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  */