| 1 | /* Target-dependent code for OpenBSD/powerpc. |
| 2 | |
| 3 | Copyright (C) 2004-2018 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 3 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, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "arch-utils.h" |
| 22 | #include "frame.h" |
| 23 | #include "frame-unwind.h" |
| 24 | #include "gdbtypes.h" |
| 25 | #include "osabi.h" |
| 26 | #include "regcache.h" |
| 27 | #include "regset.h" |
| 28 | #include "symtab.h" |
| 29 | #include "trad-frame.h" |
| 30 | |
| 31 | #include "ppc-tdep.h" |
| 32 | #include "ppc-obsd-tdep.h" |
| 33 | #include "solib-svr4.h" |
| 34 | |
| 35 | /* Register offsets from <machine/reg.h>. */ |
| 36 | struct ppc_reg_offsets ppcobsd_reg_offsets; |
| 37 | struct ppc_reg_offsets ppcobsd_fpreg_offsets; |
| 38 | \f |
| 39 | |
| 40 | /* Core file support. */ |
| 41 | |
| 42 | /* Supply register REGNUM in the general-purpose register set REGSET |
| 43 | from the buffer specified by GREGS and LEN to register cache |
| 44 | REGCACHE. If REGNUM is -1, do this for all registers in REGSET. */ |
| 45 | |
| 46 | void |
| 47 | ppcobsd_supply_gregset (const struct regset *regset, |
| 48 | struct regcache *regcache, int regnum, |
| 49 | const void *gregs, size_t len) |
| 50 | { |
| 51 | ppc_supply_gregset (regset, regcache, regnum, gregs, len); |
| 52 | ppc_supply_fpregset (regset, regcache, regnum, gregs, len); |
| 53 | } |
| 54 | |
| 55 | /* Collect register REGNUM in the general-purpose register set |
| 56 | REGSET, from register cache REGCACHE into the buffer specified by |
| 57 | GREGS and LEN. If REGNUM is -1, do this for all registers in |
| 58 | REGSET. */ |
| 59 | |
| 60 | void |
| 61 | ppcobsd_collect_gregset (const struct regset *regset, |
| 62 | const struct regcache *regcache, int regnum, |
| 63 | void *gregs, size_t len) |
| 64 | { |
| 65 | ppc_collect_gregset (regset, regcache, regnum, gregs, len); |
| 66 | ppc_collect_fpregset (regset, regcache, regnum, gregs, len); |
| 67 | } |
| 68 | |
| 69 | /* OpenBSD/powerpc register set. */ |
| 70 | |
| 71 | const struct regset ppcobsd_gregset = |
| 72 | { |
| 73 | &ppcobsd_reg_offsets, |
| 74 | ppcobsd_supply_gregset |
| 75 | }; |
| 76 | |
| 77 | const struct regset ppcobsd_fpregset = |
| 78 | { |
| 79 | &ppcobsd_fpreg_offsets, |
| 80 | ppc_supply_fpregset |
| 81 | }; |
| 82 | |
| 83 | /* Iterate over core file register note sections. */ |
| 84 | |
| 85 | static void |
| 86 | ppcobsd_iterate_over_regset_sections (struct gdbarch *gdbarch, |
| 87 | iterate_over_regset_sections_cb *cb, |
| 88 | void *cb_data, |
| 89 | const struct regcache *regcache) |
| 90 | { |
| 91 | cb (".reg", 412, &ppcobsd_gregset, NULL, cb_data); |
| 92 | } |
| 93 | \f |
| 94 | |
| 95 | /* Signal trampolines. */ |
| 96 | |
| 97 | /* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page |
| 98 | in virtual memory. The randomness makes it somewhat tricky to |
| 99 | detect it, but fortunately we can rely on the fact that the start |
| 100 | of the sigtramp routine is page-aligned. We recognize the |
| 101 | trampoline by looking for the code that invokes the sigreturn |
| 102 | system call. The offset where we can find that code varies from |
| 103 | release to release. |
| 104 | |
| 105 | By the way, the mapping mentioned above is read-only, so you cannot |
| 106 | place a breakpoint in the signal trampoline. */ |
| 107 | |
| 108 | /* Default page size. */ |
| 109 | static const int ppcobsd_page_size = 4096; |
| 110 | |
| 111 | /* Offset for sigreturn(2). */ |
| 112 | static const int ppcobsd_sigreturn_offset[] = { |
| 113 | 0x98, /* OpenBSD 3.8 */ |
| 114 | 0x0c, /* OpenBSD 3.2 */ |
| 115 | -1 |
| 116 | }; |
| 117 | |
| 118 | static int |
| 119 | ppcobsd_sigtramp_frame_sniffer (const struct frame_unwind *self, |
| 120 | struct frame_info *this_frame, |
| 121 | void **this_cache) |
| 122 | { |
| 123 | struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| 124 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 125 | CORE_ADDR pc = get_frame_pc (this_frame); |
| 126 | CORE_ADDR start_pc = (pc & ~(ppcobsd_page_size - 1)); |
| 127 | const int *offset; |
| 128 | const char *name; |
| 129 | |
| 130 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 131 | if (name) |
| 132 | return 0; |
| 133 | |
| 134 | for (offset = ppcobsd_sigreturn_offset; *offset != -1; offset++) |
| 135 | { |
| 136 | gdb_byte buf[2 * PPC_INSN_SIZE]; |
| 137 | unsigned long insn; |
| 138 | |
| 139 | if (!safe_frame_unwind_memory (this_frame, start_pc + *offset, |
| 140 | buf, sizeof buf)) |
| 141 | continue; |
| 142 | |
| 143 | /* Check for "li r0,SYS_sigreturn". */ |
| 144 | insn = extract_unsigned_integer (buf, PPC_INSN_SIZE, byte_order); |
| 145 | if (insn != 0x38000067) |
| 146 | continue; |
| 147 | |
| 148 | /* Check for "sc". */ |
| 149 | insn = extract_unsigned_integer (buf + PPC_INSN_SIZE, |
| 150 | PPC_INSN_SIZE, byte_order); |
| 151 | if (insn != 0x44000002) |
| 152 | continue; |
| 153 | |
| 154 | return 1; |
| 155 | } |
| 156 | |
| 157 | return 0; |
| 158 | } |
| 159 | |
| 160 | static struct trad_frame_cache * |
| 161 | ppcobsd_sigtramp_frame_cache (struct frame_info *this_frame, void **this_cache) |
| 162 | { |
| 163 | struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| 164 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 165 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 166 | struct trad_frame_cache *cache; |
| 167 | CORE_ADDR addr, base, func; |
| 168 | gdb_byte buf[PPC_INSN_SIZE]; |
| 169 | unsigned long insn, sigcontext_offset; |
| 170 | int i; |
| 171 | |
| 172 | if (*this_cache) |
| 173 | return (struct trad_frame_cache *) *this_cache; |
| 174 | |
| 175 | cache = trad_frame_cache_zalloc (this_frame); |
| 176 | *this_cache = cache; |
| 177 | |
| 178 | func = get_frame_pc (this_frame); |
| 179 | func &= ~(ppcobsd_page_size - 1); |
| 180 | if (!safe_frame_unwind_memory (this_frame, func, buf, sizeof buf)) |
| 181 | return cache; |
| 182 | |
| 183 | /* Calculate the offset where we can find `struct sigcontext'. We |
| 184 | base our calculation on the amount of stack space reserved by the |
| 185 | first instruction of the signal trampoline. */ |
| 186 | insn = extract_unsigned_integer (buf, PPC_INSN_SIZE, byte_order); |
| 187 | sigcontext_offset = (0x10000 - (insn & 0x0000ffff)) + 8; |
| 188 | |
| 189 | base = get_frame_register_unsigned (this_frame, gdbarch_sp_regnum (gdbarch)); |
| 190 | addr = base + sigcontext_offset + 2 * tdep->wordsize; |
| 191 | for (i = 0; i < ppc_num_gprs; i++, addr += tdep->wordsize) |
| 192 | { |
| 193 | int regnum = i + tdep->ppc_gp0_regnum; |
| 194 | trad_frame_set_reg_addr (cache, regnum, addr); |
| 195 | } |
| 196 | trad_frame_set_reg_addr (cache, tdep->ppc_lr_regnum, addr); |
| 197 | addr += tdep->wordsize; |
| 198 | trad_frame_set_reg_addr (cache, tdep->ppc_cr_regnum, addr); |
| 199 | addr += tdep->wordsize; |
| 200 | trad_frame_set_reg_addr (cache, tdep->ppc_xer_regnum, addr); |
| 201 | addr += tdep->wordsize; |
| 202 | trad_frame_set_reg_addr (cache, tdep->ppc_ctr_regnum, addr); |
| 203 | addr += tdep->wordsize; |
| 204 | trad_frame_set_reg_addr (cache, gdbarch_pc_regnum (gdbarch), addr); |
| 205 | /* SRR0? */ |
| 206 | addr += tdep->wordsize; |
| 207 | |
| 208 | /* Construct the frame ID using the function start. */ |
| 209 | trad_frame_set_id (cache, frame_id_build (base, func)); |
| 210 | |
| 211 | return cache; |
| 212 | } |
| 213 | |
| 214 | static void |
| 215 | ppcobsd_sigtramp_frame_this_id (struct frame_info *this_frame, |
| 216 | void **this_cache, struct frame_id *this_id) |
| 217 | { |
| 218 | struct trad_frame_cache *cache = |
| 219 | ppcobsd_sigtramp_frame_cache (this_frame, this_cache); |
| 220 | |
| 221 | trad_frame_get_id (cache, this_id); |
| 222 | } |
| 223 | |
| 224 | static struct value * |
| 225 | ppcobsd_sigtramp_frame_prev_register (struct frame_info *this_frame, |
| 226 | void **this_cache, int regnum) |
| 227 | { |
| 228 | struct trad_frame_cache *cache = |
| 229 | ppcobsd_sigtramp_frame_cache (this_frame, this_cache); |
| 230 | |
| 231 | return trad_frame_get_register (cache, this_frame, regnum); |
| 232 | } |
| 233 | |
| 234 | static const struct frame_unwind ppcobsd_sigtramp_frame_unwind = { |
| 235 | SIGTRAMP_FRAME, |
| 236 | default_frame_unwind_stop_reason, |
| 237 | ppcobsd_sigtramp_frame_this_id, |
| 238 | ppcobsd_sigtramp_frame_prev_register, |
| 239 | NULL, |
| 240 | ppcobsd_sigtramp_frame_sniffer |
| 241 | }; |
| 242 | \f |
| 243 | |
| 244 | static void |
| 245 | ppcobsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 246 | { |
| 247 | /* OpenBSD doesn't support the 128-bit `long double' from the psABI. */ |
| 248 | set_gdbarch_long_double_bit (gdbarch, 64); |
| 249 | set_gdbarch_long_double_format (gdbarch, floatformats_ieee_double); |
| 250 | |
| 251 | /* OpenBSD currently uses a broken GCC. */ |
| 252 | set_gdbarch_return_value (gdbarch, ppc_sysv_abi_broken_return_value); |
| 253 | |
| 254 | /* OpenBSD uses SVR4-style shared libraries. */ |
| 255 | set_solib_svr4_fetch_link_map_offsets |
| 256 | (gdbarch, svr4_ilp32_fetch_link_map_offsets); |
| 257 | |
| 258 | set_gdbarch_iterate_over_regset_sections |
| 259 | (gdbarch, ppcobsd_iterate_over_regset_sections); |
| 260 | |
| 261 | frame_unwind_append_unwinder (gdbarch, &ppcobsd_sigtramp_frame_unwind); |
| 262 | } |
| 263 | |
| 264 | void |
| 265 | _initialize_ppcobsd_tdep (void) |
| 266 | { |
| 267 | gdbarch_register_osabi (bfd_arch_rs6000, 0, GDB_OSABI_OPENBSD, |
| 268 | ppcobsd_init_abi); |
| 269 | gdbarch_register_osabi (bfd_arch_powerpc, 0, GDB_OSABI_OPENBSD, |
| 270 | ppcobsd_init_abi); |
| 271 | |
| 272 | /* Avoid initializing the register offsets again if they were |
| 273 | already initialized by ppcobsd-nat.c. */ |
| 274 | if (ppcobsd_reg_offsets.pc_offset == 0) |
| 275 | { |
| 276 | /* General-purpose registers. */ |
| 277 | ppcobsd_reg_offsets.r0_offset = 0; |
| 278 | ppcobsd_reg_offsets.gpr_size = 4; |
| 279 | ppcobsd_reg_offsets.xr_size = 4; |
| 280 | ppcobsd_reg_offsets.pc_offset = 384; |
| 281 | ppcobsd_reg_offsets.ps_offset = 388; |
| 282 | ppcobsd_reg_offsets.cr_offset = 392; |
| 283 | ppcobsd_reg_offsets.lr_offset = 396; |
| 284 | ppcobsd_reg_offsets.ctr_offset = 400; |
| 285 | ppcobsd_reg_offsets.xer_offset = 404; |
| 286 | ppcobsd_reg_offsets.mq_offset = 408; |
| 287 | |
| 288 | /* Floating-point registers. */ |
| 289 | ppcobsd_reg_offsets.f0_offset = 128; |
| 290 | ppcobsd_reg_offsets.fpscr_offset = -1; |
| 291 | |
| 292 | /* AltiVec registers. */ |
| 293 | ppcobsd_reg_offsets.vr0_offset = 0; |
| 294 | ppcobsd_reg_offsets.vscr_offset = 512; |
| 295 | ppcobsd_reg_offsets.vrsave_offset = 520; |
| 296 | } |
| 297 | |
| 298 | if (ppcobsd_fpreg_offsets.fpscr_offset == 0) |
| 299 | { |
| 300 | /* Floating-point registers. */ |
| 301 | ppcobsd_reg_offsets.f0_offset = 0; |
| 302 | ppcobsd_reg_offsets.fpscr_offset = 256; |
| 303 | ppcobsd_reg_offsets.fpscr_size = 4; |
| 304 | } |
| 305 | } |