summaryrefslogtreecommitdiffstats
path: root/arch/um/kernel/tt/tracer.c
blob: b9195355075ab3e9540dd0e880be38b1cd08556a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
/* 
 * 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 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:
 */