1 /* Target-dependent code for NetBSD/i386.
2
3 Copyright 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002,
4 2003, 2004
5 Free Software Foundation, 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 2 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, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
23
24 #include "defs.h"
25 #include "arch-utils.h"
26 #include "gdbcore.h"
27 #include "regcache.h"
28 #include "regset.h"
29 #include "osabi.h"
30
31 #include "gdb_assert.h"
32 #include "gdb_string.h"
33
34 #include "i386-tdep.h"
35 #include "i387-tdep.h"
36 #include "nbsd-tdep.h"
37 #include "solib-svr4.h"
38
39 /* From <machine/reg.h>. */
40 static int i386nbsd_r_reg_offset[] =
41 {
42 0 * 4, /* %eax */
43 1 * 4, /* %ecx */
44 2 * 4, /* %edx */
45 3 * 4, /* %ebx */
46 4 * 4, /* %esp */
47 5 * 4, /* %ebp */
48 6 * 4, /* %esi */
49 7 * 4, /* %edi */
50 8 * 4, /* %eip */
51 9 * 4, /* %eflags */
52 10 * 4, /* %cs */
53 11 * 4, /* %ss */
54 12 * 4, /* %ds */
55 13 * 4, /* %es */
56 14 * 4, /* %fs */
57 15 * 4 /* %gs */
58 };
59
60 static void
i386nbsd_aout_supply_regset(const struct regset * regset,struct regcache * regcache,int regnum,const void * regs,size_t len)61 i386nbsd_aout_supply_regset (const struct regset *regset,
62 struct regcache *regcache, int regnum,
63 const void *regs, size_t len)
64 {
65 const struct gdbarch_tdep *tdep = regset->descr;
66
67 gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
68
69 i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
70 i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset);
71 }
72
73 static const struct regset *
i386nbsd_aout_regset_from_core_section(struct gdbarch * gdbarch,const char * sect_name,size_t sect_size)74 i386nbsd_aout_regset_from_core_section (struct gdbarch *gdbarch,
75 const char *sect_name,
76 size_t sect_size)
77 {
78 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
79
80 /* NetBSD a.out core dumps don't use seperate register sets for the
81 general-purpose and floating-point registers. */
82
83 if (strcmp (sect_name, ".reg") == 0
84 && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE)
85 {
86 if (tdep->gregset == NULL)
87 {
88 tdep->gregset = XMALLOC (struct regset);
89 tdep->gregset->descr = tdep;
90 tdep->gregset->supply_regset = i386nbsd_aout_supply_regset;
91 }
92 return tdep->gregset;
93 }
94
95 return NULL;
96 }
97
98 /* Under NetBSD/i386, signal handler invocations can be identified by the
99 designated code sequence that is used to return from a signal handler.
100 In particular, the return address of a signal handler points to the
101 following code sequence:
102
103 leal 0x10(%esp), %eax
104 pushl %eax
105 pushl %eax
106 movl $0x127, %eax # __sigreturn14
107 int $0x80
108
109 Each instruction has a unique encoding, so we simply attempt to match
110 the instruction the PC is pointing to with any of the above instructions.
111 If there is a hit, we know the offset to the start of the designated
112 sequence and can then check whether we really are executing in the
113 signal trampoline. If not, -1 is returned, otherwise the offset from the
114 start of the return sequence is returned. */
115 #define RETCODE_INSN1 0x8d
116 #define RETCODE_INSN2 0x50
117 #define RETCODE_INSN3 0x50
118 #define RETCODE_INSN4 0xb8
119 #define RETCODE_INSN5 0xcd
120
121 #define RETCODE_INSN2_OFF 4
122 #define RETCODE_INSN3_OFF 5
123 #define RETCODE_INSN4_OFF 6
124 #define RETCODE_INSN5_OFF 11
125
126 static const unsigned char sigtramp_retcode[] =
127 {
128 RETCODE_INSN1, 0x44, 0x24, 0x10,
129 RETCODE_INSN2,
130 RETCODE_INSN3,
131 RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
132 RETCODE_INSN5, 0x80,
133 };
134
135 static LONGEST
i386nbsd_sigtramp_offset(CORE_ADDR pc)136 i386nbsd_sigtramp_offset (CORE_ADDR pc)
137 {
138 unsigned char ret[sizeof(sigtramp_retcode)], insn;
139 LONGEST off;
140 int i;
141
142 if (read_memory_nobpt (pc, &insn, 1) != 0)
143 return -1;
144
145 switch (insn)
146 {
147 case RETCODE_INSN1:
148 off = 0;
149 break;
150
151 case RETCODE_INSN2:
152 /* INSN2 and INSN3 are the same. Read at the location of PC+1
153 to determine if we're actually looking at INSN2 or INSN3. */
154 if (read_memory_nobpt (pc + 1, &insn, 1) != 0)
155 return -1;
156
157 if (insn == RETCODE_INSN3)
158 off = RETCODE_INSN2_OFF;
159 else
160 off = RETCODE_INSN3_OFF;
161 break;
162
163 case RETCODE_INSN4:
164 off = RETCODE_INSN4_OFF;
165 break;
166
167 case RETCODE_INSN5:
168 off = RETCODE_INSN5_OFF;
169 break;
170
171 default:
172 return -1;
173 }
174
175 pc -= off;
176
177 if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
178 return -1;
179
180 if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
181 return off;
182
183 return -1;
184 }
185
186 static int
i386nbsd_pc_in_sigtramp(CORE_ADDR pc,char * name)187 i386nbsd_pc_in_sigtramp (CORE_ADDR pc, char *name)
188 {
189 return (nbsd_pc_in_sigtramp (pc, name)
190 || i386nbsd_sigtramp_offset (pc) >= 0);
191 }
192
193 /* From <machine/signal.h>. */
194 int i386nbsd_sc_reg_offset[] =
195 {
196 10 * 4, /* %eax */
197 9 * 4, /* %ecx */
198 8 * 4, /* %edx */
199 7 * 4, /* %ebx */
200 14 * 4, /* %esp */
201 6 * 4, /* %ebp */
202 5 * 4, /* %esi */
203 4 * 4, /* %edi */
204 11 * 4, /* %eip */
205 13 * 4, /* %eflags */
206 12 * 4, /* %cs */
207 15 * 4, /* %ss */
208 3 * 4, /* %ds */
209 2 * 4, /* %es */
210 1 * 4, /* %fs */
211 0 * 4 /* %gs */
212 };
213
214 static void
i386nbsd_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)215 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
216 {
217 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
218
219 /* Obviously NetBSD is BSD-based. */
220 i386bsd_init_abi (info, gdbarch);
221
222 /* NetBSD has a different `struct reg'. */
223 tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
224 tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
225 tdep->sizeof_gregset = 16 * 4;
226
227 /* NetBSD has different signal trampoline conventions. */
228 set_gdbarch_pc_in_sigtramp (gdbarch, i386nbsd_pc_in_sigtramp);
229 /* FIXME: kettenis/20020906: We should probably provide
230 NetBSD-specific versions of these functions if we want to
231 recognize signal trampolines that live on the stack. */
232 set_gdbarch_sigtramp_start (gdbarch, NULL);
233 set_gdbarch_sigtramp_end (gdbarch, NULL);
234
235 /* NetBSD uses -freg-struct-return by default. */
236 tdep->struct_return = reg_struct_return;
237
238 /* NetBSD has a `struct sigcontext' that's different from the
239 origional 4.3 BSD. */
240 tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
241 tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
242 }
243
244 /* NetBSD a.out. */
245
246 static void
i386nbsdaout_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)247 i386nbsdaout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
248 {
249 i386nbsd_init_abi (info, gdbarch);
250
251 /* NetBSD a.out has a single register set. */
252 set_gdbarch_regset_from_core_section
253 (gdbarch, i386nbsd_aout_regset_from_core_section);
254 }
255
256 /* NetBSD ELF. */
257
258 static void
i386nbsdelf_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)259 i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
260 {
261 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
262
263 /* It's still NetBSD. */
264 i386nbsd_init_abi (info, gdbarch);
265
266 /* But ELF-based. */
267 i386_elf_init_abi (info, gdbarch);
268
269 /* NetBSD ELF uses SVR4-style shared libraries. */
270 set_gdbarch_in_solib_call_trampoline
271 (gdbarch, generic_in_solib_call_trampoline);
272 set_solib_svr4_fetch_link_map_offsets
273 (gdbarch, svr4_ilp32_fetch_link_map_offsets);
274
275 /* NetBSD ELF uses -fpcc-struct-return by default. */
276 tdep->struct_return = pcc_struct_return;
277 }
278
279 void
_initialize_i386nbsd_tdep(void)280 _initialize_i386nbsd_tdep (void)
281 {
282 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
283 i386nbsdaout_init_abi);
284 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
285 i386nbsdelf_init_abi);
286 }
287