1 /* Target-dependent code for OpenBSD/mips64.
2
3 Copyright 2004 Free Software Foundation, Inc.
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
9 the Free Software Foundation; either version 2 of the License, or
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
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
21
22 #include "defs.h"
23 #include "gdbcore.h"
24 #include "osabi.h"
25 #include "regcache.h"
26 #include "regset.h"
27 #include "trad-frame.h"
28 #include "tramp-frame.h"
29
30 #include "gdb_assert.h"
31 #include "gdb_string.h"
32
33 #include "mips-tdep.h"
34 #include "obsd-tdep.h"
35 #include "solib-svr4.h"
36
37 #define MIPS64OBSD_NUM_REGS 73
38
39 /* Core file support. */
40
41 /* Supply register REGNUM from the buffer specified by GREGS and LEN
42 in the general-purpose register set REGSET to register cache
43 REGCACHE. If REGNUM is -1, do this for all registers in REGSET. */
44
45 static void
mips64obsd_supply_gregset(const struct regset * regset,struct regcache * regcache,int regnum,const void * gregs,size_t len)46 mips64obsd_supply_gregset (const struct regset *regset,
47 struct regcache *regcache, int regnum,
48 const void *gregs, size_t len)
49 {
50 const char *regs = gregs;
51 int i;
52
53 for (i = 0; i < MIPS64OBSD_NUM_REGS; i++)
54 {
55 if (regnum == i || regnum == -1)
56 regcache_raw_supply (regcache, i, regs + i * 8);
57 }
58 }
59
60 /* OpenBSD/mips64 register set. */
61
62 static struct regset mips64obsd_gregset =
63 {
64 NULL,
65 mips64obsd_supply_gregset
66 };
67
68 /* Return the appropriate register set for the core section identified
69 by SECT_NAME and SECT_SIZE. */
70
71 static const struct regset *
mips64obsd_regset_from_core_section(struct gdbarch * gdbarch,const char * sect_name,size_t sect_size)72 mips64obsd_regset_from_core_section (struct gdbarch *gdbarch,
73 const char *sect_name, size_t sect_size)
74 {
75 if (strcmp (sect_name, ".reg") == 0 && sect_size >= MIPS64OBSD_NUM_REGS * 8)
76 return &mips64obsd_gregset;
77
78 return NULL;
79 }
80
81
82 /* Signal trampolines. */
83
84 static void
mips64obsd_sigframe_init(const struct tramp_frame * self,struct frame_info * next_frame,struct trad_frame_cache * cache,CORE_ADDR func)85 mips64obsd_sigframe_init (const struct tramp_frame *self,
86 struct frame_info *next_frame,
87 struct trad_frame_cache *cache,
88 CORE_ADDR func)
89 {
90 struct gdbarch *gdbarch = get_frame_arch (next_frame);
91 CORE_ADDR sp, sigcontext_addr, addr;
92 int regnum;
93
94 /* We find the appropriate instance of `struct sigcontext' at a
95 fixed offset in the signal frame. */
96 sp = frame_unwind_register_signed (next_frame, MIPS_SP_REGNUM + NUM_REGS);
97 sigcontext_addr = sp + 32;
98
99 /* PC. */
100 regnum = mips_regnum (gdbarch)->pc;
101 trad_frame_set_reg_addr (cache, regnum + NUM_REGS, sigcontext_addr + 16);
102
103 /* GPRs. */
104 for (regnum = MIPS_AT_REGNUM, addr = sigcontext_addr + 32;
105 regnum <= MIPS_RA_REGNUM; regnum++, addr += 8)
106 trad_frame_set_reg_addr (cache, regnum + NUM_REGS, addr);
107
108 /* HI and LO. */
109 regnum = mips_regnum (gdbarch)->lo;
110 trad_frame_set_reg_addr (cache, regnum + NUM_REGS, sigcontext_addr + 280);
111 regnum = mips_regnum (gdbarch)->hi;
112 trad_frame_set_reg_addr (cache, regnum + NUM_REGS, sigcontext_addr + 288);
113
114 /* TODO: Handle the floating-point registers. */
115
116 trad_frame_set_id (cache, frame_id_build (sp, func));
117 }
118
119 static const struct tramp_frame mips64obsd_sigframe =
120 {
121 SIGTRAMP_FRAME,
122 MIPS_INSN32_SIZE,
123 {
124 { 0x67a40020, -1 }, /* daddiu a0,sp,32 */
125 { 0x24020067, -1 }, /* li v0,103 */
126 { 0x0000000c, -1 }, /* syscall */
127 { 0x0000000d, -1 }, /* break */
128 { TRAMP_SENTINEL_INSN, -1 }
129 },
130 mips64obsd_sigframe_init
131 };
132
133
134 /* Check the code at PC for a dynamic linker lazy resolution stub. Because
135 they aren't in the .plt section, we pattern-match on the code generated
136 by GNU ld. They look like this:
137
138 ld t9,0x8010(gp)
139 daddu t7,ra
140 jalr t9,ra
141 daddiu t8,zero,INDEX
142
143 Also return the dynamic symbol index used in the last instruction. */
144
145 static int
mips64obsd_in_dynsym_stub(CORE_ADDR pc,char * name)146 mips64obsd_in_dynsym_stub (CORE_ADDR pc, char *name)
147 {
148 unsigned char buf[28], *p;
149 ULONGEST insn;
150
151 read_memory (pc - 12, buf, 28);
152
153 p = buf + 12;
154 while (p >= buf)
155 {
156 insn = extract_unsigned_integer (p, 4);
157 /* ld t9,0x8010(gp) */
158 if (insn == 0xdf998010)
159 break;
160 p -= 4;
161 }
162 if (p < buf)
163 return 0;
164
165 insn = extract_unsigned_integer (p + 4, 4);
166 /* daddu t7,ra */
167 if (insn != 0x03e0782d)
168 return 0;
169
170 insn = extract_unsigned_integer (p + 8, 4);
171 /* jalr t9,ra */
172 if (insn != 0x0320f809)
173 return 0;
174
175 insn = extract_unsigned_integer (p + 12, 4);
176 /* daddiu t8,zero,0 */
177 if ((insn & 0xffff0000) != 0x64180000)
178 return 0;
179
180 return (insn & 0xffff);
181 }
182
183 /* Return non-zero iff PC belongs to the dynamic linker resolution code
184 or to a stub. */
185
186 int
mips64obsd_in_dynsym_resolve_code(CORE_ADDR pc)187 mips64obsd_in_dynsym_resolve_code (CORE_ADDR pc)
188 {
189 /* Check whether PC is in the dynamic linker. This also checks whether
190 it is in the .plt section, which MIPS does not use. */
191 if (in_solib_dynsym_resolve_code (pc))
192 return 1;
193
194 /* Pattern match for the stub. It would be nice if there were a more
195 efficient way to avoid this check. */
196 if (mips64obsd_in_dynsym_stub (pc, NULL))
197 return 1;
198
199 return 0;
200 }
201
202
203 static void
mips64obsd_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)204 mips64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
205 {
206 /* OpenBSD/mips64 only supports the n64 ABI, but the braindamaged
207 way GDB works, forces us to pretend we can handle them all. */
208
209 set_gdbarch_regset_from_core_section
210 (gdbarch, mips64obsd_regset_from_core_section);
211
212 tramp_frame_prepend_unwinder (gdbarch, &mips64obsd_sigframe);
213
214 #if 0
215 set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
216 #endif
217
218 /* OpenBSD/mips64 has SVR4-style shared libraries. */
219 set_gdbarch_in_solib_call_trampoline (gdbarch, mips64obsd_in_dynsym_stub);
220 set_solib_svr4_fetch_link_map_offsets
221 (gdbarch, svr4_lp64_fetch_link_map_offsets);
222 set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
223 }
224
225
226 /* Provide a prototype to silence -Wmissing-prototypes. */
227 void _initialize_mips64obsd_tdep (void);
228
229 void
_initialize_mips64obsd_tdep(void)230 _initialize_mips64obsd_tdep (void)
231 {
232 gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_OPENBSD_ELF,
233 mips64obsd_init_abi);
234 }
235