path: root/gdb/i386-darwin-tdep.c

/* Darwin support for GDB, the GNU debugger.
   Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2005, 2008, 2009, 2010, 2011
   Free Software Foundation, Inc.

   Contributed by Apple Computer, 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 "inferior.h"
#include "gdbcore.h"
#include "target.h"
#include "floatformat.h"
#include "symtab.h"
#include "regcache.h"
#include "libbfd.h"
#include "objfiles.h"

#include "i387-tdep.h"
#include "i386-tdep.h"
#include "osabi.h"
#include "ui-out.h"
#include "symtab.h"
#include "frame.h"
#include "gdb_assert.h"
#include "i386-darwin-tdep.h"
#include "solib.h"
#include "solib-darwin.h"
#include "dwarf2-frame.h"

/* Offsets into the struct i386_thread_state where we'll find the saved regs.
   From <mach/i386/thread_status.h> and i386-tdep.h.  */
int i386_darwin_thread_state_reg_offset[] =
{
   0 * 4,   /* EAX */
   2 * 4,   /* ECX */
   3 * 4,   /* EDX */
   1 * 4,   /* EBX */
   7 * 4,   /* ESP */
   6 * 4,   /* EBP */
   5 * 4,   /* ESI */
   4 * 4,   /* EDI */
  10 * 4,   /* EIP */
   9 * 4,   /* EFLAGS */
  11 * 4,   /* CS */
   8,       /* SS */
  12 * 4,   /* DS */
  13 * 4,   /* ES */
  14 * 4,   /* FS */
  15 * 4    /* GS */
};

const int i386_darwin_thread_state_num_regs = 
  ARRAY_SIZE (i386_darwin_thread_state_reg_offset);

/* Assuming THIS_FRAME is a Darwin sigtramp routine, return the
   address of the associated sigcontext structure.  */

static CORE_ADDR
i386_darwin_sigcontext_addr (struct frame_info *this_frame)
{
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  CORE_ADDR bp;
  CORE_ADDR si;
  gdb_byte buf[4];

  get_frame_register (this_frame, I386_EBP_REGNUM, buf);
  bp = extract_unsigned_integer (buf, 4, byte_order);

  /* A pointer to the ucontext is passed as the fourth argument
     to the signal handler.  */
  read_memory (bp + 24, buf, 4);
  si = extract_unsigned_integer (buf, 4, byte_order);

  /* The pointer to mcontext is at offset 28.  */
  read_memory (si + 28, buf, 4);

  /* First register (eax) is at offset 12.  */
  return extract_unsigned_integer (buf, 4, byte_order) + 12;
}

/* Return true if the PC of THIS_FRAME is in a signal trampoline which
   may have DWARF-2 CFI.

   On Darwin, signal trampolines have DWARF-2 CFI but it has only one FDE
   that covers only the indirect call to the user handler.
   Without this function, the frame is recognized as a normal frame which is
   not expected.  */

int
darwin_dwarf_signal_frame_p (struct gdbarch *gdbarch,
			     struct frame_info *this_frame)
{
  return i386_sigtramp_p (this_frame);
}

/* Check wether TYPE is a 128-bit vector (__m128, __m128d or __m128i).  */

static int
i386_m128_p (struct type *type)
{
  return (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type)
          && TYPE_LENGTH (type) == 16);
}

/* Return the alignment for TYPE when passed as an argument.  */

static int
i386_darwin_arg_type_alignment (struct type *type)
{
  type = check_typedef (type);
  /* According to Mac OS X ABI document (passing arguments):
     6.  The caller places 64-bit vectors (__m64) on the parameter area,
         aligned to 8-byte boundaries.
     7.  [...]  The caller aligns 128-bit vectors in the parameter area to
         16-byte boundaries.  */
  if (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type))
    return TYPE_LENGTH (type);
  /* 4.  The caller places all the fields of structures (or unions) with no
         vector elements in the parameter area.  These structures are 4-byte
         aligned.
     5.  The caller places structures with vector elements on the stack,
         16-byte aligned.  */
  if (TYPE_CODE (type) == TYPE_CODE_STRUCT
      || TYPE_CODE (type) == TYPE_CODE_UNION)
    {
      int i;
      int res = 4;
      for (i = 0; i < TYPE_NFIELDS (type); i++)
        res = max (res,
                   i386_darwin_arg_type_alignment (TYPE_FIELD_TYPE (type, i)));
      return res;
    }
  /* 2.  The caller aligns nonvector arguments to 4-byte boundaries.  */
  return 4;
}

static CORE_ADDR
i386_darwin_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
			     struct regcache *regcache, CORE_ADDR bp_addr,
			     int nargs, struct value **args, CORE_ADDR sp,
			     int struct_return, CORE_ADDR struct_addr)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  gdb_byte buf[4];
  int i;
  int write_pass;

  /* Determine the total space required for arguments and struct
     return address in a first pass, then push arguments in a second pass.  */

  for (write_pass = 0; write_pass < 2; write_pass++)
    {
      int args_space = 0;
      int num_m128 = 0;

      if (struct_return)
	{
	  if (write_pass)
	    {
	      /* Push value address.  */
	      store_unsigned_integer (buf, 4, byte_order, struct_addr);
	      write_memory (sp, buf, 4);
	    }
          args_space += 4;
	}

      for (i = 0; i < nargs; i++)
	{
          struct type *arg_type = value_enclosing_type (args[i]);

          if (i386_m128_p (arg_type) && num_m128 < 4)
            {
              if (write_pass)
                {
                  const gdb_byte *val = value_contents_all (args[i]);
                  regcache_raw_write
                    (regcache, I387_MM0_REGNUM(tdep) + num_m128, val);
                }
              num_m128++;
            }
          else
            {
              int len = TYPE_LENGTH (arg_type);
              int align = i386_darwin_arg_type_alignment (arg_type);

              args_space = align_up (args_space, align);
              if (write_pass)
                write_memory (sp + args_space,
                              value_contents_all (args[i]), len);

              /* The System V ABI says that:
                 
                 "An argument's size is increased, if necessary, to make it a
                 multiple of [32-bit] words.  This may require tail padding,
                 depending on the size of the argument."
                 
                 This makes sure the stack stays word-aligned.  */
              args_space += align_up (len, 4);
            }
        }

      /* Darwin i386 ABI:
	 1.  The caller ensures that the stack is 16-byte aligned at the point
	     of the function call.  */
      if (!write_pass)
	sp = align_down (sp - args_space, 16);
    }

  /* Store return address.  */
  sp -= 4;
  store_unsigned_integer (buf, 4, byte_order, bp_addr);
  write_memory (sp, buf, 4);

  /* Finally, update the stack pointer...  */
  store_unsigned_integer (buf, 4, byte_order, sp);
  regcache_cooked_write (regcache, I386_ESP_REGNUM, buf);

  /* ...and fake a frame pointer.  */
  regcache_cooked_write (regcache, I386_EBP_REGNUM, buf);

  /* MarkK wrote: This "+ 8" is all over the place:
     (i386_frame_this_id, i386_sigtramp_frame_this_id,
     i386_dummy_id).  It's there, since all frame unwinders for
     a given target have to agree (within a certain margin) on the
     definition of the stack address of a frame.  Otherwise frame id
     comparison might not work correctly.  Since DWARF2/GCC uses the
     stack address *before* the function call as a frame's CFA.  On
     the i386, when %ebp is used as a frame pointer, the offset
     between the contents %ebp and the CFA as defined by GCC.  */
  return sp + 8;
}

static void
i386_darwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* We support the SSE registers.  */
  tdep->num_xmm_regs = I386_NUM_XREGS - 1;
  set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS);

  dwarf2_frame_set_signal_frame_p (gdbarch, darwin_dwarf_signal_frame_p);
  set_gdbarch_push_dummy_call (gdbarch, i386_darwin_push_dummy_call);

  tdep->struct_return = reg_struct_return;

  tdep->sigtramp_p = i386_sigtramp_p;
  tdep->sigcontext_addr = i386_darwin_sigcontext_addr;
  tdep->sc_reg_offset = i386_darwin_thread_state_reg_offset;
  tdep->sc_num_regs = i386_darwin_thread_state_num_regs;

  tdep->jb_pc_offset = 48;

  /* Although the i387 extended floating-point has only 80 significant
     bits, a `long double' actually takes up 128, probably to enforce
     alignment.  */
  set_gdbarch_long_double_bit (gdbarch, 128);

  set_solib_ops (gdbarch, &darwin_so_ops);
}

static enum gdb_osabi
i386_mach_o_osabi_sniffer (bfd *abfd)
{
  if (!bfd_check_format (abfd, bfd_object))
    return GDB_OSABI_UNKNOWN;
  
  if (bfd_get_arch (abfd) == bfd_arch_i386)
    return GDB_OSABI_DARWIN;

  return GDB_OSABI_UNKNOWN;
}

void
_initialize_i386_darwin_tdep (void)
{
  gdbarch_register_osabi_sniffer (bfd_arch_unknown, bfd_target_mach_o_flavour,
                                  i386_mach_o_osabi_sniffer);

  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_i386_i386,
			  GDB_OSABI_DARWIN, i386_darwin_init_abi);
}