binutils-gdb/gdb/i386lynx-nat.c

/* Native-dependent code for Lynx running on i386's, for GDB.
   Copyright 1988, 1989, 1991, 1992, 1993
   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 "gdbcore.h"
#include "target.h"

#include <sys/ptrace.h>
#include "/usr/include/sys/wait.h"

/* these values indicate the offset of the named register in the econtext
   structure */

#define	EAX	10
#define	ECX	9
#define	EDX	8
#define	EBX	7
#define	ESP	16
#define	EBP	5
#define	ESI	4
#define	EDI	3
#define	EIP	13
#define	EFL	15
#define	CS	14
#define	SS	17
#define	DS	2
#define	ES	1

/* Currently these are not being used. So set them to 0 */

#define	FS	0
#define	GS	0

/* this table must line up with REGISTER_NAMES in m-i386.h */
static unsigned int regmap[] = 
{
  EAX, ECX, EDX, EBX,
  ESP, EBP, ESI, EDI,
  EIP, EFL, CS, SS,
  DS, ES, FS, GS,
};

/* Return the address in the core dump or inferior of register REGNO.
   BLOCKEND is the address of the econtext structure */

static unsigned int
register_addr (regno, blockend)
     int regno, blockend;
{
  if (regno < 0 || regno >= NUM_REGS)
    error ("Invalid register number %d.", regno);

  return (blockend + regmap[regno] * sizeof (long));
}

/* Fetch one register.  */

static void
fetch_register (regno, offset, bpid)
     int regno, bpid;
     unsigned int offset;
{
  unsigned int regaddr;
  char buf[MAX_REGISTER_RAW_SIZE];
  char mess[128];				/* For messages */
  int i;

  regaddr = register_addr (regno, offset);
  for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (int))
    {
      errno = 0;
      *(int *) &buf[i] = ptrace (PTRACE_PEEKTHREAD, bpid,
				 (PTRACE_ARG3_TYPE) regaddr, 0);
      regaddr += sizeof (int);
      if (errno != 0)
	{
	  sprintf (mess, "reading register %s (#%d)", reg_names[regno], regno);
	  perror_with_name (mess);
	}
    }
  supply_register (regno, buf);
}

/* Store our register values back into the inferior.
   If REGNO is -1, do this for all registers.
   Otherwise, REGNO specifies which register (so we can save time).  */

static void
store_register (regno, offset, bpid)
     int regno, bpid;
     unsigned int offset;
{
  unsigned int regaddr;
  char mess[128];
  extern char registers[];
  int i;

  regaddr = register_addr (regno, offset);
  for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof(int))
    {
      errno = 0;
      ptrace (PTRACE_POKEUSER, bpid, (PTRACE_ARG3_TYPE) regaddr,
	      *(int *) &registers[REGISTER_BYTE (regno) + i]);
      if (errno != 0)
        {  
	  sprintf (mess, "writing register number %d(%d)", regno, i);
	  perror_with_name (mess);
        }
      regaddr += sizeof(int);
    }
}

/* return an offset for use with register_addr() */

static unsigned int
fetch_offset (pid)
    int pid;
{
  struct st_entry s;
  unsigned int specpage_off, offset = (char *) &s.ecp - (char *) &s;

  errno = 0;
  specpage_off = ptrace (PTRACE_THREADUSER, pid, (PTRACE_ARG3_TYPE) 0, 0);
  if (errno != 0)
    perror_with_name ("ptrace");
  errno = 0;
  offset = ptrace (PTRACE_PEEKTHREAD, pid, (PTRACE_ARG3_TYPE) offset, 0)
      - specpage_off;
  if (errno != 0)
    perror_with_name ("ptrace");
  return offset;
}

/* Fetch all registers, or just one, from the child process.  */

void
fetch_inferior_registers (regno)
     int regno;
{
  unsigned int offset = fetch_offset (inferior_pid);

  if (regno == -1)
    {
      for (regno = 0; regno < NUM_REGS; regno++)
        fetch_register (regno, offset, inferior_pid);
    }
  else
    fetch_register (regno, offset, inferior_pid);
}

/* Store all registers, or just one, to the child process.  */

void
store_inferior_registers (regno)
     int regno;
{
    unsigned int offset = fetch_offset (inferior_pid);

    if (regno == -1)
      {
        for (regno = 0; regno < NUM_REGS; regno++)
	  store_register (regno, offset, inferior_pid);
      }
    else
      store_register (regno, offset, inferior_pid);
}

/* Extract the register values out of the core file and store
   them where `read_register' will find them.

   CORE_REG_SECT points to the register values themselves, read into memory.
   CORE_REG_SIZE is the size of that area.
   WHICH says which set of registers we are handling (0 = int, 2 = float
         on machines where they are discontiguous).
   REG_ADDR is the offset from u.u_ar0 to the register values relative to
            core_reg_sect.  This is used with old-fashioned core files to
	    locate the registers in a large upage-plus-stack ".reg" section.
	    Original upage address X is at location core_reg_sect+x+reg_addr.
 */

void
fetch_core_registers (core_reg_sect, core_reg_size, which, reg_addr)
     char *core_reg_sect;
     unsigned core_reg_size;
     int which;
     unsigned reg_addr;
{
  struct st_entry s;
  unsigned int regno, addr;

  for (regno = 0; regno < NUM_REGS; regno++)
    {
      addr = register_addr (regno, (char *) &s.ec - (char *) &s);
      supply_register (regno, core_reg_sect + addr);
    }
}

/* Wait for child to do something.  Return pid of child, or -1 in case
   of error; store status through argument pointer STATUS.  */

int
child_wait (status)
     int *status;
{
  int pid;
  int save_errno;
  int thread;

  while (1)
    {
      int sig;

      if (attach_flag)
	set_sigint_trap();	/* Causes SIGINT to be passed on to the
				   attached process. */
      pid = wait (status);
      save_errno = errno;

      if (attach_flag)
	clear_sigint_trap();

      if (pid == -1)
	{
	  if (save_errno == EINTR)
	    continue;
	  fprintf (stderr, "Child process unexpectedly missing: %s.\n",
		   safe_strerror (save_errno));
	  *status = 42;		/* Claim it exited with signal 42 */
	  return -1;
	}

      if (pid != PIDGET (inferior_pid))	/* Some other process?!? */
	continue;

/*      thread = WIFTID (*status);*/
      thread = *status >> 16;

      /* Initial thread value can only be acquired via wait, so we have to
	 resort to this hack.  */

      if (TIDGET (inferior_pid) == 0)
	{
	  inferior_pid = BUILDPID (inferior_pid, thread);
	  add_thread (inferior_pid);
	}

      pid = BUILDPID (pid, thread);

      return pid;
    }
}

/* Return the PC of the caller from the call frame.  Assumes the subr prologue
   has already been executed, and the frame pointer setup.  If this is the
   outermost frame, we check to see if we are in a system call by examining the
   previous instruction.  If so, then the return PC is actually at SP+4 because
   system calls use a different calling sequence.  */

CORE_ADDR
i386lynx_saved_pc_after_call (frame)
     struct frame_info *frame;
{
  char opcode[7];
  static const char call_inst[] = {0x9a, 0, 0, 0, 0, 8, 0}; /* lcall 0x8,0x0 */

  read_memory (frame->pc - 7, opcode, 7);
  if (memcmp (opcode, call_inst, 7) == 0)
    return read_memory_integer (read_register (SP_REGNUM) + 4, 4);

  return read_memory_integer (read_register (SP_REGNUM), 4);
}

/* Convert a Lynx process ID to a string.  Returns the string in a static
   buffer.  */

char *
i386lynx_pid_to_str (pid)
     int pid;
{
  static char buf[40];

  sprintf (buf, "process %d thread %d", PIDGET (pid), TIDGET (pid));

  return buf;
}