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
 188         capture_signal_stack();
 189         signal(SIGPIPE, SIG_IGN);
 190         setup_tracer_winch();
 191         tracing_pid = os_getpid();
 192         printf("tracing thread pid = %d\n", tracing_pid);
 193
 194         pid = clone(signal_tramp, sp, CLONE_FILES | SIGCHLD, init_proc);
 195         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 196         if(n < 0){
 197                 printf("waitpid on idle thread failed, errno = %d\n", errno);
 198                 exit(1);
 199         }
 200         if((ptrace(PTRACE_CONT, pid, 0, 0) < 0)){
 201                 printf("Failed to continue idle thread, errno = %d\n", errno);
 202                 exit(1);
 203         }
 204
 205         signal(SIGSEGV, (sighandler_t) tracer_segv);
 206         signal(SIGUSR1, signal_usr1);
 207         if(debug_trace){
 208                 printf("Tracing thread pausing to be attached\n");
 209                 stop();
 210         }
 211         if(debug){
 212                 if(gdb_pid != -1)
 213                         debugger_pid = attach_debugger(pid, gdb_pid, 1);
 214                 else debugger_pid = init_ptrace_proxy(pid, 1, debug_stop);
 215                 if(debug_parent){
 216                         debugger_parent = os_process_parent(debugger_pid);
 217                         init_parent_proxy(debugger_parent);
 218                         err = attach(debugger_parent);
 219                         if(err){
 220                                 printf("Failed to attach debugger parent %d, "
 221                                        "errno = %d\n", debugger_parent, -err);
 222                                 debugger_parent = -1;
 223                         }
 224                         else {
 225                                 if(ptrace(PTRACE_SYSCALL, debugger_parent,
 226                                           0, 0) < 0){
 227                                         printf("Failed to continue debugger "
 228                                                "parent, errno = %d\n", errno);
 229                                         debugger_parent = -1;
 230                                 }
 231                         }
 232                 }
 233         }
 234         set_cmdline("(tracing thread)");
 235         while(1){
 236                 CATCH_EINTR(pid = waitpid(-1, &status, WUNTRACED));
 237                 if(pid <= 0){
 238                         if(errno != ECHILD){
 239                                 printf("wait failed - errno = %d\n", errno);
 240                         }
 241                         continue;
 242                 }
 243                 if(pid == debugger_pid){
 244                         int cont = 0;
 245
 246                         if(WIFEXITED(status) || WIFSIGNALED(status))
 247                                 debugger_pid = -1;
 248                         /* XXX Figure out how to deal with gdb and SMP */
 249                         else cont = debugger_signal(status, cpu_tasks[0].pid);
 250                         if(cont == PTRACE_SYSCALL) strace = 1;
 251                         continue;
 252                 }
 253                 else if(pid == debugger_parent){
 254                         debugger_parent_signal(status, pid);
 255                         continue;
 256                 }
 257                 nsignals++;
 258                 if(WIFEXITED(status)) ;
 259 #ifdef notdef
 260                 {
 261                         printf("Child %d exited with status %d\n", pid,
 262                                WEXITSTATUS(status));
 263                 }
 264 #endif
 265                 else if(WIFSIGNALED(status)){
 266                         sig = WTERMSIG(status);
 267                         if(sig != 9){
 268                                 printf("Child %d exited with signal %d\n", pid,
 269                                        sig);
 270                         }
 271                 }
 272                 else if(WIFSTOPPED(status)){
 273                         proc_id = pid_to_processor_id(pid);
 274                         sig = WSTOPSIG(status);
 275                         if(signal_index[proc_id] == 1024){
 276                                 signal_index[proc_id] = 0;
 277                                 last_index = 1023;
 278                         }
 279                         else last_index = signal_index[proc_id] - 1;
 280                         if(((sig == SIGPROF) || (sig == SIGVTALRM) ||
 281                             (sig == SIGALRM)) &&
 282                            (signal_record[proc_id][last_index].signal == sig)&&
 283                            (signal_record[proc_id][last_index].pid == pid))
 284                                 signal_index[proc_id] = last_index;
 285                         signal_record[proc_id][signal_index[proc_id]].pid = pid;
 286                         gettimeofday(&signal_record[proc_id][signal_index[proc_id]].time, NULL);
 287                         eip = ptrace(PTRACE_PEEKUSER, pid, PT_IP_OFFSET, 0);
 288                         signal_record[proc_id][signal_index[proc_id]].addr = eip;
 289                         signal_record[proc_id][signal_index[proc_id]++].signal = sig;
 290
 291                         if(proc_id == -1){
 292                                 sleeping_process_signal(pid, sig);
 293                                 continue;
 294                         }
 295
 296                         task = cpu_tasks[proc_id].task;
 297                         tracing = is_tracing(task);
 298                         old_tracing = tracing;
 299
 300                         switch(sig){
 301                         case SIGUSR1:
 302                                 sig = 0;
 303                                 op = do_proc_op(task, proc_id);
 304                                 switch(op){
 305                                 case OP_TRACE_ON:
 306                                         arch_leave_kernel(task, pid);
 307                                         tracing = 1;
 308                                         break;
 309                                 case OP_REBOOT:
 310                                 case OP_HALT:
 311                                         unmap_physmem();
 312                                         kmalloc_ok = 0;
 313                                         ptrace(PTRACE_KILL, pid, 0, 0);
 314                                         return(op == OP_REBOOT);
 315                                 case OP_NONE:
 316                                         printf("Detaching pid %d\n", pid);
 317                                         detach(pid, SIGSTOP);
 318                                         continue;
 319                                 default:
 320                                         break;
 321                                 }
 322                                 /* OP_EXEC switches host processes on us,
 323                                  * we want to continue the new one.
 324                                  */
 325                                 pid = cpu_tasks[proc_id].pid;
 326                                 break;
 327                         case SIGTRAP:
 328                                 if(!tracing && (debugger_pid != -1)){
 329                                         child_signal(pid, status);
 330                                         continue;
 331                                 }
 332                                 tracing = 0;
 333                                 if(do_syscall(task, pid))
 334                                         sig = SIGUSR2;
 335                                 else clear_singlestep(task);
 336                                 break;
 337                         case SIGPROF:
 338                                 if(tracing) sig = 0;
 339                                 break;
 340                         case SIGCHLD:
 341                         case SIGHUP:
 342                                 sig = 0;
 343                                 break;
 344                         case SIGSEGV:
 345                         case SIGIO:
 346                         case SIGALRM:
 347                         case SIGVTALRM:
 348                         case SIGFPE:
 349                         case SIGBUS:
 350                         case SIGILL:
 351                         case SIGWINCH:
 352                         default:
 353                                 tracing = 0;
 354                                 break;
 355                         }
 356                         set_tracing(task, tracing);
 357
 358                         if(!tracing && old_tracing)
 359                                 arch_enter_kernel(task, pid);
 360
 361                         if(!tracing && (debugger_pid != -1) && (sig != 0) &&
 362                                 (sig != SIGALRM) && (sig != SIGVTALRM) &&
 363                                 (sig != SIGSEGV) && (sig != SIGTRAP) &&
 364                                 (sig != SIGUSR2) && (sig != SIGIO) &&
 365                                 (sig != SIGFPE)){
 366                                 child_signal(pid, status);
 367                                 continue;
 368                         }
 369
 370                         if(tracing){
 371                                 if(singlestepping_tt(task))
 372                                         cont_type = PTRACE_SINGLESTEP;
 373                                 else cont_type = PTRACE_SYSCALL;
 374                         }
 375                         else cont_type = PTRACE_CONT;
 376
 377                         if((cont_type == PTRACE_CONT) &&
 378                            (debugger_pid != -1) && strace)
 379                                 cont_type = PTRACE_SYSCALL;
 380
 381                         if(ptrace(cont_type, pid, 0, sig) != 0){
 382                                 tracer_panic("ptrace failed to continue "
 383                                              "process - errno = %d\n",
 384                                              errno);
 385                         }
 386                 }
 387         }
 388         return(0);
 389 }
 390
 391 static int __init uml_debug_setup(char *line, int *add)
 392 {
 393         char *next;
 394
 395         debug = 1;
 396         *add = 0;
 397         if(*line != '=') return(0);
 398         line++;
 399
 400         while(line != NULL){
 401                 next = strchr(line, ',');
 402                 if(next) *next++ = '\0';
 403
 404                 if(!strcmp(line, "go")) debug_stop = 0;
 405                 else if(!strcmp(line, "parent")) debug_parent = 1;
 406                 else printf("Unknown debug option : '%s'\n", line);
 407
 408                 line = next;
 409         }
 410         return(0);
 411 }
 412
 413 __uml_setup("debug", uml_debug_setup,
 414 "debug\n"
 415 "    Starts up the kernel under the control of gdb. See the \n"
 416 "    kernel debugging tutorial and the debugging session pages\n"
 417 "    at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
 418 );
 419
 420 static int __init uml_debugtrace_setup(char *line, int *add)
 421 {
 422         debug_trace = 1;
 423         return 0;
 424 }
 425 __uml_setup("debugtrace", uml_debugtrace_setup,
 426 "debugtrace\n"
 427 "    Causes the tracing thread to pause until it is attached by a\n"
 428 "    debugger and continued.  This is mostly for debugging crashes\n"
 429 "    early during boot, and should be pretty much obsoleted by\n"
 430 "    the debug switch.\n\n"
 431 );
 432
 433 static int __init uml_honeypot_setup(char *line, int *add)
 434 {
 435         jail_setup("", add);
 436         honeypot = 1;
 437         return 0;
 438 }
 439 __uml_setup("honeypot", uml_honeypot_setup,
 440 "honeypot\n"
 441 "    This makes UML put process stacks in the same location as they are\n"
 442 "    on the host, allowing expoits such as stack smashes to work against\n"
 443 "    UML.  This implies 'jail'.\n\n"
 444 );
 445
 446 /*
 447  * Overrides for Emacs so that we follow Linus's tabbing style.
 448  * Emacs will notice this stuff at the end of the file and automatically
 449  * adjust the settings for this buffer only.  This must remain at the end
 450  * of the file.
 451  * ---------------------------------------------------------------------------
 452  * Local variables:
 453  * c-file-style: "linux"
 454  * End:
 455  */