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(struct frame_info * next_frame)135 i386nbsd_sigtramp_offset (struct frame_info *next_frame)
136 {
137 CORE_ADDR pc = frame_pc_unwind (next_frame);
138 unsigned char ret[sizeof(sigtramp_retcode)], insn;
139 LONGEST off;
140 int i;
141
142 if (!safe_frame_unwind_memory (next_frame, pc, &insn, 1))
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 (!safe_frame_unwind_memory (next_frame, pc + 1, &insn, 1))
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 (!safe_frame_unwind_memory (next_frame, pc, ret, sizeof (ret)))
178 return -1;
179
180 if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
181 return off;
182
183 return -1;
184 }
185
186 /* Return whether the frame preceding NEXT_FRAME corresponds to a
187 NetBSD sigtramp routine. */
188
189 static int
i386nbsd_sigtramp_p(struct frame_info * next_frame)190 i386nbsd_sigtramp_p (struct frame_info *next_frame)
191 {
192 CORE_ADDR pc = frame_pc_unwind (next_frame);
193 char *name;
194
195 find_pc_partial_function (pc, &name, NULL, NULL);
196 return (nbsd_pc_in_sigtramp (pc, name)
197 || i386nbsd_sigtramp_offset (next_frame) >= 0);
198 }
199
200 /* From <machine/signal.h>. */
201 int i386nbsd_sc_reg_offset[] =
202 {
203 10 * 4, /* %eax */
204 9 * 4, /* %ecx */
205 8 * 4, /* %edx */
206 7 * 4, /* %ebx */
207 14 * 4, /* %esp */
208 6 * 4, /* %ebp */
209 5 * 4, /* %esi */
210 4 * 4, /* %edi */
211 11 * 4, /* %eip */
212 13 * 4, /* %eflags */
213 12 * 4, /* %cs */
214 15 * 4, /* %ss */
215 3 * 4, /* %ds */
216 2 * 4, /* %es */
217 1 * 4, /* %fs */
218 0 * 4 /* %gs */
219 };
220
221 static void
i386nbsd_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)222 i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
223 {
224 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
225
226 /* Obviously NetBSD is BSD-based. */
227 i386bsd_init_abi (info, gdbarch);
228
229 /* NetBSD has a different `struct reg'. */
230 tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
231 tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
232 tdep->sizeof_gregset = 16 * 4;
233
234 /* NetBSD has different signal trampoline conventions. */
235 tdep->sigtramp_start = 0;
236 tdep->sigtramp_end = 0;
237 tdep->sigtramp_p = i386nbsd_sigtramp_p;
238
239 /* NetBSD uses -freg-struct-return by default. */
240 tdep->struct_return = reg_struct_return;
241
242 /* NetBSD has a `struct sigcontext' that's different from the
243 original 4.3 BSD. */
244 tdep->sc_reg_offset = i386nbsd_sc_reg_offset;
245 tdep->sc_num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);
246 }
247
248 /* NetBSD a.out. */
249
250 static void
i386nbsdaout_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)251 i386nbsdaout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
252 {
253 i386nbsd_init_abi (info, gdbarch);
254
255 /* NetBSD a.out has a single register set. */
256 set_gdbarch_regset_from_core_section
257 (gdbarch, i386nbsd_aout_regset_from_core_section);
258 }
259
260 /* NetBSD ELF. */
261
262 static void
i386nbsdelf_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)263 i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
264 {
265 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
266
267 /* It's still NetBSD. */
268 i386nbsd_init_abi (info, gdbarch);
269
270 /* But ELF-based. */
271 i386_elf_init_abi (info, gdbarch);
272
273 /* NetBSD ELF uses SVR4-style shared libraries. */
274 set_gdbarch_in_solib_call_trampoline
275 (gdbarch, generic_in_solib_call_trampoline);
276 set_solib_svr4_fetch_link_map_offsets
277 (gdbarch, svr4_ilp32_fetch_link_map_offsets);
278
279 /* NetBSD ELF uses -fpcc-struct-return by default. */
280 tdep->struct_return = pcc_struct_return;
281 }
282
283 void
_initialize_i386nbsd_tdep(void)284 _initialize_i386nbsd_tdep (void)
285 {
286 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
287 i386nbsdaout_init_abi);
288 gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
289 i386nbsdelf_init_abi);
290 }
291