gdb-6.4/gdb/amd64-linux-nat.c - toolchain/gdb - Git at Google

 /* Native-dependent code for GNU/Linux x86-64.

    Copyright 2001, 2002, 2003, 2004, 2005 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 "regcache.h"
 #include "linux-nat.h"

 #include "gdb_assert.h"
 #include "gdb_string.h"
 #include <sys/ptrace.h>
 #include <sys/debugreg.h>
 #include <sys/syscall.h>
 #include <sys/procfs.h>
 #include <asm/prctl.h>
 /* FIXME ezannoni-2003-07-09: we need <sys/reg.h> to be included after
    <asm/ptrace.h> because the latter redefines FS and GS for no apparent
    reason, and those definitions don't match the ones that libpthread_db
    uses, which come from <sys/reg.h>.  */
 /* ezannoni-2003-07-09: I think this is fixed. The extraneous defs have
    been removed from ptrace.h in the kernel.  However, better safe than
    sorry.  */
 #include <asm/ptrace.h>
 #include <sys/reg.h>
 #include "gdb_proc_service.h"

 /* Prototypes for supply_gregset etc.  */
 #include "gregset.h"

 #include "amd64-tdep.h"
 #include "i386-linux-tdep.h"
 #include "amd64-nat.h"

 /* Mapping between the general-purpose registers in GNU/Linux x86-64
    `struct user' format and GDB's register cache layout.  */

 static int amd64_linux_gregset64_reg_offset[] =
 {
   RAX * 8, RBX * 8,		/* %rax, %rbx */
   RCX * 8, RDX * 8,		/* %rcx, %rdx */
   RSI * 8, RDI * 8,		/* %rsi, %rdi */
   RBP * 8, RSP * 8,		/* %rbp, %rsp */
   R8 * 8, R9 * 8,		/* %r8 ... */
   R10 * 8, R11 * 8,
   R12 * 8, R13 * 8,
   R14 * 8, R15 * 8,		/* ... %r15 */
   RIP * 8, EFLAGS * 8,		/* %rip, %eflags */
   CS * 8, SS * 8,		/* %cs, %ss */
   DS * 8, ES * 8,		/* %ds, %es */
   FS * 8, GS * 8		/* %fs, %gs */
 };


 /* Mapping between the general-purpose registers in GNU/Linux x86-64
    `struct user' format and GDB's register cache layout for GNU/Linux
    i386.

    Note that most GNU/Linux x86-64 registers are 64-bit, while the
    GNU/Linux i386 registers are all 32-bit, but since we're
    little-endian we get away with that.  */

 /* From <sys/reg.h> on GNU/Linux i386.  */
 static int amd64_linux_gregset32_reg_offset[] =
 {
   RAX * 8, RCX * 8,		/* %eax, %ecx */
   RDX * 8, RBX * 8,		/* %edx, %ebx */
   RSP * 8, RBP * 8,		/* %esp, %ebp */
   RSI * 8, RDI * 8,		/* %esi, %edi */
   RIP * 8, EFLAGS * 8,		/* %eip, %eflags */
   CS * 8, SS * 8,		/* %cs, %ss */
   DS * 8, ES * 8,		/* %ds, %es */
   FS * 8, GS * 8,		/* %fs, %gs */
   -1, -1, -1, -1, -1, -1, -1, -1,
   -1, -1, -1, -1, -1, -1, -1, -1,
   -1, -1, -1, -1, -1, -1, -1, -1, -1,
   ORIG_RAX * 8			/* "orig_eax" */
 };


 /* Transfering the general-purpose registers between GDB, inferiors
    and core files.  */

 /* Fill GDB's register cache with the general-purpose register values
    in *GREGSETP.  */

 void
 supply_gregset (elf_gregset_t *gregsetp)
 {
   amd64_supply_native_gregset (current_regcache, gregsetp, -1);
 }

 /* Fill register REGNUM (if it is a general-purpose register) in
    *GREGSETP with the value in GDB's register cache.  If REGNUM is -1,
    do this for all registers.  */

 void
 fill_gregset (elf_gregset_t *gregsetp, int regnum)
 {
   amd64_collect_native_gregset (current_regcache, gregsetp, regnum);
 }

 /* Transfering floating-point registers between GDB, inferiors and cores.  */

 /* Fill GDB's register cache with the floating-point and SSE register
    values in *FPREGSETP.  */

 void
 supply_fpregset (elf_fpregset_t *fpregsetp)
 {
   amd64_supply_fxsave (current_regcache, -1, fpregsetp);
 }

 /* Fill register REGNUM (if it is a floating-point or SSE register) in
    *FPREGSETP with the value in GDB's register cache.  If REGNUM is
    -1, do this for all registers.  */

 void
 fill_fpregset (elf_fpregset_t *fpregsetp, int regnum)
 {
   amd64_collect_fxsave (current_regcache, regnum, fpregsetp);
 }


 /* Transferring arbitrary registers between GDB and inferior.  */

 /* Fetch register REGNUM from the child process.  If REGNUM is -1, do
    this for all registers (including the floating point and SSE
    registers).  */

 static void
 amd64_linux_fetch_inferior_registers (int regnum)
 {
   int tid;

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

   if (regnum == -1 || amd64_native_gregset_supplies_p (regnum))
     {
       elf_gregset_t regs;

       if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
 	perror_with_name (_("Couldn't get registers"));

       amd64_supply_native_gregset (current_regcache, &regs, -1);
       if (regnum != -1)
 	return;
     }

   if (regnum == -1 || !amd64_native_gregset_supplies_p (regnum))
     {
       elf_fpregset_t fpregs;

       if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0)
 	perror_with_name (_("Couldn't get floating point status"));

       amd64_supply_fxsave (current_regcache, -1, &fpregs);
     }
 }

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

 static void
 amd64_linux_store_inferior_registers (int regnum)
 {
   int tid;

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

   if (regnum == -1 || amd64_native_gregset_supplies_p (regnum))
     {
       elf_gregset_t regs;

       if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
 	perror_with_name (_("Couldn't get registers"));

       amd64_collect_native_gregset (current_regcache, &regs, regnum);

       if (ptrace (PTRACE_SETREGS, tid, 0, (long) &regs) < 0)
 	perror_with_name (_("Couldn't write registers"));

       if (regnum != -1)
 	return;
     }

   if (regnum == -1 || !amd64_native_gregset_supplies_p (regnum))
     {
       elf_fpregset_t fpregs;

       if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0)
 	perror_with_name (_("Couldn't get floating point status"));

       amd64_collect_fxsave (current_regcache, regnum, &fpregs);

       if (ptrace (PTRACE_SETFPREGS, tid, 0, (long) &fpregs) < 0)
 	perror_with_name (_("Couldn't write floating point status"));

       return;
     }
 }


 static unsigned long
 amd64_linux_dr_get (int regnum)
 {
   int tid;
   unsigned long value;

   /* FIXME: kettenis/2001-01-29: It's not clear what we should do with
      multi-threaded processes here.  For now, pretend there is just
      one thread.  */
   tid = PIDGET (inferior_ptid);

   /* FIXME: kettenis/2001-03-27: Calling perror_with_name if the
      ptrace call fails breaks debugging remote targets.  The correct
      way to fix this is to add the hardware breakpoint and watchpoint
      stuff to the target vectore.  For now, just return zero if the
      ptrace call fails.  */
   errno = 0;
   value = ptrace (PT_READ_U, tid,
 		  offsetof (struct user, u_debugreg[regnum]), 0);
   if (errno != 0)
 #if 0
     perror_with_name (_("Couldn't read debug register"));
 #else
     return 0;
 #endif

   return value;
 }

 static void
 amd64_linux_dr_set (int regnum, unsigned long value)
 {
   int tid;

   /* FIXME: kettenis/2001-01-29: It's not clear what we should do with
      multi-threaded processes here.  For now, pretend there is just
      one thread.  */
   tid = PIDGET (inferior_ptid);

   errno = 0;
   ptrace (PT_WRITE_U, tid, offsetof (struct user, u_debugreg[regnum]), value);
   if (errno != 0)
     perror_with_name (_("Couldn't write debug register"));
 }

 void
 amd64_linux_dr_set_control (unsigned long control)
 {
   amd64_linux_dr_set (DR_CONTROL, control);
 }

 void
 amd64_linux_dr_set_addr (int regnum, CORE_ADDR addr)
 {
   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);

   amd64_linux_dr_set (DR_FIRSTADDR + regnum, addr);
 }

 void
 amd64_linux_dr_reset_addr (int regnum)
 {
   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);

   amd64_linux_dr_set (DR_FIRSTADDR + regnum, 0L);
 }

 unsigned long
 amd64_linux_dr_get_status (void)
 {
   return amd64_linux_dr_get (DR_STATUS);
 }


 /* This function is called by libthread_db as part of its handling of
    a request for a thread's local storage address.  */

 ps_err_e
 ps_get_thread_area (const struct ps_prochandle *ph,
                     lwpid_t lwpid, int idx, void **base)
 {
   if (gdbarch_ptr_bit (current_gdbarch) == 32)
     {
       /* The full structure is found in <asm-i386/ldt.h>.  The second
 	 integer is the LDT's base_address and that is used to locate
 	 the thread's local storage.  See i386-linux-nat.c more
 	 info.  */
       unsigned int desc[4];

       /* This code assumes that "int" is 32 bits and that
 	 GET_THREAD_AREA returns no more than 4 int values.  */
       gdb_assert (sizeof (int) == 4);
 #ifndef PTRACE_GET_THREAD_AREA
 #define PTRACE_GET_THREAD_AREA 25
 #endif
       if  (ptrace (PTRACE_GET_THREAD_AREA,
 		   lwpid, (void *) (long) idx, (unsigned long) &desc) < 0)
 	return PS_ERR;

       /* Extend the value to 64 bits.  Here it's assumed that a "long"
 	 and a "void *" are the same.  */
       (*base) = (void *) (long) desc[1];
       return PS_OK;
     }
   else
     {
       /* This definition comes from prctl.h, but some kernels may not
          have it.  */
 #ifndef PTRACE_ARCH_PRCTL
 #define PTRACE_ARCH_PRCTL      30
 #endif
       /* FIXME: ezannoni-2003-07-09 see comment above about include
 	 file order.  We could be getting bogus values for these two.  */
       gdb_assert (FS < ELF_NGREG);
       gdb_assert (GS < ELF_NGREG);
       switch (idx)
 	{
 	case FS:
 	  if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_FS) == 0)
 	    return PS_OK;
 	  break;
 	case GS:
 	  if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_GS) == 0)
 	    return PS_OK;
 	  break;
 	default:                   /* Should not happen.  */
 	  return PS_BADADDR;
 	}
     }
   return PS_ERR;               /* ptrace failed.  */
 }


 static void (*super_post_startup_inferior) (ptid_t ptid);

 static void
 amd64_linux_child_post_startup_inferior (ptid_t ptid)
 {
   i386_cleanup_dregs ();
   super_post_startup_inferior (ptid);
 }


 /* Provide a prototype to silence -Wmissing-prototypes.  */
 void _initialize_amd64_linux_nat (void);

 void
 _initialize_amd64_linux_nat (void)
 {
   struct target_ops *t;

   amd64_native_gregset32_reg_offset = amd64_linux_gregset32_reg_offset;
   amd64_native_gregset32_num_regs = I386_LINUX_NUM_REGS;
   amd64_native_gregset64_reg_offset = amd64_linux_gregset64_reg_offset;

   gdb_assert (ARRAY_SIZE (amd64_linux_gregset32_reg_offset)
 	      == amd64_native_gregset32_num_regs);
   gdb_assert (ARRAY_SIZE (amd64_linux_gregset64_reg_offset)
 	      == amd64_native_gregset64_num_regs);

   /* Fill in the generic GNU/Linux methods.  */
   t = linux_target ();

   /* Override the GNU/Linux inferior startup hook.  */
   super_post_startup_inferior = t->to_post_startup_inferior;
   t->to_post_startup_inferior = amd64_linux_child_post_startup_inferior;

   /* Add our register access methods.  */
   t->to_fetch_registers = amd64_linux_fetch_inferior_registers;
   t->to_store_registers = amd64_linux_store_inferior_registers;

   /* Register the target.  */
   add_target (t);
 }
	/* Native-dependent code for GNU/Linux x86-64.

	Copyright 2001, 2002, 2003, 2004, 2005 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 "regcache.h"
	#include "linux-nat.h"

	#include "gdb_assert.h"
	#include "gdb_string.h"
	#include <sys/ptrace.h>
	#include <sys/debugreg.h>
	#include <sys/syscall.h>
	#include <sys/procfs.h>
	#include <asm/prctl.h>
	/* FIXME ezannoni-2003-07-09: we need <sys/reg.h> to be included after
	<asm/ptrace.h> because the latter redefines FS and GS for no apparent
	reason, and those definitions don't match the ones that libpthread_db
	uses, which come from <sys/reg.h>. */
	/* ezannoni-2003-07-09: I think this is fixed. The extraneous defs have
	been removed from ptrace.h in the kernel. However, better safe than
	sorry. */
	#include <asm/ptrace.h>
	#include <sys/reg.h>
	#include "gdb_proc_service.h"

	/* Prototypes for supply_gregset etc. */
	#include "gregset.h"

	#include "amd64-tdep.h"
	#include "i386-linux-tdep.h"
	#include "amd64-nat.h"

	/* Mapping between the general-purpose registers in GNU/Linux x86-64
	`struct user' format and GDB's register cache layout. */

	static int amd64_linux_gregset64_reg_offset[] =
	{
	RAX * 8, RBX * 8, /* %rax, %rbx */
	RCX * 8, RDX * 8, /* %rcx, %rdx */
	RSI * 8, RDI * 8, /* %rsi, %rdi */
	RBP * 8, RSP * 8, /* %rbp, %rsp */
	R8 * 8, R9 * 8, /* %r8 ... */
	R10 * 8, R11 * 8,
	R12 * 8, R13 * 8,
	R14 * 8, R15 * 8, /* ... %r15 */
	RIP * 8, EFLAGS * 8, /* %rip, %eflags */
	CS * 8, SS * 8, /* %cs, %ss */
	DS * 8, ES * 8, /* %ds, %es */
	FS * 8, GS * 8 /* %fs, %gs */
	};


	/* Mapping between the general-purpose registers in GNU/Linux x86-64
	`struct user' format and GDB's register cache layout for GNU/Linux
	i386.

	Note that most GNU/Linux x86-64 registers are 64-bit, while the
	GNU/Linux i386 registers are all 32-bit, but since we're
	little-endian we get away with that. */

	/* From <sys/reg.h> on GNU/Linux i386. */
	static int amd64_linux_gregset32_reg_offset[] =
	{
	RAX * 8, RCX * 8, /* %eax, %ecx */
	RDX * 8, RBX * 8, /* %edx, %ebx */
	RSP * 8, RBP * 8, /* %esp, %ebp */
	RSI * 8, RDI * 8, /* %esi, %edi */
	RIP * 8, EFLAGS * 8, /* %eip, %eflags */
	CS * 8, SS * 8, /* %cs, %ss */
	DS * 8, ES * 8, /* %ds, %es */
	FS * 8, GS * 8, /* %fs, %gs */
	-1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1,
	ORIG_RAX * 8 /* "orig_eax" */
	};


	/* Transfering the general-purpose registers between GDB, inferiors
	and core files. */

	/* Fill GDB's register cache with the general-purpose register values
	in GREGSETP. /

	void
	supply_gregset (elf_gregset_t *gregsetp)
	{
	amd64_supply_native_gregset (current_regcache, gregsetp, -1);
	}

	/* Fill register REGNUM (if it is a general-purpose register) in
	*GREGSETP with the value in GDB's register cache. If REGNUM is -1,
	do this for all registers. */

	void
	fill_gregset (elf_gregset_t *gregsetp, int regnum)
	{
	amd64_collect_native_gregset (current_regcache, gregsetp, regnum);
	}

	/* Transfering floating-point registers between GDB, inferiors and cores. */

	/* Fill GDB's register cache with the floating-point and SSE register
	values in FPREGSETP. /

	void
	supply_fpregset (elf_fpregset_t *fpregsetp)
	{
	amd64_supply_fxsave (current_regcache, -1, fpregsetp);
	}

	/* Fill register REGNUM (if it is a floating-point or SSE register) in
	*FPREGSETP with the value in GDB's register cache. If REGNUM is
	-1, do this for all registers. */

	void
	fill_fpregset (elf_fpregset_t *fpregsetp, int regnum)
	{
	amd64_collect_fxsave (current_regcache, regnum, fpregsetp);
	}


	/* Transferring arbitrary registers between GDB and inferior. */

	/* Fetch register REGNUM from the child process. If REGNUM is -1, do
	this for all registers (including the floating point and SSE
	registers). */

	static void
	amd64_linux_fetch_inferior_registers (int regnum)
	{
	int tid;

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

	if (regnum == -1 \|\| amd64_native_gregset_supplies_p (regnum))
	{
	elf_gregset_t regs;

	if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
	perror_with_name (_("Couldn't get registers"));

	amd64_supply_native_gregset (current_regcache, &regs, -1);
	if (regnum != -1)
	return;
	}

	if (regnum == -1 \|\| !amd64_native_gregset_supplies_p (regnum))
	{
	elf_fpregset_t fpregs;

	if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0)
	perror_with_name (_("Couldn't get floating point status"));

	amd64_supply_fxsave (current_regcache, -1, &fpregs);
	}
	}

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

	static void
	amd64_linux_store_inferior_registers (int regnum)
	{
	int tid;

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

	if (regnum == -1 \|\| amd64_native_gregset_supplies_p (regnum))
	{
	elf_gregset_t regs;

	if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
	perror_with_name (_("Couldn't get registers"));

	amd64_collect_native_gregset (current_regcache, &regs, regnum);

	if (ptrace (PTRACE_SETREGS, tid, 0, (long) &regs) < 0)
	perror_with_name (_("Couldn't write registers"));

	if (regnum != -1)
	return;
	}

	if (regnum == -1 \|\| !amd64_native_gregset_supplies_p (regnum))
	{
	elf_fpregset_t fpregs;

	if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0)
	perror_with_name (_("Couldn't get floating point status"));

	amd64_collect_fxsave (current_regcache, regnum, &fpregs);

	if (ptrace (PTRACE_SETFPREGS, tid, 0, (long) &fpregs) < 0)
	perror_with_name (_("Couldn't write floating point status"));

	return;
	}
	}


	static unsigned long
	amd64_linux_dr_get (int regnum)
	{
	int tid;
	unsigned long value;

	/* FIXME: kettenis/2001-01-29: It's not clear what we should do with
	multi-threaded processes here. For now, pretend there is just
	one thread. */
	tid = PIDGET (inferior_ptid);

	/* FIXME: kettenis/2001-03-27: Calling perror_with_name if the
	ptrace call fails breaks debugging remote targets. The correct
	way to fix this is to add the hardware breakpoint and watchpoint
	stuff to the target vectore. For now, just return zero if the
	ptrace call fails. */
	errno = 0;
	value = ptrace (PT_READ_U, tid,
	offsetof (struct user, u_debugreg[regnum]), 0);
	if (errno != 0)
	#if 0
	perror_with_name (_("Couldn't read debug register"));
	#else
	return 0;
	#endif

	return value;
	}

	static void
	amd64_linux_dr_set (int regnum, unsigned long value)
	{
	int tid;

	/* FIXME: kettenis/2001-01-29: It's not clear what we should do with
	multi-threaded processes here. For now, pretend there is just
	one thread. */
	tid = PIDGET (inferior_ptid);

	errno = 0;
	ptrace (PT_WRITE_U, tid, offsetof (struct user, u_debugreg[regnum]), value);
	if (errno != 0)
	perror_with_name (_("Couldn't write debug register"));
	}

	void
	amd64_linux_dr_set_control (unsigned long control)
	{
	amd64_linux_dr_set (DR_CONTROL, control);
	}

	void
	amd64_linux_dr_set_addr (int regnum, CORE_ADDR addr)
	{
	gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);

	amd64_linux_dr_set (DR_FIRSTADDR + regnum, addr);
	}

	void
	amd64_linux_dr_reset_addr (int regnum)
	{
	gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);

	amd64_linux_dr_set (DR_FIRSTADDR + regnum, 0L);
	}

	unsigned long
	amd64_linux_dr_get_status (void)
	{
	return amd64_linux_dr_get (DR_STATUS);
	}


	/* This function is called by libthread_db as part of its handling of
	a request for a thread's local storage address. */

	ps_err_e
	ps_get_thread_area (const struct ps_prochandle *ph,
	lwpid_t lwpid, int idx, void **base)
	{
	if (gdbarch_ptr_bit (current_gdbarch) == 32)
	{
	/* The full structure is found in <asm-i386/ldt.h>. The second
	integer is the LDT's base_address and that is used to locate
	the thread's local storage. See i386-linux-nat.c more
	info. */
	unsigned int desc[4];

	/* This code assumes that "int" is 32 bits and that
	GET_THREAD_AREA returns no more than 4 int values. */
	gdb_assert (sizeof (int) == 4);
	#ifndef PTRACE_GET_THREAD_AREA
	#define PTRACE_GET_THREAD_AREA 25
	#endif
	if (ptrace (PTRACE_GET_THREAD_AREA,
	lwpid, (void *) (long) idx, (unsigned long) &desc) < 0)
	return PS_ERR;

	/* Extend the value to 64 bits. Here it's assumed that a "long"
	and a "void " are the same. /
	(base) = (void ) (long) desc[1];
	return PS_OK;
	}
	else
	{
	/* This definition comes from prctl.h, but some kernels may not
	have it. */
	#ifndef PTRACE_ARCH_PRCTL
	#define PTRACE_ARCH_PRCTL 30
	#endif
	/* FIXME: ezannoni-2003-07-09 see comment above about include
	file order. We could be getting bogus values for these two. */
	gdb_assert (FS < ELF_NGREG);
	gdb_assert (GS < ELF_NGREG);
	switch (idx)
	{
	case FS:
	if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_FS) == 0)
	return PS_OK;
	break;
	case GS:
	if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_GS) == 0)
	return PS_OK;
	break;
	default: /* Should not happen. */
	return PS_BADADDR;
	}
	}
	return PS_ERR; /* ptrace failed. */
	}


	static void (*super_post_startup_inferior) (ptid_t ptid);

	static void
	amd64_linux_child_post_startup_inferior (ptid_t ptid)
	{
	i386_cleanup_dregs ();
	super_post_startup_inferior (ptid);
	}


	/* Provide a prototype to silence -Wmissing-prototypes. */
	void _initialize_amd64_linux_nat (void);

	void
	_initialize_amd64_linux_nat (void)
	{
	struct target_ops *t;

	amd64_native_gregset32_reg_offset = amd64_linux_gregset32_reg_offset;
	amd64_native_gregset32_num_regs = I386_LINUX_NUM_REGS;
	amd64_native_gregset64_reg_offset = amd64_linux_gregset64_reg_offset;

	gdb_assert (ARRAY_SIZE (amd64_linux_gregset32_reg_offset)
	== amd64_native_gregset32_num_regs);
	gdb_assert (ARRAY_SIZE (amd64_linux_gregset64_reg_offset)
	== amd64_native_gregset64_num_regs);

	/* Fill in the generic GNU/Linux methods. */
	t = linux_target ();

	/* Override the GNU/Linux inferior startup hook. */
	super_post_startup_inferior = t->to_post_startup_inferior;
	t->to_post_startup_inferior = amd64_linux_child_post_startup_inferior;

	/* Add our register access methods. */
	t->to_fetch_registers = amd64_linux_fetch_inferior_registers;
	t->to_store_registers = amd64_linux_store_inferior_registers;

	/* Register the target. */
	add_target (t);
	}