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/* Target-dependent code for GNU/Linux running on x86-64, for GDB.

   Copyright 2001 Free Software Foundation, Inc.

   Contributed by Jiri Smid, SuSE Labs.

   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., 59 Temple Place - Suite 330,

   Boston, MA 02111-1307, USA.  */

#include "defs.h"

#include "inferior.h"

#include "gdbcore.h"

#include "gdb_string.h"

#include "regcache.h"

#include "x86-64-tdep.h"

#include "dwarf2cfi.h"

#define LINUX_SIGTRAMP_INSN0 (0x48)     /* mov $NNNNNNNN,%rax */

#define LINUX_SIGTRAMP_OFFSET0 (0)

#define LINUX_SIGTRAMP_INSN1 (0x0f)     /* syscall */

#define LINUX_SIGTRAMP_OFFSET1 (7)

static const unsigned char linux_sigtramp_code[] = {

  LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x89, 0x00, 0x00, 0x00,     /*  mov $0x89,%rax */

  LINUX_SIGTRAMP_INSN1, 0x05    /* syscall */

};

#define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)

/* If PC is in a sigtramp routine, return the address of the start of

   the routine.  Otherwise, return 0.  */

static CORE_ADDR

x86_64_linux_sigtramp_start (CORE_ADDR pc)

{

  unsigned char buf[LINUX_SIGTRAMP_LEN];

  if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)

    return 0;

  if (buf[0] != LINUX_SIGTRAMP_INSN0)

    {

      if (buf[0] != LINUX_SIGTRAMP_INSN1)

        return 0;

      pc -= LINUX_SIGTRAMP_OFFSET1;

      if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)

        return 0;

    }

  if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)

    return 0;

  return pc;

}

#define LINUX_SIGINFO_SIZE 128

/* Offset to struct sigcontext in ucontext, from <asm/ucontext.h>.  */

#define LINUX_UCONTEXT_SIGCONTEXT_OFFSET (36)

/* Assuming FRAME is for a GNU/Linux sigtramp routine, return the

   address of the associated sigcontext structure.  */

CORE_ADDR

x86_64_linux_sigcontext_addr (struct frame_info *frame)

{

  CORE_ADDR pc;

  pc = x86_64_linux_sigtramp_start (frame->pc);

  if (pc)

    {

      if (frame->next)

        /* If this isn't the top frame, the next frame must be for the

           signal handler itself.  The sigcontext structure is part of

           the user context. */

        return frame->next->frame + LINUX_SIGINFO_SIZE +

          LINUX_UCONTEXT_SIGCONTEXT_OFFSET;

      /* This is the top frame. */

      return read_register (SP_REGNUM) + LINUX_SIGINFO_SIZE +

        LINUX_UCONTEXT_SIGCONTEXT_OFFSET;

    }

  error ("Couldn't recognize signal trampoline.");

  return 0;

}

/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>.  */

#define LINUX_SIGCONTEXT_PC_OFFSET (136)

/* Assuming FRAME is for a GNU/Linux sigtramp routine, return the

   saved program counter.  */

CORE_ADDR

x86_64_linux_sigtramp_saved_pc (struct frame_info *frame)

{

  CORE_ADDR addr;

  addr = x86_64_linux_sigcontext_addr (frame);

  return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 8);

}

/* Immediately after a function call, return the saved pc.  */

CORE_ADDR

x86_64_linux_saved_pc_after_call (struct frame_info *frame)

{

  if (frame->signal_handler_caller)

    return x86_64_linux_sigtramp_saved_pc (frame);

  return read_memory_integer (read_register (SP_REGNUM), 8);

}

/* Saved Pc.  Get it from sigcontext if within sigtramp.  */

CORE_ADDR

x86_64_linux_frame_saved_pc (struct frame_info *frame)

{

  if (frame->signal_handler_caller)

    return x86_64_linux_sigtramp_saved_pc (frame);

  return cfi_get_ra (frame);

}