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[PATCH] uml ubd driver: various little changes
[linux-2.6.git] / arch / um / kernel / tt / tracer.c
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"
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"
28 #include "irq_user.h"
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 {
36         if(pid != os_getpgrp())
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 {
92         struct faultinfo fi;
93         GET_FAULTINFO_FROM_SC(fi, &sc);
94         printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
95                FAULT_ADDRESS(fi), SC_IP(&sc));
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());
122         init_irq_signals(0);
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
180 extern void signal_usr1(int sig);
181
182 int tracing_pid = -1;
183
184 int tracer(int (*init_proc)(void *), void *sp)
185 {
186         void *task = NULL;
187         int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
188         int proc_id = 0, n, err, old_tracing = 0, strace = 0;
189         int local_using_sysemu = 0;
190
191         signal(SIGPIPE, SIG_IGN);
192         setup_tracer_winch();
193         tracing_pid = os_getpid();
194         printf("tracing thread pid = %d\n", tracing_pid);
195
196         pid = clone(signal_tramp, sp, CLONE_FILES | SIGCHLD, init_proc);
197         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
198         if(n < 0){
199                 printf("waitpid on idle thread failed, errno = %d\n", errno);
200                 exit(1);
201         }
202         if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) {
203                 printf("Failed to PTRACE_SETOPTIONS for idle thread, errno = %d\n", errno);
204                 exit(1);
205         }
206         if((ptrace(PTRACE_CONT, pid, 0, 0) < 0)){
207                 printf("Failed to continue idle thread, errno = %d\n", errno);
208                 exit(1);
209         }
210
211         signal(SIGSEGV, (sighandler_t) tracer_segv);
212         signal(SIGUSR1, signal_usr1);
213         if(debug_trace){
214                 printf("Tracing thread pausing to be attached\n");
215                 stop();
216         }
217         if(debug){
218                 if(gdb_pid != -1) 
219                         debugger_pid = attach_debugger(pid, gdb_pid, 1);
220                 else debugger_pid = init_ptrace_proxy(pid, 1, debug_stop);
221                 if(debug_parent){
222                         debugger_parent = os_process_parent(debugger_pid);
223                         init_parent_proxy(debugger_parent);
224                         err = attach(debugger_parent);
225                         if(err){
226                                 printf("Failed to attach debugger parent %d, "
227                                        "errno = %d\n", debugger_parent, -err);
228                                 debugger_parent = -1;
229                         }
230                         else {
231                                 if(ptrace(PTRACE_SYSCALL, debugger_parent, 
232                                           0, 0) < 0){
233                                         printf("Failed to continue debugger "
234                                                "parent, errno = %d\n", errno);
235                                         debugger_parent = -1;
236                                 }
237                         }
238                 }
239         }
240         set_cmdline("(tracing thread)");
241         while(1){
242                 CATCH_EINTR(pid = waitpid(-1, &status, WUNTRACED));
243                 if(pid <= 0){
244                         if(errno != ECHILD){
245                                 printf("wait failed - errno = %d\n", errno);
246                         }
247                         continue;
248                 }
249                 if(pid == debugger_pid){
250                         int cont = 0;
251
252                         if(WIFEXITED(status) || WIFSIGNALED(status))
253                                 debugger_pid = -1;
254                         /* XXX Figure out how to deal with gdb and SMP */
255                         else cont = debugger_signal(status, cpu_tasks[0].pid);
256                         if(cont == PTRACE_SYSCALL) strace = 1;
257                         continue;
258                 }
259                 else if(pid == debugger_parent){
260                         debugger_parent_signal(status, pid);
261                         continue;
262                 }
263                 nsignals++;
264                 if(WIFEXITED(status)) ;
265 #ifdef notdef
266                 {
267                         printf("Child %d exited with status %d\n", pid, 
268                                WEXITSTATUS(status));
269                 }
270 #endif
271                 else if(WIFSIGNALED(status)){
272                         sig = WTERMSIG(status);
273                         if(sig != 9){
274                                 printf("Child %d exited with signal %d\n", pid,
275                                        sig);
276                         }
277                 }
278                 else if(WIFSTOPPED(status)){
279                         proc_id = pid_to_processor_id(pid);
280                         sig = WSTOPSIG(status);
281                         if(proc_id == -1){
282                                 sleeping_process_signal(pid, sig);
283                                 continue;
284                         }
285
286                         task = cpu_tasks[proc_id].task;
287                         tracing = is_tracing(task);
288                         old_tracing = tracing;
289
290                         /* Assume: no syscall, when coming from user */
291                         if ( tracing )
292                                 do_sigtrap(task);
293
294                         switch(sig){
295                         case SIGUSR1:
296                                 sig = 0;
297                                 op = do_proc_op(task, proc_id);
298                                 switch(op){
299                                 /*
300                                  * This is called when entering user mode; after
301                                  * this, we start intercepting syscalls.
302                                  *
303                                  * In fact, a process is started in kernel mode,
304                                  * so with is_tracing() == 0 (and that is reset
305                                  * when executing syscalls, since UML kernel has
306                                  * the right to do syscalls);
307                                  */
308                                 case OP_TRACE_ON:
309                                         arch_leave_kernel(task, pid);
310                                         tracing = 1;
311                                         break;
312                                 case OP_REBOOT:
313                                 case OP_HALT:
314                                         unmap_physmem();
315                                         kmalloc_ok = 0;
316                                         os_kill_ptraced_process(pid, 0);
317                                         /* Now let's reap remaining zombies */
318                                         errno = 0;
319                                         do {
320                                                 waitpid(-1, &status,
321                                                         WUNTRACED);
322                                         } while (errno != ECHILD);
323                                         return(op == OP_REBOOT);
324                                 case OP_NONE:
325                                         printf("Detaching pid %d\n", pid);
326                                         detach(pid, SIGSTOP);
327                                         continue;
328                                 default:
329                                         break;
330                                 }
331                                 /* OP_EXEC switches host processes on us,
332                                  * we want to continue the new one.
333                                  */
334                                 pid = cpu_tasks[proc_id].pid;
335                                 break;
336                         case (SIGTRAP + 0x80):
337                                 if(!tracing && (debugger_pid != -1)){
338                                         child_signal(pid, status & 0x7fff);
339                                         continue;
340                                 }
341                                 tracing = 0;
342                                 /* local_using_sysemu has been already set
343                                  * below, since if we are here, is_tracing() on
344                                  * the traced task was 1, i.e. the process had
345                                  * already run through one iteration of the
346                                  * loop which executed a OP_TRACE_ON request.*/
347                                 do_syscall(task, pid, local_using_sysemu);
348                                 sig = SIGUSR2;
349                                 break;
350                         case SIGTRAP:
351                                 if(!tracing && (debugger_pid != -1)){
352                                         child_signal(pid, status);
353                                         continue;
354                                 }
355                                 tracing = 0;
356                                 break;
357                         case SIGPROF:
358                                 if(tracing) sig = 0;
359                                 break;
360                         case SIGCHLD:
361                         case SIGHUP:
362                                 sig = 0;
363                                 break;
364                         case SIGSEGV:
365                         case SIGIO:
366                         case SIGALRM:
367                         case SIGVTALRM:
368                         case SIGFPE:
369                         case SIGBUS:
370                         case SIGILL:
371                         case SIGWINCH:
372
373                         default:
374                                 tracing = 0;
375                                 break;
376                         }
377                         set_tracing(task, tracing);
378
379                         if(!tracing && old_tracing)
380                                 arch_enter_kernel(task, pid);
381
382                         if(!tracing && (debugger_pid != -1) && (sig != 0) &&
383                                 (sig != SIGALRM) && (sig != SIGVTALRM) &&
384                                 (sig != SIGSEGV) && (sig != SIGTRAP) &&
385                                 (sig != SIGUSR2) && (sig != SIGIO) &&
386                                 (sig != SIGFPE)){
387                                 child_signal(pid, status);
388                                 continue;
389                         }
390
391                         local_using_sysemu = get_using_sysemu();
392
393                         if(tracing)
394                                 cont_type = SELECT_PTRACE_OPERATION(local_using_sysemu,
395                                                                     singlestepping(task));
396                         else if((debugger_pid != -1) && strace)
397                                 cont_type = PTRACE_SYSCALL;
398                         else
399                                 cont_type = PTRACE_CONT;
400
401                         if(ptrace(cont_type, pid, 0, sig) != 0){
402                                 tracer_panic("ptrace failed to continue "
403                                              "process - errno = %d\n", 
404                                              errno);
405                         }
406                 }
407         }
408         return(0);
409 }
410
411 static int __init uml_debug_setup(char *line, int *add)
412 {
413         char *next;
414
415         debug = 1;
416         *add = 0;
417         if(*line != '=') return(0);
418         line++;
419
420         while(line != NULL){
421                 next = strchr(line, ',');
422                 if(next) *next++ = '\0';
423                 
424                 if(!strcmp(line, "go")) debug_stop = 0;
425                 else if(!strcmp(line, "parent")) debug_parent = 1;
426                 else printf("Unknown debug option : '%s'\n", line);
427
428                 line = next;
429         }
430         return(0);
431 }
432
433 __uml_setup("debug", uml_debug_setup,
434 "debug\n"
435 "    Starts up the kernel under the control of gdb. See the \n"
436 "    kernel debugging tutorial and the debugging session pages\n"
437 "    at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
438 );
439
440 static int __init uml_debugtrace_setup(char *line, int *add)
441 {
442         debug_trace = 1;
443         return 0;
444 }
445 __uml_setup("debugtrace", uml_debugtrace_setup,
446 "debugtrace\n"
447 "    Causes the tracing thread to pause until it is attached by a\n"
448 "    debugger and continued.  This is mostly for debugging crashes\n"
449 "    early during boot, and should be pretty much obsoleted by\n"
450 "    the debug switch.\n\n"
451 );
452
453 /*
454  * Overrides for Emacs so that we follow Linus's tabbing style.
455  * Emacs will notice this stuff at the end of the file and automatically
456  * adjust the settings for this buffer only.  This must remain at the end
457  * of the file.
458  * ---------------------------------------------------------------------------
459  * Local variables:
460  * c-file-style: "linux"
461  * End:
462  */