servers/pm/trace.c

   1 /* This file handles the process manager's part of debugging, using the
   2  * ptrace system call. Most of the commands are passed on to the system
   3  * task for completion.
   4  *
   5  * The debugging commands available are:
   6  * T_STOP       stop the process
   7  * T_OK         enable tracing by parent for this process
   8  * T_GETINS     return value from instruction space
   9  * T_GETDATA    return value from data space
  10  * T_GETUSER    return value from user process table
  11  * T_SETINS     set value in instruction space
  12  * T_SETDATA    set value in data space
  13  * T_SETUSER    set value in user process table
  14  * T_RESUME     resume execution
  15  * T_EXIT       exit
  16  * T_STEP       set trace bit
  17  *
  18  * The T_OK and T_EXIT commands are handled here, and the T_RESUME and
  19  * T_STEP commands are partially handled here and completed by the system
  20  * task. The rest are handled entirely by the system task.
  21  */
  22
  23 #include "pm.h"
  24 #include <minix/com.h>
  25 #include <sys/ptrace.h>
  26 #include <signal.h>
  27 #include "mproc.h"
  28 #include "param.h"
  29
  30 #define NIL_MPROC       ((struct mproc *) 0)
  31
  32 FORWARD _PROTOTYPE( struct mproc *find_proc, (pid_t lpid) );
  33
  34 /*===========================================================================*
  35  *                              do_trace                                     *
  36  *===========================================================================*/
  37 PUBLIC int do_trace()
  38 {
  39   register struct mproc *child;
  40   int r;
  41
  42   /* the T_OK call is made by the child fork of the debugger before it execs
  43    * the process to be traced
  44    */
  45   if (m_in.request == T_OK) {   /* enable tracing by parent for this proc */
  46         mp->mp_flags |= TRACED;
  47         mp->mp_reply.reply_trace = 0;
  48         return(OK);
  49   }
  50   if (m_in.request == T_READB_INS)
  51   {
  52         /* Special hack for reading text segments */
  53         if (mp->mp_effuid != SUPER_USER)
  54                 return(EPERM);
  55         if ((child=find_proc(m_in.pid))==NIL_MPROC)
  56                 return(ESRCH);
  57
  58         r= sys_trace(m_in.request,child->mp_endpoint,m_in.taddr,&m_in.data);
  59         if (r != OK) return(r);
  60
  61         mp->mp_reply.reply_trace = m_in.data;
  62         return(OK);
  63   }
  64   if (m_in.request == T_WRITEB_INS)
  65   {
  66         /* Special hack for patching text segments */
  67         if (mp->mp_effuid != SUPER_USER)
  68                 return(EPERM);
  69         if ((child=find_proc(m_in.pid))==NIL_MPROC)
  70                 return(ESRCH);
  71
  72         r= sys_trace(m_in.request,child->mp_endpoint,m_in.taddr,&m_in.data);
  73         if (r != OK) return(r);
  74
  75         mp->mp_reply.reply_trace = m_in.data;
  76         return(OK);
  77   }
  78
  79   if ((child=find_proc(m_in.pid))==NIL_MPROC || !(child->mp_flags & STOPPED)) {
  80         return(ESRCH);
  81   }
  82   /* all the other calls are made by the parent fork of the debugger to
  83    * control execution of the child
  84    */
  85   switch (m_in.request) {
  86   case T_EXIT:          /* exit */
  87         pm_exit(child, (int) m_in.data, TRUE /*for_trace*/);
  88         /* Do not reply to the caller until FS has processed the exit
  89          * request.
  90          */
  91         return SUSPEND;
  92   case T_RESUME:
  93   case T_STEP:          /* resume execution */
  94         if (m_in.data < 0 || m_in.data > _NSIG) return(EIO);
  95         if (m_in.data > 0) {            /* issue signal */
  96                 child->mp_flags &= ~TRACED;  /* so signal is not diverted */
  97                 sig_proc(child, (int) m_in.data);
  98                 child->mp_flags |= TRACED;
  99         }
 100         child->mp_flags &= ~STOPPED;
 101         break;
 102   }
 103   r= sys_trace(m_in.request,child->mp_endpoint,m_in.taddr,&m_in.data);
 104   if (r != OK) return(r);
 105
 106   mp->mp_reply.reply_trace = m_in.data;
 107   return(OK);
 108 }
 109
 110 /*===========================================================================*
 111  *                              find_proc                                    *
 112  *===========================================================================*/
 113 PRIVATE struct mproc *find_proc(lpid)
 114 pid_t lpid;
 115 {
 116   register struct mproc *rmp;
 117
 118   for (rmp = &mproc[0]; rmp < &mproc[NR_PROCS]; rmp++)
 119         if (rmp->mp_flags & IN_USE && rmp->mp_pid == lpid) return(rmp);
 120   return(NIL_MPROC);
 121 }
 122
 123 /*===========================================================================*
 124  *                              stop_proc                                    *
 125  *===========================================================================*/
 126 PUBLIC void stop_proc(rmp, signo)
 127 register struct mproc *rmp;
 128 int signo;
 129 {
 130 /* A traced process got a signal so stop it. */
 131
 132   register struct mproc *rpmp = mproc + rmp->mp_parent;
 133   int r;
 134
 135   r= sys_trace(-1, rmp->mp_endpoint, 0L, (long *) 0);
 136   if (r != OK) panic("pm", "sys_trace failed", r);
 137
 138   rmp->mp_flags |= STOPPED;
 139   if (rpmp->mp_flags & WAITING) {
 140         rpmp->mp_flags &= ~WAITING;     /* parent is no longer waiting */
 141         rpmp->mp_reply.reply_res2 = 0177 | (signo << 8);
 142         setreply(rmp->mp_parent, rmp->mp_pid);
 143   } else {
 144         rmp->mp_sigstatus = signo;
 145   }
 146   return;
 147 }