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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 2 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, write to the Free Software
20 Foundation, Inc., 51 Franklin Street, Fifth Floor,
21 Boston, MA 02110-1301, USA. */
22
23 #include "defs.h"
24 #include "arch-utils.h"
25 #include "frame.h"
26 #include "gdbcore.h"
27 #include "regcache.h"
28 #include "regset.h"
29 #include "osabi.h"
30 #include "symtab.h"
31
32 #include "gdb_assert.h"
33 #include "gdb_string.h"
34
35 #include "i386-tdep.h"
36 #include "i387-tdep.h"
37 #include "nbsd-tdep.h"
38 #include "solib-svr4.h"
39
40 /* From <machine/reg.h>. */
41 static int i386nbsd_r_reg_offset[] =
42 {
43 0 * 4, /* %eax */
44 1 * 4, /* %ecx */
45 2 * 4, /* %edx */
46 3 * 4, /* %ebx */
47 4 * 4, /* %esp */
48 5 * 4, /* %ebp */
49 6 * 4, /* %esi */
50 7 * 4, /* %edi */
51 8 * 4, /* %eip */
52 9 * 4, /* %eflags */
53 10 * 4, /* %cs */
54 11 * 4, /* %ss */
55 12 * 4, /* %ds */
56 13 * 4, /* %es */
57 14 * 4, /* %fs */
58 15 * 4 /* %gs */
59 };
60
61 static void
62 i386nbsd_aout_supply_regset (const struct regset *regset,
63 struct regcache *regcache, int regnum,
64 const void *regs, size_t len)
65 {
66 const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
67
68 gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
69
70 i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
71 i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset);
72 }
73
74 static const struct regset *
75 i386nbsd_aout_regset_from_core_section (struct gdbarch *gdbarch,
76 const char *sect_name,
77 size_t sect_size)
78 {
79 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
80
81 /* NetBSD a.out core dumps don't use seperate register sets for the
82 general-purpose and floating-point registers. */
83
84 if (strcmp (sect_name, ".reg") == 0
85 && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE)
86 {
87 if (tdep->gregset == NULL)
88 tdep->gregset =
89 regset_alloc (gdbarch, i386nbsd_aout_supply_regset, NULL);
90 return tdep->gregset;
91 }
92
93 return NULL;
94 }
95
96 /* Under NetBSD/i386, signal handler invocations can be identified by the
97 designated code sequence that is used to return from a signal handler.
98 In particular, the return address of a signal handler points to the
99 following code sequence:
100
101 leal 0x10(%esp), %eax
102 pushl %eax
103 pushl %eax
104 movl $0x127, %eax # __sigreturn14
105 int $0x80
106
107 Each instruction has a unique encoding, so we simply attempt to match
108 the instruction the PC is pointing to with any of the above instructions.
109 If there is a hit, we know the offset to the start of the designated
110 sequence and can then check whether we really are executing in the
111 signal trampoline. If not, -1 is returned, otherwise the offset from the
112 start of the return sequence is returned. */
113 #define RETCODE_INSN1 0x8d
114 #define RETCODE_INSN2 0x50
115 #define RETCODE_INSN3 0x50
116 #define RETCODE_INSN4 0xb8
117 #define RETCODE_INSN5 0xcd
118
119 #define RETCODE_INSN2_OFF 4
120 #define RETCODE_INSN3_OFF 5
121 #define RETCODE_INSN4_OFF 6
122 #define RETCODE_INSN5_OFF 11
123
124 static const unsigned char sigtramp_retcode[] =
125 {
126 RETCODE_INSN1, 0x44, 0x24, 0x10,
127 RETCODE_INSN2,
128 RETCODE_INSN3,
129 RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
130 RETCODE_INSN5, 0x80,
131 };
132
133 static LONGEST
134 i386nbsd_sigtramp_offset (struct frame_info *next_frame)
135 {
136 CORE_ADDR pc = frame_pc_unwind (next_frame);
137 unsigned char ret[sizeof(sigtramp_retcode)], insn;
138 LONGEST off;
139 int i;
140
141 if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
142 return -1;
143
144 switch (insn)
145 {
146 case RETCODE_INSN1:
147 off = 0;
148 break;
149
150 case RETCODE_INSN2:
151 /* INSN2 and INSN3 are the same. Read at the location of PC+1
152 to determine if we're actually looking at INSN2 or INSN3. */
153 if (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
154 return -1;
155
156 if (insn == RETCODE_INSN3)
157 off = RETCODE_INSN2_OFF;
158 else
159 off = RETCODE_INSN3_OFF;
160 break;
161
162 case RETCODE_INSN4:
163 off = RETCODE_INSN4_OFF;
164 break;
165
166 case RETCODE_INSN5:
167 off = RETCODE_INSN5_OFF;
168 break;
169
170 default:
171 return -1;
172 }
173
174 pc -= off;
175
176 if (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
177 return -1;
178
179 if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
180 return off;
181
182 return -1;
183 }
184
185 /* Return whether the frame preceding NEXT_FRAME corresponds to a
186 NetBSD sigtramp routine. */
187
188 static int
189 i386nbsd_sigtramp_p (struct frame_info *next_frame)
190 {
191 CORE_ADDR pc = frame_pc_unwind (next_frame);
192 char *name;
193
194 find_pc_partial_function (pc, &name, NULL, NULL);
195 return (nbsd_pc_in_sigtramp (pc, name)
196 || i386nbsd_sigtramp_offset (next_frame) >= 0);
197 }
198
199 /* From <machine/signal.h>. */
200 int i386nbsd_sc_reg_offset[] =
201 {
202 10 * 4, /* %eax */
203 9 * 4, /* %ecx */
204 8 * 4, /* %edx */
205 7 * 4, /* %ebx */
206 14 * 4, /* %esp */
207 6 * 4, /* %ebp */
208 5 * 4, /* %esi */
209 4 * 4, /* %edi */
210 11 * 4, /* %eip */
211 13 * 4, /* %eflags */
212 12 * 4, /* %cs */
213 15 * 4, /* %ss */
214 3 * 4, /* %ds */
215 2 * 4, /* %es */
216 1 * 4, /* %fs */
217 0 * 4 /* %gs */
218 };
219
220 static void
221 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
222 {
223 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
224
225 /* Obviously NetBSD is BSD-based. */
226 i386bsd_init_abi (info, gdbarch);
227
228 /* NetBSD has a different `struct reg'. */
229 tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
230 tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
231 tdep->sizeof_gregset = 16 * 4;
232
233 /* NetBSD has different signal trampoline conventions. */
234 tdep->sigtramp_start = 0;
235 tdep->sigtramp_end = 0;
236 tdep->sigtramp_p = i386nbsd_sigtramp_p;
237
238 /* NetBSD uses -freg-struct-return by default. */
239 tdep->struct_return = reg_struct_return;
240
241 /* NetBSD has a `struct sigcontext' that's different from the
242 original 4.3 BSD. */
243 tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
244 tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
245 }
246
247 /* NetBSD a.out. */
248
249 static void
250 i386nbsdaout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
251 {
252 i386nbsd_init_abi (info, gdbarch);
253
254 /* NetBSD a.out has a single register set. */
255 set_gdbarch_regset_from_core_section
256 (gdbarch, i386nbsd_aout_regset_from_core_section);
257 }
258
259 /* NetBSD ELF. */
260
261 static void
262 i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
263 {
264 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
265
266 /* It's still NetBSD. */
267 i386nbsd_init_abi (info, gdbarch);
268
269 /* But ELF-based. */
270 i386_elf_init_abi (info, gdbarch);
271
272 /* NetBSD ELF uses SVR4-style shared libraries. */
273 set_solib_svr4_fetch_link_map_offsets
274 (gdbarch, svr4_ilp32_fetch_link_map_offsets);
275
276 /* NetBSD ELF uses -fpcc-struct-return by default. */
277 tdep->struct_return = pcc_struct_return;
278 }
279
280 void
281 _initialize_i386nbsd_tdep (void)
282 {
283 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
284 i386nbsdaout_init_abi);
285 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
286 i386nbsdelf_init_abi);
287 }