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5f572dec | 1 | /* Linux-specific ptrace manipulation routines. |
28e7fd62 | 2 | Copyright (C) 2012-2013 Free Software Foundation, Inc. |
5f572dec JK |
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 | #ifdef GDBSERVER | |
20 | #include "server.h" | |
21 | #else | |
22 | #include "defs.h" | |
23 | #include "gdb_string.h" | |
24 | #endif | |
25 | ||
26 | #include "linux-ptrace.h" | |
87b0bb13 | 27 | #include "linux-procfs.h" |
96d7229d | 28 | #include "nat/linux-waitpid.h" |
87b0bb13 | 29 | #include "buffer.h" |
aa7c7447 | 30 | #include "gdb_assert.h" |
8bdce1ff | 31 | #include "gdb_wait.h" |
87b0bb13 | 32 | |
96d7229d LM |
33 | /* Stores the currently supported ptrace options. A value of |
34 | -1 means we did not check for features yet. A value of 0 means | |
35 | there are no supported features. */ | |
36 | static int current_ptrace_options = -1; | |
37 | ||
87b0bb13 JK |
38 | /* Find all possible reasons we could fail to attach PID and append these |
39 | newline terminated reason strings to initialized BUFFER. '\0' termination | |
40 | of BUFFER must be done by the caller. */ | |
41 | ||
42 | void | |
43 | linux_ptrace_attach_warnings (pid_t pid, struct buffer *buffer) | |
44 | { | |
45 | pid_t tracerpid; | |
46 | ||
47 | tracerpid = linux_proc_get_tracerpid (pid); | |
48 | if (tracerpid > 0) | |
49 | buffer_xml_printf (buffer, _("warning: process %d is already traced " | |
50 | "by process %d\n"), | |
51 | (int) pid, (int) tracerpid); | |
52 | ||
53 | if (linux_proc_pid_is_zombie (pid)) | |
54 | buffer_xml_printf (buffer, _("warning: process %d is a zombie " | |
55 | "- the process has already terminated\n"), | |
56 | (int) pid); | |
57 | } | |
aa7c7447 | 58 | |
6e3c039e | 59 | #if defined __i386__ || defined __x86_64__ |
aa7c7447 JK |
60 | |
61 | /* Address of the 'ret' instruction in asm code block below. */ | |
62 | extern void (linux_ptrace_test_ret_to_nx_instr) (void); | |
63 | ||
64 | #include <sys/reg.h> | |
65 | #include <sys/mman.h> | |
66 | #include <signal.h> | |
aa7c7447 JK |
67 | #include <stdint.h> |
68 | ||
6e3c039e | 69 | #endif /* defined __i386__ || defined __x86_64__ */ |
aa7c7447 JK |
70 | |
71 | /* Test broken off-trunk Linux kernel patchset for NX support on i386. It was | |
6e3c039e JK |
72 | removed in Fedora kernel 88fa1f0332d188795ed73d7ac2b1564e11a0b4cd. |
73 | ||
74 | Test also x86_64 arch for PaX support. */ | |
aa7c7447 JK |
75 | |
76 | static void | |
77 | linux_ptrace_test_ret_to_nx (void) | |
78 | { | |
6e3c039e | 79 | #if defined __i386__ || defined __x86_64__ |
aa7c7447 JK |
80 | pid_t child, got_pid; |
81 | gdb_byte *return_address, *pc; | |
82 | long l; | |
61a31a67 | 83 | int status, kill_status; |
aa7c7447 JK |
84 | |
85 | return_address = mmap (NULL, 2, PROT_READ | PROT_WRITE, | |
86 | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); | |
87 | if (return_address == MAP_FAILED) | |
88 | { | |
89 | warning (_("linux_ptrace_test_ret_to_nx: Cannot mmap: %s"), | |
90 | strerror (errno)); | |
91 | return; | |
92 | } | |
93 | ||
94 | /* Put there 'int3'. */ | |
95 | *return_address = 0xcc; | |
96 | ||
97 | child = fork (); | |
98 | switch (child) | |
99 | { | |
100 | case -1: | |
101 | warning (_("linux_ptrace_test_ret_to_nx: Cannot fork: %s"), | |
102 | strerror (errno)); | |
103 | return; | |
104 | ||
105 | case 0: | |
96d7229d LM |
106 | l = ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) NULL, |
107 | (PTRACE_TYPE_ARG4) NULL); | |
aa7c7447 JK |
108 | if (l != 0) |
109 | warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_TRACEME: %s"), | |
110 | strerror (errno)); | |
111 | else | |
112 | { | |
6e3c039e | 113 | #if defined __i386__ |
aa7c7447 JK |
114 | asm volatile ("pushl %0;" |
115 | ".globl linux_ptrace_test_ret_to_nx_instr;" | |
116 | "linux_ptrace_test_ret_to_nx_instr:" | |
117 | "ret" | |
118 | : : "r" (return_address) : "%esp", "memory"); | |
6e3c039e JK |
119 | #elif defined __x86_64__ |
120 | asm volatile ("pushq %0;" | |
121 | ".globl linux_ptrace_test_ret_to_nx_instr;" | |
122 | "linux_ptrace_test_ret_to_nx_instr:" | |
123 | "ret" | |
bdad4180 MF |
124 | : : "r" ((uint64_t) (uintptr_t) return_address) |
125 | : "%rsp", "memory"); | |
6e3c039e JK |
126 | #else |
127 | # error "!__i386__ && !__x86_64__" | |
128 | #endif | |
aa7c7447 JK |
129 | gdb_assert_not_reached ("asm block did not terminate"); |
130 | } | |
131 | ||
132 | _exit (1); | |
133 | } | |
134 | ||
6e3c039e | 135 | errno = 0; |
aa7c7447 | 136 | got_pid = waitpid (child, &status, 0); |
6e3c039e JK |
137 | if (got_pid != child) |
138 | { | |
139 | warning (_("linux_ptrace_test_ret_to_nx: waitpid returned %ld: %s"), | |
140 | (long) got_pid, strerror (errno)); | |
141 | return; | |
142 | } | |
143 | ||
144 | if (WIFSIGNALED (status)) | |
145 | { | |
146 | if (WTERMSIG (status) != SIGKILL) | |
147 | warning (_("linux_ptrace_test_ret_to_nx: WTERMSIG %d is not SIGKILL!"), | |
148 | (int) WTERMSIG (status)); | |
149 | else | |
150 | warning (_("Cannot call inferior functions, Linux kernel PaX " | |
151 | "protection forbids return to non-executable pages!")); | |
152 | return; | |
153 | } | |
154 | ||
155 | if (!WIFSTOPPED (status)) | |
156 | { | |
157 | warning (_("linux_ptrace_test_ret_to_nx: status %d is not WIFSTOPPED!"), | |
158 | status); | |
159 | return; | |
160 | } | |
aa7c7447 JK |
161 | |
162 | /* We may get SIGSEGV due to missing PROT_EXEC of the return_address. */ | |
6e3c039e JK |
163 | if (WSTOPSIG (status) != SIGTRAP && WSTOPSIG (status) != SIGSEGV) |
164 | { | |
165 | warning (_("linux_ptrace_test_ret_to_nx: " | |
166 | "WSTOPSIG %d is neither SIGTRAP nor SIGSEGV!"), | |
167 | (int) WSTOPSIG (status)); | |
168 | return; | |
169 | } | |
aa7c7447 JK |
170 | |
171 | errno = 0; | |
6e3c039e | 172 | #if defined __i386__ |
96d7229d LM |
173 | l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (EIP * 4), |
174 | (PTRACE_TYPE_ARG4) NULL); | |
6e3c039e | 175 | #elif defined __x86_64__ |
96d7229d LM |
176 | l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (RIP * 8), |
177 | (PTRACE_TYPE_ARG4) NULL); | |
6e3c039e JK |
178 | #else |
179 | # error "!__i386__ && !__x86_64__" | |
180 | #endif | |
181 | if (errno != 0) | |
182 | { | |
183 | warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER: %s"), | |
184 | strerror (errno)); | |
185 | return; | |
186 | } | |
aa7c7447 JK |
187 | pc = (void *) (uintptr_t) l; |
188 | ||
61a31a67 | 189 | kill (child, SIGKILL); |
96d7229d LM |
190 | ptrace (PTRACE_KILL, child, (PTRACE_TYPE_ARG3) NULL, |
191 | (PTRACE_TYPE_ARG4) NULL); | |
61a31a67 JK |
192 | |
193 | errno = 0; | |
194 | got_pid = waitpid (child, &kill_status, 0); | |
195 | if (got_pid != child) | |
6e3c039e | 196 | { |
61a31a67 JK |
197 | warning (_("linux_ptrace_test_ret_to_nx: " |
198 | "PTRACE_KILL waitpid returned %ld: %s"), | |
199 | (long) got_pid, strerror (errno)); | |
6e3c039e JK |
200 | return; |
201 | } | |
61a31a67 | 202 | if (!WIFSIGNALED (kill_status)) |
aa7c7447 | 203 | { |
61a31a67 JK |
204 | warning (_("linux_ptrace_test_ret_to_nx: " |
205 | "PTRACE_KILL status %d is not WIFSIGNALED!"), | |
206 | status); | |
207 | return; | |
aa7c7447 JK |
208 | } |
209 | ||
210 | /* + 1 is there as x86* stops after the 'int3' instruction. */ | |
211 | if (WSTOPSIG (status) == SIGTRAP && pc == return_address + 1) | |
212 | { | |
213 | /* PASS */ | |
214 | return; | |
215 | } | |
216 | ||
217 | /* We may get SIGSEGV due to missing PROT_EXEC of the RETURN_ADDRESS page. */ | |
218 | if (WSTOPSIG (status) == SIGSEGV && pc == return_address) | |
219 | { | |
220 | /* PASS */ | |
221 | return; | |
222 | } | |
223 | ||
6e3c039e JK |
224 | if ((void (*) (void)) pc != &linux_ptrace_test_ret_to_nx_instr) |
225 | warning (_("linux_ptrace_test_ret_to_nx: PC %p is neither near return " | |
226 | "address %p nor is the return instruction %p!"), | |
227 | pc, return_address, &linux_ptrace_test_ret_to_nx_instr); | |
228 | else | |
025e6dce PA |
229 | warning (_("Cannot call inferior functions on this system - " |
230 | "Linux kernel with broken i386 NX (non-executable pages) " | |
231 | "support detected!")); | |
6e3c039e | 232 | #endif /* defined __i386__ || defined __x86_64__ */ |
aa7c7447 JK |
233 | } |
234 | ||
96d7229d LM |
235 | /* Helper function to fork a process and make the child process call |
236 | the function FUNCTION, passing CHILD_STACK as parameter. | |
237 | ||
238 | For MMU-less targets, clone is used instead of fork, and | |
239 | CHILD_STACK is used as stack space for the cloned child. If NULL, | |
240 | stack space is allocated via malloc (and subsequently passed to | |
241 | FUNCTION). For MMU targets, CHILD_STACK is ignored. */ | |
242 | ||
243 | static int | |
244 | linux_fork_to_function (gdb_byte *child_stack, void (*function) (gdb_byte *)) | |
245 | { | |
246 | int child_pid; | |
247 | ||
248 | /* Sanity check the function pointer. */ | |
249 | gdb_assert (function != NULL); | |
250 | ||
251 | #if defined(__UCLIBC__) && defined(HAS_NOMMU) | |
252 | #define STACK_SIZE 4096 | |
253 | ||
254 | if (child_stack == NULL) | |
255 | child_stack = xmalloc (STACK_SIZE * 4); | |
256 | ||
257 | /* Use CLONE_VM instead of fork, to support uClinux (no MMU). */ | |
258 | #ifdef __ia64__ | |
259 | child_pid = __clone2 (function, child_stack, STACK_SIZE, | |
260 | CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2); | |
261 | #else /* !__ia64__ */ | |
262 | child_pid = clone (function, child_stack + STACK_SIZE, | |
263 | CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2); | |
264 | #endif /* !__ia64__ */ | |
265 | #else /* !defined(__UCLIBC) && defined(HAS_NOMMU) */ | |
266 | child_pid = fork (); | |
267 | ||
268 | if (child_pid == 0) | |
269 | function (NULL); | |
270 | #endif /* defined(__UCLIBC) && defined(HAS_NOMMU) */ | |
271 | ||
272 | if (child_pid == -1) | |
273 | perror_with_name (("fork")); | |
274 | ||
275 | return child_pid; | |
276 | } | |
277 | ||
278 | /* A helper function for linux_check_ptrace_features, called after | |
279 | the child forks a grandchild. */ | |
280 | ||
281 | static void | |
282 | linux_grandchild_function (gdb_byte *child_stack) | |
283 | { | |
284 | /* Free any allocated stack. */ | |
285 | xfree (child_stack); | |
286 | ||
287 | /* This code is only reacheable by the grandchild (child's child) | |
288 | process. */ | |
289 | _exit (0); | |
290 | } | |
291 | ||
292 | /* A helper function for linux_check_ptrace_features, called after | |
293 | the parent process forks a child. The child allows itself to | |
294 | be traced by its parent. */ | |
295 | ||
296 | static void | |
297 | linux_child_function (gdb_byte *child_stack) | |
298 | { | |
299 | ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0); | |
300 | kill (getpid (), SIGSTOP); | |
301 | ||
302 | /* Fork a grandchild. */ | |
303 | linux_fork_to_function (child_stack, linux_grandchild_function); | |
304 | ||
305 | /* This code is only reacheable by the child (grandchild's parent) | |
306 | process. */ | |
307 | _exit (0); | |
308 | } | |
309 | ||
310 | /* Determine ptrace features available on this target. */ | |
311 | ||
312 | static void | |
313 | linux_check_ptrace_features (void) | |
314 | { | |
315 | int child_pid, ret, status; | |
316 | long second_pid; | |
317 | ||
318 | /* Initialize the options. */ | |
319 | current_ptrace_options = 0; | |
320 | ||
321 | /* Fork a child so we can do some testing. The child will call | |
322 | linux_child_function and will get traced. The child will | |
323 | eventually fork a grandchild so we can test fork event | |
324 | reporting. */ | |
325 | child_pid = linux_fork_to_function (NULL, linux_child_function); | |
326 | ||
327 | ret = my_waitpid (child_pid, &status, 0); | |
328 | if (ret == -1) | |
329 | perror_with_name (("waitpid")); | |
330 | else if (ret != child_pid) | |
331 | error (_("linux_check_ptrace_features: waitpid: unexpected result %d."), | |
332 | ret); | |
333 | if (! WIFSTOPPED (status)) | |
334 | error (_("linux_check_ptrace_features: waitpid: unexpected status %d."), | |
335 | status); | |
336 | ||
337 | /* First, set the PTRACE_O_TRACEFORK option. If this fails, we | |
338 | know for sure that it is not supported. */ | |
339 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, | |
340 | (PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK); | |
341 | ||
342 | if (ret != 0) | |
343 | { | |
344 | ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0, | |
345 | (PTRACE_TYPE_ARG4) 0); | |
346 | if (ret != 0) | |
347 | { | |
348 | warning (_("linux_check_ptrace_features: failed to kill child")); | |
349 | return; | |
350 | } | |
351 | ||
352 | ret = my_waitpid (child_pid, &status, 0); | |
353 | if (ret != child_pid) | |
354 | warning (_("linux_check_ptrace_features: failed " | |
355 | "to wait for killed child")); | |
356 | else if (!WIFSIGNALED (status)) | |
357 | warning (_("linux_check_ptrace_features: unexpected " | |
358 | "wait status 0x%x from killed child"), status); | |
359 | ||
360 | return; | |
361 | } | |
362 | ||
363 | #ifdef GDBSERVER | |
364 | /* gdbserver does not support PTRACE_O_TRACESYSGOOD or | |
365 | PTRACE_O_TRACEVFORKDONE yet. */ | |
366 | #else | |
367 | /* Check if the target supports PTRACE_O_TRACESYSGOOD. */ | |
368 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, | |
369 | (PTRACE_TYPE_ARG4) PTRACE_O_TRACESYSGOOD); | |
370 | if (ret == 0) | |
371 | current_ptrace_options |= PTRACE_O_TRACESYSGOOD; | |
372 | ||
373 | /* Check if the target supports PTRACE_O_TRACEVFORKDONE. */ | |
374 | ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, | |
375 | (PTRACE_TYPE_ARG4) (PTRACE_O_TRACEFORK | |
376 | | PTRACE_O_TRACEVFORKDONE)); | |
377 | if (ret == 0) | |
378 | current_ptrace_options |= PTRACE_O_TRACEVFORKDONE; | |
379 | #endif | |
380 | ||
381 | /* Setting PTRACE_O_TRACEFORK did not cause an error, however we | |
382 | don't know for sure that the feature is available; old | |
383 | versions of PTRACE_SETOPTIONS ignored unknown options. | |
384 | Therefore, we attach to the child process, use PTRACE_SETOPTIONS | |
385 | to enable fork tracing, and let it fork. If the process exits, | |
386 | we assume that we can't use PTRACE_O_TRACEFORK; if we get the | |
387 | fork notification, and we can extract the new child's PID, then | |
388 | we assume that we can. | |
389 | ||
390 | We do not explicitly check for vfork tracing here. It is | |
391 | assumed that vfork tracing is available whenever fork tracing | |
392 | is available. */ | |
393 | ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_TYPE_ARG3) 0, | |
394 | (PTRACE_TYPE_ARG4) 0); | |
395 | if (ret != 0) | |
396 | warning (_("linux_check_ptrace_features: failed to resume child")); | |
397 | ||
398 | ret = my_waitpid (child_pid, &status, 0); | |
399 | ||
400 | /* Check if we received a fork event notification. */ | |
401 | if (ret == child_pid && WIFSTOPPED (status) | |
402 | && status >> 16 == PTRACE_EVENT_FORK) | |
403 | { | |
404 | /* We did receive a fork event notification. Make sure its PID | |
405 | is reported. */ | |
406 | second_pid = 0; | |
407 | ret = ptrace (PTRACE_GETEVENTMSG, child_pid, (PTRACE_TYPE_ARG3) 0, | |
408 | (PTRACE_TYPE_ARG4) &second_pid); | |
409 | if (ret == 0 && second_pid != 0) | |
410 | { | |
411 | int second_status; | |
412 | ||
413 | /* We got the PID from the grandchild, which means fork | |
414 | tracing is supported. */ | |
415 | #ifdef GDBSERVER | |
416 | /* Do not enable all the options for now since gdbserver does not | |
417 | properly support them. This restriction will be lifted when | |
418 | gdbserver is augmented to support them. */ | |
419 | current_ptrace_options |= PTRACE_O_TRACECLONE; | |
420 | #else | |
421 | current_ptrace_options |= PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | |
422 | | PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC; | |
423 | ||
424 | /* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to | |
425 | support read-only process state. */ | |
426 | #endif | |
427 | ||
428 | /* Do some cleanup and kill the grandchild. */ | |
429 | my_waitpid (second_pid, &second_status, 0); | |
430 | ret = ptrace (PTRACE_KILL, second_pid, (PTRACE_TYPE_ARG3) 0, | |
431 | (PTRACE_TYPE_ARG4) 0); | |
432 | if (ret != 0) | |
433 | warning (_("linux_check_ptrace_features: " | |
434 | "failed to kill second child")); | |
435 | my_waitpid (second_pid, &status, 0); | |
436 | } | |
437 | } | |
438 | else | |
439 | warning (_("linux_check_ptrace_features: unexpected result from waitpid " | |
440 | "(%d, status 0x%x)"), ret, status); | |
441 | ||
442 | /* Clean things up and kill any pending children. */ | |
443 | do | |
444 | { | |
445 | ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0, | |
446 | (PTRACE_TYPE_ARG4) 0); | |
447 | if (ret != 0) | |
448 | warning ("linux_check_ptrace_features: failed to kill child"); | |
449 | my_waitpid (child_pid, &status, 0); | |
450 | } | |
451 | while (WIFSTOPPED (status)); | |
452 | } | |
453 | ||
454 | /* Enable reporting of all currently supported ptrace events. */ | |
455 | ||
456 | void | |
457 | linux_enable_event_reporting (pid_t pid) | |
458 | { | |
459 | /* Check if we have initialized the ptrace features for this | |
460 | target. If not, do it now. */ | |
461 | if (current_ptrace_options == -1) | |
462 | linux_check_ptrace_features (); | |
463 | ||
464 | /* Set the options. */ | |
465 | ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0, | |
466 | (PTRACE_TYPE_ARG4) (uintptr_t) current_ptrace_options); | |
467 | } | |
468 | ||
469 | /* Returns non-zero if PTRACE_OPTIONS is contained within | |
470 | CURRENT_PTRACE_OPTIONS, therefore supported. Returns 0 | |
471 | otherwise. */ | |
472 | ||
473 | static int | |
474 | ptrace_supports_feature (int ptrace_options) | |
475 | { | |
476 | gdb_assert (current_ptrace_options >= 0); | |
477 | ||
478 | return ((current_ptrace_options & ptrace_options) == ptrace_options); | |
479 | } | |
480 | ||
481 | /* Returns non-zero if PTRACE_EVENT_FORK is supported by ptrace, | |
482 | 0 otherwise. Note that if PTRACE_EVENT_FORK is supported so is | |
483 | PTRACE_EVENT_CLONE, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK, | |
484 | since they were all added to the kernel at the same time. */ | |
485 | ||
486 | int | |
487 | linux_supports_tracefork (void) | |
488 | { | |
489 | return ptrace_supports_feature (PTRACE_O_TRACEFORK); | |
490 | } | |
491 | ||
492 | /* Returns non-zero if PTRACE_EVENT_CLONE is supported by ptrace, | |
493 | 0 otherwise. Note that if PTRACE_EVENT_CLONE is supported so is | |
494 | PTRACE_EVENT_FORK, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK, | |
495 | since they were all added to the kernel at the same time. */ | |
496 | ||
497 | int | |
498 | linux_supports_traceclone (void) | |
499 | { | |
500 | return ptrace_supports_feature (PTRACE_O_TRACECLONE); | |
501 | } | |
502 | ||
503 | /* Returns non-zero if PTRACE_O_TRACEVFORKDONE is supported by | |
504 | ptrace, 0 otherwise. */ | |
505 | ||
506 | int | |
507 | linux_supports_tracevforkdone (void) | |
508 | { | |
509 | return ptrace_supports_feature (PTRACE_O_TRACEVFORKDONE); | |
510 | } | |
511 | ||
512 | /* Returns non-zero if PTRACE_O_TRACESYSGOOD is supported by ptrace, | |
513 | 0 otherwise. */ | |
514 | ||
515 | int | |
516 | linux_supports_tracesysgood (void) | |
517 | { | |
518 | return ptrace_supports_feature (PTRACE_O_TRACESYSGOOD); | |
519 | } | |
520 | ||
aa7c7447 JK |
521 | /* Display possible problems on this system. Display them only once per GDB |
522 | execution. */ | |
523 | ||
524 | void | |
525 | linux_ptrace_init_warnings (void) | |
526 | { | |
527 | static int warned = 0; | |
528 | ||
529 | if (warned) | |
530 | return; | |
531 | warned = 1; | |
532 | ||
533 | linux_ptrace_test_ret_to_nx (); | |
534 | } |