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/* Target-dependent code for OpenBSD/amd64.

   Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010

   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 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 "frame-unwind.h"

#include "gdbcore.h"

#include "symtab.h"

#include "objfiles.h"

#include "osabi.h"

#include "regcache.h"

#include "regset.h"

#include "target.h"

#include "trad-frame.h"

#include "gdb_assert.h"

#include "gdb_string.h"

#include "amd64-tdep.h"

#include "i387-tdep.h"

#include "solib-svr4.h"

#include "bsd-uthread.h"

/* Support for core dumps.  */

static void

amd64obsd_supply_regset (const struct regset *regset,

                         struct regcache *regcache, int regnum,

                         const void *regs, size_t len)

{

  const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);

  gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);

  i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);

  amd64_supply_fxsave (regcache, regnum,

                       ((const gdb_byte *)regs) + tdep->sizeof_gregset);

}

static const struct regset *

amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,

                                    const char *sect_name, size_t sect_size)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* OpenBSD core dumps don't use seperate register sets for the

     general-purpose and floating-point registers.  */

  if (strcmp (sect_name, ".reg") == 0

      && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)

    {

      if (tdep->gregset == NULL)

        tdep->gregset = regset_alloc (gdbarch, amd64obsd_supply_regset, NULL);

      return tdep->gregset;

    }

  return NULL;

}

/* Support for signal handlers.  */

/* Default page size.  */

static const int amd64obsd_page_size = 4096;

/* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp

   routine.  */

static int

amd64obsd_sigtramp_p (struct frame_info *this_frame)

{

  CORE_ADDR pc = get_frame_pc (this_frame);

  CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));

  const gdb_byte sigreturn[] =

  {

    0x48, 0xc7, 0xc0,

    0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */

    0xcd, 0x80                  /* int $0x80 */

  };

  size_t buflen = (sizeof sigreturn) + 1;

  gdb_byte *buf;

  char *name;

  /* If the function has a valid symbol name, it isn't a

     trampoline.  */

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

  if (name != NULL)

    return 0;

  /* If the function lives in a valid section (even without a starting

     point) it isn't a trampoline.  */

  if (find_pc_section (pc) != NULL)

    return 0;

  /* If we can't read the instructions at START_PC, return zero.  */

  buf = alloca ((sizeof sigreturn) + 1);

  if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))

    return 0;

  /* Check for sigreturn(2).  Depending on how the assembler encoded

     the `movq %rsp, %rdi' instruction, the code starts at offset 6 or

     7.  */

  if (memcmp (buf, sigreturn, sizeof sigreturn)

      && memcpy (buf + 1, sigreturn, sizeof sigreturn))

    return 0;

  return 1;

}

/* Assuming THIS_FRAME is for a BSD sigtramp routine, return the

   address of the associated sigcontext structure.  */

static CORE_ADDR

amd64obsd_sigcontext_addr (struct frame_info *this_frame)

{

  CORE_ADDR pc = get_frame_pc (this_frame);

  ULONGEST offset = (pc & (amd64obsd_page_size - 1));

  /* The %rsp register points at `struct sigcontext' upon entry of a

     signal trampoline.  The relevant part of the trampoline is

        call    *%rax

        movq    %rsp, %rdi

        pushq   %rdi

        movq    $SYS_sigreturn,%rax

        int     $0x80

     (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'

     instruction clobbers %rsp, but its value is saved in `%rdi'.  */

  if (offset > 5)

    return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);

  else

    return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);

}

/* OpenBSD 3.5 or later.  */

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

   format and GDB's register cache layout.  */

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

int amd64obsd_r_reg_offset[] =

{

  14 * 8,                       /* %rax */

  13 * 8,                       /* %rbx */

  3 * 8,                        /* %rcx */

  2 * 8,                        /* %rdx */

  1 * 8,                        /* %rsi */

  12 * 8,                       /* %rbp */

  15 * 8,                       /* %rsp */

  4 * 8,                        /* %r8 .. */

  5 * 8,

  6 * 8,

  7 * 8,

  8 * 8,

  9 * 8,

  10 * 8,

  11 * 8,                       /* ... %r15 */

  16 * 8,                       /* %rip */

  17 * 8,                       /* %eflags */

  18 * 8,                       /* %cs */

  19 * 8,                       /* %ss */

  20 * 8,                       /* %ds */

  21 * 8,                       /* %es */

  22 * 8,                       /* %fs */

  23 * 8                        /* %gs */

};

/* From <machine/signal.h>.  */

static int amd64obsd_sc_reg_offset[] =

{

  14 * 8,                       /* %rax */

  13 * 8,                       /* %rbx */

  3 * 8,                        /* %rcx */

  2 * 8,                        /* %rdx */

  1 * 8,                        /* %rsi */

  12 * 8,                       /* %rbp */

  24 * 8,                       /* %rsp */

  4 * 8,                        /* %r8 ... */

  5 * 8,

  6 * 8,

  7 * 8,

  8 * 8,

  9 * 8,

  10 * 8,

  11 * 8,                       /* ... %r15 */

  21 * 8,                       /* %rip */

  23 * 8,                       /* %eflags */

  22 * 8,                       /* %cs */

  25 * 8,                       /* %ss */

  18 * 8,                       /* %ds */

  17 * 8,                       /* %es */

  16 * 8,                       /* %fs */

  15 * 8                        /* %gs */

};

/* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */

static int amd64obsd_uthread_reg_offset[] =

{

  19 * 8,                       /* %rax */

  16 * 8,                       /* %rbx */

  18 * 8,                       /* %rcx */

  17 * 8,                       /* %rdx */

  14 * 8,                       /* %rsi */

  13 * 8,                       /* %rdi */

  15 * 8,                       /* %rbp */

  -1,                           /* %rsp */

  12 * 8,                       /* %r8 ... */

  11 * 8,

  10 * 8,

  9 * 8,

  8 * 8,

  7 * 8,

  6 * 8,

  5 * 8,                        /* ... %r15 */

  20 * 8,                       /* %rip */

  4 * 8,                        /* %eflags */

  21 * 8,                       /* %cs */

  -1,                           /* %ss */

  3 * 8,                        /* %ds */

  2 * 8,                        /* %es */

  1 * 8,                        /* %fs */

};

/* Offset within the thread structure where we can find the saved

   stack pointer (%esp).  */

#define AMD64OBSD_UTHREAD_RSP_OFFSET    400

static void

amd64obsd_supply_uthread (struct regcache *regcache,

                          int regnum, CORE_ADDR addr)

{

  struct gdbarch *gdbarch = get_regcache_arch (regcache);

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;

  CORE_ADDR sp = 0;

  gdb_byte buf[8];

  int i;

  gdb_assert (regnum >= -1);

  if (regnum == -1 || regnum == AMD64_RSP_REGNUM)

    {

      int offset;

      /* Fetch stack pointer from thread structure.  */

      sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);

      /* Adjust the stack pointer such that it looks as if we just

         returned from _thread_machdep_switch.  */

      offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;

      store_unsigned_integer (buf, 8, byte_order, sp + offset);

      regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);

    }

  for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)

    {

      if (amd64obsd_uthread_reg_offset[i] != -1

          && (regnum == -1 || regnum == i))

        {

          /* Fetch stack pointer from thread structure (if we didn't

             do so already).  */

          if (sp == 0)

            sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);

          /* Read the saved register from the stack frame.  */

          read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);

          regcache_raw_supply (regcache, i, buf);

        }

    }

}

static void

amd64obsd_collect_uthread (const struct regcache *regcache,

                           int regnum, CORE_ADDR addr)

{

  struct gdbarch *gdbarch = get_regcache_arch (regcache);

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;

  CORE_ADDR sp = 0;

  gdb_byte buf[8];

  int i;

  gdb_assert (regnum >= -1);

  if (regnum == -1 || regnum == AMD64_RSP_REGNUM)

    {

      int offset;

      /* Calculate the stack pointer (frame pointer) that will be

         stored into the thread structure.  */

      offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;

      regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);

      sp = extract_unsigned_integer (buf, 8, byte_order) - offset;

      /* Store the stack pointer.  */

      write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);

      /* The stack pointer was (potentially) modified.  Make sure we

         build a proper stack frame.  */

      regnum = -1;

    }

  for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)

    {

      if (amd64obsd_uthread_reg_offset[i] != -1

          && (regnum == -1 || regnum == i))

        {

          /* Fetch stack pointer from thread structure (if we didn't

             calculate it already).  */

          if (sp == 0)

            sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);

          /* Write the register into the stack frame.  */

          regcache_raw_collect (regcache, i, buf);

          write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);

        }

    }

}

/* Kernel debugging support.  */

/* From <machine/frame.h>.  Easy since `struct trapframe' matches

   `struct sigcontext'.  */

#define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset

static struct trad_frame_cache *

amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  struct trad_frame_cache *cache;

  CORE_ADDR func, sp, addr;

  ULONGEST cs;

  char *name;

  int i;

  if (*this_cache)

    return *this_cache;

  cache = trad_frame_cache_zalloc (this_frame);

  *this_cache = cache;

  func = get_frame_func (this_frame);

  sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);

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

  if (name && strncmp (name, "Xintr", 5) == 0)

    addr = sp + 8;              /* It's an interrupt frame.  */

  else

    addr = sp;

  for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)

    if (amd64obsd_tf_reg_offset[i] != -1)

      trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);

  /* Read %cs from trap frame.  */

  addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];

  cs = read_memory_unsigned_integer (addr, 8, byte_order);

  if ((cs & I386_SEL_RPL) == I386_SEL_UPL)

    {

      /* Trap from user space; terminate backtrace.  */

      trad_frame_set_id (cache, outer_frame_id);

    }

  else

    {

      /* Construct the frame ID using the function start.  */

      trad_frame_set_id (cache, frame_id_build (sp + 16, func));

    }

  return cache;

}

static void

amd64obsd_trapframe_this_id (struct frame_info *this_frame,

                             void **this_cache, struct frame_id *this_id)

{

  struct trad_frame_cache *cache =

    amd64obsd_trapframe_cache (this_frame, this_cache);

  trad_frame_get_id (cache, this_id);

}

static struct value *

amd64obsd_trapframe_prev_register (struct frame_info *this_frame,

                                   void **this_cache, int regnum)

{

  struct trad_frame_cache *cache =

    amd64obsd_trapframe_cache (this_frame, this_cache);

  return trad_frame_get_register (cache, this_frame, regnum);

}

static int

amd64obsd_trapframe_sniffer (const struct frame_unwind *self,

                             struct frame_info *this_frame,

                             void **this_prologue_cache)

{

  ULONGEST cs;

  char *name;

  /* Check Current Privilege Level and bail out if we're not executing

     in kernel space.  */

  cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);

  if ((cs & I386_SEL_RPL) == I386_SEL_UPL)

    return 0;

  find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);

  return (name && ((strcmp (name, "calltrap") == 0)

                   || (strcmp (name, "osyscall1") == 0)

                   || (strcmp (name, "Xsyscall") == 0)

                   || (strncmp (name, "Xintr", 5) == 0)));

}

static const struct frame_unwind amd64obsd_trapframe_unwind = {

  /* FIXME: kettenis/20051219: This really is more like an interrupt

     frame, but SIGTRAMP_FRAME would print <signal handler called>,

     which really is not what we want here.  */

  NORMAL_FRAME,

  amd64obsd_trapframe_this_id,

  amd64obsd_trapframe_prev_register,

  NULL,

  amd64obsd_trapframe_sniffer

};

static void

amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  amd64_init_abi (info, gdbarch);

  /* Initialize general-purpose register set details.  */

  tdep->gregset_reg_offset = amd64obsd_r_reg_offset;

  tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);

  tdep->sizeof_gregset = 24 * 8;

  set_gdbarch_regset_from_core_section (gdbarch,

                                        amd64obsd_regset_from_core_section);

  tdep->jb_pc_offset = 7 * 8;

  tdep->sigtramp_p = amd64obsd_sigtramp_p;

  tdep->sigcontext_addr = amd64obsd_sigcontext_addr;

  tdep->sc_reg_offset = amd64obsd_sc_reg_offset;

  tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);

  /* OpenBSD provides a user-level threads implementation.  */

  bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);

  bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);

  /* OpenBSD uses SVR4-style shared libraries.  */

  set_solib_svr4_fetch_link_map_offsets

    (gdbarch, svr4_lp64_fetch_link_map_offsets);

  /* Unwind kernel trap frames correctly.  */

  frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);

}

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

void _initialize_amd64obsd_tdep (void);

void

_initialize_amd64obsd_tdep (void)

{

  /* The OpenBSD/amd64 native dependent code makes this assumption.  */

  gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);

  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,

                          GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);

  /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */

  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,

                          GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);

}