gdb/infptrace.c

/* Low level Unix child interface to ptrace, for GDB when running under Unix.
   Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
   1998, 1999, 2000, 2001, 2002, 2004
   Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.  */

#include "defs.h"
#include "command.h"
#include "frame.h"
#include "gdbcore.h"
#include "inferior.h"
#include "regcache.h"
#include "target.h"

#include "gdb_assert.h"
#include "gdb_wait.h"
#include "gdb_string.h"

#include <sys/param.h>
#include "gdb_dirent.h"
#include <signal.h>
#include <sys/ioctl.h>

#include "gdb_ptrace.h"

#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif

#if !defined (FETCH_INFERIOR_REGISTERS)
#include <sys/user.h>		/* Probably need to poke the user structure */
#endif /* !FETCH_INFERIOR_REGISTERS */

#if !defined (CHILD_XFER_MEMORY)
static void udot_info (char *, int);
#endif

void _initialize_infptrace (void);


int
call_ptrace (int request, int pid, PTRACE_ARG3_TYPE addr, int data)
{
  return ptrace (request, pid, addr, data);
}

/* Wait for a process to finish, possibly running a target-specific
   hook before returning.  */

/* NOTE: cagney: 2004-09-29: Dependant on the native configuration,
   "hppah-nat.c" may either call this or infttrace.c's implementation
   of ptrace_wait.  See "hppahpux.mh".  */

int
ptrace_wait (ptid_t ptid, int *status)
{
  int wstate;

  wstate = wait (status);
  return wstate;
}

#ifndef DEPRECATED_KILL_INFERIOR
/* NOTE: cagney/2004-09-12: Instead of definining this macro, code
   should call inf_ptrace_target to get a basic ptrace target and then
   locally update any necessary methods.  See ppcnbsd-nat.c.  */

void
kill_inferior (void)
{
  int status;
  int pid =  PIDGET (inferior_ptid);

  if (pid == 0)
    return;

  /* This once used to call "kill" to kill the inferior just in case
     the inferior was still running.  As others have noted in the past
     (kingdon) there shouldn't be any way to get here if the inferior
     is still running -- else there's a major problem elsewere in gdb
     and it needs to be fixed.

     The kill call causes problems under hpux10, so it's been removed;
     if this causes problems we'll deal with them as they arise.  */
  ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3) 0, 0);
  wait (&status);
  target_mourn_inferior ();
}
#endif /* DEPRECATED_KILL_INFERIOR */

#ifndef DEPRECATED_CHILD_RESUME
/* NOTE: cagney/2004-09-12: Instead of definining this macro, code
   should call inf_ptrace_target to get a basic ptrace target and then
   locally update any necessary methods.  See ppcnbsd-nat.c.  */

/* Resume execution of the inferior process.
   If STEP is nonzero, single-step it.
   If SIGNAL is nonzero, give it that signal.  */

void
child_resume (ptid_t ptid, int step, enum target_signal signal)
{
  int request = PT_CONTINUE;
  int pid = PIDGET (ptid);

  if (pid == -1)
    /* Resume all threads.  */
    /* I think this only gets used in the non-threaded case, where "resume
       all threads" and "resume inferior_ptid" are the same.  */
    pid = PIDGET (inferior_ptid);

  if (step)
    {
      /* If this system does not support PT_STEP, a higher level
	 function will have called single_step() to transmute the step
	 request into a continue request (by setting breakpoints on
	 all possible successor instructions), so we don't have to
	 worry about that here.  */

      gdb_assert (!SOFTWARE_SINGLE_STEP_P ());
      request = PT_STEP;
    }

  /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
     where it was.  If GDB wanted it to start some other way, we have
     already written a new PC value to the child.  */

  errno = 0;
  ptrace (request, pid, (PTRACE_TYPE_ARG3)1, target_signal_to_host (signal));
  if (errno != 0)
    perror_with_name (("ptrace"));
}
#endif /* DEPRECATED_CHILD_RESUME */


/* Start debugging the process whose number is PID.  */

int
attach (int pid)
{
#ifdef PT_ATTACH
  errno = 0;
  ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3) 0, 0);
  if (errno != 0)
    perror_with_name (("ptrace"));
  attach_flag = 1;
  return pid;
#else
  error (_("This system does not support attaching to a process"));
#endif
}

/* Stop debugging the process whose number is PID and continue it with
   signal number SIGNAL.  SIGNAL = 0 means just continue it.  */

void
detach (int signal)
{
#ifdef PT_DETACH
  int pid = PIDGET (inferior_ptid);

  errno = 0;
  ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3) 1, signal);
  if (errno != 0)
    perror_with_name (("ptrace"));
  attach_flag = 0;
#else
  error (_("This system does not support detaching from a process"));
#endif
}


#ifndef FETCH_INFERIOR_REGISTERS

/* U_REGS_OFFSET is the offset of the registers within the u area.  */
#ifndef U_REGS_OFFSET

#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
#endif

#define U_REGS_OFFSET \
  ptrace (PT_READ_U, PIDGET (inferior_ptid), \
	  (PTRACE_TYPE_ARG3) (offsetof (struct user, u_ar0)), 0) \
    - KERNEL_U_ADDR
#endif

/* Fetch register REGNUM from the inferior.  */

static void
fetch_register (int regnum)
{
  CORE_ADDR addr;
  size_t size;
  PTRACE_TYPE_RET *buf;
  int tid, i;

  if (CANNOT_FETCH_REGISTER (regnum))
    {
      regcache_raw_supply (current_regcache, regnum, NULL);
      return;
    }

  /* GNU/Linux LWP ID's are process ID's.  */
  tid = TIDGET (inferior_ptid);
  if (tid == 0)
    tid = PIDGET (inferior_ptid); /* Not a threaded program.  */

  /* This isn't really an address.  But ptrace thinks of it as one.  */
  addr = register_addr (regnum, U_REGS_OFFSET);
  size = register_size (current_gdbarch, regnum);

  gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
  buf = alloca (size);

  /* Read the register contents from the inferior a chuck at the time.  */
  for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
    {
      errno = 0;
      buf[i] = ptrace (PT_READ_U, tid, (PTRACE_TYPE_ARG3) addr, 0);
      if (errno != 0)
	error (_("Couldn't read register %s (#%d): %s."), REGISTER_NAME (regnum),
	       regnum, safe_strerror (errno));

      addr += sizeof (PTRACE_TYPE_RET);
    }
  regcache_raw_supply (current_regcache, regnum, buf);
}

/* Fetch register REGNUM from the inferior.  If REGNUM is -1, do this
   for all registers.  */

void
fetch_inferior_registers (int regnum)
{
  if (regnum == -1)
    for (regnum = 0; regnum < NUM_REGS; regnum++)
      fetch_register (regnum);
  else
    fetch_register (regnum);
}

/* Store register REGNUM into the inferior.  */

static void
store_register (int regnum)
{
  CORE_ADDR addr;
  size_t size;
  PTRACE_TYPE_RET *buf;
  int tid, i;

  if (CANNOT_STORE_REGISTER (regnum))
    return;

  /* GNU/Linux LWP ID's are process ID's.  */
  tid = TIDGET (inferior_ptid);
  if (tid == 0)
    tid = PIDGET (inferior_ptid); /* Not a threaded program.  */

  /* This isn't really an address.  But ptrace thinks of it as one.  */
  addr = register_addr (regnum, U_REGS_OFFSET);
  size = register_size (current_gdbarch, regnum);

  gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
  buf = alloca (size);

  /* Write the register contents into the inferior a chunk at the time.  */
  regcache_raw_collect (current_regcache, regnum, buf);
  for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
    {
      errno = 0;
      ptrace (PT_WRITE_U, tid, (PTRACE_TYPE_ARG3) addr, buf[i]);
      if (errno != 0)
	error (_("Couldn't write register %s (#%d): %s."),
	       REGISTER_NAME (regnum), regnum, safe_strerror (errno));

      addr += sizeof (PTRACE_TYPE_RET);
    }
}

/* Store register REGNUM back into the inferior.  If REGNUM is -1, do
   this for all registers (including the floating point registers).  */

void
store_inferior_registers (int regnum)
{
  if (regnum == -1)
    for (regnum = 0; regnum < NUM_REGS; regnum++)
      store_register (regnum);
  else
    store_register (regnum);
}

#endif /* not FETCH_INFERIOR_REGISTERS.  */


/* Set an upper limit on alloca.  */
#ifndef GDB_MAX_ALLOCA
#define GDB_MAX_ALLOCA 0x1000
#endif

#if !defined (CHILD_XFER_MEMORY)
/* NOTE! I tried using PTRACE_READDATA, etc., to read and write memory
   in the NEW_SUN_PTRACE case.  It ought to be straightforward.  But
   it appears that writing did not write the data that I specified.  I
   cannot understand where it got the data that it actually did write.  */

/* Copy LEN bytes to or from inferior's memory starting at MEMADDR to
   debugger memory starting at MYADDR.  Copy to inferior if WRITE is
   nonzero.  TARGET is ignored.

   Returns the length copied, which is either the LEN argument or
   zero.  This xfer function does not do partial moves, since
   deprecated_child_ops doesn't allow memory operations to cross below
   us in the target stack anyway.  */

int
child_xfer_memory (CORE_ADDR memaddr, gdb_byte *myaddr, int len, int write,
		   struct mem_attrib *attrib, struct target_ops *target)
{
  int i;
  /* Round starting address down to longword boundary.  */
  CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_TYPE_RET);
  /* Round ending address up; get number of longwords that makes.  */
  int count = ((((memaddr + len) - addr) + sizeof (PTRACE_TYPE_RET) - 1)
	       / sizeof (PTRACE_TYPE_RET));
  int alloc = count * sizeof (PTRACE_TYPE_RET);
  PTRACE_TYPE_RET *buffer;
  struct cleanup *old_chain = NULL;

#ifdef PT_IO
  /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO request
     that promises to be much more efficient in reading and writing
     data in the traced process's address space.  */

  {
    struct ptrace_io_desc piod;

    /* NOTE: We assume that there are no distinct address spaces for
       instruction and data.  */
    piod.piod_op = write ? PIOD_WRITE_D : PIOD_READ_D;
    piod.piod_offs = (void *) memaddr;
    piod.piod_addr = myaddr;
    piod.piod_len = len;

    if (ptrace (PT_IO, PIDGET (inferior_ptid), (caddr_t) &piod, 0) == -1)
      {
	/* If the PT_IO request is somehow not supported, fallback on
           using PT_WRITE_D/PT_READ_D.  Otherwise we will return zero
           to indicate failure.  */
	if (errno != EINVAL)
	  return 0;
      }
    else
      {
	/* Return the actual number of bytes read or written.  */
	return piod.piod_len;
      }
  }
#endif

  /* Allocate buffer of that many longwords.  */
  if (len < GDB_MAX_ALLOCA)
    {
      buffer = (PTRACE_TYPE_RET *) alloca (alloc);
    }
  else
    {
      buffer = (PTRACE_TYPE_RET *) xmalloc (alloc);
      old_chain = make_cleanup (xfree, buffer);
    }

  if (write)
    {
      /* Fill start and end extra bytes of buffer with existing memory
         data.  */
      if (addr != memaddr || len < (int) sizeof (PTRACE_TYPE_RET))
	{
	  /* Need part of initial word -- fetch it.  */
	  buffer[0] = ptrace (PT_READ_I, PIDGET (inferior_ptid), 
			      (PTRACE_TYPE_ARG3) addr, 0);
	}

      if (count > 1)		/* FIXME, avoid if even boundary.  */
	{
	  buffer[count - 1] =
	    ptrace (PT_READ_I, PIDGET (inferior_ptid),
		    ((PTRACE_TYPE_ARG3)
		     (addr + (count - 1) * sizeof (PTRACE_TYPE_RET))), 0);
	}

      /* Copy data to be written over corresponding part of buffer.  */
      memcpy ((char *) buffer + (memaddr & (sizeof (PTRACE_TYPE_RET) - 1)),
	      myaddr, len);

      /* Write the entire buffer.  */
      for (i = 0; i < count; i++, addr += sizeof (PTRACE_TYPE_RET))
	{
	  errno = 0;
	  ptrace (PT_WRITE_D, PIDGET (inferior_ptid), 
		  (PTRACE_TYPE_ARG3) addr, buffer[i]);
	  if (errno)
	    {
	      /* Using the appropriate one (I or D) is necessary for
	         Gould NP1, at least.  */
	      errno = 0;
	      ptrace (PT_WRITE_I, PIDGET (inferior_ptid), 
		      (PTRACE_TYPE_ARG3) addr, buffer[i]);
	    }
	  if (errno)
	    return 0;
	}
    }
  else
    {
      /* Read all the longwords.  */
      for (i = 0; i < count; i++, addr += sizeof (PTRACE_TYPE_RET))
	{
	  errno = 0;
	  buffer[i] = ptrace (PT_READ_I, PIDGET (inferior_ptid),
			      (PTRACE_TYPE_ARG3) addr, 0);
	  if (errno)
	    return 0;
	  QUIT;
	}

      /* Copy appropriate bytes out of the buffer.  */
      memcpy (myaddr,
	      (char *) buffer + (memaddr & (sizeof (PTRACE_TYPE_RET) - 1)),
	      len);
    }

  if (old_chain != NULL)
    do_cleanups (old_chain);
  return len;
}


static void
udot_info (char *dummy1, int dummy2)
{
#if defined (KERNEL_U_SIZE)
  long udot_off;			/* Offset into user struct */
  int udot_val;			/* Value from user struct at udot_off */
  char mess[128];		/* For messages */
#endif

  if (!target_has_execution)
    {
      error (_("The program is not being run."));
    }

#if !defined (KERNEL_U_SIZE)

  /* Adding support for this command is easy.  Typically you just add a
     routine, called "kernel_u_size" that returns the size of the user
     struct, to the appropriate *-nat.c file and then add to the native
     config file "#define KERNEL_U_SIZE kernel_u_size()" */
  error (_("Don't know how large ``struct user'' is in this version of gdb."));

#else

  for (udot_off = 0; udot_off < KERNEL_U_SIZE; udot_off += sizeof (udot_val))
    {
      if ((udot_off % 24) == 0)
	{
	  if (udot_off > 0)
	    {
	      printf_filtered ("\n");
	    }
	  printf_filtered ("%s:", paddr (udot_off));
	}
      udot_val = ptrace (PT_READ_U, PIDGET (inferior_ptid), (PTRACE_TYPE_ARG3) udot_off, 0);
      if (errno != 0)
	{
	  sprintf (mess, "\nreading user struct at offset 0x%s",
		   paddr_nz (udot_off));
	  perror_with_name (mess);
	}
      /* Avoid using nonportable (?) "*" in print specs */
      printf_filtered (sizeof (int) == 4 ? " 0x%08x" : " 0x%16x", udot_val);
    }
  printf_filtered ("\n");

#endif
}
#endif /* !defined (CHILD_XFER_MEMORY).  */


void
_initialize_infptrace (void)
{
#if !defined (CHILD_XFER_MEMORY)
  add_info ("udot", udot_info,
	    _("Print contents of kernel ``struct user'' for current child."));
#endif
}