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 "signal_user.h"
  23 #include "user_util.h"
  24 #include "mem_user.h"
  25 #include "process.h"
  26 #include "kern_util.h"
  27 #include "chan_user.h"
  28 #include "ptrace_user.h"
  29 #include "irq_user.h"
  30 #include "mode.h"
  31 #include "tt.h"
  32
  33 static int tracer_winch[2];
  34
  35 int is_tracer_winch(int pid, int fd, void *data)
  36 {
  37         if(pid != os_getpgrp())
  38                 return(0);
  39
  40         register_winch_irq(tracer_winch[0], fd, -1, data);
  41         return(1);
  42 }
  43
  44 static void tracer_winch_handler(int sig)
  45 {
  46         int n;
  47         char c = 1;
  48
  49         n = os_write_file(tracer_winch[1], &c, sizeof(c));
  50         if(n != sizeof(c))
  51                 printk("tracer_winch_handler - write failed, err = %d\n", -n);
  52 }
  53
  54 /* Called only by the tracing thread during initialization */
  55
  56 static void setup_tracer_winch(void)
  57 {
  58         int err;
  59
  60         err = os_pipe(tracer_winch, 1, 1);
  61         if(err < 0){
  62                 printk("setup_tracer_winch : os_pipe failed, err = %d\n", -err);
  63                 return;
  64         }
  65         signal(SIGWINCH, tracer_winch_handler);
  66 }
  67
  68 void attach_process(int pid)
  69 {
  70         if((ptrace(PTRACE_ATTACH, pid, 0, 0) < 0) ||
  71            (ptrace(PTRACE_CONT, pid, 0, 0) < 0))
  72                 tracer_panic("OP_FORK failed to attach pid");
  73         wait_for_stop(pid, SIGSTOP, PTRACE_CONT, NULL);
  74         if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
  75                 tracer_panic("OP_FORK: PTRACE_SETOPTIONS failed, errno = %d", errno);
  76         if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
  77                 tracer_panic("OP_FORK failed to continue process");
  78 }
  79
  80 void tracer_panic(char *format, ...)
  81 {
  82         va_list ap;
  83
  84         va_start(ap, format);
  85         vprintf(format, ap);
  86         va_end(ap);
  87         printf("\n");
  88         while(1) pause();
  89 }
  90
  91 static void tracer_segv(int sig, struct sigcontext sc)
  92 {
  93         struct faultinfo fi;
  94         GET_FAULTINFO_FROM_SC(fi, &sc);
  95         printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
  96                FAULT_ADDRESS(fi), SC_IP(&sc));
  97         while(1)
  98                 pause();
  99 }
 100
 101 /* Changed early in boot, and then only read */
 102 int debug = 0;
 103 int debug_stop = 1;
 104 int debug_parent = 0;
 105 int honeypot = 0;
 106
 107 static int signal_tramp(void *arg)
 108 {
 109         int (*proc)(void *);
 110
 111         if(honeypot && munmap((void *) (host_task_size - 0x10000000),
 112                               0x10000000))
 113                 panic("Unmapping stack failed");
 114         if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0)
 115                 panic("ptrace PTRACE_TRACEME failed");
 116         os_stop_process(os_getpid());
 117         change_sig(SIGWINCH, 0);
 118         signal(SIGUSR1, SIG_IGN);
 119         change_sig(SIGCHLD, 0);
 120         signal(SIGSEGV, (__sighandler_t) sig_handler);
 121         set_cmdline("(idle thread)");
 122         set_init_pid(os_getpid());
 123         init_irq_signals(0);
 124         proc = arg;
 125         return((*proc)(NULL));
 126 }
 127
 128 static void sleeping_process_signal(int pid, int sig)
 129 {
 130         switch(sig){
 131         /* These two result from UML being ^Z-ed and bg-ed.  PTRACE_CONT is
 132          * right because the process must be in the kernel already.
 133          */
 134         case SIGCONT:
 135         case SIGTSTP:
 136                 if(ptrace(PTRACE_CONT, pid, 0, sig) < 0)
 137                         tracer_panic("sleeping_process_signal : Failed to "
 138                                      "continue pid %d, signal = %d, "
 139                                      "errno = %d\n", pid, sig, errno);
 140                 break;
 141
 142         /* This happens when the debugger (e.g. strace) is doing system call
 143          * tracing on the kernel.  During a context switch, the current task
 144          * will be set to the incoming process and the outgoing process will
 145          * hop into write and then read.  Since it's not the current process
 146          * any more, the trace of those will land here.  So, we need to just
 147          * PTRACE_SYSCALL it.
 148          */
 149         case (SIGTRAP + 0x80):
 150                 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
 151                         tracer_panic("sleeping_process_signal : Failed to "
 152                                      "PTRACE_SYSCALL pid %d, errno = %d\n",
 153                                      pid, errno);
 154                 break;
 155         case SIGSTOP:
 156                 break;
 157         default:
 158                 tracer_panic("sleeping process %d got unexpected "
 159                              "signal : %d\n", pid, sig);
 160                 break;
 161         }
 162 }
 163
 164 /* Accessed only by the tracing thread */
 165 int debugger_pid = -1;
 166 int debugger_parent = -1;
 167 int debugger_fd = -1;
 168 int gdb_pid = -1;
 169
 170 struct {
 171         int pid;
 172         int signal;
 173         unsigned long addr;
 174         struct timeval time;
 175 } signal_record[1024][32];
 176
 177 int signal_index[32];
 178 int nsignals = 0;
 179 int debug_trace = 0;
 180 extern int io_nsignals, io_count, intr_count;
 181
 182 extern void signal_usr1(int sig);
 183
 184 int tracing_pid = -1;
 185
 186 int tracer(int (*init_proc)(void *), void *sp)
 187 {
 188         void *task = NULL;
 189         int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
 190         int proc_id = 0, n, err, old_tracing = 0, strace = 0;
 191         int local_using_sysemu = 0;
 192 #ifdef UML_CONFIG_SYSCALL_DEBUG
 193         unsigned long eip = 0;
 194         int last_index;
 195 #endif
 196         signal(SIGPIPE, SIG_IGN);
 197         setup_tracer_winch();
 198         tracing_pid = os_getpid();
 199         printf("tracing thread pid = %d\n", tracing_pid);
 200
 201         pid = clone(signal_tramp, sp, CLONE_FILES | SIGCHLD, init_proc);
 202         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 203         if(n < 0){
 204                 printf("waitpid on idle thread failed, errno = %d\n", errno);
 205                 exit(1);
 206         }
 207         if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) {
 208                 printf("Failed to PTRACE_SETOPTIONS for idle thread, errno = %d\n", errno);
 209                 exit(1);
 210         }
 211         if((ptrace(PTRACE_CONT, pid, 0, 0) < 0)){
 212                 printf("Failed to continue idle thread, errno = %d\n", errno);
 213                 exit(1);
 214         }
 215
 216         signal(SIGSEGV, (sighandler_t) tracer_segv);
 217         signal(SIGUSR1, signal_usr1);
 218         if(debug_trace){
 219                 printf("Tracing thread pausing to be attached\n");
 220                 stop();
 221         }
 222         if(debug){
 223                 if(gdb_pid != -1)
 224                         debugger_pid = attach_debugger(pid, gdb_pid, 1);
 225                 else debugger_pid = init_ptrace_proxy(pid, 1, debug_stop);
 226                 if(debug_parent){
 227                         debugger_parent = os_process_parent(debugger_pid);
 228                         init_parent_proxy(debugger_parent);
 229                         err = attach(debugger_parent);
 230                         if(err){
 231                                 printf("Failed to attach debugger parent %d, "
 232                                        "errno = %d\n", debugger_parent, -err);
 233                                 debugger_parent = -1;
 234                         }
 235                         else {
 236                                 if(ptrace(PTRACE_SYSCALL, debugger_parent,
 237                                           0, 0) < 0){
 238                                         printf("Failed to continue debugger "
 239                                                "parent, errno = %d\n", errno);
 240                                         debugger_parent = -1;
 241                                 }
 242                         }
 243                 }
 244         }
 245         set_cmdline("(tracing thread)");
 246         while(1){
 247                 CATCH_EINTR(pid = waitpid(-1, &status, WUNTRACED));
 248                 if(pid <= 0){
 249                         if(errno != ECHILD){
 250                                 printf("wait failed - errno = %d\n", errno);
 251                         }
 252                         continue;
 253                 }
 254                 if(pid == debugger_pid){
 255                         int cont = 0;
 256
 257                         if(WIFEXITED(status) || WIFSIGNALED(status))
 258                                 debugger_pid = -1;
 259                         /* XXX Figure out how to deal with gdb and SMP */
 260                         else cont = debugger_signal(status, cpu_tasks[0].pid);
 261                         if(cont == PTRACE_SYSCALL) strace = 1;
 262                         continue;
 263                 }
 264                 else if(pid == debugger_parent){
 265                         debugger_parent_signal(status, pid);
 266                         continue;
 267                 }
 268                 nsignals++;
 269                 if(WIFEXITED(status)) ;
 270 #ifdef notdef
 271                 {
 272                         printf("Child %d exited with status %d\n", pid,
 273                                WEXITSTATUS(status));
 274                 }
 275 #endif
 276                 else if(WIFSIGNALED(status)){
 277                         sig = WTERMSIG(status);
 278                         if(sig != 9){
 279                                 printf("Child %d exited with signal %d\n", pid,
 280                                        sig);
 281                         }
 282                 }
 283                 else if(WIFSTOPPED(status)){
 284                         proc_id = pid_to_processor_id(pid);
 285                         sig = WSTOPSIG(status);
 286 #ifdef UML_CONFIG_SYSCALL_DEBUG
 287                         if(signal_index[proc_id] == 1024){
 288                                 signal_index[proc_id] = 0;
 289                                 last_index = 1023;
 290                         }
 291                         else last_index = signal_index[proc_id] - 1;
 292                         if(((sig == SIGPROF) || (sig == SIGVTALRM) ||
 293                             (sig == SIGALRM)) &&
 294                            (signal_record[proc_id][last_index].signal == sig)&&
 295                            (signal_record[proc_id][last_index].pid == pid))
 296                                 signal_index[proc_id] = last_index;
 297                         signal_record[proc_id][signal_index[proc_id]].pid = pid;
 298                         gettimeofday(&signal_record[proc_id][signal_index[proc_id]].time, NULL);
 299                         eip = ptrace(PTRACE_PEEKUSR, pid, PT_IP_OFFSET, 0);
 300                         signal_record[proc_id][signal_index[proc_id]].addr = eip;
 301                         signal_record[proc_id][signal_index[proc_id]++].signal = sig;
 302 #endif
 303                         if(proc_id == -1){
 304                                 sleeping_process_signal(pid, sig);
 305                                 continue;
 306                         }
 307
 308                         task = cpu_tasks[proc_id].task;
 309                         tracing = is_tracing(task);
 310                         old_tracing = tracing;
 311
 312                         /* Assume: no syscall, when coming from user */
 313                         if ( tracing )
 314                                 do_sigtrap(task);
 315
 316                         switch(sig){
 317                         case SIGUSR1:
 318                                 sig = 0;
 319                                 op = do_proc_op(task, proc_id);
 320                                 switch(op){
 321                                 /*
 322                                  * This is called when entering user mode; after
 323                                  * this, we start intercepting syscalls.
 324                                  *
 325                                  * In fact, a process is started in kernel mode,
 326                                  * so with is_tracing() == 0 (and that is reset
 327                                  * when executing syscalls, since UML kernel has
 328                                  * the right to do syscalls);
 329                                  */
 330                                 case OP_TRACE_ON:
 331                                         arch_leave_kernel(task, pid);
 332                                         tracing = 1;
 333                                         break;
 334                                 case OP_REBOOT:
 335                                 case OP_HALT:
 336                                         unmap_physmem();
 337                                         kmalloc_ok = 0;
 338                                         os_kill_ptraced_process(pid, 0);
 339                                         /* Now let's reap remaining zombies */
 340                                         errno = 0;
 341                                         do {
 342                                                 waitpid(-1, &status,
 343                                                         WUNTRACED);
 344                                         } while (errno != ECHILD);
 345                                         return(op == OP_REBOOT);
 346                                 case OP_NONE:
 347                                         printf("Detaching pid %d\n", pid);
 348                                         detach(pid, SIGSTOP);
 349                                         continue;
 350                                 default:
 351                                         break;
 352                                 }
 353                                 /* OP_EXEC switches host processes on us,
 354                                  * we want to continue the new one.
 355                                  */
 356                                 pid = cpu_tasks[proc_id].pid;
 357                                 break;
 358                         case (SIGTRAP + 0x80):
 359                                 if(!tracing && (debugger_pid != -1)){
 360                                         child_signal(pid, status & 0x7fff);
 361                                         continue;
 362                                 }
 363                                 tracing = 0;
 364                                 /* local_using_sysemu has been already set
 365                                  * below, since if we are here, is_tracing() on
 366                                  * the traced task was 1, i.e. the process had
 367                                  * already run through one iteration of the
 368                                  * loop which executed a OP_TRACE_ON request.*/
 369                                 do_syscall(task, pid, local_using_sysemu);
 370                                 sig = SIGUSR2;
 371                                 break;
 372                         case SIGTRAP:
 373                                 if(!tracing && (debugger_pid != -1)){
 374                                         child_signal(pid, status);
 375                                         continue;
 376                                 }
 377                                 tracing = 0;
 378                                 break;
 379                         case SIGPROF:
 380                                 if(tracing) sig = 0;
 381                                 break;
 382                         case SIGCHLD:
 383                         case SIGHUP:
 384                                 sig = 0;
 385                                 break;
 386                         case SIGSEGV:
 387                         case SIGIO:
 388                         case SIGALRM:
 389                         case SIGVTALRM:
 390                         case SIGFPE:
 391                         case SIGBUS:
 392                         case SIGILL:
 393                         case SIGWINCH:
 394
 395                         default:
 396                                 tracing = 0;
 397                                 break;
 398                         }
 399                         set_tracing(task, tracing);
 400
 401                         if(!tracing && old_tracing)
 402                                 arch_enter_kernel(task, pid);
 403
 404                         if(!tracing && (debugger_pid != -1) && (sig != 0) &&
 405                                 (sig != SIGALRM) && (sig != SIGVTALRM) &&
 406                                 (sig != SIGSEGV) && (sig != SIGTRAP) &&
 407                                 (sig != SIGUSR2) && (sig != SIGIO) &&
 408                                 (sig != SIGFPE)){
 409                                 child_signal(pid, status);
 410                                 continue;
 411                         }
 412
 413                         local_using_sysemu = get_using_sysemu();
 414
 415                         if(tracing)
 416                                 cont_type = SELECT_PTRACE_OPERATION(local_using_sysemu,
 417                                                                     singlestepping(task));
 418                         else if((debugger_pid != -1) && strace)
 419                                 cont_type = PTRACE_SYSCALL;
 420                         else
 421                                 cont_type = PTRACE_CONT;
 422
 423                         if(ptrace(cont_type, pid, 0, sig) != 0){
 424                                 tracer_panic("ptrace failed to continue "
 425                                              "process - errno = %d\n",
 426                                              errno);
 427                         }
 428                 }
 429         }
 430         return(0);
 431 }
 432
 433 static int __init uml_debug_setup(char *line, int *add)
 434 {
 435         char *next;
 436
 437         debug = 1;
 438         *add = 0;
 439         if(*line != '=') return(0);
 440         line++;
 441
 442         while(line != NULL){
 443                 next = strchr(line, ',');
 444                 if(next) *next++ = '\0';
 445
 446                 if(!strcmp(line, "go")) debug_stop = 0;
 447                 else if(!strcmp(line, "parent")) debug_parent = 1;
 448                 else printf("Unknown debug option : '%s'\n", line);
 449
 450                 line = next;
 451         }
 452         return(0);
 453 }
 454
 455 __uml_setup("debug", uml_debug_setup,
 456 "debug\n"
 457 "    Starts up the kernel under the control of gdb. See the \n"
 458 "    kernel debugging tutorial and the debugging session pages\n"
 459 "    at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
 460 );
 461
 462 static int __init uml_debugtrace_setup(char *line, int *add)
 463 {
 464         debug_trace = 1;
 465         return 0;
 466 }
 467 __uml_setup("debugtrace", uml_debugtrace_setup,
 468 "debugtrace\n"
 469 "    Causes the tracing thread to pause until it is attached by a\n"
 470 "    debugger and continued.  This is mostly for debugging crashes\n"
 471 "    early during boot, and should be pretty much obsoleted by\n"
 472 "    the debug switch.\n\n"
 473 );
 474
 475 /*
 476  * Overrides for Emacs so that we follow Linus's tabbing style.
 477  * Emacs will notice this stuff at the end of the file and automatically
 478  * adjust the settings for this buffer only.  This must remain at the end
 479  * of the file.
 480  * ---------------------------------------------------------------------------
 481  * Local variables:
 482  * c-file-style: "linux"
 483  * End:
 484  */