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 "frame.h"
27 #include "gdbcore.h"
28 #include "regcache.h"
29 #include "regset.h"
30 #include "osabi.h"
31 #include "symtab.h"
32
33 #include "gdb_assert.h"
34 #include "gdb_string.h"
35
36 #include "i386-tdep.h"
37 #include "i387-tdep.h"
38 #include "nbsd-tdep.h"
39 #include "solib-svr4.h"
40
41 /* From <machine/reg.h>. */
42 static int i386nbsd_r_reg_offset[] =
43 {
44 0 * 4, /* %eax */
45 1 * 4, /* %ecx */
46 2 * 4, /* %edx */
47 3 * 4, /* %ebx */
48 4 * 4, /* %esp */
49 5 * 4, /* %ebp */
50 6 * 4, /* %esi */
51 7 * 4, /* %edi */
52 8 * 4, /* %eip */
53 9 * 4, /* %eflags */
54 10 * 4, /* %cs */
55 11 * 4, /* %ss */
56 12 * 4, /* %ds */
57 13 * 4, /* %es */
58 14 * 4, /* %fs */
59 15 * 4 /* %gs */
60 };
61
62 static void
i386nbsd_aout_supply_regset(const struct regset * regset,struct regcache * regcache,int regnum,const void * regs,size_t len)63 i386nbsd_aout_supply_regset (const struct regset *regset,
64 struct regcache *regcache, int regnum,
65 const void *regs, size_t len)
66 {
67 const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
68
69 gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE);
70
71 i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
72 i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset);
73 }
74
75 static const struct regset *
i386nbsd_aout_regset_from_core_section(struct gdbarch * gdbarch,const char * sect_name,size_t sect_size)76 i386nbsd_aout_regset_from_core_section (struct gdbarch *gdbarch,
77 const char *sect_name,
78 size_t sect_size)
79 {
80 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
81
82 /* NetBSD a.out core dumps don't use seperate register sets for the
83 general-purpose and floating-point registers. */
84
85 if (strcmp (sect_name, ".reg") == 0
86 && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE)
87 {
88 if (tdep->gregset == NULL)
89 tdep->gregset =
90 regset_alloc (gdbarch, i386nbsd_aout_supply_regset, NULL);
91 return tdep->gregset;
92 }
93
94 return NULL;
95 }
96
97 /* Under NetBSD/i386, signal handler invocations can be identified by the
98 designated code sequence that is used to return from a signal handler.
99 In particular, the return address of a signal handler points to the
100 following code sequence:
101
102 leal 0x10(%esp), %eax
103 pushl %eax
104 pushl %eax
105 movl $0x127, %eax # __sigreturn14
106 int $0x80
107
108 Each instruction has a unique encoding, so we simply attempt to match
109 the instruction the PC is pointing to with any of the above instructions.
110 If there is a hit, we know the offset to the start of the designated
111 sequence and can then check whether we really are executing in the
112 signal trampoline. If not, -1 is returned, otherwise the offset from the
113 start of the return sequence is returned. */
114 #define RETCODE_INSN1 0x8d
115 #define RETCODE_INSN2 0x50
116 #define RETCODE_INSN3 0x50
117 #define RETCODE_INSN4 0xb8
118 #define RETCODE_INSN5 0xcd
119
120 #define RETCODE_INSN2_OFF 4
121 #define RETCODE_INSN3_OFF 5
122 #define RETCODE_INSN4_OFF 6
123 #define RETCODE_INSN5_OFF 11
124
125 static const unsigned char sigtramp_retcode[] =
126 {
127 RETCODE_INSN1, 0x44, 0x24, 0x10,
128 RETCODE_INSN2,
129 RETCODE_INSN3,
130 RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
131 RETCODE_INSN5, 0x80,
132 };
133
134 static LONGEST
i386nbsd_sigtramp_offset(CORE_ADDR pc)135 i386nbsd_sigtramp_offset (CORE_ADDR pc)
136 {
137 unsigned char ret[sizeof(sigtramp_retcode)], insn;
138 LONGEST off;
139 int i;
140
141 if (read_memory_nobpt (pc, &insn, 1) != 0)
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 (read_memory_nobpt (pc + 1, &insn, 1) != 0)
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 (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
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
i386nbsd_sigtramp_p(struct frame_info * next_frame)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 (pc) >= 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
i386nbsd_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)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
i386nbsdaout_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)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
i386nbsdelf_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)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_gdbarch_in_solib_call_trampoline
274 (gdbarch, generic_in_solib_call_trampoline);
275 set_solib_svr4_fetch_link_map_offsets
276 (gdbarch, svr4_ilp32_fetch_link_map_offsets);
277
278 /* NetBSD ELF uses -fpcc-struct-return by default. */
279 tdep->struct_return = pcc_struct_return;
280 }
281
282 void
_initialize_i386nbsd_tdep(void)283 _initialize_i386nbsd_tdep (void)
284 {
285 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
286 i386nbsdaout_init_abi);
287 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
288 i386nbsdelf_init_abi);
289 }
290