[deliverable/linux.git] / arch / um / kernel / tt / tracer.c

/* 
 * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sched.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <sys/wait.h>
#include "user.h"
#include "sysdep/ptrace.h"
#include "sigcontext.h"
#include "sysdep/sigcontext.h"
#include "os.h"
#include "user_util.h"
#include "mem_user.h"
#include "process.h"
#include "kern_util.h"
#include "chan_user.h"
#include "ptrace_user.h"
#include "irq_user.h"
#include "mode.h"
#include "tt.h"

static int tracer_winch[2];

int is_tracer_winch(int pid, int fd, void *data)
{
	if(pid != os_getpgrp())
		return(0);

	register_winch_irq(tracer_winch[0], fd, -1, data);
	return(1);
}

static void tracer_winch_handler(int sig)
{
	int n;
	char c = 1;

	n = os_write_file(tracer_winch[1], &c, sizeof(c));
	if(n != sizeof(c))
		printk("tracer_winch_handler - write failed, err = %d\n", -n);
}

/* Called only by the tracing thread during initialization */

static void setup_tracer_winch(void)
{
	int err;

	err = os_pipe(tracer_winch, 1, 1);
	if(err < 0){
		printk("setup_tracer_winch : os_pipe failed, err = %d\n", -err);
		return;
	}
	signal(SIGWINCH, tracer_winch_handler);
}

void attach_process(int pid)
{
	if((ptrace(PTRACE_ATTACH, pid, 0, 0) < 0) ||
	   (ptrace(PTRACE_CONT, pid, 0, 0) < 0))
		tracer_panic("OP_FORK failed to attach pid");
	wait_for_stop(pid, SIGSTOP, PTRACE_CONT, NULL);
	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
		tracer_panic("OP_FORK: PTRACE_SETOPTIONS failed, errno = %d", errno);
	if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
		tracer_panic("OP_FORK failed to continue process");
}

void tracer_panic(char *format, ...)
{
	va_list ap;

	va_start(ap, format);
	vprintf(format, ap);
	va_end(ap);
	printf("\n");
	while(1) pause();
}

static void tracer_segv(int sig, struct sigcontext sc)
{
        struct faultinfo fi;
        GET_FAULTINFO_FROM_SC(fi, &sc);
	printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
               FAULT_ADDRESS(fi), SC_IP(&sc));
	while(1)
		pause();
}

/* Changed early in boot, and then only read */
int debug = 0;
int debug_stop = 1;
int debug_parent = 0;
int honeypot = 0;

static int signal_tramp(void *arg)
{
	int (*proc)(void *);

	if(honeypot && munmap((void *) (host_task_size - 0x10000000),
			      0x10000000)) 
		panic("Unmapping stack failed");
	if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0)
		panic("ptrace PTRACE_TRACEME failed");
	os_stop_process(os_getpid());
	change_sig(SIGWINCH, 0);
	signal(SIGUSR1, SIG_IGN);
	change_sig(SIGCHLD, 0);
	signal(SIGSEGV, (__sighandler_t) sig_handler);
	set_cmdline("(idle thread)");
	set_init_pid(os_getpid());
	init_irq_signals(0);
	proc = arg;
	return((*proc)(NULL));
}

static void sleeping_process_signal(int pid, int sig)
{
	switch(sig){
	/* These two result from UML being ^Z-ed and bg-ed.  PTRACE_CONT is
	 * right because the process must be in the kernel already.
	 */
	case SIGCONT:
	case SIGTSTP:
		if(ptrace(PTRACE_CONT, pid, 0, sig) < 0)
			tracer_panic("sleeping_process_signal : Failed to "
				     "continue pid %d, signal = %d, "
				     "errno = %d\n", pid, sig, errno);
		break;

	/* This happens when the debugger (e.g. strace) is doing system call 
	 * tracing on the kernel.  During a context switch, the current task
	 * will be set to the incoming process and the outgoing process will
	 * hop into write and then read.  Since it's not the current process
	 * any more, the trace of those will land here.  So, we need to just 
	 * PTRACE_SYSCALL it.
	 */
	case (SIGTRAP + 0x80):
		if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
			tracer_panic("sleeping_process_signal : Failed to "
				     "PTRACE_SYSCALL pid %d, errno = %d\n",
				     pid, errno);
		break;
	case SIGSTOP:
		break;
	default:
		tracer_panic("sleeping process %d got unexpected "
			     "signal : %d\n", pid, sig);
		break;
	}
}

/* Accessed only by the tracing thread */
int debugger_pid = -1;
int debugger_parent = -1;
int debugger_fd = -1;
int gdb_pid = -1;

struct {
	int pid;
	int signal;
	unsigned long addr;
	struct timeval time;
} signal_record[1024][32];

int signal_index[32];
int nsignals = 0;
int debug_trace = 0;
extern int io_nsignals, io_count, intr_count;

extern void signal_usr1(int sig);

int tracing_pid = -1;

int tracer(int (*init_proc)(void *), void *sp)
{
	void *task = NULL;
	int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
	int proc_id = 0, n, err, old_tracing = 0, strace = 0;
	int local_using_sysemu = 0;

	signal(SIGPIPE, SIG_IGN);
	setup_tracer_winch();
	tracing_pid = os_getpid();
	printf("tracing thread pid = %d\n", tracing_pid);

	pid = clone(signal_tramp, sp, CLONE_FILES | SIGCHLD, init_proc);
	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	if(n < 0){
		printf("waitpid on idle thread failed, errno = %d\n", errno);
		exit(1);
	}
	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) {
		printf("Failed to PTRACE_SETOPTIONS for idle thread, errno = %d\n", errno);
		exit(1);
	}
	if((ptrace(PTRACE_CONT, pid, 0, 0) < 0)){
		printf("Failed to continue idle thread, errno = %d\n", errno);
		exit(1);
	}

	signal(SIGSEGV, (sighandler_t) tracer_segv);
	signal(SIGUSR1, signal_usr1);
	if(debug_trace){
		printf("Tracing thread pausing to be attached\n");
		stop();
	}
	if(debug){
		if(gdb_pid != -1) 
			debugger_pid = attach_debugger(pid, gdb_pid, 1);
		else debugger_pid = init_ptrace_proxy(pid, 1, debug_stop);
		if(debug_parent){
			debugger_parent = os_process_parent(debugger_pid);
			init_parent_proxy(debugger_parent);
			err = attach(debugger_parent);
			if(err){
				printf("Failed to attach debugger parent %d, "
				       "errno = %d\n", debugger_parent, -err);
				debugger_parent = -1;
			}
			else {
				if(ptrace(PTRACE_SYSCALL, debugger_parent, 
					  0, 0) < 0){
					printf("Failed to continue debugger "
					       "parent, errno = %d\n", errno);
					debugger_parent = -1;
				}
			}
		}
	}
	set_cmdline("(tracing thread)");
	while(1){
		CATCH_EINTR(pid = waitpid(-1, &status, WUNTRACED));
		if(pid <= 0){
			if(errno != ECHILD){
				printf("wait failed - errno = %d\n", errno);
			}
			continue;
		}
		if(pid == debugger_pid){
			int cont = 0;

			if(WIFEXITED(status) || WIFSIGNALED(status))
				debugger_pid = -1;
			/* XXX Figure out how to deal with gdb and SMP */
			else cont = debugger_signal(status, cpu_tasks[0].pid);
			if(cont == PTRACE_SYSCALL) strace = 1;
			continue;
		}
		else if(pid == debugger_parent){
			debugger_parent_signal(status, pid);
			continue;
		}
		nsignals++;
		if(WIFEXITED(status)) ;
#ifdef notdef
		{
			printf("Child %d exited with status %d\n", pid, 
			       WEXITSTATUS(status));
		}
#endif
		else if(WIFSIGNALED(status)){
			sig = WTERMSIG(status);
			if(sig != 9){
				printf("Child %d exited with signal %d\n", pid,
				       sig);
			}
		}
		else if(WIFSTOPPED(status)){
			proc_id = pid_to_processor_id(pid);
			sig = WSTOPSIG(status);
			if(proc_id == -1){
				sleeping_process_signal(pid, sig);
				continue;
			}

			task = cpu_tasks[proc_id].task;
			tracing = is_tracing(task);
			old_tracing = tracing;

			/* Assume: no syscall, when coming from user */
			if ( tracing )
				do_sigtrap(task);

			switch(sig){
			case SIGUSR1:
				sig = 0;
				op = do_proc_op(task, proc_id);
				switch(op){
				/*
				 * This is called when entering user mode; after
				 * this, we start intercepting syscalls.
				 *
				 * In fact, a process is started in kernel mode,
				 * so with is_tracing() == 0 (and that is reset
				 * when executing syscalls, since UML kernel has
				 * the right to do syscalls);
				 */
				case OP_TRACE_ON:
					arch_leave_kernel(task, pid);
					tracing = 1;
					break;
				case OP_REBOOT:
				case OP_HALT:
					unmap_physmem();
					kmalloc_ok = 0;
					os_kill_ptraced_process(pid, 0);
					/* Now let's reap remaining zombies */
					errno = 0;
					do {
						waitpid(-1, &status,
							WUNTRACED);
					} while (errno != ECHILD);
					return(op == OP_REBOOT);
				case OP_NONE:
					printf("Detaching pid %d\n", pid);
					detach(pid, SIGSTOP);
					continue;
				default:
					break;
				}
				/* OP_EXEC switches host processes on us,
				 * we want to continue the new one.
				 */
				pid = cpu_tasks[proc_id].pid;
				break;
			case (SIGTRAP + 0x80):
				if(!tracing && (debugger_pid != -1)){
					child_signal(pid, status & 0x7fff);
					continue;
				}
				tracing = 0;
				/* local_using_sysemu has been already set
				 * below, since if we are here, is_tracing() on
				 * the traced task was 1, i.e. the process had
				 * already run through one iteration of the
				 * loop which executed a OP_TRACE_ON request.*/
				do_syscall(task, pid, local_using_sysemu);
				sig = SIGUSR2;
				break;
			case SIGTRAP:
				if(!tracing && (debugger_pid != -1)){
					child_signal(pid, status);
					continue;
				}
				tracing = 0;
				break;
			case SIGPROF:
				if(tracing) sig = 0;
				break;
			case SIGCHLD:
			case SIGHUP:
				sig = 0;
				break;
			case SIGSEGV:
			case SIGIO:
			case SIGALRM:
			case SIGVTALRM:
			case SIGFPE:
			case SIGBUS:
			case SIGILL:
			case SIGWINCH:

			default:
				tracing = 0;
				break;
			}
			set_tracing(task, tracing);

			if(!tracing && old_tracing)
				arch_enter_kernel(task, pid);

			if(!tracing && (debugger_pid != -1) && (sig != 0) &&
				(sig != SIGALRM) && (sig != SIGVTALRM) &&
				(sig != SIGSEGV) && (sig != SIGTRAP) &&
				(sig != SIGUSR2) && (sig != SIGIO) &&
				(sig != SIGFPE)){
				child_signal(pid, status);
				continue;
			}

			local_using_sysemu = get_using_sysemu();

			if(tracing)
				cont_type = SELECT_PTRACE_OPERATION(local_using_sysemu,
				                                    singlestepping(task));
			else if((debugger_pid != -1) && strace)
				cont_type = PTRACE_SYSCALL;
			else
				cont_type = PTRACE_CONT;

			if(ptrace(cont_type, pid, 0, sig) != 0){
				tracer_panic("ptrace failed to continue "
					     "process - errno = %d\n", 
					     errno);
			}
		}
	}
	return(0);
}

static int __init uml_debug_setup(char *line, int *add)
{
	char *next;

	debug = 1;
	*add = 0;
	if(*line != '=') return(0);
	line++;

	while(line != NULL){
		next = strchr(line, ',');
		if(next) *next++ = '\0';
		
		if(!strcmp(line, "go"))	debug_stop = 0;
		else if(!strcmp(line, "parent")) debug_parent = 1;
		else printf("Unknown debug option : '%s'\n", line);

		line = next;
	}
	return(0);
}

__uml_setup("debug", uml_debug_setup,
"debug\n"
"    Starts up the kernel under the control of gdb. See the \n"
"    kernel debugging tutorial and the debugging session pages\n"
"    at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
);

static int __init uml_debugtrace_setup(char *line, int *add)
{
	debug_trace = 1;
	return 0;
}
__uml_setup("debugtrace", uml_debugtrace_setup,
"debugtrace\n"
"    Causes the tracing thread to pause until it is attached by a\n"
"    debugger and continued.  This is mostly for debugging crashes\n"
"    early during boot, and should be pretty much obsoleted by\n"
"    the debug switch.\n\n"
);

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-file-style: "linux"
 * End:
 */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
	3	* Licensed under the GPL
	4	*/
	5
	6	#include <stdio.h>
	7	#include <stdlib.h>
	8	#include <stdarg.h>
	9	#include <unistd.h>
	10	#include <signal.h>
	11	#include <errno.h>
	12	#include <sched.h>
	13	#include <string.h>
	14	#include <sys/mman.h>
	15	#include <sys/time.h>
	16	#include <sys/wait.h>
	17	#include "user.h"
	18	#include "sysdep/ptrace.h"
	19	#include "sigcontext.h"
	20	#include "sysdep/sigcontext.h"
	21	#include "os.h"
1da177e4 LT	22	#include "user_util.h"
	23	#include "mem_user.h"
	24	#include "process.h"
	25	#include "kern_util.h"
	26	#include "chan_user.h"
	27	#include "ptrace_user.h"
cd2ee4a3	28	#include "irq_user.h"
1da177e4 LT	29	#include "mode.h"
	30	#include "tt.h"
	31
	32	static int tracer_winch[2];
	33
	34	int is_tracer_winch(int pid, int fd, void *data)
	35	{
cd2ee4a3	36	if(pid != os_getpgrp())
1da177e4 LT	37	return(0);
	38
	39	register_winch_irq(tracer_winch[0], fd, -1, data);
	40	return(1);
	41	}
	42
	43	static void tracer_winch_handler(int sig)
	44	{
	45	int n;
	46	char c = 1;
	47
	48	n = os_write_file(tracer_winch[1], &c, sizeof(c));
	49	if(n != sizeof(c))
	50	printk("tracer_winch_handler - write failed, err = %d\n", -n);
	51	}
	52
	53	/* Called only by the tracing thread during initialization */
	54
	55	static void setup_tracer_winch(void)
	56	{
	57	int err;
	58
	59	err = os_pipe(tracer_winch, 1, 1);
	60	if(err < 0){
	61	printk("setup_tracer_winch : os_pipe failed, err = %d\n", -err);
	62	return;
	63	}
	64	signal(SIGWINCH, tracer_winch_handler);
	65	}
	66
	67	void attach_process(int pid)
	68	{
	69	if((ptrace(PTRACE_ATTACH, pid, 0, 0) < 0) \|\|
	70	(ptrace(PTRACE_CONT, pid, 0, 0) < 0))
	71	tracer_panic("OP_FORK failed to attach pid");
	72	wait_for_stop(pid, SIGSTOP, PTRACE_CONT, NULL);
	73	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
	74	tracer_panic("OP_FORK: PTRACE_SETOPTIONS failed, errno = %d", errno);
	75	if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
	76	tracer_panic("OP_FORK failed to continue process");
	77	}
	78
	79	void tracer_panic(char *format, ...)
	80	{
	81	va_list ap;
	82
	83	va_start(ap, format);
	84	vprintf(format, ap);
	85	va_end(ap);
	86	printf("\n");
	87	while(1) pause();
	88	}
	89
	90	static void tracer_segv(int sig, struct sigcontext sc)
	91	{
c578455a BS	92	struct faultinfo fi;
c578455a BS	93	GET_FAULTINFO_FROM_SC(fi, &sc);
1da177e4	94	printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
c578455a	95	FAULT_ADDRESS(fi), SC_IP(&sc));
1da177e4 LT	96	while(1)
	97	pause();
	98	}
	99
	100	/* Changed early in boot, and then only read */
	101	int debug = 0;
	102	int debug_stop = 1;
	103	int debug_parent = 0;
	104	int honeypot = 0;
	105
	106	static int signal_tramp(void *arg)
	107	{
	108	int (proc)(void );
	109
	110	if(honeypot && munmap((void *) (host_task_size - 0x10000000),
	111	0x10000000))
	112	panic("Unmapping stack failed");
	113	if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0)
	114	panic("ptrace PTRACE_TRACEME failed");
	115	os_stop_process(os_getpid());
	116	change_sig(SIGWINCH, 0);
	117	signal(SIGUSR1, SIG_IGN);
	118	change_sig(SIGCHLD, 0);
	119	signal(SIGSEGV, (__sighandler_t) sig_handler);
	120	set_cmdline("(idle thread)");
	121	set_init_pid(os_getpid());
cd2ee4a3	122	init_irq_signals(0);
1da177e4 LT	123	proc = arg;
	124	return((*proc)(NULL));
	125	}
	126
	127	static void sleeping_process_signal(int pid, int sig)
	128	{
	129	switch(sig){
	130	/* These two result from UML being ^Z-ed and bg-ed. PTRACE_CONT is
	131	* right because the process must be in the kernel already.
	132	*/
	133	case SIGCONT:
	134	case SIGTSTP:
	135	if(ptrace(PTRACE_CONT, pid, 0, sig) < 0)
	136	tracer_panic("sleeping_process_signal : Failed to "
	137	"continue pid %d, signal = %d, "
	138	"errno = %d\n", pid, sig, errno);
	139	break;
	140
	141	/* This happens when the debugger (e.g. strace) is doing system call
	142	* tracing on the kernel. During a context switch, the current task
	143	* will be set to the incoming process and the outgoing process will
	144	* hop into write and then read. Since it's not the current process
	145	* any more, the trace of those will land here. So, we need to just
	146	* PTRACE_SYSCALL it.
	147	*/
	148	case (SIGTRAP + 0x80):
	149	if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
	150	tracer_panic("sleeping_process_signal : Failed to "
	151	"PTRACE_SYSCALL pid %d, errno = %d\n",
	152	pid, errno);
	153	break;
	154	case SIGSTOP:
	155	break;
	156	default:
	157	tracer_panic("sleeping process %d got unexpected "
	158	"signal : %d\n", pid, sig);
	159	break;
	160	}
	161	}
	162
	163	/* Accessed only by the tracing thread */
	164	int debugger_pid = -1;
	165	int debugger_parent = -1;
	166	int debugger_fd = -1;
	167	int gdb_pid = -1;
	168
	169	struct {
	170	int pid;
	171	int signal;
	172	unsigned long addr;
	173	struct timeval time;
	174	} signal_record[1024][32];
	175
	176	int signal_index[32];
	177	int nsignals = 0;
	178	int debug_trace = 0;
	179	extern int io_nsignals, io_count, intr_count;
	180
	181	extern void signal_usr1(int sig);
	182
	183	int tracing_pid = -1;
	184
	185	int tracer(int (init_proc)(void ), void *sp)
	186	{
187	void *task = NULL;
188	int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
189	int proc_id = 0, n, err, old_tracing = 0, strace = 0;
190	int local_using_sysemu = 0;
469226a4	191
1da177e4 LT	192	signal(SIGPIPE, SIG_IGN);
	193	setup_tracer_winch();
	194	tracing_pid = os_getpid();
	195	printf("tracing thread pid = %d\n", tracing_pid);
	196
	197	pid = clone(signal_tramp, sp, CLONE_FILES \| SIGCHLD, init_proc);
	198	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	199	if(n < 0){
	200	printf("waitpid on idle thread failed, errno = %d\n", errno);
	201	exit(1);
	202	}
	203	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) {
	204	printf("Failed to PTRACE_SETOPTIONS for idle thread, errno = %d\n", errno);
	205	exit(1);
	206	}
	207	if((ptrace(PTRACE_CONT, pid, 0, 0) < 0)){
	208	printf("Failed to continue idle thread, errno = %d\n", errno);
	209	exit(1);
	210	}
	211
	212	signal(SIGSEGV, (sighandler_t) tracer_segv);
	213	signal(SIGUSR1, signal_usr1);
	214	if(debug_trace){
	215	printf("Tracing thread pausing to be attached\n");
	216	stop();
	217	}
	218	if(debug){
	219	if(gdb_pid != -1)
	220	debugger_pid = attach_debugger(pid, gdb_pid, 1);
	221	else debugger_pid = init_ptrace_proxy(pid, 1, debug_stop);
	222	if(debug_parent){
	223	debugger_parent = os_process_parent(debugger_pid);
	224	init_parent_proxy(debugger_parent);
	225	err = attach(debugger_parent);
	226	if(err){
	227	printf("Failed to attach debugger parent %d, "
	228	"errno = %d\n", debugger_parent, -err);
	229	debugger_parent = -1;
	230	}
	231	else {
	232	if(ptrace(PTRACE_SYSCALL, debugger_parent,
	233	0, 0) < 0){
	234	printf("Failed to continue debugger "
	235	"parent, errno = %d\n", errno);
	236	debugger_parent = -1;
	237	}
	238	}
	239	}
	240	}
	241	set_cmdline("(tracing thread)");
	242	while(1){
	243	CATCH_EINTR(pid = waitpid(-1, &status, WUNTRACED));
	244	if(pid <= 0){
	245	if(errno != ECHILD){
	246	printf("wait failed - errno = %d\n", errno);
	247	}
	248	continue;
	249	}
	250	if(pid == debugger_pid){
	251	int cont = 0;
	252
	253	if(WIFEXITED(status) \|\| WIFSIGNALED(status))
	254	debugger_pid = -1;
	255	/* XXX Figure out how to deal with gdb and SMP */
256	else cont = debugger_signal(status, cpu_tasks[0].pid);
257	if(cont == PTRACE_SYSCALL) strace = 1;
258	continue;
259	}
260	else if(pid == debugger_parent){
261	debugger_parent_signal(status, pid);
262	continue;
263	}
264	nsignals++;
265	if(WIFEXITED(status)) ;
266	#ifdef notdef
267	{
268	printf("Child %d exited with status %d\n", pid,
269	WEXITSTATUS(status));
270	}
271	#endif
272	else if(WIFSIGNALED(status)){
273	sig = WTERMSIG(status);
274	if(sig != 9){
275	printf("Child %d exited with signal %d\n", pid,
276	sig);
277	}
278	}
279	else if(WIFSTOPPED(status)){
280	proc_id = pid_to_processor_id(pid);
281	sig = WSTOPSIG(status);
1da177e4 LT	282	if(proc_id == -1){
	283	sleeping_process_signal(pid, sig);
	284	continue;
	285	}
	286
	287	task = cpu_tasks[proc_id].task;
	288	tracing = is_tracing(task);
	289	old_tracing = tracing;
	290
	291	/* Assume: no syscall, when coming from user */
	292	if ( tracing )
	293	do_sigtrap(task);
	294
	295	switch(sig){
	296	case SIGUSR1:
	297	sig = 0;
	298	op = do_proc_op(task, proc_id);
	299	switch(op){
	300	/*
	301	* This is called when entering user mode; after
	302	* this, we start intercepting syscalls.
	303	*
	304	* In fact, a process is started in kernel mode,
	305	* so with is_tracing() == 0 (and that is reset
	306	* when executing syscalls, since UML kernel has
	307	* the right to do syscalls);
	308	*/
	309	case OP_TRACE_ON:
	310	arch_leave_kernel(task, pid);
	311	tracing = 1;
	312	break;
	313	case OP_REBOOT:
	314	case OP_HALT:
	315	unmap_physmem();
	316	kmalloc_ok = 0;
	317	os_kill_ptraced_process(pid, 0);
	318	/* Now let's reap remaining zombies */
	319	errno = 0;
	320	do {
	321	waitpid(-1, &status,
	322	WUNTRACED);
	323	} while (errno != ECHILD);
	324	return(op == OP_REBOOT);
	325	case OP_NONE:
	326	printf("Detaching pid %d\n", pid);
	327	detach(pid, SIGSTOP);
	328	continue;
	329	default:
	330	break;
	331	}
	332	/* OP_EXEC switches host processes on us,
	333	* we want to continue the new one.
	334	*/
	335	pid = cpu_tasks[proc_id].pid;
	336	break;
	337	case (SIGTRAP + 0x80):
	338	if(!tracing && (debugger_pid != -1)){
	339	child_signal(pid, status & 0x7fff);
	340	continue;
	341	}
	342	tracing = 0;
	343	/* local_using_sysemu has been already set
	344	* below, since if we are here, is_tracing() on
	345	* the traced task was 1, i.e. the process had
346	* already run through one iteration of the
347	* loop which executed a OP_TRACE_ON request.*/
348	do_syscall(task, pid, local_using_sysemu);
349	sig = SIGUSR2;
350	break;
351	case SIGTRAP:
352	if(!tracing && (debugger_pid != -1)){
353	child_signal(pid, status);
354	continue;
355	}
356	tracing = 0;
357	break;
358	case SIGPROF:
359	if(tracing) sig = 0;
360	break;
361	case SIGCHLD:
362	case SIGHUP:
363	sig = 0;
364	break;
365	case SIGSEGV:
366	case SIGIO:
367	case SIGALRM:
368	case SIGVTALRM:
369	case SIGFPE:
370	case SIGBUS:
371	case SIGILL:
372	case SIGWINCH:
373
374	default:
375	tracing = 0;
376	break;
377	}
378	set_tracing(task, tracing);
379
380	if(!tracing && old_tracing)
381	arch_enter_kernel(task, pid);
382
383	if(!tracing && (debugger_pid != -1) && (sig != 0) &&
384	(sig != SIGALRM) && (sig != SIGVTALRM) &&
385	(sig != SIGSEGV) && (sig != SIGTRAP) &&
386	(sig != SIGUSR2) && (sig != SIGIO) &&
387	(sig != SIGFPE)){
388	child_signal(pid, status);
389	continue;
390	}
391
392	local_using_sysemu = get_using_sysemu();
393
394	if(tracing)
395	cont_type = SELECT_PTRACE_OPERATION(local_using_sysemu,
396	singlestepping(task));
397	else if((debugger_pid != -1) && strace)
398	cont_type = PTRACE_SYSCALL;
399	else
400	cont_type = PTRACE_CONT;
401
402	if(ptrace(cont_type, pid, 0, sig) != 0){
403	tracer_panic("ptrace failed to continue "
404	"process - errno = %d\n",
405	errno);
406	}
407	}
408	}
409	return(0);
410	}
411
412	static int __init uml_debug_setup(char line, int add)
413	{
414	char *next;
415
416	debug = 1;
417	*add = 0;
418	if(*line != '=') return(0);
419	line++;
420
421	while(line != NULL){
422	next = strchr(line, ',');
423	if(next) *next++ = '\0';
424
425	if(!strcmp(line, "go")) debug_stop = 0;
426	else if(!strcmp(line, "parent")) debug_parent = 1;
427	else printf("Unknown debug option : '%s'\n", line);
428
429	line = next;
430	}
431	return(0);
432	}
433
434	__uml_setup("debug", uml_debug_setup,
435	"debug\n"
436	" Starts up the kernel under the control of gdb. See the \n"
437	" kernel debugging tutorial and the debugging session pages\n"
438	" at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
439	);
440
441	static int __init uml_debugtrace_setup(char line, int add)
442	{
443	debug_trace = 1;
444	return 0;
445	}
446	__uml_setup("debugtrace", uml_debugtrace_setup,
447	"debugtrace\n"
448	" Causes the tracing thread to pause until it is attached by a\n"
449	" debugger and continued. This is mostly for debugging crashes\n"
450	" early during boot, and should be pretty much obsoleted by\n"
451	" the debug switch.\n\n"
452	);
453
454	/*
455	* Overrides for Emacs so that we follow Linus's tabbing style.
456	* Emacs will notice this stuff at the end of the file and automatically
457	* adjust the settings for this buffer only. This must remain at the end
458	* of the file.
459	* ---------------------------------------------------------------------------
460	* Local variables:
461	* c-file-style: "linux"
462	* End:
463	*/