i386-darwin-tdep.c revision 1.8 
1/* Darwin support for GDB, the GNU debugger.
2   Copyright (C) 1997-2019 Free Software Foundation, Inc.
3
4   Contributed by Apple Computer, Inc.
5
6   This file is part of GDB.
7
8   This program is free software; you can redistribute it and/or modify
9   it under the terms of the GNU General Public License as published by
10   the Free Software Foundation; either version 3 of the License, or
11   (at your option) any later version.
12
13   This program is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   You should have received a copy of the GNU General Public License
19   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
20
21#include "defs.h"
22#include "frame.h"
23#include "inferior.h"
24#include "gdbcore.h"
25#include "target.h"
26#include "symtab.h"
27#include "regcache.h"
28#include "objfiles.h"
29
30#include "i387-tdep.h"
31#include "i386-tdep.h"
32#include "osabi.h"
33#include "ui-out.h"
34#include "i386-darwin-tdep.h"
35#include "solib.h"
36#include "solib-darwin.h"
37#include "dwarf2-frame.h"
38#include <algorithm>
39
40/* Offsets into the struct i386_thread_state where we'll find the saved regs.
41   From <mach/i386/thread_status.h> and i386-tdep.h.  */
42int i386_darwin_thread_state_reg_offset[] =
43{
44   0 * 4,   /* EAX */
45   2 * 4,   /* ECX */
46   3 * 4,   /* EDX */
47   1 * 4,   /* EBX */
48   7 * 4,   /* ESP */
49   6 * 4,   /* EBP */
50   5 * 4,   /* ESI */
51   4 * 4,   /* EDI */
52  10 * 4,   /* EIP */
53   9 * 4,   /* EFLAGS */
54  11 * 4,   /* CS */
55   8 * 4,   /* SS */
56  12 * 4,   /* DS */
57  13 * 4,   /* ES */
58  14 * 4,   /* FS */
59  15 * 4    /* GS */
60};
61
62const int i386_darwin_thread_state_num_regs =
63  ARRAY_SIZE (i386_darwin_thread_state_reg_offset);
64
65/* Assuming THIS_FRAME is a Darwin sigtramp routine, return the
66   address of the associated sigcontext structure.  */
67
68static CORE_ADDR
69i386_darwin_sigcontext_addr (struct frame_info *this_frame)
70{
71  struct gdbarch *gdbarch = get_frame_arch (this_frame);
72  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
73  CORE_ADDR bp;
74  CORE_ADDR si;
75  gdb_byte buf[4];
76
77  get_frame_register (this_frame, I386_EBP_REGNUM, buf);
78  bp = extract_unsigned_integer (buf, 4, byte_order);
79
80  /* A pointer to the ucontext is passed as the fourth argument
81     to the signal handler.  */
82  read_memory (bp + 24, buf, 4);
83  si = extract_unsigned_integer (buf, 4, byte_order);
84
85  /* The pointer to mcontext is at offset 28.  */
86  read_memory (si + 28, buf, 4);
87
88  /* First register (eax) is at offset 12.  */
89  return extract_unsigned_integer (buf, 4, byte_order) + 12;
90}
91
92/* Return true if the PC of THIS_FRAME is in a signal trampoline which
93   may have DWARF-2 CFI.
94
95   On Darwin, signal trampolines have DWARF-2 CFI but it has only one FDE
96   that covers only the indirect call to the user handler.
97   Without this function, the frame is recognized as a normal frame which is
98   not expected.  */
99
100int
101darwin_dwarf_signal_frame_p (struct gdbarch *gdbarch,
102			     struct frame_info *this_frame)
103{
104  return i386_sigtramp_p (this_frame);
105}
106
107/* Check wether TYPE is a 128-bit vector (__m128, __m128d or __m128i).  */
108
109static int
110i386_m128_p (struct type *type)
111{
112  return (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type)
113          && TYPE_LENGTH (type) == 16);
114}
115
116/* Return the alignment for TYPE when passed as an argument.  */
117
118static int
119i386_darwin_arg_type_alignment (struct type *type)
120{
121  type = check_typedef (type);
122  /* According to Mac OS X ABI document (passing arguments):
123     6.  The caller places 64-bit vectors (__m64) on the parameter area,
124         aligned to 8-byte boundaries.
125     7.  [...]  The caller aligns 128-bit vectors in the parameter area to
126         16-byte boundaries.  */
127  if (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type))
128    return TYPE_LENGTH (type);
129  /* 4.  The caller places all the fields of structures (or unions) with no
130         vector elements in the parameter area.  These structures are 4-byte
131         aligned.
132     5.  The caller places structures with vector elements on the stack,
133         16-byte aligned.  */
134  if (TYPE_CODE (type) == TYPE_CODE_STRUCT
135      || TYPE_CODE (type) == TYPE_CODE_UNION)
136    {
137      int i;
138      int res = 4;
139      for (i = 0; i < TYPE_NFIELDS (type); i++)
140	{
141	  int align
142	    = i386_darwin_arg_type_alignment (TYPE_FIELD_TYPE (type, i));
143
144	  res = std::max (res, align);
145	}
146      return res;
147    }
148  /* 2.  The caller aligns nonvector arguments to 4-byte boundaries.  */
149  return 4;
150}
151
152static CORE_ADDR
153i386_darwin_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
154			     struct regcache *regcache, CORE_ADDR bp_addr,
155			     int nargs, struct value **args, CORE_ADDR sp,
156			     function_call_return_method return_method,
157			     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 (return_method == return_method_struct)
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 (I387_MM0_REGNUM(tdep) + num_m128, val);
194                }
195              num_m128++;
196            }
197          else
198            {
199              args_space = align_up (args_space,
200				     i386_darwin_arg_type_alignment (arg_type));
201              if (write_pass)
202                write_memory (sp + args_space,
203                              value_contents_all (args[i]),
204			      TYPE_LENGTH (arg_type));
205
206              /* The System V ABI says that:
207
208                 "An argument's size is increased, if necessary, to make it a
209                 multiple of [32-bit] words.  This may require tail padding,
210                 depending on the size of the argument."
211
212                 This makes sure the stack stays word-aligned.  */
213              args_space += align_up (TYPE_LENGTH (arg_type), 4);
214            }
215        }
216
217      /* Darwin i386 ABI:
218	 1.  The caller ensures that the stack is 16-byte aligned at the point
219	     of the function call.  */
220      if (!write_pass)
221	sp = align_down (sp - args_space, 16);
222    }
223
224  /* Store return address.  */
225  sp -= 4;
226  store_unsigned_integer (buf, 4, byte_order, bp_addr);
227  write_memory (sp, buf, 4);
228
229  /* Finally, update the stack pointer...  */
230  store_unsigned_integer (buf, 4, byte_order, sp);
231  regcache->cooked_write (I386_ESP_REGNUM, buf);
232
233  /* ...and fake a frame pointer.  */
234  regcache->cooked_write (I386_EBP_REGNUM, buf);
235
236  /* MarkK wrote: This "+ 8" is all over the place:
237     (i386_frame_this_id, i386_sigtramp_frame_this_id,
238     i386_dummy_id).  It's there, since all frame unwinders for
239     a given target have to agree (within a certain margin) on the
240     definition of the stack address of a frame.  Otherwise frame id
241     comparison might not work correctly.  Since DWARF2/GCC uses the
242     stack address *before* the function call as a frame's CFA.  On
243     the i386, when %ebp is used as a frame pointer, the offset
244     between the contents %ebp and the CFA as defined by GCC.  */
245  return sp + 8;
246}
247
248static void
249i386_darwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
250{
251  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
252
253  /* We support the SSE registers.  */
254  tdep->num_xmm_regs = I386_NUM_XREGS - 1;
255  set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS);
256
257  dwarf2_frame_set_signal_frame_p (gdbarch, darwin_dwarf_signal_frame_p);
258  set_gdbarch_push_dummy_call (gdbarch, i386_darwin_push_dummy_call);
259
260  tdep->struct_return = reg_struct_return;
261
262  tdep->sigtramp_p = i386_sigtramp_p;
263  tdep->sigcontext_addr = i386_darwin_sigcontext_addr;
264  tdep->sc_reg_offset = i386_darwin_thread_state_reg_offset;
265  tdep->sc_num_regs = i386_darwin_thread_state_num_regs;
266
267  tdep->jb_pc_offset = 48;
268
269  /* Although the i387 extended floating-point has only 80 significant
270     bits, a `long double' actually takes up 128, probably to enforce
271     alignment.  */
272  set_gdbarch_long_double_bit (gdbarch, 128);
273
274  set_solib_ops (gdbarch, &darwin_so_ops);
275}
276
277static enum gdb_osabi
278i386_mach_o_osabi_sniffer (bfd *abfd)
279{
280  if (!bfd_check_format (abfd, bfd_object))
281    return GDB_OSABI_UNKNOWN;
282
283  if (bfd_get_arch (abfd) == bfd_arch_i386)
284    return GDB_OSABI_DARWIN;
285
286  return GDB_OSABI_UNKNOWN;
287}
288
289void
290_initialize_i386_darwin_tdep (void)
291{
292  gdbarch_register_osabi_sniffer (bfd_arch_unknown, bfd_target_mach_o_flavour,
293                                  i386_mach_o_osabi_sniffer);
294
295  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_i386_i386,
296			  GDB_OSABI_DARWIN, i386_darwin_init_abi);
297}
298