| 1 | /* Target-dependent code for OpenBSD/i386. |
| 2 | |
| 3 | Copyright 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002, |
| 4 | 2003, 2004, 2005 |
| 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 "symtab.h" |
| 31 | #include "objfiles.h" |
| 32 | #include "osabi.h" |
| 33 | #include "target.h" |
| 34 | |
| 35 | #include "gdb_assert.h" |
| 36 | #include "gdb_string.h" |
| 37 | |
| 38 | #include "i386-tdep.h" |
| 39 | #include "i387-tdep.h" |
| 40 | #include "solib-svr4.h" |
| 41 | #include "bsd-uthread.h" |
| 42 | |
| 43 | /* Support for signal handlers. */ |
| 44 | |
| 45 | /* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page |
| 46 | in virtual memory. The randomness makes it somewhat tricky to |
| 47 | detect it, but fortunately we can rely on the fact that the start |
| 48 | of the sigtramp routine is page-aligned. By the way, the mapping |
| 49 | is read-only, so you cannot place a breakpoint in the signal |
| 50 | trampoline. */ |
| 51 | |
| 52 | /* Default page size. */ |
| 53 | static const int i386obsd_page_size = 4096; |
| 54 | |
| 55 | /* Return whether the frame preceding NEXT_FRAME corresponds to an |
| 56 | OpenBSD sigtramp routine. */ |
| 57 | |
| 58 | static int |
| 59 | i386obsd_sigtramp_p (struct frame_info *next_frame) |
| 60 | { |
| 61 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 62 | CORE_ADDR start_pc = (pc & ~(i386obsd_page_size - 1)); |
| 63 | const char sigreturn[] = |
| 64 | { |
| 65 | 0xb8, |
| 66 | 0x67, 0x00, 0x00, 0x00, /* movl $SYS_sigreturn, %eax */ |
| 67 | 0xcd, 0x80 /* int $0x80 */ |
| 68 | }; |
| 69 | size_t buflen = sizeof sigreturn; |
| 70 | char *name, *buf; |
| 71 | |
| 72 | /* If the function has a valid symbol name, it isn't a |
| 73 | trampoline. */ |
| 74 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 75 | if (name != NULL) |
| 76 | return 0; |
| 77 | |
| 78 | /* If the function lives in a valid section (even without a starting |
| 79 | point) it isn't a trampoline. */ |
| 80 | if (find_pc_section (pc) != NULL) |
| 81 | return 0; |
| 82 | |
| 83 | /* Allocate buffer. */ |
| 84 | buf = alloca (buflen); |
| 85 | |
| 86 | /* If we can't read the instructions at START_PC, return zero. */ |
| 87 | if (!safe_frame_unwind_memory (next_frame, start_pc + 0x0a, buf, buflen)) |
| 88 | return 0; |
| 89 | |
| 90 | /* Check for sigreturn(2). */ |
| 91 | if (memcmp (buf, sigreturn, buflen) == 0) |
| 92 | return 1; |
| 93 | |
| 94 | /* If we can't read the instructions at START_PC, return zero. */ |
| 95 | if (!safe_frame_unwind_memory (next_frame, start_pc + 0x14, buf, buflen)) |
| 96 | return 0; |
| 97 | |
| 98 | /* Check for sigreturn(2) (again). */ |
| 99 | if (memcmp (buf, sigreturn, buflen) == 0) |
| 100 | return 1; |
| 101 | |
| 102 | return 0; |
| 103 | } |
| 104 | \f |
| 105 | /* Mapping between the general-purpose registers in `struct reg' |
| 106 | format and GDB's register cache layout. */ |
| 107 | |
| 108 | /* From <machine/reg.h>. */ |
| 109 | static int i386obsd_r_reg_offset[] = |
| 110 | { |
| 111 | 0 * 4, /* %eax */ |
| 112 | 1 * 4, /* %ecx */ |
| 113 | 2 * 4, /* %edx */ |
| 114 | 3 * 4, /* %ebx */ |
| 115 | 4 * 4, /* %esp */ |
| 116 | 5 * 4, /* %ebp */ |
| 117 | 6 * 4, /* %esi */ |
| 118 | 7 * 4, /* %edi */ |
| 119 | 8 * 4, /* %eip */ |
| 120 | 9 * 4, /* %eflags */ |
| 121 | 10 * 4, /* %cs */ |
| 122 | 11 * 4, /* %ss */ |
| 123 | 12 * 4, /* %ds */ |
| 124 | 13 * 4, /* %es */ |
| 125 | 14 * 4, /* %fs */ |
| 126 | 15 * 4 /* %gs */ |
| 127 | }; |
| 128 | |
| 129 | static void |
| 130 | i386obsd_aout_supply_regset (const struct regset *regset, |
| 131 | struct regcache *regcache, int regnum, |
| 132 | const void *regs, size_t len) |
| 133 | { |
| 134 | const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch); |
| 135 | |
| 136 | gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE); |
| 137 | |
| 138 | i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset); |
| 139 | i387_supply_fsave (regcache, regnum, (char *) regs + tdep->sizeof_gregset); |
| 140 | } |
| 141 | |
| 142 | static const struct regset * |
| 143 | i386obsd_aout_regset_from_core_section (struct gdbarch *gdbarch, |
| 144 | const char *sect_name, |
| 145 | size_t sect_size) |
| 146 | { |
| 147 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 148 | |
| 149 | /* OpenBSD a.out core dumps don't use seperate register sets for the |
| 150 | general-purpose and floating-point registers. */ |
| 151 | |
| 152 | if (strcmp (sect_name, ".reg") == 0 |
| 153 | && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE) |
| 154 | { |
| 155 | if (tdep->gregset == NULL) |
| 156 | tdep->gregset = |
| 157 | regset_alloc (gdbarch, i386obsd_aout_supply_regset, NULL); |
| 158 | return tdep->gregset; |
| 159 | } |
| 160 | |
| 161 | return NULL; |
| 162 | } |
| 163 | \f |
| 164 | |
| 165 | /* Sigtramp routine location for OpenBSD 3.1 and earlier releases. */ |
| 166 | CORE_ADDR i386obsd_sigtramp_start_addr = 0xbfbfdf20; |
| 167 | CORE_ADDR i386obsd_sigtramp_end_addr = 0xbfbfdff0; |
| 168 | |
| 169 | /* From <machine/signal.h>. */ |
| 170 | int i386obsd_sc_reg_offset[I386_NUM_GREGS] = |
| 171 | { |
| 172 | 10 * 4, /* %eax */ |
| 173 | 9 * 4, /* %ecx */ |
| 174 | 8 * 4, /* %edx */ |
| 175 | 7 * 4, /* %ebx */ |
| 176 | 14 * 4, /* %esp */ |
| 177 | 6 * 4, /* %ebp */ |
| 178 | 5 * 4, /* %esi */ |
| 179 | 4 * 4, /* %edi */ |
| 180 | 11 * 4, /* %eip */ |
| 181 | 13 * 4, /* %eflags */ |
| 182 | 12 * 4, /* %cs */ |
| 183 | 15 * 4, /* %ss */ |
| 184 | 3 * 4, /* %ds */ |
| 185 | 2 * 4, /* %es */ |
| 186 | 1 * 4, /* %fs */ |
| 187 | 0 * 4 /* %gs */ |
| 188 | }; |
| 189 | |
| 190 | /* From /usr/src/lib/libpthread/arch/i386/uthread_machdep.c. */ |
| 191 | static int i386obsd_uthread_reg_offset[] = |
| 192 | { |
| 193 | 11 * 4, /* %eax */ |
| 194 | 10 * 4, /* %ecx */ |
| 195 | 9 * 4, /* %edx */ |
| 196 | 8 * 4, /* %ebx */ |
| 197 | -1, /* %esp */ |
| 198 | 6 * 4, /* %ebp */ |
| 199 | 5 * 4, /* %esi */ |
| 200 | 4 * 4, /* %edi */ |
| 201 | 12 * 4, /* %eip */ |
| 202 | -1, /* %eflags */ |
| 203 | 13 * 4, /* %cs */ |
| 204 | -1, /* %ss */ |
| 205 | 3 * 4, /* %ds */ |
| 206 | 2 * 4, /* %es */ |
| 207 | 1 * 4, /* %fs */ |
| 208 | 0 * 4 /* %gs */ |
| 209 | }; |
| 210 | |
| 211 | /* Offset within the thread structure where we can find the saved |
| 212 | stack pointer (%esp). */ |
| 213 | #define I386OBSD_UTHREAD_ESP_OFFSET 176 |
| 214 | |
| 215 | static void |
| 216 | i386obsd_supply_uthread (struct regcache *regcache, |
| 217 | int regnum, CORE_ADDR addr) |
| 218 | { |
| 219 | CORE_ADDR sp_addr = addr + I386OBSD_UTHREAD_ESP_OFFSET; |
| 220 | CORE_ADDR sp = 0; |
| 221 | char buf[4]; |
| 222 | int i; |
| 223 | |
| 224 | gdb_assert (regnum >= -1); |
| 225 | |
| 226 | if (regnum == -1 || regnum == I386_ESP_REGNUM) |
| 227 | { |
| 228 | int offset; |
| 229 | |
| 230 | /* Fetch stack pointer from thread structure. */ |
| 231 | sp = read_memory_unsigned_integer (sp_addr, 4); |
| 232 | |
| 233 | /* Adjust the stack pointer such that it looks as if we just |
| 234 | returned from _thread_machdep_switch. */ |
| 235 | offset = i386obsd_uthread_reg_offset[I386_EIP_REGNUM] + 4; |
| 236 | store_unsigned_integer (buf, 4, sp + offset); |
| 237 | regcache_raw_supply (regcache, I386_ESP_REGNUM, buf); |
| 238 | } |
| 239 | |
| 240 | for (i = 0; i < ARRAY_SIZE (i386obsd_uthread_reg_offset); i++) |
| 241 | { |
| 242 | if (i386obsd_uthread_reg_offset[i] != -1 |
| 243 | && (regnum == -1 || regnum == i)) |
| 244 | { |
| 245 | /* Fetch stack pointer from thread structure (if we didn't |
| 246 | do so already). */ |
| 247 | if (sp == 0) |
| 248 | sp = read_memory_unsigned_integer (sp_addr, 4); |
| 249 | |
| 250 | /* Read the saved register from the stack frame. */ |
| 251 | read_memory (sp + i386obsd_uthread_reg_offset[i], buf, 4); |
| 252 | regcache_raw_supply (regcache, i, buf); |
| 253 | } |
| 254 | } |
| 255 | |
| 256 | } |
| 257 | |
| 258 | static void |
| 259 | i386obsd_collect_uthread (const struct regcache *regcache, |
| 260 | int regnum, CORE_ADDR addr) |
| 261 | { |
| 262 | CORE_ADDR sp_addr = addr + I386OBSD_UTHREAD_ESP_OFFSET; |
| 263 | CORE_ADDR sp = 0; |
| 264 | char buf[4]; |
| 265 | int i; |
| 266 | |
| 267 | gdb_assert (regnum >= -1); |
| 268 | |
| 269 | if (regnum == -1 || regnum == I386_ESP_REGNUM) |
| 270 | { |
| 271 | int offset; |
| 272 | |
| 273 | /* Calculate the stack pointer (frame pointer) that will be |
| 274 | stored into the thread structure. */ |
| 275 | offset = i386obsd_uthread_reg_offset[I386_EIP_REGNUM] + 4; |
| 276 | regcache_raw_collect (regcache, I386_ESP_REGNUM, buf); |
| 277 | sp = extract_unsigned_integer (buf, 4) - offset; |
| 278 | |
| 279 | /* Store the stack pointer. */ |
| 280 | write_memory_unsigned_integer (sp_addr, 4, sp); |
| 281 | |
| 282 | /* The stack pointer was (potentially) modified. Make sure we |
| 283 | build a proper stack frame. */ |
| 284 | regnum = -1; |
| 285 | } |
| 286 | |
| 287 | for (i = 0; i < ARRAY_SIZE (i386obsd_uthread_reg_offset); i++) |
| 288 | { |
| 289 | if (i386obsd_uthread_reg_offset[i] != -1 |
| 290 | && (regnum == -1 || regnum == i)) |
| 291 | { |
| 292 | /* Fetch stack pointer from thread structure (if we didn't |
| 293 | calculate it already). */ |
| 294 | if (sp == 0) |
| 295 | sp = read_memory_unsigned_integer (sp_addr, 4); |
| 296 | |
| 297 | /* Write the register into the stack frame. */ |
| 298 | regcache_raw_collect (regcache, i, buf); |
| 299 | write_memory (sp + i386obsd_uthread_reg_offset[i], buf, 4); |
| 300 | } |
| 301 | } |
| 302 | } |
| 303 | |
| 304 | static void |
| 305 | i386obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 306 | { |
| 307 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 308 | |
| 309 | /* Obviously OpenBSD is BSD-based. */ |
| 310 | i386bsd_init_abi (info, gdbarch); |
| 311 | |
| 312 | /* OpenBSD has a different `struct reg'. */ |
| 313 | tdep->gregset_reg_offset = i386obsd_r_reg_offset; |
| 314 | tdep->gregset_num_regs = ARRAY_SIZE (i386obsd_r_reg_offset); |
| 315 | tdep->sizeof_gregset = 16 * 4; |
| 316 | |
| 317 | /* OpenBSD uses -freg-struct-return by default. */ |
| 318 | tdep->struct_return = reg_struct_return; |
| 319 | |
| 320 | /* OpenBSD uses a different memory layout. */ |
| 321 | tdep->sigtramp_start = i386obsd_sigtramp_start_addr; |
| 322 | tdep->sigtramp_end = i386obsd_sigtramp_end_addr; |
| 323 | tdep->sigtramp_p = i386obsd_sigtramp_p; |
| 324 | |
| 325 | /* OpenBSD has a `struct sigcontext' that's different from the |
| 326 | original 4.3 BSD. */ |
| 327 | tdep->sc_reg_offset = i386obsd_sc_reg_offset; |
| 328 | tdep->sc_num_regs = ARRAY_SIZE (i386obsd_sc_reg_offset); |
| 329 | |
| 330 | /* OpenBSD provides a user-level threads implementation. */ |
| 331 | bsd_uthread_set_supply_uthread (gdbarch, i386obsd_supply_uthread); |
| 332 | bsd_uthread_set_collect_uthread (gdbarch, i386obsd_collect_uthread); |
| 333 | } |
| 334 | |
| 335 | /* OpenBSD a.out. */ |
| 336 | |
| 337 | static void |
| 338 | i386obsd_aout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 339 | { |
| 340 | i386obsd_init_abi (info, gdbarch); |
| 341 | |
| 342 | /* OpenBSD a.out has a single register set. */ |
| 343 | set_gdbarch_regset_from_core_section |
| 344 | (gdbarch, i386obsd_aout_regset_from_core_section); |
| 345 | } |
| 346 | |
| 347 | /* OpenBSD ELF. */ |
| 348 | |
| 349 | static void |
| 350 | i386obsd_elf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 351 | { |
| 352 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 353 | |
| 354 | /* It's still OpenBSD. */ |
| 355 | i386obsd_init_abi (info, gdbarch); |
| 356 | |
| 357 | /* But ELF-based. */ |
| 358 | i386_elf_init_abi (info, gdbarch); |
| 359 | |
| 360 | /* OpenBSD ELF uses SVR4-style shared libraries. */ |
| 361 | set_solib_svr4_fetch_link_map_offsets |
| 362 | (gdbarch, svr4_ilp32_fetch_link_map_offsets); |
| 363 | } |
| 364 | \f |
| 365 | |
| 366 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 367 | void _initialize_i386obsd_tdep (void); |
| 368 | |
| 369 | void |
| 370 | _initialize_i386obsd_tdep (void) |
| 371 | { |
| 372 | /* FIXME: kettenis/20021020: Since OpenBSD/i386 binaries are |
| 373 | indistingushable from NetBSD/i386 a.out binaries, building a GDB |
| 374 | that should support both these targets will probably not work as |
| 375 | expected. */ |
| 376 | #define GDB_OSABI_OPENBSD_AOUT GDB_OSABI_NETBSD_AOUT |
| 377 | |
| 378 | gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_OPENBSD_AOUT, |
| 379 | i386obsd_aout_init_abi); |
| 380 | gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_OPENBSD_ELF, |
| 381 | i386obsd_elf_init_abi); |
| 382 | } |