| 1 | /* Linux-specific ptrace manipulation routines. |
| 2 | Copyright (C) 2012-2021 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GDB. |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 3 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include "gdbsupport/common-defs.h" |
| 20 | #include "linux-ptrace.h" |
| 21 | #include "linux-procfs.h" |
| 22 | #include "linux-waitpid.h" |
| 23 | #include "gdbsupport/buffer.h" |
| 24 | #ifdef HAVE_SYS_PROCFS_H |
| 25 | #include <sys/procfs.h> |
| 26 | #endif |
| 27 | |
| 28 | /* Stores the ptrace options supported by the running kernel. |
| 29 | A value of -1 means we did not check for features yet. A value |
| 30 | of 0 means there are no supported features. */ |
| 31 | static int supported_ptrace_options = -1; |
| 32 | |
| 33 | /* Find all possible reasons we could fail to attach PID and return these |
| 34 | as a string. An empty string is returned if we didn't find any reason. */ |
| 35 | |
| 36 | std::string |
| 37 | linux_ptrace_attach_fail_reason (pid_t pid) |
| 38 | { |
| 39 | pid_t tracerpid = linux_proc_get_tracerpid_nowarn (pid); |
| 40 | std::string result; |
| 41 | |
| 42 | if (tracerpid > 0) |
| 43 | string_appendf (result, |
| 44 | _("process %d is already traced by process %d"), |
| 45 | (int) pid, (int) tracerpid); |
| 46 | |
| 47 | if (linux_proc_pid_is_zombie_nowarn (pid)) |
| 48 | string_appendf (result, |
| 49 | _("process %d is a zombie - the process has already " |
| 50 | "terminated"), |
| 51 | (int) pid); |
| 52 | |
| 53 | return result; |
| 54 | } |
| 55 | |
| 56 | /* See linux-ptrace.h. */ |
| 57 | |
| 58 | std::string |
| 59 | linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err) |
| 60 | { |
| 61 | long lwpid = ptid.lwp (); |
| 62 | std::string reason = linux_ptrace_attach_fail_reason (lwpid); |
| 63 | |
| 64 | if (!reason.empty ()) |
| 65 | return string_printf ("%s (%d), %s", safe_strerror (err), err, |
| 66 | reason.c_str ()); |
| 67 | else |
| 68 | return string_printf ("%s (%d)", safe_strerror (err), err); |
| 69 | } |
| 70 | |
| 71 | #if defined __i386__ || defined __x86_64__ |
| 72 | |
| 73 | /* Address of the 'ret' instruction in asm code block below. */ |
| 74 | EXTERN_C void linux_ptrace_test_ret_to_nx_instr (void); |
| 75 | |
| 76 | #include <sys/reg.h> |
| 77 | #include <sys/mman.h> |
| 78 | #include <signal.h> |
| 79 | |
| 80 | #endif /* defined __i386__ || defined __x86_64__ */ |
| 81 | |
| 82 | /* Kill CHILD. WHO is used to report warnings. */ |
| 83 | |
| 84 | static void |
| 85 | kill_child (pid_t child, const char *who) |
| 86 | { |
| 87 | pid_t got_pid; |
| 88 | int kill_status; |
| 89 | |
| 90 | if (kill (child, SIGKILL) != 0) |
| 91 | { |
| 92 | warning (_("%s: failed to kill child pid %ld %s"), |
| 93 | who, (long) child, safe_strerror (errno)); |
| 94 | return; |
| 95 | } |
| 96 | |
| 97 | errno = 0; |
| 98 | got_pid = my_waitpid (child, &kill_status, 0); |
| 99 | if (got_pid != child) |
| 100 | { |
| 101 | warning (_("%s: " |
| 102 | "kill waitpid returned %ld: %s"), |
| 103 | who, (long) got_pid, safe_strerror (errno)); |
| 104 | return; |
| 105 | } |
| 106 | if (!WIFSIGNALED (kill_status)) |
| 107 | { |
| 108 | warning (_("%s: " |
| 109 | "kill status %d is not WIFSIGNALED!"), |
| 110 | who, kill_status); |
| 111 | return; |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | /* Test broken off-trunk Linux kernel patchset for NX support on i386. It was |
| 116 | removed in Fedora kernel 88fa1f0332d188795ed73d7ac2b1564e11a0b4cd. |
| 117 | |
| 118 | Test also x86_64 arch for PaX support. */ |
| 119 | |
| 120 | static void |
| 121 | linux_ptrace_test_ret_to_nx (void) |
| 122 | { |
| 123 | #if defined __i386__ || defined __x86_64__ |
| 124 | pid_t child, got_pid; |
| 125 | gdb_byte *return_address, *pc; |
| 126 | long l; |
| 127 | int status; |
| 128 | elf_gregset_t regs; |
| 129 | |
| 130 | return_address |
| 131 | = (gdb_byte *) mmap (NULL, 2, PROT_READ | PROT_WRITE, |
| 132 | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 133 | if (return_address == MAP_FAILED) |
| 134 | { |
| 135 | warning (_("linux_ptrace_test_ret_to_nx: Cannot mmap: %s"), |
| 136 | safe_strerror (errno)); |
| 137 | return; |
| 138 | } |
| 139 | |
| 140 | /* Put there 'int3'. */ |
| 141 | *return_address = 0xcc; |
| 142 | |
| 143 | child = fork (); |
| 144 | switch (child) |
| 145 | { |
| 146 | case -1: |
| 147 | warning (_("linux_ptrace_test_ret_to_nx: Cannot fork: %s"), |
| 148 | safe_strerror (errno)); |
| 149 | return; |
| 150 | |
| 151 | case 0: |
| 152 | l = ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) NULL, |
| 153 | (PTRACE_TYPE_ARG4) NULL); |
| 154 | if (l != 0) |
| 155 | warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_TRACEME: %s"), |
| 156 | safe_strerror (errno)); |
| 157 | else |
| 158 | { |
| 159 | #if defined __i386__ |
| 160 | asm volatile ("pushl %0;" |
| 161 | ".globl linux_ptrace_test_ret_to_nx_instr;" |
| 162 | "linux_ptrace_test_ret_to_nx_instr:" |
| 163 | "ret" |
| 164 | : : "r" (return_address) : "memory"); |
| 165 | #elif defined __x86_64__ |
| 166 | asm volatile ("pushq %0;" |
| 167 | ".globl linux_ptrace_test_ret_to_nx_instr;" |
| 168 | "linux_ptrace_test_ret_to_nx_instr:" |
| 169 | "ret" |
| 170 | : : "r" ((uint64_t) (uintptr_t) return_address) |
| 171 | : "memory"); |
| 172 | #else |
| 173 | # error "!__i386__ && !__x86_64__" |
| 174 | #endif |
| 175 | gdb_assert_not_reached ("asm block did not terminate"); |
| 176 | } |
| 177 | |
| 178 | _exit (1); |
| 179 | } |
| 180 | |
| 181 | errno = 0; |
| 182 | got_pid = waitpid (child, &status, 0); |
| 183 | if (got_pid != child) |
| 184 | { |
| 185 | warning (_("linux_ptrace_test_ret_to_nx: waitpid returned %ld: %s"), |
| 186 | (long) got_pid, safe_strerror (errno)); |
| 187 | return; |
| 188 | } |
| 189 | |
| 190 | if (WIFSIGNALED (status)) |
| 191 | { |
| 192 | if (WTERMSIG (status) != SIGKILL) |
| 193 | warning (_("linux_ptrace_test_ret_to_nx: WTERMSIG %d is not SIGKILL!"), |
| 194 | (int) WTERMSIG (status)); |
| 195 | else |
| 196 | warning (_("Cannot call inferior functions, Linux kernel PaX " |
| 197 | "protection forbids return to non-executable pages!")); |
| 198 | return; |
| 199 | } |
| 200 | |
| 201 | if (!WIFSTOPPED (status)) |
| 202 | { |
| 203 | warning (_("linux_ptrace_test_ret_to_nx: status %d is not WIFSTOPPED!"), |
| 204 | status); |
| 205 | kill_child (child, "linux_ptrace_test_ret_to_nx"); |
| 206 | return; |
| 207 | } |
| 208 | |
| 209 | /* We may get SIGSEGV due to missing PROT_EXEC of the return_address. */ |
| 210 | if (WSTOPSIG (status) != SIGTRAP && WSTOPSIG (status) != SIGSEGV) |
| 211 | { |
| 212 | warning (_("linux_ptrace_test_ret_to_nx: " |
| 213 | "WSTOPSIG %d is neither SIGTRAP nor SIGSEGV!"), |
| 214 | (int) WSTOPSIG (status)); |
| 215 | kill_child (child, "linux_ptrace_test_ret_to_nx"); |
| 216 | return; |
| 217 | } |
| 218 | |
| 219 | if (ptrace (PTRACE_GETREGS, child, (PTRACE_TYPE_ARG3) 0, |
| 220 | (PTRACE_TYPE_ARG4) ®s) < 0) |
| 221 | { |
| 222 | warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_GETREGS: %s"), |
| 223 | safe_strerror (errno)); |
| 224 | } |
| 225 | #if defined __i386__ |
| 226 | pc = (gdb_byte *) (uintptr_t) regs[EIP]; |
| 227 | #elif defined __x86_64__ |
| 228 | pc = (gdb_byte *) (uintptr_t) regs[RIP]; |
| 229 | #else |
| 230 | # error "!__i386__ && !__x86_64__" |
| 231 | #endif |
| 232 | |
| 233 | kill_child (child, "linux_ptrace_test_ret_to_nx"); |
| 234 | |
| 235 | /* + 1 is there as x86* stops after the 'int3' instruction. */ |
| 236 | if (WSTOPSIG (status) == SIGTRAP && pc == return_address + 1) |
| 237 | { |
| 238 | /* PASS */ |
| 239 | return; |
| 240 | } |
| 241 | |
| 242 | /* We may get SIGSEGV due to missing PROT_EXEC of the RETURN_ADDRESS page. */ |
| 243 | if (WSTOPSIG (status) == SIGSEGV && pc == return_address) |
| 244 | { |
| 245 | /* PASS */ |
| 246 | return; |
| 247 | } |
| 248 | |
| 249 | if ((void (*) (void)) pc != &linux_ptrace_test_ret_to_nx_instr) |
| 250 | warning (_("linux_ptrace_test_ret_to_nx: PC %p is neither near return " |
| 251 | "address %p nor is the return instruction %p!"), |
| 252 | pc, return_address, &linux_ptrace_test_ret_to_nx_instr); |
| 253 | else |
| 254 | warning (_("Cannot call inferior functions on this system - " |
| 255 | "Linux kernel with broken i386 NX (non-executable pages) " |
| 256 | "support detected!")); |
| 257 | #endif /* defined __i386__ || defined __x86_64__ */ |
| 258 | } |
| 259 | |
| 260 | /* Helper function to fork a process and make the child process call |
| 261 | the function FUNCTION, passing CHILD_STACK as parameter. |
| 262 | |
| 263 | For MMU-less targets, clone is used instead of fork, and |
| 264 | CHILD_STACK is used as stack space for the cloned child. If NULL, |
| 265 | stack space is allocated via malloc (and subsequently passed to |
| 266 | FUNCTION). For MMU targets, CHILD_STACK is ignored. */ |
| 267 | |
| 268 | static int |
| 269 | linux_fork_to_function (gdb_byte *child_stack, int (*function) (void *)) |
| 270 | { |
| 271 | int child_pid; |
| 272 | |
| 273 | /* Sanity check the function pointer. */ |
| 274 | gdb_assert (function != NULL); |
| 275 | |
| 276 | #if defined(__UCLIBC__) && defined(HAS_NOMMU) |
| 277 | #define STACK_SIZE 4096 |
| 278 | |
| 279 | if (child_stack == NULL) |
| 280 | child_stack = (gdb_byte *) xmalloc (STACK_SIZE * 4); |
| 281 | |
| 282 | /* Use CLONE_VM instead of fork, to support uClinux (no MMU). */ |
| 283 | #ifdef __ia64__ |
| 284 | child_pid = __clone2 (function, child_stack, STACK_SIZE, |
| 285 | CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2); |
| 286 | #else /* !__ia64__ */ |
| 287 | child_pid = clone (function, child_stack + STACK_SIZE, |
| 288 | CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2); |
| 289 | #endif /* !__ia64__ */ |
| 290 | #else /* !defined(__UCLIBC) && defined(HAS_NOMMU) */ |
| 291 | child_pid = fork (); |
| 292 | |
| 293 | if (child_pid == 0) |
| 294 | function (NULL); |
| 295 | #endif /* defined(__UCLIBC) && defined(HAS_NOMMU) */ |
| 296 | |
| 297 | if (child_pid == -1) |
| 298 | perror_with_name (("fork")); |
| 299 | |
| 300 | return child_pid; |
| 301 | } |
| 302 | |
| 303 | /* A helper function for linux_check_ptrace_features, called after |
| 304 | the child forks a grandchild. */ |
| 305 | |
| 306 | static int |
| 307 | linux_grandchild_function (void *child_stack) |
| 308 | { |
| 309 | /* Free any allocated stack. */ |
| 310 | xfree (child_stack); |
| 311 | |
| 312 | /* This code is only reacheable by the grandchild (child's child) |
| 313 | process. */ |
| 314 | _exit (0); |
| 315 | } |
| 316 | |
| 317 | /* A helper function for linux_check_ptrace_features, called after |
| 318 | the parent process forks a child. The child allows itself to |
| 319 | be traced by its parent. */ |
| 320 | |
| 321 | static int |
| 322 | linux_child_function (void *child_stack) |
| 323 | { |
| 324 | ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0); |
| 325 | kill (getpid (), SIGSTOP); |
| 326 | |
| 327 | /* Fork a grandchild. */ |
| 328 | linux_fork_to_function ((gdb_byte *) child_stack, linux_grandchild_function); |
| 329 | |
| 330 | /* This code is only reacheable by the child (grandchild's parent) |
| 331 | process. */ |
| 332 | _exit (0); |
| 333 | } |
| 334 | |
| 335 | static void linux_test_for_tracesysgood (int child_pid); |
| 336 | static void linux_test_for_tracefork (int child_pid); |
| 337 | static void linux_test_for_exitkill (int child_pid); |
| 338 | |
| 339 | /* Determine ptrace features available on this target. */ |
| 340 | |
| 341 | void |
| 342 | linux_check_ptrace_features (void) |
| 343 | { |
| 344 | int child_pid, ret, status; |
| 345 | |
| 346 | /* Initialize the options. */ |
| 347 | supported_ptrace_options = 0; |
| 348 | |
| 349 | /* Fork a child so we can do some testing. The child will call |
| 350 | linux_child_function and will get traced. The child will |
| 351 | eventually fork a grandchild so we can test fork event |
| 352 | reporting. */ |
| 353 | child_pid = linux_fork_to_function (NULL, linux_child_function); |
| 354 | |
| 355 | ret = my_waitpid (child_pid, &status, 0); |
| 356 | if (ret == -1) |
| 357 | perror_with_name (("waitpid")); |
| 358 | else if (ret != child_pid) |
| 359 | error (_("linux_check_ptrace_features: waitpid: unexpected result %d."), |
| 360 | ret); |
| 361 | if (! WIFSTOPPED (status)) |
| 362 | error (_("linux_check_ptrace_features: waitpid: unexpected status %d."), |
| 363 | status); |
| 364 | |
| 365 | linux_test_for_tracesysgood (child_pid); |
| 366 | |
| 367 | linux_test_for_tracefork (child_pid); |
| 368 | |
| 369 | linux_test_for_exitkill (child_pid); |
| 370 | |
| 371 | /* Kill child_pid. */ |
| 372 | kill_child (child_pid, "linux_check_ptrace_features"); |
| 373 | } |
| 374 | |
| 375 | /* Determine if PTRACE_O_TRACESYSGOOD can be used to catch |
| 376 | syscalls. */ |
| 377 | |
| 378 | static void |
| 379 | linux_test_for_tracesysgood (int child_pid) |
| 380 | { |
| 381 | int ret; |
| 382 | |
| 383 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, |
| 384 | (PTRACE_TYPE_ARG4) PTRACE_O_TRACESYSGOOD); |
| 385 | |
| 386 | if (ret == 0) |
| 387 | supported_ptrace_options |= PTRACE_O_TRACESYSGOOD; |
| 388 | } |
| 389 | |
| 390 | /* Determine if PTRACE_O_TRACEFORK can be used to follow fork |
| 391 | events. */ |
| 392 | |
| 393 | static void |
| 394 | linux_test_for_tracefork (int child_pid) |
| 395 | { |
| 396 | int ret, status; |
| 397 | long second_pid; |
| 398 | |
| 399 | /* First, set the PTRACE_O_TRACEFORK option. If this fails, we |
| 400 | know for sure that it is not supported. */ |
| 401 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, |
| 402 | (PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK); |
| 403 | |
| 404 | if (ret != 0) |
| 405 | return; |
| 406 | |
| 407 | /* Check if the target supports PTRACE_O_TRACEVFORKDONE. */ |
| 408 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, |
| 409 | (PTRACE_TYPE_ARG4) (PTRACE_O_TRACEFORK |
| 410 | | PTRACE_O_TRACEVFORKDONE)); |
| 411 | if (ret == 0) |
| 412 | supported_ptrace_options |= PTRACE_O_TRACEVFORKDONE; |
| 413 | |
| 414 | /* Setting PTRACE_O_TRACEFORK did not cause an error, however we |
| 415 | don't know for sure that the feature is available; old |
| 416 | versions of PTRACE_SETOPTIONS ignored unknown options. |
| 417 | Therefore, we attach to the child process, use PTRACE_SETOPTIONS |
| 418 | to enable fork tracing, and let it fork. If the process exits, |
| 419 | we assume that we can't use PTRACE_O_TRACEFORK; if we get the |
| 420 | fork notification, and we can extract the new child's PID, then |
| 421 | we assume that we can. |
| 422 | |
| 423 | We do not explicitly check for vfork tracing here. It is |
| 424 | assumed that vfork tracing is available whenever fork tracing |
| 425 | is available. */ |
| 426 | ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_TYPE_ARG3) 0, |
| 427 | (PTRACE_TYPE_ARG4) 0); |
| 428 | if (ret != 0) |
| 429 | warning (_("linux_test_for_tracefork: failed to resume child")); |
| 430 | |
| 431 | ret = my_waitpid (child_pid, &status, 0); |
| 432 | |
| 433 | /* Check if we received a fork event notification. */ |
| 434 | if (ret == child_pid && WIFSTOPPED (status) |
| 435 | && linux_ptrace_get_extended_event (status) == PTRACE_EVENT_FORK) |
| 436 | { |
| 437 | /* We did receive a fork event notification. Make sure its PID |
| 438 | is reported. */ |
| 439 | second_pid = 0; |
| 440 | ret = ptrace (PTRACE_GETEVENTMSG, child_pid, (PTRACE_TYPE_ARG3) 0, |
| 441 | (PTRACE_TYPE_ARG4) &second_pid); |
| 442 | if (ret == 0 && second_pid != 0) |
| 443 | { |
| 444 | int second_status; |
| 445 | |
| 446 | /* We got the PID from the grandchild, which means fork |
| 447 | tracing is supported. */ |
| 448 | supported_ptrace_options |= PTRACE_O_TRACECLONE; |
| 449 | supported_ptrace_options |= (PTRACE_O_TRACEFORK |
| 450 | | PTRACE_O_TRACEVFORK |
| 451 | | PTRACE_O_TRACEEXEC); |
| 452 | |
| 453 | /* Do some cleanup and kill the grandchild. */ |
| 454 | my_waitpid (second_pid, &second_status, 0); |
| 455 | kill_child (second_pid, "linux_test_for_tracefork"); |
| 456 | } |
| 457 | } |
| 458 | else |
| 459 | warning (_("linux_test_for_tracefork: unexpected result from waitpid " |
| 460 | "(%d, status 0x%x)"), ret, status); |
| 461 | } |
| 462 | |
| 463 | /* Determine if PTRACE_O_EXITKILL can be used. */ |
| 464 | |
| 465 | static void |
| 466 | linux_test_for_exitkill (int child_pid) |
| 467 | { |
| 468 | int ret; |
| 469 | |
| 470 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, |
| 471 | (PTRACE_TYPE_ARG4) PTRACE_O_EXITKILL); |
| 472 | |
| 473 | if (ret == 0) |
| 474 | supported_ptrace_options |= PTRACE_O_EXITKILL; |
| 475 | } |
| 476 | |
| 477 | /* Enable reporting of all currently supported ptrace events. |
| 478 | OPTIONS is a bit mask of extended features we want enabled, |
| 479 | if supported by the kernel. PTRACE_O_TRACECLONE is always |
| 480 | enabled, if supported. */ |
| 481 | |
| 482 | void |
| 483 | linux_enable_event_reporting (pid_t pid, int options) |
| 484 | { |
| 485 | /* Check if we have initialized the ptrace features for this |
| 486 | target. If not, do it now. */ |
| 487 | if (supported_ptrace_options == -1) |
| 488 | linux_check_ptrace_features (); |
| 489 | |
| 490 | /* We always want clone events. */ |
| 491 | options |= PTRACE_O_TRACECLONE; |
| 492 | |
| 493 | /* Filter out unsupported options. */ |
| 494 | options &= supported_ptrace_options; |
| 495 | |
| 496 | /* Set the options. */ |
| 497 | ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0, |
| 498 | (PTRACE_TYPE_ARG4) (uintptr_t) options); |
| 499 | } |
| 500 | |
| 501 | /* Disable reporting of all currently supported ptrace events. */ |
| 502 | |
| 503 | void |
| 504 | linux_disable_event_reporting (pid_t pid) |
| 505 | { |
| 506 | /* Set the options. */ |
| 507 | ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0, 0); |
| 508 | } |
| 509 | |
| 510 | /* Returns non-zero if PTRACE_OPTIONS is contained within |
| 511 | SUPPORTED_PTRACE_OPTIONS, therefore supported. Returns 0 |
| 512 | otherwise. */ |
| 513 | |
| 514 | static int |
| 515 | ptrace_supports_feature (int ptrace_options) |
| 516 | { |
| 517 | if (supported_ptrace_options == -1) |
| 518 | linux_check_ptrace_features (); |
| 519 | |
| 520 | return ((supported_ptrace_options & ptrace_options) == ptrace_options); |
| 521 | } |
| 522 | |
| 523 | /* Returns non-zero if PTRACE_EVENT_FORK is supported by ptrace, |
| 524 | 0 otherwise. Note that if PTRACE_EVENT_FORK is supported so is |
| 525 | PTRACE_EVENT_CLONE, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK, |
| 526 | since they were all added to the kernel at the same time. */ |
| 527 | |
| 528 | int |
| 529 | linux_supports_tracefork (void) |
| 530 | { |
| 531 | return ptrace_supports_feature (PTRACE_O_TRACEFORK); |
| 532 | } |
| 533 | |
| 534 | /* Returns non-zero if PTRACE_EVENT_EXEC is supported by ptrace, |
| 535 | 0 otherwise. Note that if PTRACE_EVENT_FORK is supported so is |
| 536 | PTRACE_EVENT_CLONE, PTRACE_EVENT_FORK and PTRACE_EVENT_VFORK, |
| 537 | since they were all added to the kernel at the same time. */ |
| 538 | |
| 539 | int |
| 540 | linux_supports_traceexec (void) |
| 541 | { |
| 542 | return ptrace_supports_feature (PTRACE_O_TRACEEXEC); |
| 543 | } |
| 544 | |
| 545 | /* Returns non-zero if PTRACE_EVENT_CLONE is supported by ptrace, |
| 546 | 0 otherwise. Note that if PTRACE_EVENT_CLONE is supported so is |
| 547 | PTRACE_EVENT_FORK, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK, |
| 548 | since they were all added to the kernel at the same time. */ |
| 549 | |
| 550 | int |
| 551 | linux_supports_traceclone (void) |
| 552 | { |
| 553 | return ptrace_supports_feature (PTRACE_O_TRACECLONE); |
| 554 | } |
| 555 | |
| 556 | /* Returns non-zero if PTRACE_O_TRACEVFORKDONE is supported by |
| 557 | ptrace, 0 otherwise. */ |
| 558 | |
| 559 | int |
| 560 | linux_supports_tracevforkdone (void) |
| 561 | { |
| 562 | return ptrace_supports_feature (PTRACE_O_TRACEVFORKDONE); |
| 563 | } |
| 564 | |
| 565 | /* Returns non-zero if PTRACE_O_TRACESYSGOOD is supported by ptrace, |
| 566 | 0 otherwise. */ |
| 567 | |
| 568 | int |
| 569 | linux_supports_tracesysgood (void) |
| 570 | { |
| 571 | return ptrace_supports_feature (PTRACE_O_TRACESYSGOOD); |
| 572 | } |
| 573 | |
| 574 | /* Display possible problems on this system. Display them only once per GDB |
| 575 | execution. */ |
| 576 | |
| 577 | void |
| 578 | linux_ptrace_init_warnings (void) |
| 579 | { |
| 580 | static int warned = 0; |
| 581 | |
| 582 | if (warned) |
| 583 | return; |
| 584 | warned = 1; |
| 585 | |
| 586 | linux_ptrace_test_ret_to_nx (); |
| 587 | } |
| 588 | |
| 589 | /* Extract extended ptrace event from wait status. */ |
| 590 | |
| 591 | int |
| 592 | linux_ptrace_get_extended_event (int wstat) |
| 593 | { |
| 594 | return (wstat >> 16); |
| 595 | } |
| 596 | |
| 597 | /* Determine whether wait status denotes an extended event. */ |
| 598 | |
| 599 | int |
| 600 | linux_is_extended_waitstatus (int wstat) |
| 601 | { |
| 602 | return (linux_ptrace_get_extended_event (wstat) != 0); |
| 603 | } |
| 604 | |
| 605 | /* Return true if the event in LP may be caused by breakpoint. */ |
| 606 | |
| 607 | int |
| 608 | linux_wstatus_maybe_breakpoint (int wstat) |
| 609 | { |
| 610 | return (WIFSTOPPED (wstat) |
| 611 | && (WSTOPSIG (wstat) == SIGTRAP |
| 612 | /* SIGILL and SIGSEGV are also treated as traps in case a |
| 613 | breakpoint is inserted at the current PC. */ |
| 614 | || WSTOPSIG (wstat) == SIGILL |
| 615 | || WSTOPSIG (wstat) == SIGSEGV)); |
| 616 | } |