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1 | /* Target-dependent code for OpenBSD/vax. |
2 | ||
9b254dd1 | 3 | Copyright (C) 2005, 2007, 2008 Free Software Foundation, Inc. |
cfaf379b MK |
4 | |
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
a9762ec7 | 9 | the Free Software Foundation; either version 3 of the License, or |
cfaf379b MK |
10 | (at your option) any later version. |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
a9762ec7 | 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
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19 | |
20 | #include "defs.h" | |
21 | #include "arch-utils.h" | |
22 | #include "frame.h" | |
23 | #include "frame-unwind.h" | |
24 | #include "osabi.h" | |
25 | #include "symtab.h" | |
26 | #include "trad-frame.h" | |
27 | ||
28 | #include "vax-tdep.h" | |
29 | ||
30 | #include "gdb_string.h" | |
31 | ||
32 | /* Signal trampolines. */ | |
33 | ||
34 | /* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page | |
35 | in virtual memory. The randomness makes it somewhat tricky to | |
36 | detect it, but fortunately we can rely on the fact that the start | |
37 | of the sigtramp routine is page-aligned. We recognize the | |
38 | trampoline by looking for the code that invokes the sigreturn | |
39 | system call. The offset where we can find that code varies from | |
40 | release to release. | |
41 | ||
42 | By the way, the mapping mentioned above is read-only, so you cannot | |
43 | place a breakpoint in the signal trampoline. */ | |
44 | ||
45 | /* Default page size. */ | |
46 | static const int vaxobsd_page_size = 4096; | |
47 | ||
48 | /* Offset for sigreturn(2). */ | |
49 | static const int vaxobsd_sigreturn_offset = 0x11; | |
50 | ||
51 | /* Instruction sequence for sigreturn(2). VAX doesn't have | |
52 | fixed-length instructions so we include the ensuing exit(2) to | |
53 | reduce the chance of spurious matches. */ | |
54 | static const gdb_byte vaxobsd_sigreturn[] = { | |
55 | 0xbc, 0x8f, 0x67, 0x00, /* chmk $SYS_sigreturn */ | |
56 | 0xbc, 0x01 /* chmk $SYS_exit */ | |
57 | }; | |
58 | ||
59 | static int | |
60 | vaxobsd_sigtramp_p (struct frame_info *next_frame) | |
61 | { | |
62 | CORE_ADDR pc = frame_pc_unwind (next_frame); | |
63 | CORE_ADDR start_pc = (pc & ~(vaxobsd_page_size - 1)); | |
64 | CORE_ADDR sigreturn_addr = start_pc + vaxobsd_sigreturn_offset; | |
65 | gdb_byte *buf; | |
66 | char *name; | |
67 | ||
68 | find_pc_partial_function (pc, &name, NULL, NULL); | |
69 | if (name) | |
70 | return 0; | |
71 | ||
72 | buf = alloca(sizeof vaxobsd_sigreturn); | |
73 | if (!safe_frame_unwind_memory (next_frame, sigreturn_addr, | |
74 | buf, sizeof vaxobsd_sigreturn)) | |
75 | return 0; | |
76 | ||
77 | if (memcmp(buf, vaxobsd_sigreturn, sizeof vaxobsd_sigreturn) == 0) | |
78 | return 1; | |
79 | ||
80 | return 0; | |
81 | } | |
82 | ||
83 | static struct trad_frame_cache * | |
84 | vaxobsd_sigtramp_frame_cache (struct frame_info *next_frame, void **this_cache) | |
85 | { | |
86 | struct trad_frame_cache *cache; | |
87 | CORE_ADDR addr, base, func; | |
88 | ||
89 | if (*this_cache) | |
90 | return *this_cache; | |
91 | ||
92 | cache = trad_frame_cache_zalloc (next_frame); | |
93 | *this_cache = cache; | |
94 | ||
95 | func = frame_pc_unwind (next_frame); | |
96 | func &= ~(vaxobsd_page_size - 1); | |
97 | ||
98 | base = frame_unwind_register_unsigned (next_frame, VAX_SP_REGNUM); | |
99 | addr = get_frame_memory_unsigned (next_frame, base - 4, 4); | |
100 | ||
101 | trad_frame_set_reg_addr (cache, VAX_SP_REGNUM, addr + 8); | |
102 | trad_frame_set_reg_addr (cache, VAX_FP_REGNUM, addr + 12); | |
103 | trad_frame_set_reg_addr (cache, VAX_AP_REGNUM, addr + 16); | |
104 | trad_frame_set_reg_addr (cache, VAX_PC_REGNUM, addr + 20); | |
105 | trad_frame_set_reg_addr (cache, VAX_PS_REGNUM, addr + 24); | |
106 | ||
107 | /* Construct the frame ID using the function start. */ | |
108 | trad_frame_set_id (cache, frame_id_build (base, func)); | |
109 | ||
110 | return cache; | |
111 | } | |
112 | ||
113 | static void | |
114 | vaxobsd_sigtramp_frame_this_id (struct frame_info *next_frame, | |
115 | void **this_cache, struct frame_id *this_id) | |
116 | { | |
117 | struct trad_frame_cache *cache = | |
118 | vaxobsd_sigtramp_frame_cache (next_frame, this_cache); | |
119 | ||
120 | trad_frame_get_id (cache, this_id); | |
121 | } | |
122 | ||
123 | static void | |
124 | vaxobsd_sigtramp_frame_prev_register (struct frame_info *next_frame, | |
125 | void **this_cache, int regnum, | |
126 | int *optimizedp, enum lval_type *lvalp, | |
127 | CORE_ADDR *addrp, int *realnump, | |
128 | gdb_byte *valuep) | |
129 | { | |
130 | struct trad_frame_cache *cache = | |
131 | vaxobsd_sigtramp_frame_cache (next_frame, this_cache); | |
132 | ||
133 | trad_frame_get_register (cache, next_frame, regnum, | |
134 | optimizedp, lvalp, addrp, realnump, valuep); | |
135 | } | |
136 | ||
137 | static const struct frame_unwind vaxobsd_sigtramp_frame_unwind = { | |
138 | SIGTRAMP_FRAME, | |
139 | vaxobsd_sigtramp_frame_this_id, | |
140 | vaxobsd_sigtramp_frame_prev_register | |
141 | }; | |
142 | ||
143 | static const struct frame_unwind * | |
144 | vaxobsd_sigtramp_frame_sniffer (struct frame_info *next_frame) | |
145 | { | |
146 | if (vaxobsd_sigtramp_p (next_frame)) | |
147 | return &vaxobsd_sigtramp_frame_unwind; | |
148 | ||
149 | return NULL; | |
150 | } | |
151 | \f | |
152 | ||
153 | /* OpenBSD a.out. */ | |
154 | ||
155 | static void | |
156 | vaxobsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) | |
157 | { | |
158 | frame_unwind_append_sniffer (gdbarch, vaxobsd_sigtramp_frame_sniffer); | |
159 | } | |
160 | ||
161 | /* FIXME: kettenis/20050821: Since OpenBSD/vax binaries are | |
162 | indistingushable from NetBSD/vax a.out binaries, building a GDB | |
163 | that should support both these targets will probably not work as | |
164 | expected. */ | |
165 | #define GDB_OSABI_OPENBSD_AOUT GDB_OSABI_NETBSD_AOUT | |
166 | ||
167 | static enum gdb_osabi | |
168 | vaxobsd_aout_osabi_sniffer (bfd *abfd) | |
169 | { | |
170 | if (strcmp (bfd_get_target (abfd), "a.out-vax-netbsd") == 0) | |
171 | return GDB_OSABI_OPENBSD_AOUT; | |
172 | ||
173 | return GDB_OSABI_UNKNOWN; | |
174 | } | |
175 | \f | |
176 | ||
177 | /* Provide a prototype to silence -Wmissing-prototypes. */ | |
178 | void _initialize_vaxobsd_tdep (void); | |
179 | ||
180 | void | |
181 | _initialize_vaxobsd_tdep (void) | |
182 | { | |
183 | gdbarch_register_osabi_sniffer (bfd_arch_vax, bfd_target_aout_flavour, | |
184 | vaxobsd_aout_osabi_sniffer); | |
185 | ||
186 | gdbarch_register_osabi (bfd_arch_vax, 0, GDB_OSABI_OPENBSD_AOUT, | |
187 | vaxobsd_init_abi); | |
188 | } |