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 "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 != tracing_pid)
  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         printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
  93                SC_FAULT_ADDR(&sc), SC_IP(&sc));
  94         while(1)
  95                 pause();
  96 }
  97
  98 /* Changed early in boot, and then only read */
  99 int debug = 0;
 100 int debug_stop = 1;
 101 int debug_parent = 0;
 102 int honeypot = 0;
 103
 104 static int signal_tramp(void *arg)
 105 {
 106         int (*proc)(void *);
 107
 108         if(honeypot && munmap((void *) (host_task_size - 0x10000000),
 109                               0x10000000))
 110                 panic("Unmapping stack failed");
 111         if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0)
 112                 panic("ptrace PTRACE_TRACEME failed");
 113         os_stop_process(os_getpid());
 114         change_sig(SIGWINCH, 0);
 115         signal(SIGUSR1, SIG_IGN);
 116         change_sig(SIGCHLD, 0);
 117         signal(SIGSEGV, (__sighandler_t) sig_handler);
 118         set_cmdline("(idle thread)");
 119         set_init_pid(os_getpid());
 120         proc = arg;
 121         return((*proc)(NULL));
 122 }
 123
 124 static void sleeping_process_signal(int pid, int sig)
 125 {
 126         switch(sig){
 127         /* These two result from UML being ^Z-ed and bg-ed.  PTRACE_CONT is
 128          * right because the process must be in the kernel already.
 129          */
 130         case SIGCONT:
 131         case SIGTSTP:
 132                 if(ptrace(PTRACE_CONT, pid, 0, sig) < 0)
 133                         tracer_panic("sleeping_process_signal : Failed to "
 134                                      "continue pid %d, signal = %d, "
 135                                      "errno = %d\n", pid, sig, errno);
 136                 break;
 137
 138         /* This happens when the debugger (e.g. strace) is doing system call
 139          * tracing on the kernel.  During a context switch, the current task
 140          * will be set to the incoming process and the outgoing process will
 141          * hop into write and then read.  Since it's not the current process
 142          * any more, the trace of those will land here.  So, we need to just
 143          * PTRACE_SYSCALL it.
 144          */
 145         case (SIGTRAP + 0x80):
 146                 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
 147                         tracer_panic("sleeping_process_signal : Failed to "
 148                                      "PTRACE_SYSCALL pid %d, errno = %d\n",
 149                                      pid, errno);
 150                 break;
 151         case SIGSTOP:
 152                 break;
 153         default:
 154                 tracer_panic("sleeping process %d got unexpected "
 155                              "signal : %d\n", pid, sig);
 156                 break;
 157         }
 158 }
 159
 160 /* Accessed only by the tracing thread */
 161 int debugger_pid = -1;
 162 int debugger_parent = -1;
 163 int debugger_fd = -1;
 164 int gdb_pid = -1;
 165
 166 struct {
 167         int pid;
 168         int signal;
 169         unsigned long addr;
 170         struct timeval time;
 171 } signal_record[1024][32];
 172
 173 int signal_index[32];
 174 int nsignals = 0;
 175 int debug_trace = 0;
 176 extern int io_nsignals, io_count, intr_count;
 177
 178 extern void signal_usr1(int sig);
 179
 180 int tracing_pid = -1;
 181
 182 int tracer(int (*init_proc)(void *), void *sp)
 183 {
 184         void *task = NULL;
 185         int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
 186         int proc_id = 0, n, err, old_tracing = 0, strace = 0;
 187         int local_using_sysemu = 0;
 188 #ifdef UML_CONFIG_SYSCALL_DEBUG
 189         unsigned long eip = 0;
 190         int last_index;
 191 #endif
 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);
 282 #ifdef UML_CONFIG_SYSCALL_DEBUG
 283                         if(signal_index[proc_id] == 1024){
 284                                 signal_index[proc_id] = 0;
 285                                 last_index = 1023;
 286                         }
 287                         else last_index = signal_index[proc_id] - 1;
 288                         if(((sig == SIGPROF) || (sig == SIGVTALRM) ||
 289                             (sig == SIGALRM)) &&
 290                            (signal_record[proc_id][last_index].signal == sig)&&
 291                            (signal_record[proc_id][last_index].pid == pid))
 292                                 signal_index[proc_id] = last_index;
 293                         signal_record[proc_id][signal_index[proc_id]].pid = pid;
 294                         gettimeofday(&signal_record[proc_id][signal_index[proc_id]].time, NULL);
 295                         eip = ptrace(PTRACE_PEEKUSR, pid, PT_IP_OFFSET, 0);
 296                         signal_record[proc_id][signal_index[proc_id]].addr = eip;
 297                         signal_record[proc_id][signal_index[proc_id]++].signal = sig;
 298 #endif
 299                         if(proc_id == -1){
 300                                 sleeping_process_signal(pid, sig);
 301                                 continue;
 302                         }
 303
 304                         task = cpu_tasks[proc_id].task;
 305                         tracing = is_tracing(task);
 306                         old_tracing = tracing;
 307
 308                         /* Assume: no syscall, when coming from user */
 309                         if ( tracing )
 310                                 do_sigtrap(task);
 311
 312                         switch(sig){
 313                         case SIGUSR1:
 314                                 sig = 0;
 315                                 op = do_proc_op(task, proc_id);
 316                                 switch(op){
 317                                 /*
 318                                  * This is called when entering user mode; after
 319                                  * this, we start intercepting syscalls.
 320                                  *
 321                                  * In fact, a process is started in kernel mode,
 322                                  * so with is_tracing() == 0 (and that is reset
 323                                  * when executing syscalls, since UML kernel has
 324                                  * the right to do syscalls);
 325                                  */
 326                                 case OP_TRACE_ON:
 327                                         arch_leave_kernel(task, pid);
 328                                         tracing = 1;
 329                                         break;
 330                                 case OP_REBOOT:
 331                                 case OP_HALT:
 332                                         unmap_physmem();
 333                                         kmalloc_ok = 0;
 334                                         os_kill_ptraced_process(pid, 0);
 335                                         /* Now let's reap remaining zombies */
 336                                         errno = 0;
 337                                         do {
 338                                                 waitpid(-1, &status,
 339                                                         WUNTRACED);
 340                                         } while (errno != ECHILD);
 341                                         return(op == OP_REBOOT);
 342                                 case OP_NONE:
 343                                         printf("Detaching pid %d\n", pid);
 344                                         detach(pid, SIGSTOP);
 345                                         continue;
 346                                 default:
 347                                         break;
 348                                 }
 349                                 /* OP_EXEC switches host processes on us,
 350                                  * we want to continue the new one.
 351                                  */
 352                                 pid = cpu_tasks[proc_id].pid;
 353                                 break;
 354                         case (SIGTRAP + 0x80):
 355                                 if(!tracing && (debugger_pid != -1)){
 356                                         child_signal(pid, status & 0x7fff);
 357                                         continue;
 358                                 }
 359                                 tracing = 0;
 360                                 /* local_using_sysemu has been already set
 361                                  * below, since if we are here, is_tracing() on
 362                                  * the traced task was 1, i.e. the process had
 363                                  * already run through one iteration of the
 364                                  * loop which executed a OP_TRACE_ON request.*/
 365                                 do_syscall(task, pid, local_using_sysemu);
 366                                 sig = SIGUSR2;
 367                                 break;
 368                         case SIGTRAP:
 369                                 if(!tracing && (debugger_pid != -1)){
 370                                         child_signal(pid, status);
 371                                         continue;
 372                                 }
 373                                 tracing = 0;
 374                                 break;
 375                         case SIGPROF:
 376                                 if(tracing) sig = 0;
 377                                 break;
 378                         case SIGCHLD:
 379                         case SIGHUP:
 380                                 sig = 0;
 381                                 break;
 382                         case SIGSEGV:
 383                         case SIGIO:
 384                         case SIGALRM:
 385                         case SIGVTALRM:
 386                         case SIGFPE:
 387                         case SIGBUS:
 388                         case SIGILL:
 389                         case SIGWINCH:
 390
 391                         default:
 392                                 tracing = 0;
 393                                 break;
 394                         }
 395                         set_tracing(task, tracing);
 396
 397                         if(!tracing && old_tracing)
 398                                 arch_enter_kernel(task, pid);
 399
 400                         if(!tracing && (debugger_pid != -1) && (sig != 0) &&
 401                                 (sig != SIGALRM) && (sig != SIGVTALRM) &&
 402                                 (sig != SIGSEGV) && (sig != SIGTRAP) &&
 403                                 (sig != SIGUSR2) && (sig != SIGIO) &&
 404                                 (sig != SIGFPE)){
 405                                 child_signal(pid, status);
 406                                 continue;
 407                         }
 408
 409                         local_using_sysemu = get_using_sysemu();
 410
 411                         if(tracing)
 412                                 cont_type = SELECT_PTRACE_OPERATION(local_using_sysemu,
 413                                                                     singlestepping(task));
 414                         else if((debugger_pid != -1) && strace)
 415                                 cont_type = PTRACE_SYSCALL;
 416                         else
 417                                 cont_type = PTRACE_CONT;
 418
 419                         if(ptrace(cont_type, pid, 0, sig) != 0){
 420                                 tracer_panic("ptrace failed to continue "
 421                                              "process - errno = %d\n",
 422                                              errno);
 423                         }
 424                 }
 425         }
 426         return(0);
 427 }
 428
 429 static int __init uml_debug_setup(char *line, int *add)
 430 {
 431         char *next;
 432
 433         debug = 1;
 434         *add = 0;
 435         if(*line != '=') return(0);
 436         line++;
 437
 438         while(line != NULL){
 439                 next = strchr(line, ',');
 440                 if(next) *next++ = '\0';
 441
 442                 if(!strcmp(line, "go")) debug_stop = 0;
 443                 else if(!strcmp(line, "parent")) debug_parent = 1;
 444                 else printf("Unknown debug option : '%s'\n", line);
 445
 446                 line = next;
 447         }
 448         return(0);
 449 }
 450
 451 __uml_setup("debug", uml_debug_setup,
 452 "debug\n"
 453 "    Starts up the kernel under the control of gdb. See the \n"
 454 "    kernel debugging tutorial and the debugging session pages\n"
 455 "    at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
 456 );
 457
 458 static int __init uml_debugtrace_setup(char *line, int *add)
 459 {
 460         debug_trace = 1;
 461         return 0;
 462 }
 463 __uml_setup("debugtrace", uml_debugtrace_setup,
 464 "debugtrace\n"
 465 "    Causes the tracing thread to pause until it is attached by a\n"
 466 "    debugger and continued.  This is mostly for debugging crashes\n"
 467 "    early during boot, and should be pretty much obsoleted by\n"
 468 "    the debug switch.\n\n"
 469 );
 470
 471 /*
 472  * Overrides for Emacs so that we follow Linus's tabbing style.
 473  * Emacs will notice this stuff at the end of the file and automatically
 474  * adjust the settings for this buffer only.  This must remain at the end
 475  * of the file.
 476  * ---------------------------------------------------------------------------
 477  * Local variables:
 478  * c-file-style: "linux"
 479  * End:
 480  */