1/* Target-dependent code for NetBSD/i386.
2
3   Copyright (C) 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002, 2003,
4   2004, 2007 Free Software Foundation, 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 "arch-utils.h"
23#include "frame.h"
24#include "gdbcore.h"
25#include "regcache.h"
26#include "regset.h"
27#include "osabi.h"
28#include "symtab.h"
29
30#include "gdb_assert.h"
31#include "gdb_string.h"
32
33#include "i386-tdep.h"
34#include "i387-tdep.h"
35#include "nbsd-tdep.h"
36#include "solib-svr4.h"
37
38/* From <machine/reg.h>.  */
39static int i386nbsd_r_reg_offset[] =
40{
41  0 * 4,			/* %eax */
42  1 * 4,			/* %ecx */
43  2 * 4,			/* %edx */
44  3 * 4,			/* %ebx */
45  4 * 4,			/* %esp */
46  5 * 4,			/* %ebp */
47  6 * 4,			/* %esi */
48  7 * 4,			/* %edi */
49  8 * 4,			/* %eip */
50  9 * 4,			/* %eflags */
51  10 * 4,			/* %cs */
52  11 * 4,			/* %ss */
53  12 * 4,			/* %ds */
54  13 * 4,			/* %es */
55  14 * 4,			/* %fs */
56  15 * 4			/* %gs */
57};
58
59static void
60i386nbsd_aout_supply_regset (const struct regset *regset,
61			     struct regcache *regcache, int regnum,
62			     const void *regs, size_t len)
63{
64  const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
65
66  gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
67
68  i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
69  i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset);
70}
71
72static const struct regset *
73i386nbsd_aout_regset_from_core_section (struct gdbarch *gdbarch,
74					const char *sect_name,
75					size_t sect_size)
76{
77  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
78
79  /* NetBSD a.out core dumps don't use seperate register sets for the
80     general-purpose and floating-point registers.  */
81
82  if (strcmp (sect_name, ".reg") == 0
83      && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE)
84    {
85      if (tdep->gregset == NULL)
86        tdep->gregset =
87	  regset_alloc (gdbarch, i386nbsd_aout_supply_regset, NULL);
88      return tdep->gregset;
89    }
90
91  return NULL;
92}
93
94/* Under NetBSD/i386, signal handler invocations can be identified by the
95   designated code sequence that is used to return from a signal handler.
96   In particular, the return address of a signal handler points to the
97   following code sequence:
98
99	leal	0x10(%esp), %eax
100	pushl	%eax
101	pushl	%eax
102	movl	$0x127, %eax		# __sigreturn14
103	int	$0x80
104
105   Each instruction has a unique encoding, so we simply attempt to match
106   the instruction the PC is pointing to with any of the above instructions.
107   If there is a hit, we know the offset to the start of the designated
108   sequence and can then check whether we really are executing in the
109   signal trampoline.  If not, -1 is returned, otherwise the offset from the
110   start of the return sequence is returned.  */
111#define RETCODE_INSN1		0x8d
112#define RETCODE_INSN2		0x50
113#define RETCODE_INSN3		0x50
114#define RETCODE_INSN4		0xb8
115#define RETCODE_INSN5		0xcd
116
117#define RETCODE_INSN2_OFF	4
118#define RETCODE_INSN3_OFF	5
119#define RETCODE_INSN4_OFF	6
120#define RETCODE_INSN5_OFF	11
121
122static const unsigned char sigtramp_retcode[] =
123{
124  RETCODE_INSN1, 0x44, 0x24, 0x10,
125  RETCODE_INSN2,
126  RETCODE_INSN3,
127  RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
128  RETCODE_INSN5, 0x80,
129};
130
131static LONGEST
132i386nbsd_sigtramp_offset (struct frame_info *next_frame)
133{
134  CORE_ADDR pc = frame_pc_unwind (next_frame);
135  unsigned char ret[sizeof(sigtramp_retcode)], insn;
136  LONGEST off;
137  int i;
138
139  if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
140    return -1;
141
142  switch (insn)
143    {
144    case RETCODE_INSN1:
145      off = 0;
146      break;
147
148    case RETCODE_INSN2:
149      /* INSN2 and INSN3 are the same.  Read at the location of PC+1
150	 to determine if we're actually looking at INSN2 or INSN3.  */
151      if (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
152	return -1;
153
154      if (insn == RETCODE_INSN3)
155	off = RETCODE_INSN2_OFF;
156      else
157	off = RETCODE_INSN3_OFF;
158      break;
159
160    case RETCODE_INSN4:
161      off = RETCODE_INSN4_OFF;
162      break;
163
164    case RETCODE_INSN5:
165      off = RETCODE_INSN5_OFF;
166      break;
167
168    default:
169      return -1;
170    }
171
172  pc -= off;
173
174  if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
175    return -1;
176
177  if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
178    return off;
179
180  return -1;
181}
182
183/* Return whether the frame preceding NEXT_FRAME corresponds to a
184   NetBSD sigtramp routine.  */
185
186static int
187i386nbsd_sigtramp_p (struct frame_info *next_frame)
188{
189  CORE_ADDR pc = frame_pc_unwind (next_frame);
190  char *name;
191
192  find_pc_partial_function (pc, &name, NULL, NULL);
193  return (nbsd_pc_in_sigtramp (pc, name)
194	  || i386nbsd_sigtramp_offset (next_frame) >= 0);
195}
196
197/* From <machine/signal.h>.  */
198int i386nbsd_sc_reg_offset[] =
199{
200  10 * 4,			/* %eax */
201  9 * 4,			/* %ecx */
202  8 * 4,			/* %edx */
203  7 * 4,			/* %ebx */
204  14 * 4,			/* %esp */
205  6 * 4,			/* %ebp */
206  5 * 4,			/* %esi */
207  4 * 4,			/* %edi */
208  11 * 4,			/* %eip */
209  13 * 4,			/* %eflags */
210  12 * 4,			/* %cs */
211  15 * 4,			/* %ss */
212  3 * 4,			/* %ds */
213  2 * 4,			/* %es */
214  1 * 4,			/* %fs */
215  0 * 4				/* %gs */
216};
217
218static void
219i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
220{
221  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
222
223  /* Obviously NetBSD is BSD-based.  */
224  i386bsd_init_abi (info, gdbarch);
225
226  /* NetBSD has a different `struct reg'.  */
227  tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
228  tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
229  tdep->sizeof_gregset = 16 * 4;
230
231  /* NetBSD has different signal trampoline conventions.  */
232  tdep->sigtramp_start = 0;
233  tdep->sigtramp_end = 0;
234  tdep->sigtramp_p = i386nbsd_sigtramp_p;
235
236  /* NetBSD uses -freg-struct-return by default.  */
237  tdep->struct_return = reg_struct_return;
238
239  /* NetBSD has a `struct sigcontext' that's different from the
240     original 4.3 BSD.  */
241  tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
242  tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
243}
244
245/* NetBSD a.out.  */
246
247static void
248i386nbsdaout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
249{
250  i386nbsd_init_abi (info, gdbarch);
251
252  /* NetBSD a.out has a single register set.  */
253  set_gdbarch_regset_from_core_section
254    (gdbarch, i386nbsd_aout_regset_from_core_section);
255}
256
257/* NetBSD ELF.  */
258
259static void
260i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
261{
262  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
263
264  /* It's still NetBSD.  */
265  i386nbsd_init_abi (info, gdbarch);
266
267  /* But ELF-based.  */
268  i386_elf_init_abi (info, gdbarch);
269
270  /* NetBSD ELF uses SVR4-style shared libraries.  */
271  set_solib_svr4_fetch_link_map_offsets
272    (gdbarch, svr4_ilp32_fetch_link_map_offsets);
273
274  /* NetBSD ELF uses -fpcc-struct-return by default.  */
275  tdep->struct_return = pcc_struct_return;
276}
277
278void
279_initialize_i386nbsd_tdep (void)
280{
281  gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
282			  i386nbsdaout_init_abi);
283  gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
284			  i386nbsdelf_init_abi);
285}
286