1/* Darwin support for GDB, the GNU debugger.
2   Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2005, 2008, 2009, 2010, 2011
3   Free Software Foundation, Inc.
4
5   Contributed by Apple Computer, Inc.
6
7   This file is part of GDB.
8
9   This program is free software; you can redistribute it and/or modify
10   it under the terms of the GNU General Public License as published by
11   the Free Software Foundation; either version 3 of the License, or
12   (at your option) any later version.
13
14   This program is distributed in the hope that it will be useful,
15   but WITHOUT ANY WARRANTY; without even the implied warranty of
16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17   GNU General Public License for more details.
18
19   You should have received a copy of the GNU General Public License
20   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
21
22#include "defs.h"
23#include "frame.h"
24#include "inferior.h"
25#include "gdbcore.h"
26#include "target.h"
27#include "floatformat.h"
28#include "symtab.h"
29#include "regcache.h"
30#include "libbfd.h"
31#include "objfiles.h"
32
33#include "i387-tdep.h"
34#include "i386-tdep.h"
35#include "osabi.h"
36#include "ui-out.h"
37#include "symtab.h"
38#include "frame.h"
39#include "gdb_assert.h"
40#include "i386-darwin-tdep.h"
41#include "solib.h"
42#include "solib-darwin.h"
43#include "dwarf2-frame.h"
44
45/* Offsets into the struct i386_thread_state where we'll find the saved regs.
46   From <mach/i386/thread_status.h> and i386-tdep.h.  */
47int i386_darwin_thread_state_reg_offset[] =
48{
49   0 * 4,   /* EAX */
50   2 * 4,   /* ECX */
51   3 * 4,   /* EDX */
52   1 * 4,   /* EBX */
53   7 * 4,   /* ESP */
54   6 * 4,   /* EBP */
55   5 * 4,   /* ESI */
56   4 * 4,   /* EDI */
57  10 * 4,   /* EIP */
58   9 * 4,   /* EFLAGS */
59  11 * 4,   /* CS */
60   8,       /* SS */
61  12 * 4,   /* DS */
62  13 * 4,   /* ES */
63  14 * 4,   /* FS */
64  15 * 4    /* GS */
65};
66
67const int i386_darwin_thread_state_num_regs =
68  ARRAY_SIZE (i386_darwin_thread_state_reg_offset);
69
70/* Assuming THIS_FRAME is a Darwin sigtramp routine, return the
71   address of the associated sigcontext structure.  */
72
73static CORE_ADDR
74i386_darwin_sigcontext_addr (struct frame_info *this_frame)
75{
76  struct gdbarch *gdbarch = get_frame_arch (this_frame);
77  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
78  CORE_ADDR bp;
79  CORE_ADDR si;
80  gdb_byte buf[4];
81
82  get_frame_register (this_frame, I386_EBP_REGNUM, buf);
83  bp = extract_unsigned_integer (buf, 4, byte_order);
84
85  /* A pointer to the ucontext is passed as the fourth argument
86     to the signal handler.  */
87  read_memory (bp + 24, buf, 4);
88  si = extract_unsigned_integer (buf, 4, byte_order);
89
90  /* The pointer to mcontext is at offset 28.  */
91  read_memory (si + 28, buf, 4);
92
93  /* First register (eax) is at offset 12.  */
94  return extract_unsigned_integer (buf, 4, byte_order) + 12;
95}
96
97/* Return true if the PC of THIS_FRAME is in a signal trampoline which
98   may have DWARF-2 CFI.
99
100   On Darwin, signal trampolines have DWARF-2 CFI but it has only one FDE
101   that covers only the indirect call to the user handler.
102   Without this function, the frame is recognized as a normal frame which is
103   not expected.  */
104
105int
106darwin_dwarf_signal_frame_p (struct gdbarch *gdbarch,
107			     struct frame_info *this_frame)
108{
109  return i386_sigtramp_p (this_frame);
110}
111
112/* Check wether TYPE is a 128-bit vector (__m128, __m128d or __m128i).  */
113
114static int
115i386_m128_p (struct type *type)
116{
117  return (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type)
118          && TYPE_LENGTH (type) == 16);
119}
120
121/* Return the alignment for TYPE when passed as an argument.  */
122
123static int
124i386_darwin_arg_type_alignment (struct type *type)
125{
126  type = check_typedef (type);
127  /* According to Mac OS X ABI document (passing arguments):
128     6.  The caller places 64-bit vectors (__m64) on the parameter area,
129         aligned to 8-byte boundaries.
130     7.  [...]  The caller aligns 128-bit vectors in the parameter area to
131         16-byte boundaries.  */
132  if (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type))
133    return TYPE_LENGTH (type);
134  /* 4.  The caller places all the fields of structures (or unions) with no
135         vector elements in the parameter area.  These structures are 4-byte
136         aligned.
137     5.  The caller places structures with vector elements on the stack,
138         16-byte aligned.  */
139  if (TYPE_CODE (type) == TYPE_CODE_STRUCT
140      || TYPE_CODE (type) == TYPE_CODE_UNION)
141    {
142      int i;
143      int res = 4;
144      for (i = 0; i < TYPE_NFIELDS (type); i++)
145        res = max (res,
146                   i386_darwin_arg_type_alignment (TYPE_FIELD_TYPE (type, i)));
147      return res;
148    }
149  /* 2.  The caller aligns nonvector arguments to 4-byte boundaries.  */
150  return 4;
151}
152
153static CORE_ADDR
154i386_darwin_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
155			     struct regcache *regcache, CORE_ADDR bp_addr,
156			     int nargs, struct value **args, CORE_ADDR sp,
157			     int struct_return, CORE_ADDR struct_addr)
158{
159  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
160  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
161  gdb_byte buf[4];
162  int i;
163  int write_pass;
164
165  /* Determine the total space required for arguments and struct
166     return address in a first pass, then push arguments in a second pass.  */
167
168  for (write_pass = 0; write_pass < 2; write_pass++)
169    {
170      int args_space = 0;
171      int num_m128 = 0;
172
173      if (struct_return)
174	{
175	  if (write_pass)
176	    {
177	      /* Push value address.  */
178	      store_unsigned_integer (buf, 4, byte_order, struct_addr);
179	      write_memory (sp, buf, 4);
180	    }
181          args_space += 4;
182	}
183
184      for (i = 0; i < nargs; i++)
185	{
186          struct type *arg_type = value_enclosing_type (args[i]);
187
188          if (i386_m128_p (arg_type) && num_m128 < 4)
189            {
190              if (write_pass)
191                {
192                  const gdb_byte *val = value_contents_all (args[i]);
193                  regcache_raw_write
194                    (regcache, I387_MM0_REGNUM(tdep) + num_m128, val);
195                }
196              num_m128++;
197            }
198          else
199            {
200              int len = TYPE_LENGTH (arg_type);
201              int align = i386_darwin_arg_type_alignment (arg_type);
202
203              args_space = align_up (args_space, align);
204              if (write_pass)
205                write_memory (sp + args_space,
206                              value_contents_all (args[i]), len);
207
208              /* The System V ABI says that:
209
210                 "An argument's size is increased, if necessary, to make it a
211                 multiple of [32-bit] words.  This may require tail padding,
212                 depending on the size of the argument."
213
214                 This makes sure the stack stays word-aligned.  */
215              args_space += align_up (len, 4);
216            }
217        }
218
219      /* Darwin i386 ABI:
220	 1.  The caller ensures that the stack is 16-byte aligned at the point
221	     of the function call.  */
222      if (!write_pass)
223	sp = align_down (sp - args_space, 16);
224    }
225
226  /* Store return address.  */
227  sp -= 4;
228  store_unsigned_integer (buf, 4, byte_order, bp_addr);
229  write_memory (sp, buf, 4);
230
231  /* Finally, update the stack pointer...  */
232  store_unsigned_integer (buf, 4, byte_order, sp);
233  regcache_cooked_write (regcache, I386_ESP_REGNUM, buf);
234
235  /* ...and fake a frame pointer.  */
236  regcache_cooked_write (regcache, I386_EBP_REGNUM, buf);
237
238  /* MarkK wrote: This "+ 8" is all over the place:
239     (i386_frame_this_id, i386_sigtramp_frame_this_id,
240     i386_dummy_id).  It's there, since all frame unwinders for
241     a given target have to agree (within a certain margin) on the
242     definition of the stack address of a frame.  Otherwise frame id
243     comparison might not work correctly.  Since DWARF2/GCC uses the
244     stack address *before* the function call as a frame's CFA.  On
245     the i386, when %ebp is used as a frame pointer, the offset
246     between the contents %ebp and the CFA as defined by GCC.  */
247  return sp + 8;
248}
249
250static void
251i386_darwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
252{
253  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
254
255  /* We support the SSE registers.  */
256  tdep->num_xmm_regs = I386_NUM_XREGS - 1;
257  set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS);
258
259  dwarf2_frame_set_signal_frame_p (gdbarch, darwin_dwarf_signal_frame_p);
260  set_gdbarch_push_dummy_call (gdbarch, i386_darwin_push_dummy_call);
261
262  tdep->struct_return = reg_struct_return;
263
264  tdep->sigtramp_p = i386_sigtramp_p;
265  tdep->sigcontext_addr = i386_darwin_sigcontext_addr;
266  tdep->sc_reg_offset = i386_darwin_thread_state_reg_offset;
267  tdep->sc_num_regs = i386_darwin_thread_state_num_regs;
268
269  tdep->jb_pc_offset = 48;
270
271  /* Although the i387 extended floating-point has only 80 significant
272     bits, a `long double' actually takes up 128, probably to enforce
273     alignment.  */
274  set_gdbarch_long_double_bit (gdbarch, 128);
275
276  set_solib_ops (gdbarch, &darwin_so_ops);
277}
278
279static enum gdb_osabi
280i386_mach_o_osabi_sniffer (bfd *abfd)
281{
282  if (!bfd_check_format (abfd, bfd_object))
283    return GDB_OSABI_UNKNOWN;
284
285  if (bfd_get_arch (abfd) == bfd_arch_i386)
286    return GDB_OSABI_DARWIN;
287
288  return GDB_OSABI_UNKNOWN;
289}
290
291void
292_initialize_i386_darwin_tdep (void)
293{
294  gdbarch_register_osabi_sniffer (bfd_arch_unknown, bfd_target_mach_o_flavour,
295                                  i386_mach_o_osabi_sniffer);
296
297  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_i386_i386,
298			  GDB_OSABI_DARWIN, i386_darwin_init_abi);
299}
300