODE_MAX];
	code[0] = 0xFF000001;		/* Set terminate code */
	code[1] = pid;		/* Pass out the pid */

	struct task *task = thread->task;
	xport = hostp->exc_actions[EXC_RPC_ALERT].port;	

	/* Make sure we're not catching our own exception */
	if (!IP_VALID(xport) ||
			!ip_active(xport) ||
			task->itk_space == xport->data.receiver) {

		return(KERN_FAILURE);	
	}

	wsave = thread_interrupt_level(THREAD_UNINT);	
	ret = exception_deliver(
			thread,
			EXC_RPC_ALERT, 
			code, 
			2, 
			hostp->exc_actions,
			&hostp->lock);
	(void)thread_interrupt_level(wsave);

	return(ret);
}