| 1 | /* Target-dependent code for OpenBSD/amd64. |
| 2 | |
| 3 | Copyright (C) 2003-2019 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 "frame.h" |
| 22 | #include "frame-unwind.h" |
| 23 | #include "gdbcore.h" |
| 24 | #include "symtab.h" |
| 25 | #include "objfiles.h" |
| 26 | #include "osabi.h" |
| 27 | #include "regcache.h" |
| 28 | #include "regset.h" |
| 29 | #include "target.h" |
| 30 | #include "trad-frame.h" |
| 31 | |
| 32 | #include "obsd-tdep.h" |
| 33 | #include "amd64-tdep.h" |
| 34 | #include "i387-tdep.h" |
| 35 | #include "gdbsupport/x86-xstate.h" |
| 36 | #include "solib-svr4.h" |
| 37 | #include "bsd-uthread.h" |
| 38 | |
| 39 | /* Support for signal handlers. */ |
| 40 | |
| 41 | /* Default page size. */ |
| 42 | static const int amd64obsd_page_size = 4096; |
| 43 | |
| 44 | /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp |
| 45 | routine. */ |
| 46 | |
| 47 | static int |
| 48 | amd64obsd_sigtramp_p (struct frame_info *this_frame) |
| 49 | { |
| 50 | CORE_ADDR pc = get_frame_pc (this_frame); |
| 51 | CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1)); |
| 52 | const gdb_byte osigreturn[] = |
| 53 | { |
| 54 | 0x48, 0xc7, 0xc0, |
| 55 | 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */ |
| 56 | 0xcd, 0x80 /* int $0x80 */ |
| 57 | }; |
| 58 | const gdb_byte sigreturn[] = |
| 59 | { |
| 60 | 0x48, 0xc7, 0xc0, |
| 61 | 0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */ |
| 62 | 0x0f, 0x05 /* syscall */ |
| 63 | }; |
| 64 | size_t buflen = (sizeof sigreturn) + 1; |
| 65 | gdb_byte *buf; |
| 66 | const char *name; |
| 67 | |
| 68 | /* If the function has a valid symbol name, it isn't a |
| 69 | trampoline. */ |
| 70 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 71 | if (name != NULL) |
| 72 | return 0; |
| 73 | |
| 74 | /* If the function lives in a valid section (even without a starting |
| 75 | point) it isn't a trampoline. */ |
| 76 | if (find_pc_section (pc) != NULL) |
| 77 | return 0; |
| 78 | |
| 79 | /* If we can't read the instructions at START_PC, return zero. */ |
| 80 | buf = (gdb_byte *) alloca ((sizeof sigreturn) + 1); |
| 81 | if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen)) |
| 82 | return 0; |
| 83 | |
| 84 | /* Check for sigreturn(2). Depending on how the assembler encoded |
| 85 | the `movq %rsp, %rdi' instruction, the code starts at offset 6 or |
| 86 | 7. OpenBSD 5.0 and later use the `syscall' instruction. Older |
| 87 | versions use `int $0x80'. Check for both. */ |
| 88 | if (memcmp (buf, sigreturn, sizeof sigreturn) |
| 89 | && memcmp (buf + 1, sigreturn, sizeof sigreturn) |
| 90 | && memcmp (buf, osigreturn, sizeof osigreturn) |
| 91 | && memcmp (buf + 1, osigreturn, sizeof osigreturn)) |
| 92 | return 0; |
| 93 | |
| 94 | return 1; |
| 95 | } |
| 96 | |
| 97 | /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the |
| 98 | address of the associated sigcontext structure. */ |
| 99 | |
| 100 | static CORE_ADDR |
| 101 | amd64obsd_sigcontext_addr (struct frame_info *this_frame) |
| 102 | { |
| 103 | CORE_ADDR pc = get_frame_pc (this_frame); |
| 104 | ULONGEST offset = (pc & (amd64obsd_page_size - 1)); |
| 105 | |
| 106 | /* The %rsp register points at `struct sigcontext' upon entry of a |
| 107 | signal trampoline. The relevant part of the trampoline is |
| 108 | |
| 109 | call *%rax |
| 110 | movq %rsp, %rdi |
| 111 | pushq %rdi |
| 112 | movq $SYS_sigreturn,%rax |
| 113 | int $0x80 |
| 114 | |
| 115 | (see /usr/src/sys/arch/amd64/amd64/locore.S). The `pushq' |
| 116 | instruction clobbers %rsp, but its value is saved in `%rdi'. */ |
| 117 | |
| 118 | if (offset > 5) |
| 119 | return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM); |
| 120 | else |
| 121 | return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM); |
| 122 | } |
| 123 | \f |
| 124 | /* OpenBSD 3.5 or later. */ |
| 125 | |
| 126 | /* Mapping between the general-purpose registers in `struct reg' |
| 127 | format and GDB's register cache layout. */ |
| 128 | |
| 129 | /* From <machine/reg.h>. */ |
| 130 | int amd64obsd_r_reg_offset[] = |
| 131 | { |
| 132 | 14 * 8, /* %rax */ |
| 133 | 13 * 8, /* %rbx */ |
| 134 | 3 * 8, /* %rcx */ |
| 135 | 2 * 8, /* %rdx */ |
| 136 | 1 * 8, /* %rsi */ |
| 137 | 0 * 8, /* %rdi */ |
| 138 | 12 * 8, /* %rbp */ |
| 139 | 15 * 8, /* %rsp */ |
| 140 | 4 * 8, /* %r8 .. */ |
| 141 | 5 * 8, |
| 142 | 6 * 8, |
| 143 | 7 * 8, |
| 144 | 8 * 8, |
| 145 | 9 * 8, |
| 146 | 10 * 8, |
| 147 | 11 * 8, /* ... %r15 */ |
| 148 | 16 * 8, /* %rip */ |
| 149 | 17 * 8, /* %eflags */ |
| 150 | 18 * 8, /* %cs */ |
| 151 | 19 * 8, /* %ss */ |
| 152 | 20 * 8, /* %ds */ |
| 153 | 21 * 8, /* %es */ |
| 154 | 22 * 8, /* %fs */ |
| 155 | 23 * 8 /* %gs */ |
| 156 | }; |
| 157 | |
| 158 | /* From <machine/signal.h>. */ |
| 159 | static int amd64obsd_sc_reg_offset[] = |
| 160 | { |
| 161 | 14 * 8, /* %rax */ |
| 162 | 13 * 8, /* %rbx */ |
| 163 | 3 * 8, /* %rcx */ |
| 164 | 2 * 8, /* %rdx */ |
| 165 | 1 * 8, /* %rsi */ |
| 166 | 0 * 8, /* %rdi */ |
| 167 | 12 * 8, /* %rbp */ |
| 168 | 24 * 8, /* %rsp */ |
| 169 | 4 * 8, /* %r8 ... */ |
| 170 | 5 * 8, |
| 171 | 6 * 8, |
| 172 | 7 * 8, |
| 173 | 8 * 8, |
| 174 | 9 * 8, |
| 175 | 10 * 8, |
| 176 | 11 * 8, /* ... %r15 */ |
| 177 | 21 * 8, /* %rip */ |
| 178 | 23 * 8, /* %eflags */ |
| 179 | 22 * 8, /* %cs */ |
| 180 | 25 * 8, /* %ss */ |
| 181 | 18 * 8, /* %ds */ |
| 182 | 17 * 8, /* %es */ |
| 183 | 16 * 8, /* %fs */ |
| 184 | 15 * 8 /* %gs */ |
| 185 | }; |
| 186 | |
| 187 | /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c. */ |
| 188 | static int amd64obsd_uthread_reg_offset[] = |
| 189 | { |
| 190 | 19 * 8, /* %rax */ |
| 191 | 16 * 8, /* %rbx */ |
| 192 | 18 * 8, /* %rcx */ |
| 193 | 17 * 8, /* %rdx */ |
| 194 | 14 * 8, /* %rsi */ |
| 195 | 13 * 8, /* %rdi */ |
| 196 | 15 * 8, /* %rbp */ |
| 197 | -1, /* %rsp */ |
| 198 | 12 * 8, /* %r8 ... */ |
| 199 | 11 * 8, |
| 200 | 10 * 8, |
| 201 | 9 * 8, |
| 202 | 8 * 8, |
| 203 | 7 * 8, |
| 204 | 6 * 8, |
| 205 | 5 * 8, /* ... %r15 */ |
| 206 | 20 * 8, /* %rip */ |
| 207 | 4 * 8, /* %eflags */ |
| 208 | 21 * 8, /* %cs */ |
| 209 | -1, /* %ss */ |
| 210 | 3 * 8, /* %ds */ |
| 211 | 2 * 8, /* %es */ |
| 212 | 1 * 8, /* %fs */ |
| 213 | 0 * 8 /* %gs */ |
| 214 | }; |
| 215 | |
| 216 | /* Offset within the thread structure where we can find the saved |
| 217 | stack pointer (%esp). */ |
| 218 | #define AMD64OBSD_UTHREAD_RSP_OFFSET 400 |
| 219 | |
| 220 | static void |
| 221 | amd64obsd_supply_uthread (struct regcache *regcache, |
| 222 | int regnum, CORE_ADDR addr) |
| 223 | { |
| 224 | struct gdbarch *gdbarch = regcache->arch (); |
| 225 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 226 | CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET; |
| 227 | CORE_ADDR sp = 0; |
| 228 | gdb_byte buf[8]; |
| 229 | int i; |
| 230 | |
| 231 | gdb_assert (regnum >= -1); |
| 232 | |
| 233 | if (regnum == -1 || regnum == AMD64_RSP_REGNUM) |
| 234 | { |
| 235 | int offset; |
| 236 | |
| 237 | /* Fetch stack pointer from thread structure. */ |
| 238 | sp = read_memory_unsigned_integer (sp_addr, 8, byte_order); |
| 239 | |
| 240 | /* Adjust the stack pointer such that it looks as if we just |
| 241 | returned from _thread_machdep_switch. */ |
| 242 | offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8; |
| 243 | store_unsigned_integer (buf, 8, byte_order, sp + offset); |
| 244 | regcache->raw_supply (AMD64_RSP_REGNUM, buf); |
| 245 | } |
| 246 | |
| 247 | for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++) |
| 248 | { |
| 249 | if (amd64obsd_uthread_reg_offset[i] != -1 |
| 250 | && (regnum == -1 || regnum == i)) |
| 251 | { |
| 252 | /* Fetch stack pointer from thread structure (if we didn't |
| 253 | do so already). */ |
| 254 | if (sp == 0) |
| 255 | sp = read_memory_unsigned_integer (sp_addr, 8, byte_order); |
| 256 | |
| 257 | /* Read the saved register from the stack frame. */ |
| 258 | read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8); |
| 259 | regcache->raw_supply (i, buf); |
| 260 | } |
| 261 | } |
| 262 | } |
| 263 | |
| 264 | static void |
| 265 | amd64obsd_collect_uthread (const struct regcache *regcache, |
| 266 | int regnum, CORE_ADDR addr) |
| 267 | { |
| 268 | struct gdbarch *gdbarch = regcache->arch (); |
| 269 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 270 | CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET; |
| 271 | CORE_ADDR sp = 0; |
| 272 | gdb_byte buf[8]; |
| 273 | int i; |
| 274 | |
| 275 | gdb_assert (regnum >= -1); |
| 276 | |
| 277 | if (regnum == -1 || regnum == AMD64_RSP_REGNUM) |
| 278 | { |
| 279 | int offset; |
| 280 | |
| 281 | /* Calculate the stack pointer (frame pointer) that will be |
| 282 | stored into the thread structure. */ |
| 283 | offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8; |
| 284 | regcache->raw_collect (AMD64_RSP_REGNUM, buf); |
| 285 | sp = extract_unsigned_integer (buf, 8, byte_order) - offset; |
| 286 | |
| 287 | /* Store the stack pointer. */ |
| 288 | write_memory_unsigned_integer (sp_addr, 8, byte_order, sp); |
| 289 | |
| 290 | /* The stack pointer was (potentially) modified. Make sure we |
| 291 | build a proper stack frame. */ |
| 292 | regnum = -1; |
| 293 | } |
| 294 | |
| 295 | for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++) |
| 296 | { |
| 297 | if (amd64obsd_uthread_reg_offset[i] != -1 |
| 298 | && (regnum == -1 || regnum == i)) |
| 299 | { |
| 300 | /* Fetch stack pointer from thread structure (if we didn't |
| 301 | calculate it already). */ |
| 302 | if (sp == 0) |
| 303 | sp = read_memory_unsigned_integer (sp_addr, 8, byte_order); |
| 304 | |
| 305 | /* Write the register into the stack frame. */ |
| 306 | regcache->raw_collect (i, buf); |
| 307 | write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8); |
| 308 | } |
| 309 | } |
| 310 | } |
| 311 | /* Kernel debugging support. */ |
| 312 | |
| 313 | /* From <machine/frame.h>. Easy since `struct trapframe' matches |
| 314 | `struct sigcontext'. */ |
| 315 | #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset |
| 316 | |
| 317 | static struct trad_frame_cache * |
| 318 | amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache) |
| 319 | { |
| 320 | struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| 321 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 322 | struct trad_frame_cache *cache; |
| 323 | CORE_ADDR func, sp, addr; |
| 324 | ULONGEST cs; |
| 325 | const char *name; |
| 326 | int i; |
| 327 | |
| 328 | if (*this_cache) |
| 329 | return (struct trad_frame_cache *) *this_cache; |
| 330 | |
| 331 | cache = trad_frame_cache_zalloc (this_frame); |
| 332 | *this_cache = cache; |
| 333 | |
| 334 | func = get_frame_func (this_frame); |
| 335 | sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM); |
| 336 | |
| 337 | find_pc_partial_function (func, &name, NULL, NULL); |
| 338 | if (name && startswith (name, "Xintr")) |
| 339 | addr = sp + 8; /* It's an interrupt frame. */ |
| 340 | else |
| 341 | addr = sp; |
| 342 | |
| 343 | for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++) |
| 344 | if (amd64obsd_tf_reg_offset[i] != -1) |
| 345 | trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]); |
| 346 | |
| 347 | /* Read %cs from trap frame. */ |
| 348 | addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM]; |
| 349 | cs = read_memory_unsigned_integer (addr, 8, byte_order); |
| 350 | if ((cs & I386_SEL_RPL) == I386_SEL_UPL) |
| 351 | { |
| 352 | /* Trap from user space; terminate backtrace. */ |
| 353 | trad_frame_set_id (cache, outer_frame_id); |
| 354 | } |
| 355 | else |
| 356 | { |
| 357 | /* Construct the frame ID using the function start. */ |
| 358 | trad_frame_set_id (cache, frame_id_build (sp + 16, func)); |
| 359 | } |
| 360 | |
| 361 | return cache; |
| 362 | } |
| 363 | |
| 364 | static void |
| 365 | amd64obsd_trapframe_this_id (struct frame_info *this_frame, |
| 366 | void **this_cache, struct frame_id *this_id) |
| 367 | { |
| 368 | struct trad_frame_cache *cache = |
| 369 | amd64obsd_trapframe_cache (this_frame, this_cache); |
| 370 | |
| 371 | trad_frame_get_id (cache, this_id); |
| 372 | } |
| 373 | |
| 374 | static struct value * |
| 375 | amd64obsd_trapframe_prev_register (struct frame_info *this_frame, |
| 376 | void **this_cache, int regnum) |
| 377 | { |
| 378 | struct trad_frame_cache *cache = |
| 379 | amd64obsd_trapframe_cache (this_frame, this_cache); |
| 380 | |
| 381 | return trad_frame_get_register (cache, this_frame, regnum); |
| 382 | } |
| 383 | |
| 384 | static int |
| 385 | amd64obsd_trapframe_sniffer (const struct frame_unwind *self, |
| 386 | struct frame_info *this_frame, |
| 387 | void **this_prologue_cache) |
| 388 | { |
| 389 | ULONGEST cs; |
| 390 | const char *name; |
| 391 | |
| 392 | /* Check Current Privilege Level and bail out if we're not executing |
| 393 | in kernel space. */ |
| 394 | cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM); |
| 395 | if ((cs & I386_SEL_RPL) == I386_SEL_UPL) |
| 396 | return 0; |
| 397 | |
| 398 | find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL); |
| 399 | return (name && ((strcmp (name, "calltrap") == 0) |
| 400 | || (strcmp (name, "osyscall1") == 0) |
| 401 | || (strcmp (name, "Xsyscall") == 0) |
| 402 | || (startswith (name, "Xintr")))); |
| 403 | } |
| 404 | |
| 405 | static const struct frame_unwind amd64obsd_trapframe_unwind = { |
| 406 | /* FIXME: kettenis/20051219: This really is more like an interrupt |
| 407 | frame, but SIGTRAMP_FRAME would print <signal handler called>, |
| 408 | which really is not what we want here. */ |
| 409 | NORMAL_FRAME, |
| 410 | default_frame_unwind_stop_reason, |
| 411 | amd64obsd_trapframe_this_id, |
| 412 | amd64obsd_trapframe_prev_register, |
| 413 | NULL, |
| 414 | amd64obsd_trapframe_sniffer |
| 415 | }; |
| 416 | \f |
| 417 | |
| 418 | static void |
| 419 | amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 420 | { |
| 421 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 422 | |
| 423 | amd64_init_abi (info, gdbarch, |
| 424 | amd64_target_description (X86_XSTATE_SSE_MASK, true)); |
| 425 | obsd_init_abi (info, gdbarch); |
| 426 | |
| 427 | /* Initialize general-purpose register set details. */ |
| 428 | tdep->gregset_reg_offset = amd64obsd_r_reg_offset; |
| 429 | tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset); |
| 430 | tdep->sizeof_gregset = 24 * 8; |
| 431 | |
| 432 | tdep->jb_pc_offset = 7 * 8; |
| 433 | |
| 434 | tdep->sigtramp_p = amd64obsd_sigtramp_p; |
| 435 | tdep->sigcontext_addr = amd64obsd_sigcontext_addr; |
| 436 | tdep->sc_reg_offset = amd64obsd_sc_reg_offset; |
| 437 | tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset); |
| 438 | |
| 439 | /* OpenBSD provides a user-level threads implementation. */ |
| 440 | bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread); |
| 441 | bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread); |
| 442 | |
| 443 | /* OpenBSD uses SVR4-style shared libraries. */ |
| 444 | set_solib_svr4_fetch_link_map_offsets |
| 445 | (gdbarch, svr4_lp64_fetch_link_map_offsets); |
| 446 | |
| 447 | /* Unwind kernel trap frames correctly. */ |
| 448 | frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind); |
| 449 | } |
| 450 | |
| 451 | void |
| 452 | _initialize_amd64obsd_tdep (void) |
| 453 | { |
| 454 | /* The OpenBSD/amd64 native dependent code makes this assumption. */ |
| 455 | gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS); |
| 456 | |
| 457 | gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, |
| 458 | GDB_OSABI_OPENBSD, amd64obsd_init_abi); |
| 459 | } |