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