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/ioctl.h>
  22 #include <asm/unistd.h>
  23 #include "ptrace_user.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 #ifdef __NR_waitpid
  98         case __NR_waitpid:
  99 #endif
 100         case __NR_wait4:
 101                 if(!debugger_wait(debugger, (int *) arg2, arg3,
 102                                   debugger_syscall, debugger_normal_return,
 103                                   proxy_wait_return))
 104                         return(0);
 105                 break;
 106
 107         case __NR_kill:
 108                 if(!debugger->debugee->in_context)
 109                         child = debugger->debugee->pid;
 110                 if(arg1 == debugger->debugee->pid){
 111                         result = kill(child, arg2);
 112                         syscall_cancel(debugger->pid, result);
 113                         debugger->handle_trace = debugger_syscall;
 114                         return(0);
 115                 }
 116                 else debugger->handle_trace = debugger_normal_return;
 117                 break;
 118
 119         default:
 120                 debugger->handle_trace = debugger_normal_return;
 121         }
 122
 123         syscall_continue(debugger->pid);
 124         return(0);
 125 }
 126
 127 /* Used by the tracing thread */
 128 static debugger_state parent;
 129 static int parent_syscall(debugger_state *debugger, int pid);
 130
 131 int init_parent_proxy(int pid)
 132 {
 133         parent = ((debugger_state) { .pid               = pid,
 134                                      .wait_options      = 0,
 135                                      .wait_status_ptr   = NULL,
 136                                      .waiting           = 0,
 137                                      .real_wait         = 0,
 138                                      .expecting_child   = 0,
 139                                      .handle_trace      = parent_syscall,
 140                                      .debugee           = NULL } );
 141         return(0);
 142 }
 143
 144 int parent_normal_return(debugger_state *debugger, pid_t unused)
 145 {
 146         debugger->handle_trace = parent_syscall;
 147         syscall_continue(debugger->pid);
 148         return(0);
 149 }
 150
 151 static int parent_syscall(debugger_state *debugger, int pid)
 152 {
 153         long arg1, arg2, arg3, arg4, arg5;
 154         int syscall;
 155
 156         syscall = get_syscall(pid, &arg1, &arg2, &arg3, &arg4, &arg5);
 157
 158         if((syscall == __NR_wait4)
 159 #ifdef __NR_waitpid
 160            || (syscall == __NR_waitpid)
 161 #endif
 162         ){
 163                 debugger_wait(&parent, (int *) arg2, arg3, parent_syscall,
 164                               parent_normal_return, parent_wait_return);
 165         }
 166         else ptrace(PTRACE_SYSCALL, pid, 0, 0);
 167         return(0);
 168 }
 169
 170 int debugger_normal_return(debugger_state *debugger, pid_t unused)
 171 {
 172         debugger->handle_trace = debugger_syscall;
 173         syscall_continue(debugger->pid);
 174         return(0);
 175 }
 176
 177 void debugger_cancelled_return(debugger_state *debugger, int result)
 178 {
 179         debugger->handle_trace = debugger_syscall;
 180         syscall_set_result(debugger->pid, result);
 181         syscall_continue(debugger->pid);
 182 }
 183
 184 /* Used by the tracing thread */
 185 static debugger_state debugger;
 186 static debugee_state debugee;
 187
 188 void init_proxy (pid_t debugger_pid, int stopped, int status)
 189 {
 190         debugger.pid = debugger_pid;
 191         debugger.handle_trace = debugger_syscall;
 192         debugger.debugee = &debugee;
 193         debugger.waiting = 0;
 194         debugger.real_wait = 0;
 195         debugger.expecting_child = 0;
 196
 197         debugee.pid = 0;
 198         debugee.traced = 0;
 199         debugee.stopped = stopped;
 200         debugee.event = 0;
 201         debugee.zombie = 0;
 202         debugee.died = 0;
 203         debugee.wait_status = status;
 204         debugee.in_context = 1;
 205 }
 206
 207 int debugger_proxy(int status, int pid)
 208 {
 209         int ret = 0, sig;
 210
 211         if(WIFSTOPPED(status)){
 212                 sig = WSTOPSIG(status);
 213                 if (sig == SIGTRAP)
 214                         ret = (*debugger.handle_trace)(&debugger, pid);
 215
 216                 else if(sig == SIGCHLD){
 217                         if(debugger.expecting_child){
 218                                 ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 219                                 debugger.expecting_child = 0;
 220                         }
 221                         else if(debugger.waiting)
 222                                 real_wait_return(&debugger);
 223                         else {
 224                                 ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 225                                 debugger.real_wait = 1;
 226                         }
 227                 }
 228                 else ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 229         }
 230         else if(WIFEXITED(status)){
 231                 tracer_panic("debugger (pid %d) exited with status %d",
 232                              debugger.pid, WEXITSTATUS(status));
 233         }
 234         else if(WIFSIGNALED(status)){
 235                 tracer_panic("debugger (pid %d) exited with signal %d",
 236                              debugger.pid, WTERMSIG(status));
 237         }
 238         else {
 239                 tracer_panic("proxy got unknown status (0x%x) on debugger "
 240                              "(pid %d)", status, debugger.pid);
 241         }
 242         return(ret);
 243 }
 244
 245 void child_proxy(pid_t pid, int status)
 246 {
 247         debugee.event = 1;
 248         debugee.wait_status = status;
 249
 250         if(WIFSTOPPED(status)){
 251                 debugee.stopped = 1;
 252                 debugger.expecting_child = 1;
 253                 kill(debugger.pid, SIGCHLD);
 254         }
 255         else if(WIFEXITED(status) || WIFSIGNALED(status)){
 256                 debugee.zombie = 1;
 257                 debugger.expecting_child = 1;
 258                 kill(debugger.pid, SIGCHLD);
 259         }
 260         else panic("proxy got unknown status (0x%x) on child (pid %d)",
 261                    status, pid);
 262 }
 263
 264 void debugger_parent_signal(int status, int pid)
 265 {
 266         int sig;
 267
 268         if(WIFSTOPPED(status)){
 269                 sig = WSTOPSIG(status);
 270                 if(sig == SIGTRAP) (*parent.handle_trace)(&parent, pid);
 271                 else ptrace(PTRACE_SYSCALL, pid, 0, sig);
 272         }
 273 }
 274
 275 void fake_child_exit(void)
 276 {
 277         int status, pid;
 278
 279         child_proxy(1, W_EXITCODE(0, 0));
 280         while(debugger.waiting == 1){
 281                 CATCH_EINTR(pid = waitpid(debugger.pid, &status, WUNTRACED));
 282                 if(pid != debugger.pid){
 283                         printk("fake_child_exit - waitpid failed, "
 284                                "errno = %d\n", errno);
 285                         return;
 286                 }
 287                 debugger_proxy(status, debugger.pid);
 288         }
 289         CATCH_EINTR(pid = waitpid(debugger.pid, &status, WUNTRACED));
 290         if(pid != debugger.pid){
 291                 printk("fake_child_exit - waitpid failed, "
 292                        "errno = %d\n", errno);
 293                 return;
 294         }
 295         if(ptrace(PTRACE_DETACH, debugger.pid, 0, SIGCONT) < 0)
 296                 printk("fake_child_exit - PTRACE_DETACH failed, errno = %d\n",
 297                        errno);
 298 }
 299
 300 char gdb_init_string[] =
 301 "att 1 \n\
 302 b panic \n\
 303 b stop \n\
 304 handle SIGWINCH nostop noprint pass \n\
 305 ";
 306
 307 int start_debugger(char *prog, int startup, int stop, int *fd_out)
 308 {
 309         int slave, child;
 310
 311         slave = open_gdb_chan();
 312         child = fork();
 313         if(child == 0){
 314                 char *tempname = NULL;
 315                 int fd;
 316
 317                 if(setsid() < 0) perror("setsid");
 318                 if((dup2(slave, 0) < 0) || (dup2(slave, 1) < 0) ||
 319                    (dup2(slave, 2) < 0)){
 320                         printk("start_debugger : dup2 failed, errno = %d\n",
 321                                errno);
 322                         exit(1);
 323                 }
 324                 if(ioctl(0, TIOCSCTTY, 0) < 0){
 325                         printk("start_debugger : TIOCSCTTY failed, "
 326                                "errno = %d\n", errno);
 327                         exit(1);
 328                 }
 329                 if(tcsetpgrp (1, os_getpid()) < 0){
 330                         printk("start_debugger : tcsetpgrp failed, "
 331                                "errno = %d\n", errno);
 332 #ifdef notdef
 333                         exit(1);
 334 #endif
 335                 }
 336                 fd = make_tempfile("/tmp/gdb_init-XXXXXX", &tempname, 0);
 337                 if(fd < 0){
 338                         printk("start_debugger : make_tempfile failed,"
 339                                "err = %d\n", -fd);
 340                         exit(1);
 341                 }
 342                 os_write_file(fd, gdb_init_string, sizeof(gdb_init_string) - 1);
 343                 if(startup){
 344                         if(stop){
 345                                 os_write_file(fd, "b start_kernel\n",
 346                                       strlen("b start_kernel\n"));
 347                         }
 348                         os_write_file(fd, "c\n", strlen("c\n"));
 349                 }
 350                 if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
 351                         printk("start_debugger :  PTRACE_TRACEME failed, "
 352                                "errno = %d\n", errno);
 353                         exit(1);
 354                 }
 355                 execlp("gdb", "gdb", "--command", tempname, prog, NULL);
 356                 printk("start_debugger : exec of gdb failed, errno = %d\n",
 357                        errno);
 358         }
 359         if(child < 0){
 360                 printk("start_debugger : fork for gdb failed, errno = %d\n",
 361                        errno);
 362                 return(-1);
 363         }
 364         *fd_out = slave;
 365         return(child);
 366 }
 367
 368 /*
 369  * Overrides for Emacs so that we follow Linus's tabbing style.
 370  * Emacs will notice this stuff at the end of the file and automatically
 371  * adjust the settings for this buffer only.  This must remain at the end
 372  * of the file.
 373  * ---------------------------------------------------------------------------
 374  * Local variables:
 375  * c-file-style: "linux"
 376  * End:
 377  */