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[/] [or1k/] [trunk/] [gdb-5.0/] [gdb/] [i386-linux-tdep.c] - Diff between revs 105 and 1765

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Rev 105 Rev 1765
/* Target-dependent code for Linux running on i386's, for GDB.
/* Target-dependent code for Linux running on i386's, for GDB.
   Copyright (C) 2000 Free Software Foundation, Inc.
   Copyright (C) 2000 Free Software Foundation, Inc.
 
 
   This file is part of GDB.
   This file is part of GDB.
 
 
   This program is free software; you can redistribute it and/or modify
   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
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   (at your option) any later version.
 
 
   This program is distributed in the hope that it will be useful,
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   GNU General Public License for more details.
 
 
   You should have received a copy of the GNU General Public License
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */
   Boston, MA 02111-1307, USA.  */
 
 
#include "defs.h"
#include "defs.h"
#include "gdbcore.h"
#include "gdbcore.h"
#include "frame.h"
#include "frame.h"
#include "value.h"
#include "value.h"
 
 


/* Recognizing signal handler frames.  */
/* Recognizing signal handler frames.  */
 
 
/* Linux has two flavors of signals.  Normal signal handlers, and
/* Linux has two flavors of signals.  Normal signal handlers, and
   "realtime" (RT) signals.  The RT signals can provide additional
   "realtime" (RT) signals.  The RT signals can provide additional
   information to the signal handler if the SA_SIGINFO flag is set
   information to the signal handler if the SA_SIGINFO flag is set
   when establishing a signal handler using `sigaction'.  It is not
   when establishing a signal handler using `sigaction'.  It is not
   unlikely that future versions of Linux will support SA_SIGINFO for
   unlikely that future versions of Linux will support SA_SIGINFO for
   normal signals too.  */
   normal signals too.  */
 
 
/* When the i386 Linux kernel calls a signal handler and the
/* When the i386 Linux kernel calls a signal handler and the
   SA_RESTORER flag isn't set, the return address points to a bit of
   SA_RESTORER flag isn't set, the return address points to a bit of
   code on the stack.  This function returns whether the PC appears to
   code on the stack.  This function returns whether the PC appears to
   be within this bit of code.
   be within this bit of code.
 
 
   The instruction sequence for normal signals is
   The instruction sequence for normal signals is
       pop    %eax
       pop    %eax
       mov    $0x77,%eax
       mov    $0x77,%eax
       int    $0x80
       int    $0x80
   or 0x58 0xb8 0x77 0x00 0x00 0x00 0xcd 0x80.
   or 0x58 0xb8 0x77 0x00 0x00 0x00 0xcd 0x80.
 
 
   Checking for the code sequence should be somewhat reliable, because
   Checking for the code sequence should be somewhat reliable, because
   the effect is to call the system call sigreturn.  This is unlikely
   the effect is to call the system call sigreturn.  This is unlikely
   to occur anywhere other than a signal trampoline.
   to occur anywhere other than a signal trampoline.
 
 
   It kind of sucks that we have to read memory from the process in
   It kind of sucks that we have to read memory from the process in
   order to identify a signal trampoline, but there doesn't seem to be
   order to identify a signal trampoline, but there doesn't seem to be
   any other way.  The IN_SIGTRAMP macro in tm-linux.h arranges to
   any other way.  The IN_SIGTRAMP macro in tm-linux.h arranges to
   only call us if no function name could be identified, which should
   only call us if no function name could be identified, which should
   be the case since the code is on the stack.
   be the case since the code is on the stack.
 
 
   Detection of signal trampolines for handlers that set the
   Detection of signal trampolines for handlers that set the
   SA_RESTORER flag is in general not possible.  Unfortunately this is
   SA_RESTORER flag is in general not possible.  Unfortunately this is
   what the GNU C Library has been doing for quite some time now.
   what the GNU C Library has been doing for quite some time now.
   However, as of version 2.1.2, the GNU C Library uses signal
   However, as of version 2.1.2, the GNU C Library uses signal
   trampolines (named __restore and __restore_rt) that are identical
   trampolines (named __restore and __restore_rt) that are identical
   to the ones used by the kernel.  Therefore, these trampolines are
   to the ones used by the kernel.  Therefore, these trampolines are
   supported too.  */
   supported too.  */
 
 
#define LINUX_SIGTRAMP_INSN0 (0x58)     /* pop %eax */
#define LINUX_SIGTRAMP_INSN0 (0x58)     /* pop %eax */
#define LINUX_SIGTRAMP_OFFSET0 (0)
#define LINUX_SIGTRAMP_OFFSET0 (0)
#define LINUX_SIGTRAMP_INSN1 (0xb8)     /* mov $NNNN,%eax */
#define LINUX_SIGTRAMP_INSN1 (0xb8)     /* mov $NNNN,%eax */
#define LINUX_SIGTRAMP_OFFSET1 (1)
#define LINUX_SIGTRAMP_OFFSET1 (1)
#define LINUX_SIGTRAMP_INSN2 (0xcd)     /* int */
#define LINUX_SIGTRAMP_INSN2 (0xcd)     /* int */
#define LINUX_SIGTRAMP_OFFSET2 (6)
#define LINUX_SIGTRAMP_OFFSET2 (6)
 
 
static const unsigned char linux_sigtramp_code[] =
static const unsigned char linux_sigtramp_code[] =
{
{
  LINUX_SIGTRAMP_INSN0,                                 /* pop %eax */
  LINUX_SIGTRAMP_INSN0,                                 /* pop %eax */
  LINUX_SIGTRAMP_INSN1, 0x77, 0x00, 0x00, 0x00,         /* mov $0x77,%eax */
  LINUX_SIGTRAMP_INSN1, 0x77, 0x00, 0x00, 0x00,         /* mov $0x77,%eax */
  LINUX_SIGTRAMP_INSN2, 0x80                            /* int $0x80 */
  LINUX_SIGTRAMP_INSN2, 0x80                            /* int $0x80 */
};
};
 
 
#define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
#define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
 
 
/* If PC is in a sigtramp routine, return the address of the start of
/* If PC is in a sigtramp routine, return the address of the start of
   the routine.  Otherwise, return 0.  */
   the routine.  Otherwise, return 0.  */
 
 
static CORE_ADDR
static CORE_ADDR
i386_linux_sigtramp_start (CORE_ADDR pc)
i386_linux_sigtramp_start (CORE_ADDR pc)
{
{
  unsigned char buf[LINUX_SIGTRAMP_LEN];
  unsigned char buf[LINUX_SIGTRAMP_LEN];
 
 
  /* We only recognize a signal trampoline if PC is at the start of
  /* We only recognize a signal trampoline if PC is at the start of
     one of the three instructions.  We optimize for finding the PC at
     one of the three instructions.  We optimize for finding the PC at
     the start, as will be the case when the trampoline is not the
     the start, as will be the case when the trampoline is not the
     first frame on the stack.  We assume that in the case where the
     first frame on the stack.  We assume that in the case where the
     PC is not at the start of the instruction sequence, there will be
     PC is not at the start of the instruction sequence, there will be
     a few trailing readable bytes on the stack.  */
     a few trailing readable bytes on the stack.  */
 
 
  if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
  if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
    return 0;
    return 0;
 
 
  if (buf[0] != LINUX_SIGTRAMP_INSN0)
  if (buf[0] != LINUX_SIGTRAMP_INSN0)
    {
    {
      int adjust;
      int adjust;
 
 
      switch (buf[0])
      switch (buf[0])
        {
        {
        case LINUX_SIGTRAMP_INSN1:
        case LINUX_SIGTRAMP_INSN1:
          adjust = LINUX_SIGTRAMP_OFFSET1;
          adjust = LINUX_SIGTRAMP_OFFSET1;
          break;
          break;
        case LINUX_SIGTRAMP_INSN2:
        case LINUX_SIGTRAMP_INSN2:
          adjust = LINUX_SIGTRAMP_OFFSET2;
          adjust = LINUX_SIGTRAMP_OFFSET2;
          break;
          break;
        default:
        default:
          return 0;
          return 0;
        }
        }
 
 
      pc -= adjust;
      pc -= adjust;
 
 
      if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
      if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
        return 0;
        return 0;
    }
    }
 
 
  if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
  if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
    return 0;
    return 0;
 
 
  return pc;
  return pc;
}
}
 
 
/* This function does the same for RT signals.  Here the instruction
/* This function does the same for RT signals.  Here the instruction
   sequence is
   sequence is
       mov    $0xad,%eax
       mov    $0xad,%eax
       int    $0x80
       int    $0x80
   or 0xb8 0xad 0x00 0x00 0x00 0xcd 0x80.
   or 0xb8 0xad 0x00 0x00 0x00 0xcd 0x80.
 
 
   The effect is to call the system call rt_sigreturn.  */
   The effect is to call the system call rt_sigreturn.  */
 
 
#define LINUX_RT_SIGTRAMP_INSN0 (0xb8)  /* mov $NNNN,%eax */
#define LINUX_RT_SIGTRAMP_INSN0 (0xb8)  /* mov $NNNN,%eax */
#define LINUX_RT_SIGTRAMP_OFFSET0 (0)
#define LINUX_RT_SIGTRAMP_OFFSET0 (0)
#define LINUX_RT_SIGTRAMP_INSN1 (0xcd)  /* int */
#define LINUX_RT_SIGTRAMP_INSN1 (0xcd)  /* int */
#define LINUX_RT_SIGTRAMP_OFFSET1 (5)
#define LINUX_RT_SIGTRAMP_OFFSET1 (5)
 
 
static const unsigned char linux_rt_sigtramp_code[] =
static const unsigned char linux_rt_sigtramp_code[] =
{
{
  LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00,      /* mov $0xad,%eax */
  LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00,      /* mov $0xad,%eax */
  LINUX_RT_SIGTRAMP_INSN1, 0x80                         /* int $0x80 */
  LINUX_RT_SIGTRAMP_INSN1, 0x80                         /* int $0x80 */
};
};
 
 
#define LINUX_RT_SIGTRAMP_LEN (sizeof linux_rt_sigtramp_code)
#define LINUX_RT_SIGTRAMP_LEN (sizeof linux_rt_sigtramp_code)
 
 
/* If PC is in a RT sigtramp routine, return the address of the start
/* If PC is in a RT sigtramp routine, return the address of the start
   of the routine.  Otherwise, return 0.  */
   of the routine.  Otherwise, return 0.  */
 
 
static CORE_ADDR
static CORE_ADDR
i386_linux_rt_sigtramp_start (CORE_ADDR pc)
i386_linux_rt_sigtramp_start (CORE_ADDR pc)
{
{
  unsigned char buf[LINUX_RT_SIGTRAMP_LEN];
  unsigned char buf[LINUX_RT_SIGTRAMP_LEN];
 
 
  /* We only recognize a signal trampoline if PC is at the start of
  /* We only recognize a signal trampoline if PC is at the start of
     one of the two instructions.  We optimize for finding the PC at
     one of the two instructions.  We optimize for finding the PC at
     the start, as will be the case when the trampoline is not the
     the start, as will be the case when the trampoline is not the
     first frame on the stack.  We assume that in the case where the
     first frame on the stack.  We assume that in the case where the
     PC is not at the start of the instruction sequence, there will be
     PC is not at the start of the instruction sequence, there will be
     a few trailing readable bytes on the stack.  */
     a few trailing readable bytes on the stack.  */
 
 
  if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
  if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
    return 0;
    return 0;
 
 
  if (buf[0] != LINUX_RT_SIGTRAMP_INSN0)
  if (buf[0] != LINUX_RT_SIGTRAMP_INSN0)
    {
    {
      if (buf[0] != LINUX_RT_SIGTRAMP_INSN1)
      if (buf[0] != LINUX_RT_SIGTRAMP_INSN1)
        return 0;
        return 0;
 
 
      pc -= LINUX_RT_SIGTRAMP_OFFSET1;
      pc -= LINUX_RT_SIGTRAMP_OFFSET1;
 
 
      if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
      if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
        return 0;
        return 0;
    }
    }
 
 
  if (memcmp (buf, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN) != 0)
  if (memcmp (buf, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN) != 0)
    return 0;
    return 0;
 
 
  return pc;
  return pc;
}
}
 
 
/* Return whether PC is in a Linux sigtramp routine.  */
/* Return whether PC is in a Linux sigtramp routine.  */
 
 
int
int
i386_linux_in_sigtramp (CORE_ADDR pc, char *name)
i386_linux_in_sigtramp (CORE_ADDR pc, char *name)
{
{
  if (name)
  if (name)
    return STREQ ("__restore", name) || STREQ ("__restore_rt", name);
    return STREQ ("__restore", name) || STREQ ("__restore_rt", name);
 
 
  return (i386_linux_sigtramp_start (pc) != 0
  return (i386_linux_sigtramp_start (pc) != 0
          || i386_linux_rt_sigtramp_start (pc) != 0);
          || i386_linux_rt_sigtramp_start (pc) != 0);
}
}
 
 
/* Assuming FRAME is for a Linux sigtramp routine, return the address
/* Assuming FRAME is for a Linux sigtramp routine, return the address
   of the associated sigcontext structure.  */
   of the associated sigcontext structure.  */
 
 
CORE_ADDR
CORE_ADDR
i386_linux_sigcontext_addr (struct frame_info *frame)
i386_linux_sigcontext_addr (struct frame_info *frame)
{
{
  CORE_ADDR pc;
  CORE_ADDR pc;
 
 
  pc = i386_linux_sigtramp_start (frame->pc);
  pc = i386_linux_sigtramp_start (frame->pc);
  if (pc)
  if (pc)
    {
    {
      CORE_ADDR sp;
      CORE_ADDR sp;
 
 
      if (frame->next)
      if (frame->next)
        /* If this isn't the top frame, the next frame must be for the
        /* If this isn't the top frame, the next frame must be for the
           signal handler itself.  The sigcontext structure lives on
           signal handler itself.  The sigcontext structure lives on
           the stack, right after the signum argument.  */
           the stack, right after the signum argument.  */
        return frame->next->frame + 12;
        return frame->next->frame + 12;
 
 
      /* This is the top frame.  We'll have to find the address of the
      /* This is the top frame.  We'll have to find the address of the
         sigcontext structure by looking at the stack pointer.  Keep
         sigcontext structure by looking at the stack pointer.  Keep
         in mind that the first instruction of the sigtramp code is
         in mind that the first instruction of the sigtramp code is
         "pop %eax".  If the PC is at this instruction, adjust the
         "pop %eax".  If the PC is at this instruction, adjust the
         returned value accordingly.  */
         returned value accordingly.  */
      sp = read_register (SP_REGNUM);
      sp = read_register (SP_REGNUM);
      if (pc == frame->pc)
      if (pc == frame->pc)
        return sp + 4;
        return sp + 4;
      return sp;
      return sp;
    }
    }
 
 
  pc = i386_linux_rt_sigtramp_start (frame->pc);
  pc = i386_linux_rt_sigtramp_start (frame->pc);
  if (pc)
  if (pc)
    {
    {
      if (frame->next)
      if (frame->next)
        /* If this isn't the top frame, the next frame must be for the
        /* If this isn't the top frame, the next frame must be for the
           signal handler itself.  The sigcontext structure is part of
           signal handler itself.  The sigcontext structure is part of
           the user context.  A pointer to the user context is passed
           the user context.  A pointer to the user context is passed
           as the third argument to the signal handler.  */
           as the third argument to the signal handler.  */
        return read_memory_integer (frame->next->frame + 16, 4) + 20;
        return read_memory_integer (frame->next->frame + 16, 4) + 20;
 
 
      /* This is the top frame.  Again, use the stack pointer to find
      /* This is the top frame.  Again, use the stack pointer to find
         the address of the sigcontext structure.  */
         the address of the sigcontext structure.  */
      return read_memory_integer (read_register (SP_REGNUM) + 8, 4) + 20;
      return read_memory_integer (read_register (SP_REGNUM) + 8, 4) + 20;
    }
    }
 
 
  error ("Couldn't recognize signal trampoline.");
  error ("Couldn't recognize signal trampoline.");
  return 0;
  return 0;
}
}
 
 
/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */
#define LINUX_SIGCONTEXT_PC_OFFSET (56)
#define LINUX_SIGCONTEXT_PC_OFFSET (56)
 
 
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
   program counter.  */
   program counter.  */
 
 
CORE_ADDR
CORE_ADDR
i386_linux_sigtramp_saved_pc (struct frame_info *frame)
i386_linux_sigtramp_saved_pc (struct frame_info *frame)
{
{
  CORE_ADDR addr;
  CORE_ADDR addr;
  addr = i386_linux_sigcontext_addr (frame);
  addr = i386_linux_sigcontext_addr (frame);
  return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 4);
  return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 4);
}
}
 
 
/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>.  */
/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>.  */
#define LINUX_SIGCONTEXT_SP_OFFSET (28)
#define LINUX_SIGCONTEXT_SP_OFFSET (28)
 
 
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
   stack pointer.  */
   stack pointer.  */
 
 
CORE_ADDR
CORE_ADDR
i386_linux_sigtramp_saved_sp (struct frame_info *frame)
i386_linux_sigtramp_saved_sp (struct frame_info *frame)
{
{
  CORE_ADDR addr;
  CORE_ADDR addr;
  addr = i386_linux_sigcontext_addr (frame);
  addr = i386_linux_sigcontext_addr (frame);
  return read_memory_integer (addr + LINUX_SIGCONTEXT_SP_OFFSET, 4);
  return read_memory_integer (addr + LINUX_SIGCONTEXT_SP_OFFSET, 4);
}
}
 
 
/* Immediately after a function call, return the saved pc.  */
/* Immediately after a function call, return the saved pc.  */
 
 
CORE_ADDR
CORE_ADDR
i386_linux_saved_pc_after_call (struct frame_info *frame)
i386_linux_saved_pc_after_call (struct frame_info *frame)
{
{
  if (frame->signal_handler_caller)
  if (frame->signal_handler_caller)
    return i386_linux_sigtramp_saved_pc (frame);
    return i386_linux_sigtramp_saved_pc (frame);
 
 
  return read_memory_integer (read_register (SP_REGNUM), 4);
  return read_memory_integer (read_register (SP_REGNUM), 4);
}
}
 
 

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