| 1 | /* Native-dependent code for GNU/Linux x86-64. |
| 2 | |
| 3 | Copyright (C) 2001-2019 Free Software Foundation, Inc. |
| 4 | Contributed by Jiri Smid, SuSE Labs. |
| 5 | |
| 6 | This file is part of GDB. |
| 7 | |
| 8 | This program is free software; you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation; either version 3 of the License, or |
| 11 | (at your option) any later version. |
| 12 | |
| 13 | This program is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 20 | |
| 21 | #include "defs.h" |
| 22 | #include "inferior.h" |
| 23 | #include "regcache.h" |
| 24 | #include "elf/common.h" |
| 25 | #include <sys/uio.h> |
| 26 | #include "nat/gdb_ptrace.h" |
| 27 | #include <asm/prctl.h> |
| 28 | #include <sys/reg.h> |
| 29 | #include "gregset.h" |
| 30 | #include "gdb_proc_service.h" |
| 31 | |
| 32 | #include "amd64-nat.h" |
| 33 | #include "amd64-tdep.h" |
| 34 | #include "amd64-linux-tdep.h" |
| 35 | #include "i386-linux-tdep.h" |
| 36 | #include "gdbsupport/x86-xstate.h" |
| 37 | |
| 38 | #include "x86-linux-nat.h" |
| 39 | #include "nat/linux-ptrace.h" |
| 40 | #include "nat/amd64-linux-siginfo.h" |
| 41 | |
| 42 | /* This definition comes from prctl.h. Kernels older than 2.5.64 |
| 43 | do not have it. */ |
| 44 | #ifndef PTRACE_ARCH_PRCTL |
| 45 | #define PTRACE_ARCH_PRCTL 30 |
| 46 | #endif |
| 47 | |
| 48 | struct amd64_linux_nat_target final : public x86_linux_nat_target |
| 49 | { |
| 50 | /* Add our register access methods. */ |
| 51 | void fetch_registers (struct regcache *, int) override; |
| 52 | void store_registers (struct regcache *, int) override; |
| 53 | |
| 54 | bool low_siginfo_fixup (siginfo_t *ptrace, gdb_byte *inf, int direction) |
| 55 | override; |
| 56 | }; |
| 57 | |
| 58 | static amd64_linux_nat_target the_amd64_linux_nat_target; |
| 59 | |
| 60 | /* Mapping between the general-purpose registers in GNU/Linux x86-64 |
| 61 | `struct user' format and GDB's register cache layout for GNU/Linux |
| 62 | i386. |
| 63 | |
| 64 | Note that most GNU/Linux x86-64 registers are 64-bit, while the |
| 65 | GNU/Linux i386 registers are all 32-bit, but since we're |
| 66 | little-endian we get away with that. */ |
| 67 | |
| 68 | /* From <sys/reg.h> on GNU/Linux i386. */ |
| 69 | static int amd64_linux_gregset32_reg_offset[] = |
| 70 | { |
| 71 | RAX * 8, RCX * 8, /* %eax, %ecx */ |
| 72 | RDX * 8, RBX * 8, /* %edx, %ebx */ |
| 73 | RSP * 8, RBP * 8, /* %esp, %ebp */ |
| 74 | RSI * 8, RDI * 8, /* %esi, %edi */ |
| 75 | RIP * 8, EFLAGS * 8, /* %eip, %eflags */ |
| 76 | CS * 8, SS * 8, /* %cs, %ss */ |
| 77 | DS * 8, ES * 8, /* %ds, %es */ |
| 78 | FS * 8, GS * 8, /* %fs, %gs */ |
| 79 | -1, -1, -1, -1, -1, -1, -1, -1, |
| 80 | -1, -1, -1, -1, -1, -1, -1, -1, |
| 81 | -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| 82 | -1, -1, -1, -1, -1, -1, -1, -1, |
| 83 | -1, -1, -1, -1, /* MPX registers BND0 ... BND3. */ |
| 84 | -1, -1, /* MPX registers BNDCFGU, BNDSTATUS. */ |
| 85 | -1, -1, -1, -1, -1, -1, -1, -1, /* k0 ... k7 (AVX512) */ |
| 86 | -1, -1, -1, -1, -1, -1, -1, -1, /* zmm0 ... zmm7 (AVX512) */ |
| 87 | -1, /* PKEYS register PKRU */ |
| 88 | ORIG_RAX * 8 /* "orig_eax" */ |
| 89 | }; |
| 90 | \f |
| 91 | |
| 92 | /* Transfering the general-purpose registers between GDB, inferiors |
| 93 | and core files. */ |
| 94 | |
| 95 | /* See amd64_collect_native_gregset. This linux specific version handles |
| 96 | issues with negative EAX values not being restored correctly upon syscall |
| 97 | return when debugging 32-bit targets. It has no effect on 64-bit |
| 98 | targets. */ |
| 99 | |
| 100 | static void |
| 101 | amd64_linux_collect_native_gregset (const struct regcache *regcache, |
| 102 | void *gregs, int regnum) |
| 103 | { |
| 104 | amd64_collect_native_gregset (regcache, gregs, regnum); |
| 105 | |
| 106 | struct gdbarch *gdbarch = regcache->arch (); |
| 107 | if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32) |
| 108 | { |
| 109 | /* Sign extend EAX value to avoid potential syscall restart |
| 110 | problems. |
| 111 | |
| 112 | On Linux, when a syscall is interrupted by a signal, the |
| 113 | (kernel function implementing the) syscall may return |
| 114 | -ERESTARTSYS when a signal occurs. Doing so indicates that |
| 115 | the syscall is restartable. Then, depending on settings |
| 116 | associated with the signal handler, and after the signal |
| 117 | handler is called, the kernel can then either return -EINTR |
| 118 | or it can cause the syscall to be restarted. We are |
| 119 | concerned with the latter case here. |
| 120 | |
| 121 | On (32-bit) i386, the status (-ERESTARTSYS) is placed in the |
| 122 | EAX register. When debugging a 32-bit process from a 64-bit |
| 123 | (amd64) GDB, the debugger fetches 64-bit registers even |
| 124 | though the process being debugged is only 32-bit. The |
| 125 | register cache is only 32 bits wide though; GDB discards the |
| 126 | high 32 bits when placing 64-bit values in the 32-bit |
| 127 | regcache. Normally, this is not a problem since the 32-bit |
| 128 | process should only care about the lower 32-bit portions of |
| 129 | these registers. That said, it can happen that the 64-bit |
| 130 | value being restored will be different from the 64-bit value |
| 131 | that was originally retrieved from the kernel. The one place |
| 132 | (that we know of) where it does matter is in the kernel's |
| 133 | syscall restart code. The kernel's code for restarting a |
| 134 | syscall after a signal expects to see a negative value |
| 135 | (specifically -ERESTARTSYS) in the 64-bit RAX register in |
| 136 | order to correctly cause a syscall to be restarted. |
| 137 | |
| 138 | The call to amd64_collect_native_gregset, above, is setting |
| 139 | the high 32 bits of RAX (and other registers too) to 0. For |
| 140 | syscall restart, we need to sign extend EAX so that RAX will |
| 141 | appear as a negative value when EAX is set to -ERESTARTSYS. |
| 142 | This in turn will cause the signal handling code in the |
| 143 | kernel to recognize -ERESTARTSYS which will in turn cause the |
| 144 | syscall to be restarted. |
| 145 | |
| 146 | The test case gdb.base/interrupt.exp tests for this problem. |
| 147 | Without this sign extension code in place, it'll show |
| 148 | a number of failures when testing against unix/-m32. */ |
| 149 | |
| 150 | if (regnum == -1 || regnum == I386_EAX_REGNUM) |
| 151 | { |
| 152 | void *ptr = ((gdb_byte *) gregs |
| 153 | + amd64_linux_gregset32_reg_offset[I386_EAX_REGNUM]); |
| 154 | |
| 155 | *(int64_t *) ptr = *(int32_t *) ptr; |
| 156 | } |
| 157 | } |
| 158 | } |
| 159 | |
| 160 | /* Fill GDB's register cache with the general-purpose register values |
| 161 | in *GREGSETP. */ |
| 162 | |
| 163 | void |
| 164 | supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp) |
| 165 | { |
| 166 | amd64_supply_native_gregset (regcache, gregsetp, -1); |
| 167 | } |
| 168 | |
| 169 | /* Fill register REGNUM (if it is a general-purpose register) in |
| 170 | *GREGSETP with the value in GDB's register cache. If REGNUM is -1, |
| 171 | do this for all registers. */ |
| 172 | |
| 173 | void |
| 174 | fill_gregset (const struct regcache *regcache, |
| 175 | elf_gregset_t *gregsetp, int regnum) |
| 176 | { |
| 177 | amd64_linux_collect_native_gregset (regcache, gregsetp, regnum); |
| 178 | } |
| 179 | |
| 180 | /* Transfering floating-point registers between GDB, inferiors and cores. */ |
| 181 | |
| 182 | /* Fill GDB's register cache with the floating-point and SSE register |
| 183 | values in *FPREGSETP. */ |
| 184 | |
| 185 | void |
| 186 | supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp) |
| 187 | { |
| 188 | amd64_supply_fxsave (regcache, -1, fpregsetp); |
| 189 | } |
| 190 | |
| 191 | /* Fill register REGNUM (if it is a floating-point or SSE register) in |
| 192 | *FPREGSETP with the value in GDB's register cache. If REGNUM is |
| 193 | -1, do this for all registers. */ |
| 194 | |
| 195 | void |
| 196 | fill_fpregset (const struct regcache *regcache, |
| 197 | elf_fpregset_t *fpregsetp, int regnum) |
| 198 | { |
| 199 | amd64_collect_fxsave (regcache, regnum, fpregsetp); |
| 200 | } |
| 201 | \f |
| 202 | |
| 203 | /* Transferring arbitrary registers between GDB and inferior. */ |
| 204 | |
| 205 | /* Fetch register REGNUM from the child process. If REGNUM is -1, do |
| 206 | this for all registers (including the floating point and SSE |
| 207 | registers). */ |
| 208 | |
| 209 | void |
| 210 | amd64_linux_nat_target::fetch_registers (struct regcache *regcache, int regnum) |
| 211 | { |
| 212 | struct gdbarch *gdbarch = regcache->arch (); |
| 213 | int tid; |
| 214 | |
| 215 | /* GNU/Linux LWP ID's are process ID's. */ |
| 216 | tid = regcache->ptid ().lwp (); |
| 217 | if (tid == 0) |
| 218 | tid = regcache->ptid ().pid (); /* Not a threaded program. */ |
| 219 | |
| 220 | if (regnum == -1 || amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| 221 | { |
| 222 | elf_gregset_t regs; |
| 223 | |
| 224 | if (ptrace (PTRACE_GETREGS, tid, 0, (long) ®s) < 0) |
| 225 | perror_with_name (_("Couldn't get registers")); |
| 226 | |
| 227 | amd64_supply_native_gregset (regcache, ®s, -1); |
| 228 | if (regnum != -1) |
| 229 | return; |
| 230 | } |
| 231 | |
| 232 | if (regnum == -1 || !amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| 233 | { |
| 234 | elf_fpregset_t fpregs; |
| 235 | |
| 236 | if (have_ptrace_getregset == TRIBOOL_TRUE) |
| 237 | { |
| 238 | char xstateregs[X86_XSTATE_MAX_SIZE]; |
| 239 | struct iovec iov; |
| 240 | |
| 241 | iov.iov_base = xstateregs; |
| 242 | iov.iov_len = sizeof (xstateregs); |
| 243 | if (ptrace (PTRACE_GETREGSET, tid, |
| 244 | (unsigned int) NT_X86_XSTATE, (long) &iov) < 0) |
| 245 | perror_with_name (_("Couldn't get extended state status")); |
| 246 | |
| 247 | amd64_supply_xsave (regcache, -1, xstateregs); |
| 248 | } |
| 249 | else |
| 250 | { |
| 251 | if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0) |
| 252 | perror_with_name (_("Couldn't get floating point status")); |
| 253 | |
| 254 | amd64_supply_fxsave (regcache, -1, &fpregs); |
| 255 | } |
| 256 | #ifndef HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE |
| 257 | { |
| 258 | /* PTRACE_ARCH_PRCTL is obsolete since 2.6.25, where the |
| 259 | fs_base and gs_base fields of user_regs_struct can be |
| 260 | used directly. */ |
| 261 | unsigned long base; |
| 262 | |
| 263 | if (regnum == -1 || regnum == AMD64_FSBASE_REGNUM) |
| 264 | { |
| 265 | if (ptrace (PTRACE_ARCH_PRCTL, tid, &base, ARCH_GET_FS) < 0) |
| 266 | perror_with_name (_("Couldn't get segment register fs_base")); |
| 267 | |
| 268 | regcache->raw_supply (AMD64_FSBASE_REGNUM, &base); |
| 269 | } |
| 270 | |
| 271 | if (regnum == -1 || regnum == AMD64_GSBASE_REGNUM) |
| 272 | { |
| 273 | if (ptrace (PTRACE_ARCH_PRCTL, tid, &base, ARCH_GET_GS) < 0) |
| 274 | perror_with_name (_("Couldn't get segment register gs_base")); |
| 275 | |
| 276 | regcache->raw_supply (AMD64_GSBASE_REGNUM, &base); |
| 277 | } |
| 278 | } |
| 279 | #endif |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | /* Store register REGNUM back into the child process. If REGNUM is |
| 284 | -1, do this for all registers (including the floating-point and SSE |
| 285 | registers). */ |
| 286 | |
| 287 | void |
| 288 | amd64_linux_nat_target::store_registers (struct regcache *regcache, int regnum) |
| 289 | { |
| 290 | struct gdbarch *gdbarch = regcache->arch (); |
| 291 | int tid; |
| 292 | |
| 293 | /* GNU/Linux LWP ID's are process ID's. */ |
| 294 | tid = regcache->ptid ().lwp (); |
| 295 | if (tid == 0) |
| 296 | tid = regcache->ptid ().pid (); /* Not a threaded program. */ |
| 297 | |
| 298 | if (regnum == -1 || amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| 299 | { |
| 300 | elf_gregset_t regs; |
| 301 | |
| 302 | if (ptrace (PTRACE_GETREGS, tid, 0, (long) ®s) < 0) |
| 303 | perror_with_name (_("Couldn't get registers")); |
| 304 | |
| 305 | amd64_linux_collect_native_gregset (regcache, ®s, regnum); |
| 306 | |
| 307 | if (ptrace (PTRACE_SETREGS, tid, 0, (long) ®s) < 0) |
| 308 | perror_with_name (_("Couldn't write registers")); |
| 309 | |
| 310 | if (regnum != -1) |
| 311 | return; |
| 312 | } |
| 313 | |
| 314 | if (regnum == -1 || !amd64_native_gregset_supplies_p (gdbarch, regnum)) |
| 315 | { |
| 316 | elf_fpregset_t fpregs; |
| 317 | |
| 318 | if (have_ptrace_getregset == TRIBOOL_TRUE) |
| 319 | { |
| 320 | char xstateregs[X86_XSTATE_MAX_SIZE]; |
| 321 | struct iovec iov; |
| 322 | |
| 323 | iov.iov_base = xstateregs; |
| 324 | iov.iov_len = sizeof (xstateregs); |
| 325 | if (ptrace (PTRACE_GETREGSET, tid, |
| 326 | (unsigned int) NT_X86_XSTATE, (long) &iov) < 0) |
| 327 | perror_with_name (_("Couldn't get extended state status")); |
| 328 | |
| 329 | amd64_collect_xsave (regcache, regnum, xstateregs, 0); |
| 330 | |
| 331 | if (ptrace (PTRACE_SETREGSET, tid, |
| 332 | (unsigned int) NT_X86_XSTATE, (long) &iov) < 0) |
| 333 | perror_with_name (_("Couldn't write extended state status")); |
| 334 | } |
| 335 | else |
| 336 | { |
| 337 | if (ptrace (PTRACE_GETFPREGS, tid, 0, (long) &fpregs) < 0) |
| 338 | perror_with_name (_("Couldn't get floating point status")); |
| 339 | |
| 340 | amd64_collect_fxsave (regcache, regnum, &fpregs); |
| 341 | |
| 342 | if (ptrace (PTRACE_SETFPREGS, tid, 0, (long) &fpregs) < 0) |
| 343 | perror_with_name (_("Couldn't write floating point status")); |
| 344 | } |
| 345 | |
| 346 | #ifndef HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE |
| 347 | { |
| 348 | /* PTRACE_ARCH_PRCTL is obsolete since 2.6.25, where the |
| 349 | fs_base and gs_base fields of user_regs_struct can be |
| 350 | used directly. */ |
| 351 | void *base; |
| 352 | |
| 353 | if (regnum == -1 || regnum == AMD64_FSBASE_REGNUM) |
| 354 | { |
| 355 | regcache->raw_collect (AMD64_FSBASE_REGNUM, &base); |
| 356 | |
| 357 | if (ptrace (PTRACE_ARCH_PRCTL, tid, base, ARCH_SET_FS) < 0) |
| 358 | perror_with_name (_("Couldn't write segment register fs_base")); |
| 359 | } |
| 360 | if (regnum == -1 || regnum == AMD64_GSBASE_REGNUM) |
| 361 | { |
| 362 | |
| 363 | regcache->raw_collect (AMD64_GSBASE_REGNUM, &base); |
| 364 | if (ptrace (PTRACE_ARCH_PRCTL, tid, base, ARCH_SET_GS) < 0) |
| 365 | perror_with_name (_("Couldn't write segment register gs_base")); |
| 366 | } |
| 367 | } |
| 368 | #endif |
| 369 | } |
| 370 | } |
| 371 | \f |
| 372 | |
| 373 | /* This function is called by libthread_db as part of its handling of |
| 374 | a request for a thread's local storage address. */ |
| 375 | |
| 376 | ps_err_e |
| 377 | ps_get_thread_area (struct ps_prochandle *ph, |
| 378 | lwpid_t lwpid, int idx, void **base) |
| 379 | { |
| 380 | if (gdbarch_bfd_arch_info (target_gdbarch ())->bits_per_word == 32) |
| 381 | { |
| 382 | unsigned int base_addr; |
| 383 | ps_err_e result; |
| 384 | |
| 385 | result = x86_linux_get_thread_area (lwpid, (void *) (long) idx, |
| 386 | &base_addr); |
| 387 | if (result == PS_OK) |
| 388 | { |
| 389 | /* Extend the value to 64 bits. Here it's assumed that |
| 390 | a "long" and a "void *" are the same. */ |
| 391 | (*base) = (void *) (long) base_addr; |
| 392 | } |
| 393 | return result; |
| 394 | } |
| 395 | else |
| 396 | { |
| 397 | |
| 398 | /* FIXME: ezannoni-2003-07-09 see comment above about include |
| 399 | file order. We could be getting bogus values for these two. */ |
| 400 | gdb_assert (FS < ELF_NGREG); |
| 401 | gdb_assert (GS < ELF_NGREG); |
| 402 | switch (idx) |
| 403 | { |
| 404 | case FS: |
| 405 | #ifdef HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE |
| 406 | { |
| 407 | /* PTRACE_ARCH_PRCTL is obsolete since 2.6.25, where the |
| 408 | fs_base and gs_base fields of user_regs_struct can be |
| 409 | used directly. */ |
| 410 | unsigned long fs; |
| 411 | errno = 0; |
| 412 | fs = ptrace (PTRACE_PEEKUSER, lwpid, |
| 413 | offsetof (struct user_regs_struct, fs_base), 0); |
| 414 | if (errno == 0) |
| 415 | { |
| 416 | *base = (void *) fs; |
| 417 | return PS_OK; |
| 418 | } |
| 419 | } |
| 420 | #endif |
| 421 | if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_FS) == 0) |
| 422 | return PS_OK; |
| 423 | break; |
| 424 | case GS: |
| 425 | #ifdef HAVE_STRUCT_USER_REGS_STRUCT_GS_BASE |
| 426 | { |
| 427 | unsigned long gs; |
| 428 | errno = 0; |
| 429 | gs = ptrace (PTRACE_PEEKUSER, lwpid, |
| 430 | offsetof (struct user_regs_struct, gs_base), 0); |
| 431 | if (errno == 0) |
| 432 | { |
| 433 | *base = (void *) gs; |
| 434 | return PS_OK; |
| 435 | } |
| 436 | } |
| 437 | #endif |
| 438 | if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_GS) == 0) |
| 439 | return PS_OK; |
| 440 | break; |
| 441 | default: /* Should not happen. */ |
| 442 | return PS_BADADDR; |
| 443 | } |
| 444 | } |
| 445 | return PS_ERR; /* ptrace failed. */ |
| 446 | } |
| 447 | \f |
| 448 | |
| 449 | /* Convert a ptrace/host siginfo object, into/from the siginfo in the |
| 450 | layout of the inferiors' architecture. Returns true if any |
| 451 | conversion was done; false otherwise. If DIRECTION is 1, then copy |
| 452 | from INF to PTRACE. If DIRECTION is 0, copy from PTRACE to |
| 453 | INF. */ |
| 454 | |
| 455 | bool |
| 456 | amd64_linux_nat_target::low_siginfo_fixup (siginfo_t *ptrace, |
| 457 | gdb_byte *inf, |
| 458 | int direction) |
| 459 | { |
| 460 | struct gdbarch *gdbarch = get_frame_arch (get_current_frame ()); |
| 461 | |
| 462 | /* Is the inferior 32-bit? If so, then do fixup the siginfo |
| 463 | object. */ |
| 464 | if (gdbarch_bfd_arch_info (gdbarch)->bits_per_word == 32) |
| 465 | return amd64_linux_siginfo_fixup_common (ptrace, inf, direction, |
| 466 | FIXUP_32); |
| 467 | /* No fixup for native x32 GDB. */ |
| 468 | else if (gdbarch_addr_bit (gdbarch) == 32 && sizeof (void *) == 8) |
| 469 | return amd64_linux_siginfo_fixup_common (ptrace, inf, direction, |
| 470 | FIXUP_X32); |
| 471 | else |
| 472 | return false; |
| 473 | } |
| 474 | |
| 475 | void |
| 476 | _initialize_amd64_linux_nat (void) |
| 477 | { |
| 478 | amd64_native_gregset32_reg_offset = amd64_linux_gregset32_reg_offset; |
| 479 | amd64_native_gregset32_num_regs = I386_LINUX_NUM_REGS; |
| 480 | amd64_native_gregset64_reg_offset = amd64_linux_gregset_reg_offset; |
| 481 | amd64_native_gregset64_num_regs = AMD64_LINUX_NUM_REGS; |
| 482 | |
| 483 | gdb_assert (ARRAY_SIZE (amd64_linux_gregset32_reg_offset) |
| 484 | == amd64_native_gregset32_num_regs); |
| 485 | |
| 486 | linux_target = &the_amd64_linux_nat_target; |
| 487 | |
| 488 | /* Add the target. */ |
| 489 | add_inf_child_target (linux_target); |
| 490 | } |