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

   Copyright (C) 2001, 2003, 2004, 2005, 2006, 2007, 2008

   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "frame.h"

#include "gdbcore.h"

#include "regcache.h"

#include "osabi.h"

#include "symtab.h"

#include "gdbtypes.h"

#include "reggroups.h"

#include "amd64-linux-tdep.h"

#include "gdb_string.h"

#include "amd64-tdep.h"

#include "solib-svr4.h"

/* Mapping between the general-purpose registers in `struct user'

   format and GDB's register cache layout.  */

/* From <sys/reg.h>.  */

static int amd64_linux_gregset_reg_offset[] =

{

  10 * 8,                       /* %rax */

  5 * 8,                        /* %rbx */

  11 * 8,                       /* %rcx */

  12 * 8,                       /* %rdx */

  13 * 8,                       /* %rsi */

  14 * 8,                       /* %rdi */

  4 * 8,                        /* %rbp */

  19 * 8,                       /* %rsp */

  9 * 8,                        /* %r8 ... */

  8 * 8,

  7 * 8,

  6 * 8,

  3 * 8,

  2 * 8,

  1 * 8,

  16 * 8,                       /* %rip */

  18 * 8,                       /* %eflags */

  17 * 8,                       /* %cs */

  20 * 8,                       /* %ss */

  23 * 8,                       /* %ds */

  24 * 8,                       /* %es */

  25 * 8,                       /* %fs */

  26 * 8                        /* %gs */

};

/* Support for signal handlers.  */

#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 gdb_byte linux_sigtramp_code[] =

{

  /* mov $__NR_rt_sigreturn, %rax */

  LINUX_SIGTRAMP_INSN0, 0xc7, 0xc0, 0x0f, 0x00, 0x00, 0x00,

  /* syscall */

  LINUX_SIGTRAMP_INSN1, 0x05

};

#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

amd64_linux_sigtramp_start (struct frame_info *next_frame)

{

  CORE_ADDR pc = frame_pc_unwind (next_frame);

  gdb_byte buf[LINUX_SIGTRAMP_LEN];

  /* 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

     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

     PC is not at the start of the instruction sequence, there will be

     a few trailing readable bytes on the stack.  */

  if (!safe_frame_unwind_memory (next_frame, pc, buf, sizeof buf))

    return 0;

  if (buf[0] != LINUX_SIGTRAMP_INSN0)

    {

      if (buf[0] != LINUX_SIGTRAMP_INSN1)

        return 0;

      pc -= LINUX_SIGTRAMP_OFFSET1;

      if (!safe_frame_unwind_memory (next_frame, pc, buf, sizeof buf))

        return 0;

    }

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

    return 0;

  return pc;

}

/* Return whether the frame preceding NEXT_FRAME corresponds to a

   GNU/Linux sigtramp routine.  */

static int

amd64_linux_sigtramp_p (struct frame_info *next_frame)

{

  CORE_ADDR pc = frame_pc_unwind (next_frame);

  char *name;

  find_pc_partial_function (pc, &name, NULL, NULL);

  /* If we have NAME, we can optimize the search.  The trampoline is

     named __restore_rt.  However, it isn't dynamically exported from

     the shared C library, so the trampoline may appear to be part of

     the preceding function.  This should always be sigaction,

     __sigaction, or __libc_sigaction (all aliases to the same

     function).  */

  if (name == NULL || strstr (name, "sigaction") != NULL)

    return (amd64_linux_sigtramp_start (next_frame) != 0);

  return (strcmp ("__restore_rt", name) == 0);

}

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

#define AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET 40

/* Assuming NEXT_FRAME is a frame following a GNU/Linux sigtramp

   routine, return the address of the associated sigcontext structure.  */

static CORE_ADDR

amd64_linux_sigcontext_addr (struct frame_info *next_frame)

{

  CORE_ADDR sp;

  gdb_byte buf[8];

  frame_unwind_register (next_frame,

                         gdbarch_sp_regnum (get_frame_arch (next_frame)), buf);

  sp = extract_unsigned_integer (buf, 8);

  /* The sigcontext structure is part of the user context.  A pointer

     to the user context is passed as the third argument to the signal

     handler, i.e. in %rdx.  Unfortunately %rdx isn't preserved across

     function calls so we can't use it.  Fortunately the user context

     is part of the signal frame and the unwound %rsp directly points

     at it.  */

  return sp + AMD64_LINUX_UCONTEXT_SIGCONTEXT_OFFSET;

}

/* From <asm/sigcontext.h>.  */

static int amd64_linux_sc_reg_offset[] =

{

  13 * 8,                       /* %rax */

  11 * 8,                       /* %rbx */

  14 * 8,                       /* %rcx */

  12 * 8,                       /* %rdx */

  9 * 8,                        /* %rsi */

  8 * 8,                        /* %rdi */

  10 * 8,                       /* %rbp */

  15 * 8,                       /* %rsp */

  1 * 8,                        /* %r9 */

  2 * 8,                        /* %r10 */

  3 * 8,                        /* %r11 */

  4 * 8,                        /* %r12 */

  5 * 8,                        /* %r13 */

  6 * 8,                        /* %r14 */

  7 * 8,                        /* %r15 */

  16 * 8,                       /* %rip */

  17 * 8,                       /* %eflags */

  /* FIXME: kettenis/2002030531: The registers %cs, %fs and %gs are

     available in `struct sigcontext'.  However, they only occupy two

     bytes instead of four, which makes using them here rather

     difficult.  Leave them out for now.  */

  -1,                           /* %cs */

  -1,                           /* %ss */

  -1,                           /* %ds */

  -1,                           /* %es */

  -1,                           /* %fs */

  -1                            /* %gs */

};

/* Replacement register functions which know about %orig_rax.  */

static const char *

amd64_linux_register_name (struct gdbarch *gdbarch, int reg)

{

  if (reg == AMD64_LINUX_ORIG_RAX_REGNUM)

    return "orig_rax";

  return amd64_register_name (gdbarch, reg);

}

static struct type *

amd64_linux_register_type (struct gdbarch *gdbarch, int reg)

{

  if (reg == AMD64_LINUX_ORIG_RAX_REGNUM)

    return builtin_type_int64;

  return amd64_register_type (gdbarch, reg);

}

static int

amd64_linux_register_reggroup_p (struct gdbarch *gdbarch, int regnum,

                                 struct reggroup *group)

{

  if (regnum == AMD64_LINUX_ORIG_RAX_REGNUM)

    return (group == system_reggroup

            || group == save_reggroup

            || group == restore_reggroup);

  return default_register_reggroup_p (gdbarch, regnum, group);

}

/* Set the program counter for process PTID to PC.  */

static void

amd64_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)

{

  regcache_cooked_write_unsigned (regcache, AMD64_RIP_REGNUM, pc);

  /* We must be careful with modifying the program counter.  If we

     just interrupted a system call, the kernel might try to restart

     it when we resume the inferior.  On restarting the system call,

     the kernel will try backing up the program counter even though it

     no longer points at the system call.  This typically results in a

     SIGSEGV or SIGILL.  We can prevent this by writing `-1' in the

     "orig_rax" pseudo-register.

     Note that "orig_rax" is saved when setting up a dummy call frame.

     This means that it is properly restored when that frame is

     popped, and that the interrupted system call will be restarted

     when we resume the inferior on return from a function call from

     within GDB.  In all other cases the system call will not be

     restarted.  */

  regcache_cooked_write_unsigned (regcache, AMD64_LINUX_ORIG_RAX_REGNUM, -1);

}

static void

amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;

  tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);

  tdep->sizeof_gregset = 27 * 8;

  amd64_init_abi (info, gdbarch);

  tdep->sigtramp_p = amd64_linux_sigtramp_p;

  tdep->sigcontext_addr = amd64_linux_sigcontext_addr;

  tdep->sc_reg_offset = amd64_linux_sc_reg_offset;

  tdep->sc_num_regs = ARRAY_SIZE (amd64_linux_sc_reg_offset);

  /* GNU/Linux uses SVR4-style shared libraries.  */

  set_solib_svr4_fetch_link_map_offsets

    (gdbarch, svr4_lp64_fetch_link_map_offsets);

  /* Add the %orig_rax register used for syscall restarting.  */

  set_gdbarch_write_pc (gdbarch, amd64_linux_write_pc);

  set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS);

  set_gdbarch_register_name (gdbarch, amd64_linux_register_name);

  set_gdbarch_register_type (gdbarch, amd64_linux_register_type);

  set_gdbarch_register_reggroup_p (gdbarch, amd64_linux_register_reggroup_p);

  /* Enable TLS support.  */

  set_gdbarch_fetch_tls_load_module_address (gdbarch,

                                             svr4_fetch_objfile_link_map);

}

/* Provide a prototype to silence -Wmissing-prototypes.  */

extern void _initialize_amd64_linux_tdep (void);

void

_initialize_amd64_linux_tdep (void)

{

  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,

                          GDB_OSABI_LINUX, amd64_linux_init_abi);

}