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.h"
  30 #include "os.h"
  31 #include "tempfile.h"
  32
  33 static int debugger_wait(debugger_state *debugger, int *status, int options,
  34                          int (*syscall)(debugger_state *debugger, pid_t child),
  35                          int (*normal_return)(debugger_state *debugger,
  36                                               pid_t unused),
  37                          int (*wait_return)(debugger_state *debugger,
  38                                             pid_t unused))
  39 {
  40         if(debugger->real_wait){
  41                 debugger->handle_trace = normal_return;
  42                 syscall_continue(debugger->pid);
  43                 debugger->real_wait = 0;
  44                 return(1);
  45         }
  46         debugger->wait_status_ptr = status;
  47         debugger->wait_options = options;
  48         if((debugger->debugee != NULL) && debugger->debugee->event){
  49                 syscall_continue(debugger->pid);
  50                 wait_for_stop(debugger->pid, SIGTRAP, PTRACE_SYSCALL,
  51                               NULL);
  52                 (*wait_return)(debugger, -1);
  53                 return(0);
  54         }
  55         else if(debugger->wait_options & WNOHANG){
  56                 syscall_cancel(debugger->pid, 0);
  57                 debugger->handle_trace = syscall;
  58                 return(0);
  59         }
  60         else {
  61                 syscall_pause(debugger->pid);
  62                 debugger->handle_trace = wait_return;
  63                 debugger->waiting = 1;
  64         }
  65         return(1);
  66 }
  67
  68 /*
  69  * Handle debugger trap, i.e. syscall.
  70  */
  71
  72 int debugger_syscall(debugger_state *debugger, pid_t child)
  73 {
  74         long arg1, arg2, arg3, arg4, arg5, result;
  75         int syscall, ret = 0;
  76
  77         syscall = get_syscall(debugger->pid, &arg1, &arg2, &arg3, &arg4,
  78                               &arg5);
  79
  80         switch(syscall){
  81         case __NR_execve:
  82                 /* execve never returns */
  83                 debugger->handle_trace = debugger_syscall;
  84                 break;
  85
  86         case __NR_ptrace:
  87                 if(debugger->debugee->pid != 0) arg2 = debugger->debugee->pid;
  88                 if(!debugger->debugee->in_context)
  89                         child = debugger->debugee->pid;
  90                 result = proxy_ptrace(debugger, arg1, arg2, arg3, arg4, child,
  91                                       &ret);
  92                 syscall_cancel(debugger->pid, result);
  93                 debugger->handle_trace = debugger_syscall;
  94                 return(ret);
  95
  96 #ifdef __NR_waitpid
  97         case __NR_waitpid:
  98 #endif
  99         case __NR_wait4:
 100                 if(!debugger_wait(debugger, (int *) arg2, arg3,
 101                                   debugger_syscall, debugger_normal_return,
 102                                   proxy_wait_return))
 103                         return(0);
 104                 break;
 105
 106         case __NR_kill:
 107                 if(!debugger->debugee->in_context)
 108                         child = debugger->debugee->pid;
 109                 if(arg1 == debugger->debugee->pid){
 110                         result = kill(child, arg2);
 111                         syscall_cancel(debugger->pid, result);
 112                         debugger->handle_trace = debugger_syscall;
 113                         return(0);
 114                 }
 115                 else debugger->handle_trace = debugger_normal_return;
 116                 break;
 117
 118         default:
 119                 debugger->handle_trace = debugger_normal_return;
 120         }
 121
 122         syscall_continue(debugger->pid);
 123         return(0);
 124 }
 125
 126 /* Used by the tracing thread */
 127 static debugger_state parent;
 128 static int parent_syscall(debugger_state *debugger, int pid);
 129
 130 int init_parent_proxy(int pid)
 131 {
 132         parent = ((debugger_state) { .pid               = pid,
 133                                      .wait_options      = 0,
 134                                      .wait_status_ptr   = NULL,
 135                                      .waiting           = 0,
 136                                      .real_wait         = 0,
 137                                      .expecting_child   = 0,
 138                                      .handle_trace      = parent_syscall,
 139                                      .debugee           = NULL } );
 140         return(0);
 141 }
 142
 143 int parent_normal_return(debugger_state *debugger, pid_t unused)
 144 {
 145         debugger->handle_trace = parent_syscall;
 146         syscall_continue(debugger->pid);
 147         return(0);
 148 }
 149
 150 static int parent_syscall(debugger_state *debugger, int pid)
 151 {
 152         long arg1, arg2, arg3, arg4, arg5;
 153         int syscall;
 154
 155         syscall = get_syscall(pid, &arg1, &arg2, &arg3, &arg4, &arg5);
 156
 157         if((syscall == __NR_wait4)
 158 #ifdef __NR_waitpid
 159            || (syscall == __NR_waitpid)
 160 #endif
 161         ){
 162                 debugger_wait(&parent, (int *) arg2, arg3, parent_syscall,
 163                               parent_normal_return, parent_wait_return);
 164         }
 165         else ptrace(PTRACE_SYSCALL, pid, 0, 0);
 166         return(0);
 167 }
 168
 169 int debugger_normal_return(debugger_state *debugger, pid_t unused)
 170 {
 171         debugger->handle_trace = debugger_syscall;
 172         syscall_continue(debugger->pid);
 173         return(0);
 174 }
 175
 176 void debugger_cancelled_return(debugger_state *debugger, int result)
 177 {
 178         debugger->handle_trace = debugger_syscall;
 179         syscall_set_result(debugger->pid, result);
 180         syscall_continue(debugger->pid);
 181 }
 182
 183 /* Used by the tracing thread */
 184 static debugger_state debugger;
 185 static debugee_state debugee;
 186
 187 void init_proxy (pid_t debugger_pid, int stopped, int status)
 188 {
 189         debugger.pid = debugger_pid;
 190         debugger.handle_trace = debugger_syscall;
 191         debugger.debugee = &debugee;
 192         debugger.waiting = 0;
 193         debugger.real_wait = 0;
 194         debugger.expecting_child = 0;
 195
 196         debugee.pid = 0;
 197         debugee.traced = 0;
 198         debugee.stopped = stopped;
 199         debugee.event = 0;
 200         debugee.zombie = 0;
 201         debugee.died = 0;
 202         debugee.wait_status = status;
 203         debugee.in_context = 1;
 204 }
 205
 206 int debugger_proxy(int status, int pid)
 207 {
 208         int ret = 0, sig;
 209
 210         if(WIFSTOPPED(status)){
 211                 sig = WSTOPSIG(status);
 212                 if (sig == SIGTRAP)
 213                         ret = (*debugger.handle_trace)(&debugger, pid);
 214
 215                 else if(sig == SIGCHLD){
 216                         if(debugger.expecting_child){
 217                                 ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 218                                 debugger.expecting_child = 0;
 219                         }
 220                         else if(debugger.waiting)
 221                                 real_wait_return(&debugger);
 222                         else {
 223                                 ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 224                                 debugger.real_wait = 1;
 225                         }
 226                 }
 227                 else ptrace(PTRACE_SYSCALL, debugger.pid, 0, sig);
 228         }
 229         else if(WIFEXITED(status)){
 230                 tracer_panic("debugger (pid %d) exited with status %d",
 231                              debugger.pid, WEXITSTATUS(status));
 232         }
 233         else if(WIFSIGNALED(status)){
 234                 tracer_panic("debugger (pid %d) exited with signal %d",
 235                              debugger.pid, WTERMSIG(status));
 236         }
 237         else {
 238                 tracer_panic("proxy got unknown status (0x%x) on debugger "
 239                              "(pid %d)", status, debugger.pid);
 240         }
 241         return(ret);
 242 }
 243
 244 void child_proxy(pid_t pid, int status)
 245 {
 246         debugee.event = 1;
 247         debugee.wait_status = status;
 248
 249         if(WIFSTOPPED(status)){
 250                 debugee.stopped = 1;
 251                 debugger.expecting_child = 1;
 252                 kill(debugger.pid, SIGCHLD);
 253         }
 254         else if(WIFEXITED(status) || WIFSIGNALED(status)){
 255                 debugee.zombie = 1;
 256                 debugger.expecting_child = 1;
 257                 kill(debugger.pid, SIGCHLD);
 258         }
 259         else panic("proxy got unknown status (0x%x) on child (pid %d)",
 260                    status, pid);
 261 }
 262
 263 void debugger_parent_signal(int status, int pid)
 264 {
 265         int sig;
 266
 267         if(WIFSTOPPED(status)){
 268                 sig = WSTOPSIG(status);
 269                 if(sig == SIGTRAP) (*parent.handle_trace)(&parent, pid);
 270                 else ptrace(PTRACE_SYSCALL, pid, 0, sig);
 271         }
 272 }
 273
 274 void fake_child_exit(void)
 275 {
 276         int status, pid;
 277
 278         child_proxy(1, W_EXITCODE(0, 0));
 279         while(debugger.waiting == 1){
 280                 CATCH_EINTR(pid = waitpid(debugger.pid, &status, WUNTRACED));
 281                 if(pid != debugger.pid){
 282                         printk("fake_child_exit - waitpid failed, "
 283                                "errno = %d\n", errno);
 284                         return;
 285                 }
 286                 debugger_proxy(status, debugger.pid);
 287         }
 288         CATCH_EINTR(pid = waitpid(debugger.pid, &status, WUNTRACED));
 289         if(pid != debugger.pid){
 290                 printk("fake_child_exit - waitpid failed, "
 291                        "errno = %d\n", errno);
 292                 return;
 293         }
 294         if(ptrace(PTRACE_DETACH, debugger.pid, 0, SIGCONT) < 0)
 295                 printk("fake_child_exit - PTRACE_DETACH failed, errno = %d\n",
 296                        errno);
 297 }
 298
 299 char gdb_init_string[] =
 300 "att 1 \n\
 301 b panic \n\
 302 b stop \n\
 303 handle SIGWINCH nostop noprint pass \n\
 304 ";
 305
 306 int start_debugger(char *prog, int startup, int stop, int *fd_out)
 307 {
 308         int slave, child;
 309
 310         slave = open_gdb_chan();
 311         child = fork();
 312         if(child == 0){
 313                 char *tempname = NULL;
 314                 int fd;
 315
 316                 if(setsid() < 0) perror("setsid");
 317                 if((dup2(slave, 0) < 0) || (dup2(slave, 1) < 0) ||
 318                    (dup2(slave, 2) < 0)){
 319                         printk("start_debugger : dup2 failed, errno = %d\n",
 320                                errno);
 321                         exit(1);
 322                 }
 323                 if(ioctl(0, TIOCSCTTY, 0) < 0){
 324                         printk("start_debugger : TIOCSCTTY failed, "
 325                                "errno = %d\n", errno);
 326                         exit(1);
 327                 }
 328                 if(tcsetpgrp (1, os_getpid()) < 0){
 329                         printk("start_debugger : tcsetpgrp failed, "
 330                                "errno = %d\n", errno);
 331 #ifdef notdef
 332                         exit(1);
 333 #endif
 334                 }
 335                 fd = make_tempfile("/tmp/gdb_init-XXXXXX", &tempname, 0);
 336                 if(fd < 0){
 337                         printk("start_debugger : make_tempfile failed,"
 338                                "err = %d\n", -fd);
 339                         exit(1);
 340                 }
 341                 os_write_file(fd, gdb_init_string,
 342                               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  */