binutils-gdb/gdb/i386v-nat.c

/* Intel 386 native support for SYSV systems (pre-SVR4).
   Copyright (C) 1988, 1989, 1991, 1992, 1994 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., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"
#include "frame.h"
#include "inferior.h"
#include "language.h"
#include "gdbcore.h"

#ifdef USG
#include <sys/types.h>
#endif

#include <sys/param.h>
#include <sys/dir.h>
#include <signal.h>
#include <sys/user.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#ifdef TARGET_CAN_USE_HARDWARE_WATCHPOINT
#include <sys/debugreg.h>
#endif

#include <sys/file.h>
#include <sys/stat.h>

#ifndef NO_SYS_REG_H
#include <sys/reg.h>
#endif

#include "floatformat.h"

#include "target.h"


/* this table must line up with REGISTER_NAMES in tm-i386v.h */
/* symbols like 'EAX' come from <sys/reg.h> */
static int regmap[] = 
{
  EAX, ECX, EDX, EBX,
  UESP, EBP, ESI, EDI,
  EIP, EFL, CS, SS,
  DS, ES, FS, GS,
};

/* blockend is the value of u.u_ar0, and points to the
 * place where GS is stored
 */

int
i386_register_u_addr (blockend, regnum)
     int blockend;
     int regnum;
{
#if 0
  /* this will be needed if fp registers are reinstated */
  /* for now, you can look at them with 'info float'
   * sys5 wont let you change them with ptrace anyway
   */
  if (regnum >= FP0_REGNUM && regnum <= FP7_REGNUM) 
    {
      int ubase, fpstate;
      struct user u;
      ubase = blockend + 4 * (SS + 1) - KSTKSZ;
      fpstate = ubase + ((char *)&u.u_fpstate - (char *)&u);
      return (fpstate + 0x1c + 10 * (regnum - FP0_REGNUM));
    } 
  else
#endif
    return (blockend + 4 * regmap[regnum]);
  
}

#ifdef TARGET_CAN_USE_HARDWARE_WATCHPOINT

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

/* Record the value of the debug control register.  */
static int debug_control_mirror;

/* Record which address associates with which register.  */
static CORE_ADDR address_lookup[DR_LASTADDR - DR_FIRSTADDR + 1];

static int
i386_insert_nonaligned_watchpoint PARAMS ((int, CORE_ADDR, int, int));

/* Insert a watchpoint.  */

int
i386_insert_watchpoint (pid, addr, len, rw)
     int pid;
     CORE_ADDR addr;
     int len;
     int rw;
{
  int i;
  int read_write_bits, len_bits;
  int free_debug_register;
  int register_number;
  
  /* Look for a free debug register.  */
  for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
    {
      if (address_lookup[i - DR_FIRSTADDR] == 0)
	break;
    }

  /* No more debug registers!  */
  if (i > DR_LASTADDR)
    return -1;

  read_write_bits = ((rw & 1) ? DR_RW_READ : 0) | ((rw & 2) ? DR_RW_WRITE : 0);

  if (len == 1)
    len_bits = DR_LEN_1;
  else if (len == 2)
    {
      if (addr % 2)
	return i386_insert_nonaligned_watchpoint (pid, addr, len, rw);
      len_bits = DR_LEN_2;
    }

  else if (len == 4)
    {
      if (addr % 4)
	return i386_insert_nonaligned_watchpoint (pid, addr, len, rw);
      len_bits = DR_LEN_4;
    }
  else
    return i386_insert_nonaligned_watchpoint (pid, addr, len, rw);
  
  free_debug_register = i;
  register_number = free_debug_register - DR_FIRSTADDR;
  debug_control_mirror |=
    ((read_write_bits | len_bits)
     << (DR_CONTROL_SHIFT + DR_CONTROL_SIZE * register_number));
  debug_control_mirror |=
    (1 << (DR_LOCAL_ENABLE_SHIFT + DR_ENABLE_SIZE * register_number));
  debug_control_mirror |= DR_LOCAL_SLOWDOWN;
  debug_control_mirror &= ~DR_CONTROL_RESERVED;
  
  ptrace (6, pid, offsetof (struct user, u_debugreg[DR_CONTROL]),
	  debug_control_mirror);
  ptrace (6, pid, offsetof (struct user, u_debugreg[free_debug_register]),
	  addr);

  /* Record where we came from.  */
  address_lookup[register_number] = addr;
  return 0;
}

static int
i386_insert_nonaligned_watchpoint (pid, addr, len, rw)
     int		pid;
     CORE_ADDR		addr;
     int		len;
     int		rw;
{
  int align;
  int size;
  int rv;

  static int size_try_array[16] = {
    1, 1, 1, 1,			/* trying size one */
    2, 1, 2, 1,			/* trying size two */
    2, 1, 2, 1,			/* trying size three */
    4, 1, 2, 1			/* trying size four */
  };

  rv = 0;
  while (len > 0)
    {
      align = addr % 4;
      /* Four is the maximum length for 386.  */
      size = (len > 4) ? 3 : len - 1;
      size = size_try_array[size * 4 + align];

      rv = i386_insert_watchpoint (pid, addr, size, rw);
      if (rv)
	{
	  i386_remove_watchpoint (pid, addr, size);
	  return rv;
	}
      addr += size;
      len -= size;
    }
  return rv;
}

/* Remove a watchpoint.  */

int
i386_remove_watchpoint (pid, addr, len)
     int pid;
     CORE_ADDR addr;
     int len;
{
  int i;
  int register_number;

  for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
    {
      register_number = i - DR_FIRSTADDR;
      if (address_lookup[register_number] == addr)
	{
	  debug_control_mirror &=
	    ~(1 << (DR_LOCAL_ENABLE_SHIFT + DR_ENABLE_SIZE * register_number));
	  address_lookup[register_number] = 0;
	}
    }
  ptrace (6, pid, offsetof (struct user, u_debugreg[DR_CONTROL]),
	  debug_control_mirror);
  ptrace (6, pid, offsetof (struct user, u_debugreg[DR_STATUS]), 0);

  return 0;
}

/* Check if stopped by a watchpoint.  */

CORE_ADDR
i386_stopped_by_watchpoint (pid)
    int pid;
{
  int i;
  int status;

  status = ptrace (3, pid, offsetof (struct user, u_debugreg[DR_STATUS]), 0);
  ptrace (6, pid, offsetof (struct user, u_debugreg[DR_STATUS]), 0);

  for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
    {
      if (status & (1 << (i - DR_FIRSTADDR)))
	return address_lookup[i - DR_FIRSTADDR];
    }

  return 0;
}

#endif /* TARGET_CAN_USE_HARDWARE_WATCHPOINT */

#if 0
/* using FLOAT_INFO as is would be a problem.  FLOAT_INFO is called
   via a command xxx and eventually calls ptrace without ever having
   traversed the target vector.  This would be terribly impolite
   behaviour for a sun4 hosted remote gdb.

   A fix might be to move this code into the "info registers" command.
   rich@cygnus.com 15 Sept 92. */
i386_float_info ()
{
  struct user u; /* just for address computations */
  int i;
  /* fpstate defined in <sys/user.h> */
  struct fpstate *fpstatep;
  char buf[sizeof (struct fpstate) + 2 * sizeof (int)];
  unsigned int uaddr;
  char fpvalid = 0;
  unsigned int rounded_addr;
  unsigned int rounded_size;
  extern int corechan;
  int skip;
  
  uaddr = (char *)&u.u_fpvalid - (char *)&u;
  if (target_has_execution)
    {
      unsigned int data;
      unsigned int mask;
      
      rounded_addr = uaddr & -sizeof (int);
      data = ptrace (3, inferior_pid, (PTRACE_ARG3_TYPE) rounded_addr, 0);
      mask = 0xff << ((uaddr - rounded_addr) * 8);
      
      fpvalid = ((data & mask) != 0);
    } 
#if 0
  else 
    {
      if (lseek (corechan, uaddr, 0) < 0)
	perror ("seek on core file");
      if (myread (corechan, &fpvalid, 1) < 0) 
	perror ("read on core file");
      
    }
#endif	/* no core support yet */
  
  if (fpvalid == 0) 
    {
      printf_unfiltered ("no floating point status saved\n");
      return;
    }
  
  uaddr = (char *)&U_FPSTATE(u) - (char *)&u;
  if (target_has_execution)
    {
      int *ip;
      
      rounded_addr = uaddr & -sizeof (int);
      rounded_size = (((uaddr + sizeof (struct fpstate)) - uaddr) +
		      sizeof (int) - 1) / sizeof (int);
      skip = uaddr - rounded_addr;
      
      ip = (int *)buf;
      for (i = 0; i < rounded_size; i++) 
	{
	  *ip++ = ptrace (3, inferior_pid, (PTRACE_ARG3_TYPE) rounded_addr, 0);
	  rounded_addr += sizeof (int);
	}
    } 
#if 0
  else 
    {
      if (lseek (corechan, uaddr, 0) < 0)
	perror_with_name ("seek on core file");
      if (myread (corechan, buf, sizeof (struct fpstate)) < 0) 
	perror_with_name ("read from core file");
      skip = 0;
    }
#endif	/* 0 */ 

  fpstatep = (struct fpstate *)(buf + skip);
  print_387_status (fpstatep->status, (struct env387 *)fpstatep->state);
}

#endif /* never */