arch/um/kernel/tt/ptproxy/proxy.c

   1 /**********************************************************************
   2 proxy.c
   3
   4 Copyright (C) 1999 Lars Brinkhoff.  See the file COPYING for licensing
   5 terms and conditions.
   6
   7 Jeff Dike (jdike@karaya.com) : Modified for integration into uml
   8 **********************************************************************/
   9
  10 /* XXX This file shouldn't refer to CONFIG_* */
  11
  12 #include <errno.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <signal.h>
  17 #include <string.h>
  18 #include <termios.h>
  19 #include <sys/wait.h>
  20 #include <sys/types.h>
  21 #include <sys/ptrace.h>
  22 #include <sys/ioctl.h>
  23 #include <asm/unistd.h>
  24
  25 #include "ptproxy.h"
  26 #include "sysdep.h"
  27 #include "wait.h"
  28
  29 #include "user_util.h"
  30 #include "user.h"
  31 #include "os.h"
  32 #include "tempfile.h"
  33
  34 static int debugger_wait(debugger_state *debugger, int *status, int options,
  35                          int (*syscall)(debugger_state *debugger, pid_t child),
  36                          int (*normal_return)(debugger_state *debugger,
  37                                               pid_t unused),
  38                          int (*wait_return)(debugger_state *debugger,
  39                                             pid_t unused))
  40 {
  41         if(debugger->real_wait){
  42                 debugger->handle_trace = normal_return;
  43                 syscall_continue(debugger->pid);
  44                 debugger->real_wait = 0;
  45                 return(1);
  46         }
  47         debugger->wait_status_ptr = status;
  48         debugger->wait_options = options;
  49         if((debugger->debugee != NULL) && debugger->debugee->event){
  50                 syscall_continue(debugger->pid);
  51                 wait_for_stop(debugger->pid, SIGTRAP, PTRACE_SYSCALL,
  52                               NULL);
  53                 (*wait_return)(debugger, -1);
  54                 return(0);
  55         }
  56         else if(debugger->wait_options & WNOHANG){
  57                 syscall_cancel(debugger->pid, 0);
  58                 debugger->handle_trace = syscall;
  59                 return(0);
  60         }
  61         else {
  62                 syscall_pause(debugger->pid);
  63                 debugger->handle_trace = wait_return;
  64                 debugger->waiting = 1;
  65         }
  66         return(1);
  67 }
  68
  69 /*
  70  * Handle debugger trap, i.e. syscall.
  71  */
  72
  73 int debugger_syscall(debugger_state *debugger, pid_t child)
  74 {
  75         long arg1, arg2, arg3, arg4, arg5, result;
  76         int syscall, ret = 0;
  77
  78         syscall = get_syscall(debugger->pid, &arg1, &arg2, &arg3, &arg4,
  79                               &arg5);
  80
  81         switch(syscall){
  82         case __NR_execve:
  83                 /* execve never returns */
  84                 debugger->handle_trace = debugger_syscall;
  85                 break;
  86
  87         case __NR_ptrace:
  88                 if(debugger->debugee->pid != 0) arg2 = debugger->debugee->pid;
  89                 if(!debugger->debugee->in_context)
  90                         child = debugger->debugee->pid;
  91                 result = proxy_ptrace(debugger, arg1, arg2, arg3, arg4, child,
  92                                       &ret);
  93                 syscall_cancel(debugger->pid, result);
  94                 debugger->handle_trace = debugger_syscall;
  95                 return(ret);
  96
  97         case __NR_waitpid:
  98         case __NR_wait4:
  99                 if(!debugger_wait(debugger, (int *) arg2, arg3,
 100                                   debugger_syscall, debugger_normal_return,
 101                                   proxy_wait_return))
 102                         return(0);
 103                 break;
 104
 105         case __NR_kill:
 106                 if(!debugger->debugee->in_context)
 107                         child = debugger->debugee->pid;
 108                 if(arg1 == debugger->debugee->pid){
 109                         result = kill(child, arg2);
 110                         syscall_cancel(debugger->pid, result);
 111                         debugger->handle_trace = debugger_syscall;
 112                         return(0);
 113                 }
 114                 else debugger->handle_trace = debugger_normal_return;
 115                 break;
 116
 117         default:
 118                 debugger->handle_trace = debugger_normal_return;
 119         }
 120
 121         syscall_continue(debugger->pid);
 122         return(0);
 123 }
 124
 125 /* Used by the tracing thread */
 126 static debugger_state parent;
 127 static int parent_syscall(debugger_state *debugger, int pid);
 128
 129 int init_parent_proxy(int pid)
 130 {
 131         parent = ((debugger_state) { .pid               = pid,
 132                                      .wait_options      = 0,
 133                                      .wait_status_ptr   = NULL,
 134                                      .waiting           = 0,
 135                                      .real_wait         = 0,
 136                                      .expecting_child   = 0,
 137                                      .handle_trace      = parent_syscall,
 138                                      .debugee           = NULL } );
 139         return(0);
 140 }
 141
 142 int parent_normal_return(debugger_state *debugger, pid_t unused)
 143 {
 144         debugger->handle_trace = parent_syscall;
 145         syscall_continue(debugger->pid);
 146         return(0);
 147 }
 148
 149 static int parent_syscall(debugger_state *debugger, int pid)
 150 {
 151         long arg1, arg2, arg3, arg4, arg5;
 152         int syscall;
 153
 154         syscall = get_syscall(pid, &arg1, &arg2, &arg3, &arg4, &arg5);
 155
 156         if((syscall == __NR_waitpid) || (syscall == __NR_wait4)){
 157                 debugger_wait(&parent, (int *) arg2, arg3, parent_syscall,
 158                               parent_normal_return, parent_wait_return);
 159         }
 160         else ptrace(PTRACE_SYSCALL, pid, 0, 0);
 161         return(0);
 162 }
 163
 164 int debugger_normal_return(debugger_state *debugger, pid_t unused)
 165 {
 166         debugger->handle_trace = debugger_syscall;
 167         syscall_continue(debugger->pid);
 168         return(0);
 169 }
 170
 171 void debugger_cancelled_return(debugger_state *debugger, int result)
 172 {
 173         debugger->handle_trace = debugger_syscall;
 174         syscall_set_result(debugger->pid, result);
 175         syscall_continue(debugger->pid);
 176 }
 177
 178 /* Used by the tracing thread */
 179 static debugger_state debugger;
 180 static debugee_state debugee;
 181
 182 void init_proxy (pid_t debugger_pid, int stopped, int status)
 183 {
 184         debugger.pid = debugger_pid;
 185         debugger.handle_trace = debugger_syscall;
 186         debugger.debugee = &debugee;
 187         debugger.waiting = 0;
 188         debugger.real_wait = 0;
 189         debugger.expecting_child = 0;
 190
 191         debugee.pid = 0;
 192         debugee.traced = 0;
 193         debugee.stopped = stopped;
 194         debugee.event = 0;
 195         debugee.zombie = 0;
 196         debugee.died = 0;
 197         debugee.wait_status = status;
 198         debugee.in_context = 1;
 199 }
 200
 201 int debugger_proxy(int status, int pid)
 202 {
 203         int ret = 0, sig;
 204
 205         if(WIFSTOPPED(status)){
 206                 sig = WSTOPSIG(status);
 207                 if (sig == SIGTRAP)
 208                         ret = (*debugger.handle_trace)(&debugger, pid);
 209
 210                 else if(sig == SIGCHLD){
 211                         if(debugger.expecting_child){
 212                                 ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 213                                 debugger.expecting_child = 0;
 214                         }
 215                         else if(debugger.waiting)
 216                                 real_wait_return(&debugger);
 217                         else {
 218                                 ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 219                                 debugger.real_wait = 1;
 220                         }
 221                 }
 222                 else ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 223         }
 224         else if(WIFEXITED(status)){
 225                 tracer_panic("debugger (pid %d) exited with status %d",
 226                              debugger.pid, WEXITSTATUS(status));
 227         }
 228         else if(WIFSIGNALED(status)){
 229                 tracer_panic("debugger (pid %d) exited with signal %d",
 230                              debugger.pid, WTERMSIG(status));
 231         }
 232         else {
 233                 tracer_panic("proxy got unknown status (0x%x) on debugger "
 234                              "(pid %d)", status, debugger.pid);
 235         }
 236         return(ret);
 237 }
 238
 239 void child_proxy(pid_t pid, int status)
 240 {
 241         debugee.event = 1;
 242         debugee.wait_status = status;
 243
 244         if(WIFSTOPPED(status)){
 245                 debugee.stopped = 1;
 246                 debugger.expecting_child = 1;
 247                 kill(debugger.pid, SIGCHLD);
 248         }
 249         else if(WIFEXITED(status) || WIFSIGNALED(status)){
 250                 debugee.zombie = 1;
 251                 debugger.expecting_child = 1;
 252                 kill(debugger.pid, SIGCHLD);
 253         }
 254         else panic("proxy got unknown status (0x%x) on child (pid %d)",
 255                    status, pid);
 256 }
 257
 258 void debugger_parent_signal(int status, int pid)
 259 {
 260         int sig;
 261
 262         if(WIFSTOPPED(status)){
 263                 sig = WSTOPSIG(status);
 264                 if(sig == SIGTRAP) (*parent.handle_trace)(&parent, pid);
 265                 else ptrace(PTRACE_SYSCALL, pid, 0, sig);
 266         }
 267 }
 268
 269 void fake_child_exit(void)
 270 {
 271         int status, pid;
 272
 273         child_proxy(1, W_EXITCODE(0, 0));
 274         while(debugger.waiting == 1){
 275                 CATCH_EINTR(pid = waitpid(debugger.pid, &status, WUNTRACED));
 276                 if(pid != debugger.pid){
 277                         printk("fake_child_exit - waitpid failed, "
 278                                "errno = %d\n", errno);
 279                         return;
 280                 }
 281                 debugger_proxy(status, debugger.pid);
 282         }
 283         CATCH_EINTR(pid = waitpid(debugger.pid, &status, WUNTRACED));
 284         if(pid != debugger.pid){
 285                 printk("fake_child_exit - waitpid failed, "
 286                        "errno = %d\n", errno);
 287                 return;
 288         }
 289         if(ptrace(PTRACE_DETACH, debugger.pid, 0, SIGCONT) < 0)
 290                 printk("fake_child_exit - PTRACE_DETACH failed, errno = %d\n",
 291                        errno);
 292 }
 293
 294 char gdb_init_string[] =
 295 "att 1 \n\
 296 b panic \n\
 297 b stop \n\
 298 handle SIGWINCH nostop noprint pass \n\
 299 ";
 300
 301 int start_debugger(char *prog, int startup, int stop, int *fd_out)
 302 {
 303         int slave, child;
 304
 305         slave = open_gdb_chan();
 306         child = fork();
 307         if(child == 0){
 308                 char *tempname = NULL;
 309                 int fd;
 310
 311                 if(setsid() < 0) perror("setsid");
 312                 if((dup2(slave, 0) < 0) || (dup2(slave, 1) < 0) ||
 313                    (dup2(slave, 2) < 0)){
 314                         printk("start_debugger : dup2 failed, errno = %d\n",
 315                                errno);
 316                         exit(1);
 317                 }
 318                 if(ioctl(0, TIOCSCTTY, 0) < 0){
 319                         printk("start_debugger : TIOCSCTTY failed, "
 320                                "errno = %d\n", errno);
 321                         exit(1);
 322                 }
 323                 if(tcsetpgrp (1, os_getpid()) < 0){
 324                         printk("start_debugger : tcsetpgrp failed, "
 325                                "errno = %d\n", errno);
 326 #ifdef notdef
 327                         exit(1);
 328 #endif
 329                 }
 330                 fd = make_tempfile("/tmp/gdb_init-XXXXXX", &tempname, 0);
 331                 if(fd < 0){
 332                         printk("start_debugger : make_tempfile failed,"
 333                                "err = %d\n", -fd);
 334                         exit(1);
 335                 }
 336                 os_write_file(fd, gdb_init_string, sizeof(gdb_init_string) - 1);
 337                 if(startup){
 338                         if(stop){
 339                                 os_write_file(fd, "b start_kernel\n",
 340                                       strlen("b start_kernel\n"));
 341                         }
 342                         os_write_file(fd, "c\n", strlen("c\n"));
 343                 }
 344                 if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
 345                         printk("start_debugger :  PTRACE_TRACEME failed, "
 346                                "errno = %d\n", errno);
 347                         exit(1);
 348                 }
 349                 execlp("gdb", "gdb", "--command", tempname, prog, NULL);
 350                 printk("start_debugger : exec of gdb failed, errno = %d\n",
 351                        errno);
 352         }
 353         if(child < 0){
 354                 printk("start_debugger : fork for gdb failed, errno = %d\n",
 355                        errno);
 356                 return(-1);
 357         }
 358         *fd_out = slave;
 359         return(child);
 360 }
 361
 362 /*
 363  * Overrides for Emacs so that we follow Linus's tabbing style.
 364  * Emacs will notice this stuff at the end of the file and automatically
 365  * adjust the settings for this buffer only.  This must remain at the end
 366  * of the file.
 367  * ---------------------------------------------------------------------------
 368  * Local variables:
 369  * c-file-style: "linux"
 370  * End:
 371  */