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88ac2921 RM |
1 | /* |
2 | * Tracing hooks | |
3 | * | |
4 | * Copyright (C) 2008 Red Hat, Inc. All rights reserved. | |
5 | * | |
6 | * This copyrighted material is made available to anyone wishing to use, | |
7 | * modify, copy, or redistribute it subject to the terms and conditions | |
8 | * of the GNU General Public License v.2. | |
9 | * | |
10 | * This file defines hook entry points called by core code where | |
11 | * user tracing/debugging support might need to do something. These | |
12 | * entry points are called tracehook_*(). Each hook declared below | |
13 | * has a detailed kerneldoc comment giving the context (locking et | |
14 | * al) from which it is called, and the meaning of its return value. | |
15 | * | |
16 | * Each function here typically has only one call site, so it is ok | |
17 | * to have some nontrivial tracehook_*() inlines. In all cases, the | |
18 | * fast path when no tracing is enabled should be very short. | |
19 | * | |
20 | * The purpose of this file and the tracehook_* layer is to consolidate | |
21 | * the interface that the kernel core and arch code uses to enable any | |
22 | * user debugging or tracing facility (such as ptrace). The interfaces | |
23 | * here are carefully documented so that maintainers of core and arch | |
24 | * code do not need to think about the implementation details of the | |
25 | * tracing facilities. Likewise, maintainers of the tracing code do not | |
26 | * need to understand all the calling core or arch code in detail, just | |
27 | * documented circumstances of each call, such as locking conditions. | |
28 | * | |
29 | * If the calling core code changes so that locking is different, then | |
30 | * it is ok to change the interface documented here. The maintainer of | |
31 | * core code changing should notify the maintainers of the tracing code | |
32 | * that they need to work out the change. | |
33 | * | |
34 | * Some tracehook_*() inlines take arguments that the current tracing | |
35 | * implementations might not necessarily use. These function signatures | |
36 | * are chosen to pass in all the information that is on hand in the | |
37 | * caller and might conceivably be relevant to a tracer, so that the | |
38 | * core code won't have to be updated when tracing adds more features. | |
39 | * If a call site changes so that some of those parameters are no longer | |
40 | * already on hand without extra work, then the tracehook_* interface | |
41 | * can change so there is no make-work burden on the core code. The | |
42 | * maintainer of core code changing should notify the maintainers of the | |
43 | * tracing code that they need to work out the change. | |
44 | */ | |
45 | ||
46 | #ifndef _LINUX_TRACEHOOK_H | |
47 | #define _LINUX_TRACEHOOK_H 1 | |
48 | ||
49 | #include <linux/sched.h> | |
50 | #include <linux/ptrace.h> | |
6341c393 RM |
51 | #include <linux/security.h> |
52 | struct linux_binprm; | |
53 | ||
fa8e26cc RM |
54 | /** |
55 | * tracehook_expect_breakpoints - guess if task memory might be touched | |
56 | * @task: current task, making a new mapping | |
57 | * | |
58 | * Return nonzero if @task is expected to want breakpoint insertion in | |
59 | * its memory at some point. A zero return is no guarantee it won't | |
60 | * be done, but this is a hint that it's known to be likely. | |
61 | * | |
62 | * May be called with @task->mm->mmap_sem held for writing. | |
63 | */ | |
64 | static inline int tracehook_expect_breakpoints(struct task_struct *task) | |
65 | { | |
66 | return (task_ptrace(task) & PT_PTRACED) != 0; | |
67 | } | |
68 | ||
283d7559 RM |
69 | /* |
70 | * ptrace report for syscall entry and exit looks identical. | |
71 | */ | |
72 | static inline void ptrace_report_syscall(struct pt_regs *regs) | |
73 | { | |
74 | int ptrace = task_ptrace(current); | |
75 | ||
76 | if (!(ptrace & PT_PTRACED)) | |
77 | return; | |
78 | ||
79 | ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0)); | |
80 | ||
81 | /* | |
82 | * this isn't the same as continuing with a signal, but it will do | |
83 | * for normal use. strace only continues with a signal if the | |
84 | * stopping signal is not SIGTRAP. -brl | |
85 | */ | |
86 | if (current->exit_code) { | |
87 | send_sig(current->exit_code, current, 1); | |
88 | current->exit_code = 0; | |
89 | } | |
90 | } | |
91 | ||
92 | /** | |
93 | * tracehook_report_syscall_entry - task is about to attempt a system call | |
94 | * @regs: user register state of current task | |
95 | * | |
96 | * This will be called if %TIF_SYSCALL_TRACE has been set, when the | |
97 | * current task has just entered the kernel for a system call. | |
98 | * Full user register state is available here. Changing the values | |
99 | * in @regs can affect the system call number and arguments to be tried. | |
100 | * It is safe to block here, preventing the system call from beginning. | |
101 | * | |
102 | * Returns zero normally, or nonzero if the calling arch code should abort | |
103 | * the system call. That must prevent normal entry so no system call is | |
104 | * made. If @task ever returns to user mode after this, its register state | |
105 | * is unspecified, but should be something harmless like an %ENOSYS error | |
828c365c RM |
106 | * return. It should preserve enough information so that syscall_rollback() |
107 | * can work (see asm-generic/syscall.h). | |
283d7559 RM |
108 | * |
109 | * Called without locks, just after entering kernel mode. | |
110 | */ | |
111 | static inline __must_check int tracehook_report_syscall_entry( | |
112 | struct pt_regs *regs) | |
113 | { | |
114 | ptrace_report_syscall(regs); | |
115 | return 0; | |
116 | } | |
117 | ||
118 | /** | |
119 | * tracehook_report_syscall_exit - task has just finished a system call | |
120 | * @regs: user register state of current task | |
121 | * @step: nonzero if simulating single-step or block-step | |
122 | * | |
123 | * This will be called if %TIF_SYSCALL_TRACE has been set, when the | |
124 | * current task has just finished an attempted system call. Full | |
125 | * user register state is available here. It is safe to block here, | |
126 | * preventing signals from being processed. | |
127 | * | |
128 | * If @step is nonzero, this report is also in lieu of the normal | |
129 | * trap that would follow the system call instruction because | |
130 | * user_enable_block_step() or user_enable_single_step() was used. | |
131 | * In this case, %TIF_SYSCALL_TRACE might not be set. | |
132 | * | |
133 | * Called without locks, just before checking for pending signals. | |
134 | */ | |
135 | static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) | |
136 | { | |
137 | ptrace_report_syscall(regs); | |
138 | } | |
139 | ||
6341c393 RM |
140 | /** |
141 | * tracehook_unsafe_exec - check for exec declared unsafe due to tracing | |
142 | * @task: current task doing exec | |
143 | * | |
144 | * Return %LSM_UNSAFE_* bits applied to an exec because of tracing. | |
145 | * | |
146 | * Called with task_lock() held on @task. | |
147 | */ | |
148 | static inline int tracehook_unsafe_exec(struct task_struct *task) | |
149 | { | |
150 | int unsafe = 0; | |
151 | int ptrace = task_ptrace(task); | |
152 | if (ptrace & PT_PTRACED) { | |
153 | if (ptrace & PT_PTRACE_CAP) | |
154 | unsafe |= LSM_UNSAFE_PTRACE_CAP; | |
155 | else | |
156 | unsafe |= LSM_UNSAFE_PTRACE; | |
157 | } | |
158 | return unsafe; | |
159 | } | |
160 | ||
0d094efe RM |
161 | /** |
162 | * tracehook_tracer_task - return the task that is tracing the given task | |
163 | * @tsk: task to consider | |
164 | * | |
165 | * Returns NULL if noone is tracing @task, or the &struct task_struct | |
166 | * pointer to its tracer. | |
167 | * | |
168 | * Must called under rcu_read_lock(). The pointer returned might be kept | |
169 | * live only by RCU. During exec, this may be called with task_lock() | |
170 | * held on @task, still held from when tracehook_unsafe_exec() was called. | |
171 | */ | |
172 | static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk) | |
173 | { | |
174 | if (task_ptrace(tsk) & PT_PTRACED) | |
175 | return rcu_dereference(tsk->parent); | |
176 | return NULL; | |
177 | } | |
178 | ||
6341c393 RM |
179 | /** |
180 | * tracehook_report_exec - a successful exec was completed | |
181 | * @fmt: &struct linux_binfmt that performed the exec | |
182 | * @bprm: &struct linux_binprm containing exec details | |
183 | * @regs: user-mode register state | |
184 | * | |
185 | * An exec just completed, we are shortly going to return to user mode. | |
186 | * The freshly initialized register state can be seen and changed in @regs. | |
187 | * The name, file and other pointers in @bprm are still on hand to be | |
188 | * inspected, but will be freed as soon as this returns. | |
189 | * | |
190 | * Called with no locks, but with some kernel resources held live | |
191 | * and a reference on @fmt->module. | |
192 | */ | |
193 | static inline void tracehook_report_exec(struct linux_binfmt *fmt, | |
194 | struct linux_binprm *bprm, | |
195 | struct pt_regs *regs) | |
196 | { | |
197 | if (!ptrace_event(PT_TRACE_EXEC, PTRACE_EVENT_EXEC, 0) && | |
198 | unlikely(task_ptrace(current) & PT_PTRACED)) | |
199 | send_sig(SIGTRAP, current, 0); | |
200 | } | |
88ac2921 | 201 | |
30199f5a RM |
202 | /** |
203 | * tracehook_report_exit - task has begun to exit | |
204 | * @exit_code: pointer to value destined for @current->exit_code | |
205 | * | |
206 | * @exit_code points to the value passed to do_exit(), which tracing | |
207 | * might change here. This is almost the first thing in do_exit(), | |
208 | * before freeing any resources or setting the %PF_EXITING flag. | |
209 | * | |
210 | * Called with no locks held. | |
211 | */ | |
212 | static inline void tracehook_report_exit(long *exit_code) | |
213 | { | |
214 | ptrace_event(PT_TRACE_EXIT, PTRACE_EVENT_EXIT, *exit_code); | |
215 | } | |
216 | ||
09a05394 RM |
217 | /** |
218 | * tracehook_prepare_clone - prepare for new child to be cloned | |
219 | * @clone_flags: %CLONE_* flags from clone/fork/vfork system call | |
220 | * | |
221 | * This is called before a new user task is to be cloned. | |
222 | * Its return value will be passed to tracehook_finish_clone(). | |
223 | * | |
224 | * Called with no locks held. | |
225 | */ | |
226 | static inline int tracehook_prepare_clone(unsigned clone_flags) | |
227 | { | |
228 | if (clone_flags & CLONE_UNTRACED) | |
229 | return 0; | |
230 | ||
231 | if (clone_flags & CLONE_VFORK) { | |
232 | if (current->ptrace & PT_TRACE_VFORK) | |
233 | return PTRACE_EVENT_VFORK; | |
234 | } else if ((clone_flags & CSIGNAL) != SIGCHLD) { | |
235 | if (current->ptrace & PT_TRACE_CLONE) | |
236 | return PTRACE_EVENT_CLONE; | |
237 | } else if (current->ptrace & PT_TRACE_FORK) | |
238 | return PTRACE_EVENT_FORK; | |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
243 | /** | |
244 | * tracehook_finish_clone - new child created and being attached | |
245 | * @child: new child task | |
246 | * @clone_flags: %CLONE_* flags from clone/fork/vfork system call | |
a9906a19 | 247 | * @trace: return value from tracehook_prepare_clone() |
09a05394 RM |
248 | * |
249 | * This is called immediately after adding @child to its parent's children list. | |
250 | * The @trace value is that returned by tracehook_prepare_clone(). | |
251 | * | |
252 | * Called with current's siglock and write_lock_irq(&tasklist_lock) held. | |
253 | */ | |
254 | static inline void tracehook_finish_clone(struct task_struct *child, | |
255 | unsigned long clone_flags, int trace) | |
256 | { | |
257 | ptrace_init_task(child, (clone_flags & CLONE_PTRACE) || trace); | |
258 | } | |
259 | ||
260 | /** | |
261 | * tracehook_report_clone - in parent, new child is about to start running | |
a9906a19 | 262 | * @trace: return value from tracehook_prepare_clone() |
09a05394 RM |
263 | * @regs: parent's user register state |
264 | * @clone_flags: flags from parent's system call | |
265 | * @pid: new child's PID in the parent's namespace | |
266 | * @child: new child task | |
267 | * | |
a9906a19 RM |
268 | * Called after a child is set up, but before it has been started |
269 | * running. @trace is the value returned by tracehook_prepare_clone(). | |
270 | * This is not a good place to block, because the child has not started | |
271 | * yet. Suspend the child here if desired, and then block in | |
272 | * tracehook_report_clone_complete(). This must prevent the child from | |
273 | * self-reaping if tracehook_report_clone_complete() uses the @child | |
274 | * pointer; otherwise it might have died and been released by the time | |
22f30168 | 275 | * tracehook_report_clone_complete() is called. |
09a05394 RM |
276 | * |
277 | * Called with no locks held, but the child cannot run until this returns. | |
278 | */ | |
279 | static inline void tracehook_report_clone(int trace, struct pt_regs *regs, | |
280 | unsigned long clone_flags, | |
281 | pid_t pid, struct task_struct *child) | |
282 | { | |
5861bbfc | 283 | if (unlikely(trace) || unlikely(clone_flags & CLONE_PTRACE)) { |
09a05394 RM |
284 | /* |
285 | * The child starts up with an immediate SIGSTOP. | |
286 | */ | |
287 | sigaddset(&child->pending.signal, SIGSTOP); | |
288 | set_tsk_thread_flag(child, TIF_SIGPENDING); | |
289 | } | |
290 | } | |
291 | ||
292 | /** | |
293 | * tracehook_report_clone_complete - new child is running | |
a9906a19 | 294 | * @trace: return value from tracehook_prepare_clone() |
09a05394 RM |
295 | * @regs: parent's user register state |
296 | * @clone_flags: flags from parent's system call | |
297 | * @pid: new child's PID in the parent's namespace | |
298 | * @child: child task, already running | |
299 | * | |
300 | * This is called just after the child has started running. This is | |
301 | * just before the clone/fork syscall returns, or blocks for vfork | |
302 | * child completion if @clone_flags has the %CLONE_VFORK bit set. | |
303 | * The @child pointer may be invalid if a self-reaping child died and | |
304 | * tracehook_report_clone() took no action to prevent it from self-reaping. | |
305 | * | |
306 | * Called with no locks held. | |
307 | */ | |
308 | static inline void tracehook_report_clone_complete(int trace, | |
309 | struct pt_regs *regs, | |
310 | unsigned long clone_flags, | |
311 | pid_t pid, | |
312 | struct task_struct *child) | |
313 | { | |
314 | if (unlikely(trace)) | |
315 | ptrace_event(0, trace, pid); | |
316 | } | |
317 | ||
daded34b RM |
318 | /** |
319 | * tracehook_report_vfork_done - vfork parent's child has exited or exec'd | |
320 | * @child: child task, already running | |
321 | * @pid: new child's PID in the parent's namespace | |
322 | * | |
323 | * Called after a %CLONE_VFORK parent has waited for the child to complete. | |
324 | * The clone/vfork system call will return immediately after this. | |
325 | * The @child pointer may be invalid if a self-reaping child died and | |
326 | * tracehook_report_clone() took no action to prevent it from self-reaping. | |
327 | * | |
328 | * Called with no locks held. | |
329 | */ | |
330 | static inline void tracehook_report_vfork_done(struct task_struct *child, | |
331 | pid_t pid) | |
332 | { | |
333 | ptrace_event(PT_TRACE_VFORK_DONE, PTRACE_EVENT_VFORK_DONE, pid); | |
334 | } | |
335 | ||
dae33574 RM |
336 | /** |
337 | * tracehook_prepare_release_task - task is being reaped, clean up tracing | |
338 | * @task: task in %EXIT_DEAD state | |
339 | * | |
340 | * This is called in release_task() just before @task gets finally reaped | |
341 | * and freed. This would be the ideal place to remove and clean up any | |
342 | * tracing-related state for @task. | |
343 | * | |
344 | * Called with no locks held. | |
345 | */ | |
346 | static inline void tracehook_prepare_release_task(struct task_struct *task) | |
347 | { | |
348 | } | |
349 | ||
350 | /** | |
a9906a19 | 351 | * tracehook_finish_release_task - final tracing clean-up |
dae33574 RM |
352 | * @task: task in %EXIT_DEAD state |
353 | * | |
354 | * This is called in release_task() when @task is being in the middle of | |
355 | * being reaped. After this, there must be no tracing entanglements. | |
356 | * | |
357 | * Called with write_lock_irq(&tasklist_lock) held. | |
358 | */ | |
359 | static inline void tracehook_finish_release_task(struct task_struct *task) | |
360 | { | |
361 | ptrace_release_task(task); | |
362 | } | |
363 | ||
c45aea27 RM |
364 | /** |
365 | * tracehook_signal_handler - signal handler setup is complete | |
366 | * @sig: number of signal being delivered | |
367 | * @info: siginfo_t of signal being delivered | |
368 | * @ka: sigaction setting that chose the handler | |
369 | * @regs: user register state | |
370 | * @stepping: nonzero if debugger single-step or block-step in use | |
371 | * | |
372 | * Called by the arch code after a signal handler has been set up. | |
373 | * Register and stack state reflects the user handler about to run. | |
374 | * Signal mask changes have already been made. | |
375 | * | |
376 | * Called without locks, shortly before returning to user mode | |
377 | * (or handling more signals). | |
378 | */ | |
379 | static inline void tracehook_signal_handler(int sig, siginfo_t *info, | |
380 | const struct k_sigaction *ka, | |
381 | struct pt_regs *regs, int stepping) | |
382 | { | |
383 | if (stepping) | |
384 | ptrace_notify(SIGTRAP); | |
385 | } | |
386 | ||
35de254d RM |
387 | /** |
388 | * tracehook_consider_ignored_signal - suppress short-circuit of ignored signal | |
389 | * @task: task receiving the signal | |
390 | * @sig: signal number being sent | |
391 | * @handler: %SIG_IGN or %SIG_DFL | |
392 | * | |
393 | * Return zero iff tracing doesn't care to examine this ignored signal, | |
394 | * so it can short-circuit normal delivery and never even get queued. | |
395 | * Either @handler is %SIG_DFL and @sig's default is ignore, or it's %SIG_IGN. | |
396 | * | |
397 | * Called with @task->sighand->siglock held. | |
398 | */ | |
399 | static inline int tracehook_consider_ignored_signal(struct task_struct *task, | |
400 | int sig, | |
401 | void __user *handler) | |
402 | { | |
403 | return (task_ptrace(task) & PT_PTRACED) != 0; | |
404 | } | |
405 | ||
445a91d2 RM |
406 | /** |
407 | * tracehook_consider_fatal_signal - suppress special handling of fatal signal | |
408 | * @task: task receiving the signal | |
409 | * @sig: signal number being sent | |
410 | * @handler: %SIG_DFL or %SIG_IGN | |
411 | * | |
412 | * Return nonzero to prevent special handling of this termination signal. | |
413 | * Normally @handler is %SIG_DFL. It can be %SIG_IGN if @sig is ignored, | |
414 | * in which case force_sig() is about to reset it to %SIG_DFL. | |
415 | * When this returns zero, this signal might cause a quick termination | |
416 | * that does not give the debugger a chance to intercept the signal. | |
417 | * | |
418 | * Called with or without @task->sighand->siglock held. | |
419 | */ | |
420 | static inline int tracehook_consider_fatal_signal(struct task_struct *task, | |
421 | int sig, | |
422 | void __user *handler) | |
423 | { | |
424 | return (task_ptrace(task) & PT_PTRACED) != 0; | |
425 | } | |
426 | ||
b787f7ba RM |
427 | /** |
428 | * tracehook_force_sigpending - let tracing force signal_pending(current) on | |
429 | * | |
430 | * Called when recomputing our signal_pending() flag. Return nonzero | |
431 | * to force the signal_pending() flag on, so that tracehook_get_signal() | |
432 | * will be called before the next return to user mode. | |
433 | * | |
434 | * Called with @current->sighand->siglock held. | |
435 | */ | |
436 | static inline int tracehook_force_sigpending(void) | |
437 | { | |
438 | return 0; | |
439 | } | |
440 | ||
7bcf6a2c RM |
441 | /** |
442 | * tracehook_get_signal - deliver synthetic signal to traced task | |
443 | * @task: @current | |
444 | * @regs: task_pt_regs(@current) | |
445 | * @info: details of synthetic signal | |
446 | * @return_ka: sigaction for synthetic signal | |
447 | * | |
448 | * Return zero to check for a real pending signal normally. | |
449 | * Return -1 after releasing the siglock to repeat the check. | |
450 | * Return a signal number to induce an artifical signal delivery, | |
451 | * setting *@info and *@return_ka to specify its details and behavior. | |
452 | * | |
453 | * The @return_ka->sa_handler value controls the disposition of the | |
454 | * signal, no matter the signal number. For %SIG_DFL, the return value | |
455 | * is a representative signal to indicate the behavior (e.g. %SIGTERM | |
456 | * for death, %SIGQUIT for core dump, %SIGSTOP for job control stop, | |
457 | * %SIGTSTP for stop unless in an orphaned pgrp), but the signal number | |
458 | * reported will be @info->si_signo instead. | |
459 | * | |
460 | * Called with @task->sighand->siglock held, before dequeuing pending signals. | |
461 | */ | |
462 | static inline int tracehook_get_signal(struct task_struct *task, | |
463 | struct pt_regs *regs, | |
464 | siginfo_t *info, | |
465 | struct k_sigaction *return_ka) | |
466 | { | |
467 | return 0; | |
468 | } | |
469 | ||
fa00b80b RM |
470 | /** |
471 | * tracehook_notify_jctl - report about job control stop/continue | |
472 | * @notify: nonzero if this is the last thread in the group to stop | |
473 | * @why: %CLD_STOPPED or %CLD_CONTINUED | |
474 | * | |
475 | * This is called when we might call do_notify_parent_cldstop(). | |
476 | * It's called when about to stop for job control; we are already in | |
477 | * %TASK_STOPPED state, about to call schedule(). It's also called when | |
478 | * a delayed %CLD_STOPPED or %CLD_CONTINUED report is ready to be made. | |
479 | * | |
480 | * Return nonzero to generate a %SIGCHLD with @why, which is | |
481 | * normal if @notify is nonzero. | |
482 | * | |
483 | * Called with no locks held. | |
484 | */ | |
485 | static inline int tracehook_notify_jctl(int notify, int why) | |
486 | { | |
487 | return notify || (current->ptrace & PT_PTRACED); | |
488 | } | |
489 | ||
115a326c RM |
490 | #define DEATH_REAP -1 |
491 | #define DEATH_DELAYED_GROUP_LEADER -2 | |
492 | ||
2b2a1ff6 RM |
493 | /** |
494 | * tracehook_notify_death - task is dead, ready to notify parent | |
495 | * @task: @current task now exiting | |
496 | * @death_cookie: value to pass to tracehook_report_death() | |
497 | * @group_dead: nonzero if this was the last thread in the group to die | |
498 | * | |
5c7edcd7 RM |
499 | * A return value >= 0 means call do_notify_parent() with that signal |
500 | * number. Negative return value can be %DEATH_REAP to self-reap right | |
501 | * now, or %DEATH_DELAYED_GROUP_LEADER to a zombie without notifying our | |
502 | * parent. Note that a return value of 0 means a do_notify_parent() call | |
503 | * that sends no signal, but still wakes up a parent blocked in wait*(). | |
2b2a1ff6 RM |
504 | * |
505 | * Called with write_lock_irq(&tasklist_lock) held. | |
506 | */ | |
507 | static inline int tracehook_notify_death(struct task_struct *task, | |
508 | void **death_cookie, int group_dead) | |
509 | { | |
510 | if (task->exit_signal == -1) | |
5c7edcd7 | 511 | return task->ptrace ? SIGCHLD : DEATH_REAP; |
2b2a1ff6 RM |
512 | |
513 | /* | |
514 | * If something other than our normal parent is ptracing us, then | |
515 | * send it a SIGCHLD instead of honoring exit_signal. exit_signal | |
516 | * only has special meaning to our real parent. | |
517 | */ | |
518 | if (thread_group_empty(task) && !ptrace_reparented(task)) | |
519 | return task->exit_signal; | |
520 | ||
5c7edcd7 | 521 | return task->ptrace ? SIGCHLD : DEATH_DELAYED_GROUP_LEADER; |
2b2a1ff6 RM |
522 | } |
523 | ||
524 | /** | |
525 | * tracehook_report_death - task is dead and ready to be reaped | |
526 | * @task: @current task now exiting | |
5c7edcd7 | 527 | * @signal: return value from tracheook_notify_death() |
2b2a1ff6 RM |
528 | * @death_cookie: value passed back from tracehook_notify_death() |
529 | * @group_dead: nonzero if this was the last thread in the group to die | |
530 | * | |
531 | * Thread has just become a zombie or is about to self-reap. If positive, | |
532 | * @signal is the signal number just sent to the parent (usually %SIGCHLD). | |
5c7edcd7 RM |
533 | * If @signal is %DEATH_REAP, this thread will self-reap. If @signal is |
534 | * %DEATH_DELAYED_GROUP_LEADER, this is a delayed_group_leader() zombie. | |
535 | * The @death_cookie was passed back by tracehook_notify_death(). | |
2b2a1ff6 RM |
536 | * |
537 | * If normal reaping is not inhibited, @task->exit_state might be changing | |
538 | * in parallel. | |
539 | * | |
540 | * Called without locks. | |
541 | */ | |
542 | static inline void tracehook_report_death(struct task_struct *task, | |
543 | int signal, void *death_cookie, | |
544 | int group_dead) | |
545 | { | |
546 | } | |
547 | ||
64b1208d RM |
548 | #ifdef TIF_NOTIFY_RESUME |
549 | /** | |
550 | * set_notify_resume - cause tracehook_notify_resume() to be called | |
551 | * @task: task that will call tracehook_notify_resume() | |
552 | * | |
553 | * Calling this arranges that @task will call tracehook_notify_resume() | |
554 | * before returning to user mode. If it's already running in user mode, | |
555 | * it will enter the kernel and call tracehook_notify_resume() soon. | |
556 | * If it's blocked, it will not be woken. | |
557 | */ | |
558 | static inline void set_notify_resume(struct task_struct *task) | |
559 | { | |
560 | if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME)) | |
561 | kick_process(task); | |
562 | } | |
563 | ||
564 | /** | |
565 | * tracehook_notify_resume - report when about to return to user mode | |
566 | * @regs: user-mode registers of @current task | |
567 | * | |
568 | * This is called when %TIF_NOTIFY_RESUME has been set. Now we are | |
569 | * about to return to user mode, and the user state in @regs can be | |
570 | * inspected or adjusted. The caller in arch code has cleared | |
571 | * %TIF_NOTIFY_RESUME before the call. If the flag gets set again | |
572 | * asynchronously, this will be called again before we return to | |
573 | * user mode. | |
574 | * | |
575 | * Called without locks. | |
576 | */ | |
577 | static inline void tracehook_notify_resume(struct pt_regs *regs) | |
578 | { | |
579 | } | |
580 | #endif /* TIF_NOTIFY_RESUME */ | |
581 | ||
88ac2921 | 582 | #endif /* <linux/tracehook.h> */ |