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