xref: /linux/include/linux/sched/signal.h (revision 7393febcb1b2082c0484952729cbebfe4dc508d5)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCHED_SIGNAL_H
3 #define _LINUX_SCHED_SIGNAL_H
4 
5 #include <linux/rculist.h>
6 #include <linux/signal.h>
7 #include <linux/sched.h>
8 #include <linux/sched/jobctl.h>
9 #include <linux/sched/task.h>
10 #include <linux/cred.h>
11 #include <linux/refcount.h>
12 #include <linux/pid.h>
13 #include <linux/posix-timers.h>
14 #include <linux/mm_types.h>
15 #include <asm/ptrace.h>
16 
17 /*
18  * Types defining task->signal and task->sighand and APIs using them:
19  */
20 
21 struct sighand_struct {
22 	spinlock_t		siglock;
23 	refcount_t		count;
24 	wait_queue_head_t	signalfd_wqh;
25 	struct k_sigaction	action[_NSIG];
26 };
27 
28 /*
29  * Per-process accounting stats:
30  */
31 struct pacct_struct {
32 	int			ac_flag;
33 	long			ac_exitcode;
34 	unsigned long		ac_mem;
35 	u64			ac_utime, ac_stime;
36 	unsigned long		ac_minflt, ac_majflt;
37 };
38 
39 struct cpu_itimer {
40 	u64 expires;
41 	u64 incr;
42 };
43 
44 /*
45  * This is the atomic variant of task_cputime, which can be used for
46  * storing and updating task_cputime statistics without locking.
47  */
48 struct task_cputime_atomic {
49 	atomic64_t utime;
50 	atomic64_t stime;
51 	atomic64_t sum_exec_runtime;
52 };
53 
54 #define INIT_CPUTIME_ATOMIC \
55 	(struct task_cputime_atomic) {				\
56 		.utime = ATOMIC64_INIT(0),			\
57 		.stime = ATOMIC64_INIT(0),			\
58 		.sum_exec_runtime = ATOMIC64_INIT(0),		\
59 	}
60 /**
61  * struct thread_group_cputimer - thread group interval timer counts
62  * @cputime_atomic:	atomic thread group interval timers.
63  *
64  * This structure contains the version of task_cputime, above, that is
65  * used for thread group CPU timer calculations.
66  */
67 struct thread_group_cputimer {
68 	struct task_cputime_atomic cputime_atomic;
69 };
70 
71 struct multiprocess_signals {
72 	sigset_t signal;
73 	struct hlist_node node;
74 };
75 
76 struct core_thread {
77 	struct task_struct *task;
78 	struct core_thread *next;
79 };
80 
81 struct core_state {
82 	atomic_t nr_threads;
83 	struct core_thread dumper;
84 	struct completion startup;
85 };
86 
87 /*
88  * NOTE! "signal_struct" does not have its own
89  * locking, because a shared signal_struct always
90  * implies a shared sighand_struct, so locking
91  * sighand_struct is always a proper superset of
92  * the locking of signal_struct.
93  */
94 struct signal_struct {
95 	refcount_t		sigcnt;
96 	atomic_t		live;
97 	int			nr_threads;
98 	int			quick_threads;
99 	struct list_head	thread_head;
100 
101 	wait_queue_head_t	wait_chldexit;	/* for wait4() */
102 
103 	/* current thread group signal load-balancing target: */
104 	struct task_struct	*curr_target;
105 
106 	/* shared signal handling: */
107 	struct sigpending	shared_pending;
108 
109 	/* For collecting multiprocess signals during fork */
110 	struct hlist_head	multiprocess;
111 
112 	/* thread group exit support */
113 	int			group_exit_code;
114 	/* notify group_exec_task when notify_count is less or equal to 0 */
115 	int			notify_count;
116 	struct task_struct	*group_exec_task;
117 
118 	/* thread group stop support, overloads group_exit_code too */
119 	int			group_stop_count;
120 	unsigned int		flags; /* see SIGNAL_* flags below */
121 
122 	struct core_state *core_state; /* coredumping support */
123 
124 	/*
125 	 * PR_SET_CHILD_SUBREAPER marks a process, like a service
126 	 * manager, to re-parent orphan (double-forking) child processes
127 	 * to this process instead of 'init'. The service manager is
128 	 * able to receive SIGCHLD signals and is able to investigate
129 	 * the process until it calls wait(). All children of this
130 	 * process will inherit a flag if they should look for a
131 	 * child_subreaper process at exit.
132 	 */
133 	unsigned int		is_child_subreaper:1;
134 	unsigned int		has_child_subreaper:1;
135 	unsigned int		autoreap:1;
136 
137 #ifdef CONFIG_POSIX_TIMERS
138 
139 	/* POSIX.1b Interval Timers */
140 	unsigned int		timer_create_restore_ids:1;
141 	atomic_t		next_posix_timer_id;
142 	struct hlist_head	posix_timers;
143 	struct hlist_head	ignored_posix_timers;
144 
145 	/* ITIMER_REAL timer for the process */
146 	struct hrtimer real_timer;
147 	ktime_t it_real_incr;
148 
149 	/*
150 	 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
151 	 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
152 	 * values are defined to 0 and 1 respectively
153 	 */
154 	struct cpu_itimer it[2];
155 
156 	/*
157 	 * Thread group totals for process CPU timers.
158 	 * See thread_group_cputimer(), et al, for details.
159 	 */
160 	struct thread_group_cputimer cputimer;
161 
162 #endif
163 	/* Empty if CONFIG_POSIX_TIMERS=n */
164 	struct posix_cputimers posix_cputimers;
165 
166 	/* PID/PID hash table linkage. */
167 	struct pid *pids[PIDTYPE_MAX];
168 
169 #ifdef CONFIG_NO_HZ_FULL
170 	atomic_t tick_dep_mask;
171 #endif
172 
173 	struct pid *tty_old_pgrp;
174 
175 	/* boolean value for session group leader */
176 	int leader;
177 
178 	struct tty_struct *tty; /* NULL if no tty */
179 
180 #ifdef CONFIG_SCHED_AUTOGROUP
181 	struct autogroup *autogroup;
182 #endif
183 	/*
184 	 * Cumulative resource counters for dead threads in the group,
185 	 * and for reaped dead child processes forked by this group.
186 	 * Live threads maintain their own counters and add to these
187 	 * in __exit_signal, except for the group leader.
188 	 */
189 	seqlock_t stats_lock;
190 	u64 utime, stime, cutime, cstime;
191 	u64 gtime;
192 	u64 cgtime;
193 	struct prev_cputime prev_cputime;
194 	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
195 	unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
196 	unsigned long inblock, oublock, cinblock, coublock;
197 	unsigned long maxrss, cmaxrss;
198 	struct task_io_accounting ioac;
199 
200 	/*
201 	 * Cumulative ns of schedule CPU time fo dead threads in the
202 	 * group, not including a zombie group leader, (This only differs
203 	 * from jiffies_to_ns(utime + stime) if sched_clock uses something
204 	 * other than jiffies.)
205 	 */
206 	unsigned long long sum_sched_runtime;
207 
208 	/*
209 	 * We don't bother to synchronize most readers of this at all,
210 	 * because there is no reader checking a limit that actually needs
211 	 * to get both rlim_cur and rlim_max atomically, and either one
212 	 * alone is a single word that can safely be read normally.
213 	 * getrlimit/setrlimit use task_lock(current->group_leader) to
214 	 * protect this instead of the siglock, because they really
215 	 * have no need to disable irqs.
216 	 */
217 	struct rlimit rlim[RLIM_NLIMITS];
218 
219 #ifdef CONFIG_BSD_PROCESS_ACCT
220 	struct pacct_struct pacct;	/* per-process accounting information */
221 #endif
222 #ifdef CONFIG_TASKSTATS
223 	struct taskstats *stats;
224 #endif
225 #ifdef CONFIG_AUDIT
226 	unsigned audit_tty;
227 	struct tty_audit_buf *tty_audit_buf;
228 #endif
229 
230 #ifdef CONFIG_CGROUPS
231 	struct rw_semaphore cgroup_threadgroup_rwsem;
232 #endif
233 
234 	/*
235 	 * Thread is the potential origin of an oom condition; kill first on
236 	 * oom
237 	 */
238 	bool oom_flag_origin;
239 	short oom_score_adj;		/* OOM kill score adjustment */
240 	short oom_score_adj_min;	/* OOM kill score adjustment min value.
241 					 * Only settable by CAP_SYS_RESOURCE. */
242 	struct mm_struct *oom_mm;	/* recorded mm when the thread group got
243 					 * killed by the oom killer */
244 
245 	struct mutex cred_guard_mutex;	/* guard against foreign influences on
246 					 * credential calculations
247 					 * (notably. ptrace)
248 					 * Deprecated do not use in new code.
249 					 * Use exec_update_lock instead.
250 					 */
251 	struct rw_semaphore exec_update_lock;	/* Held while task_struct is
252 						 * being updated during exec,
253 						 * and may have inconsistent
254 						 * permissions.
255 						 */
256 } __randomize_layout;
257 
258 /*
259  * Bits in flags field of signal_struct.
260  */
261 #define SIGNAL_STOP_STOPPED	0x00000001 /* job control stop in effect */
262 #define SIGNAL_STOP_CONTINUED	0x00000002 /* SIGCONT since WCONTINUED reap */
263 #define SIGNAL_GROUP_EXIT	0x00000004 /* group exit in progress */
264 /*
265  * Pending notifications to parent.
266  */
267 #define SIGNAL_CLD_STOPPED	0x00000010
268 #define SIGNAL_CLD_CONTINUED	0x00000020
269 #define SIGNAL_CLD_MASK		(SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
270 
271 #define SIGNAL_UNKILLABLE	0x00000040 /* for init: ignore fatal signals */
272 
273 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
274 			  SIGNAL_STOP_CONTINUED)
275 
signal_set_stop_flags(struct signal_struct * sig,unsigned int flags)276 static inline void signal_set_stop_flags(struct signal_struct *sig,
277 					 unsigned int flags)
278 {
279 	WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
280 	sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
281 }
282 
283 extern void flush_signals(struct task_struct *);
284 extern void ignore_signals(struct task_struct *);
285 extern void flush_signal_handlers(struct task_struct *, int force_default);
286 extern int dequeue_signal(sigset_t *mask, kernel_siginfo_t *info, enum pid_type *type);
287 
kernel_dequeue_signal(void)288 static inline int kernel_dequeue_signal(void)
289 {
290 	struct task_struct *task = current;
291 	kernel_siginfo_t __info;
292 	enum pid_type __type;
293 	int ret;
294 
295 	spin_lock_irq(&task->sighand->siglock);
296 	ret = dequeue_signal(&task->blocked, &__info, &__type);
297 	spin_unlock_irq(&task->sighand->siglock);
298 
299 	return ret;
300 }
301 
kernel_signal_stop(void)302 static inline void kernel_signal_stop(void)
303 {
304 	spin_lock_irq(&current->sighand->siglock);
305 	if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
306 		current->jobctl |= JOBCTL_STOPPED;
307 		set_special_state(TASK_STOPPED);
308 	}
309 	spin_unlock_irq(&current->sighand->siglock);
310 
311 	schedule();
312 }
313 
314 int force_sig_fault_to_task(int sig, int code, void __user *addr,
315 			    struct task_struct *t);
316 int force_sig_fault(int sig, int code, void __user *addr);
317 int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t);
318 
319 int force_sig_mceerr(int code, void __user *, short);
320 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
321 
322 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
323 int force_sig_pkuerr(void __user *addr, u32 pkey);
324 int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
325 
326 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
327 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
328 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
329 			struct task_struct *t);
330 int force_sig_seccomp(int syscall, int reason, bool force_coredump);
331 
332 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
333 extern void force_sigsegv(int sig);
334 extern int force_sig_info(struct kernel_siginfo *);
335 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
336 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
337 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
338 				const struct cred *);
339 extern int kill_pgrp(struct pid *pid, int sig, int priv);
340 extern int kill_pid(struct pid *pid, int sig, int priv);
341 extern __must_check bool do_notify_parent(struct task_struct *, int);
342 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
343 extern void force_sig(int);
344 extern void force_fatal_sig(int);
345 extern void force_exit_sig(int);
346 extern int send_sig(int, struct task_struct *, int);
347 extern int zap_other_threads(struct task_struct *p);
348 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
349 
clear_notify_signal(void)350 static inline void clear_notify_signal(void)
351 {
352 	clear_thread_flag(TIF_NOTIFY_SIGNAL);
353 	smp_mb__after_atomic();
354 }
355 
356 /*
357  * Returns 'true' if kick_process() is needed to force a transition from
358  * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
359  */
__set_notify_signal(struct task_struct * task)360 static inline bool __set_notify_signal(struct task_struct *task)
361 {
362 	return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
363 	       !wake_up_state(task, TASK_INTERRUPTIBLE);
364 }
365 
366 /*
367  * Called to break out of interruptible wait loops, and enter the
368  * exit_to_user_mode_loop().
369  */
set_notify_signal(struct task_struct * task)370 static inline void set_notify_signal(struct task_struct *task)
371 {
372 	if (__set_notify_signal(task))
373 		kick_process(task);
374 }
375 
restart_syscall(void)376 static inline int restart_syscall(void)
377 {
378 	set_tsk_thread_flag(current, TIF_SIGPENDING);
379 	return -ERESTARTNOINTR;
380 }
381 
task_sigpending(struct task_struct * p)382 static inline int task_sigpending(struct task_struct *p)
383 {
384 	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
385 }
386 
signal_pending(struct task_struct * p)387 static inline int signal_pending(struct task_struct *p)
388 {
389 	/*
390 	 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
391 	 * behavior in terms of ensuring that we break out of wait loops
392 	 * so that notify signal callbacks can be processed.
393 	 */
394 	if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
395 		return 1;
396 	return task_sigpending(p);
397 }
398 
__fatal_signal_pending(struct task_struct * p)399 static inline int __fatal_signal_pending(struct task_struct *p)
400 {
401 	return unlikely(sigismember(&p->pending.signal, SIGKILL));
402 }
403 
fatal_signal_pending(struct task_struct * p)404 static inline int fatal_signal_pending(struct task_struct *p)
405 {
406 	return task_sigpending(p) && __fatal_signal_pending(p);
407 }
408 
signal_pending_state(unsigned int state,struct task_struct * p)409 static inline int signal_pending_state(unsigned int state, struct task_struct *p)
410 {
411 	if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
412 		return 0;
413 	if (!signal_pending(p))
414 		return 0;
415 
416 	return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
417 }
418 
419 /*
420  * This should only be used in fault handlers to decide whether we
421  * should stop the current fault routine to handle the signals
422  * instead, especially with the case where we've got interrupted with
423  * a VM_FAULT_RETRY.
424  */
fault_signal_pending(vm_fault_t fault_flags,struct pt_regs * regs)425 static inline bool fault_signal_pending(vm_fault_t fault_flags,
426 					struct pt_regs *regs)
427 {
428 	return unlikely((fault_flags & VM_FAULT_RETRY) &&
429 			(fatal_signal_pending(current) ||
430 			 (user_mode(regs) && signal_pending(current))));
431 }
432 
433 /*
434  * Reevaluate whether the task has signals pending delivery.
435  * Wake the task if so.
436  * This is required every time the blocked sigset_t changes.
437  * callers must hold sighand->siglock.
438  */
439 extern void recalc_sigpending(void);
440 extern void calculate_sigpending(void);
441 
442 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
443 
signal_wake_up(struct task_struct * t,bool fatal)444 static inline void signal_wake_up(struct task_struct *t, bool fatal)
445 {
446 	unsigned int state = 0;
447 	if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
448 		t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
449 		state = TASK_WAKEKILL | __TASK_TRACED;
450 	}
451 	signal_wake_up_state(t, state);
452 }
ptrace_signal_wake_up(struct task_struct * t,bool resume)453 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
454 {
455 	unsigned int state = 0;
456 	if (resume) {
457 		t->jobctl &= ~JOBCTL_TRACED;
458 		state = __TASK_TRACED;
459 	}
460 	signal_wake_up_state(t, state);
461 }
462 
463 void task_join_group_stop(struct task_struct *task);
464 
465 #ifdef TIF_RESTORE_SIGMASK
466 /*
467  * Legacy restore_sigmask accessors.  These are inefficient on
468  * SMP architectures because they require atomic operations.
469  */
470 
471 /**
472  * set_restore_sigmask() - make sure saved_sigmask processing gets done
473  *
474  * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
475  * will run before returning to user mode, to process the flag.  For
476  * all callers, TIF_SIGPENDING is already set or it's no harm to set
477  * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
478  * arch code will notice on return to user mode, in case those bits
479  * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
480  * signal code always gets run when TIF_RESTORE_SIGMASK is set.
481  */
set_restore_sigmask(void)482 static inline void set_restore_sigmask(void)
483 {
484 	set_thread_flag(TIF_RESTORE_SIGMASK);
485 }
486 
clear_tsk_restore_sigmask(struct task_struct * task)487 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
488 {
489 	clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
490 }
491 
clear_restore_sigmask(void)492 static inline void clear_restore_sigmask(void)
493 {
494 	clear_thread_flag(TIF_RESTORE_SIGMASK);
495 }
test_tsk_restore_sigmask(struct task_struct * task)496 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
497 {
498 	return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
499 }
test_restore_sigmask(void)500 static inline bool test_restore_sigmask(void)
501 {
502 	return test_thread_flag(TIF_RESTORE_SIGMASK);
503 }
test_and_clear_restore_sigmask(void)504 static inline bool test_and_clear_restore_sigmask(void)
505 {
506 	return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
507 }
508 
509 #else	/* TIF_RESTORE_SIGMASK */
510 
511 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
set_restore_sigmask(void)512 static inline void set_restore_sigmask(void)
513 {
514 	current->restore_sigmask = true;
515 }
clear_tsk_restore_sigmask(struct task_struct * task)516 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
517 {
518 	task->restore_sigmask = false;
519 }
clear_restore_sigmask(void)520 static inline void clear_restore_sigmask(void)
521 {
522 	current->restore_sigmask = false;
523 }
test_restore_sigmask(void)524 static inline bool test_restore_sigmask(void)
525 {
526 	return current->restore_sigmask;
527 }
test_tsk_restore_sigmask(struct task_struct * task)528 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
529 {
530 	return task->restore_sigmask;
531 }
test_and_clear_restore_sigmask(void)532 static inline bool test_and_clear_restore_sigmask(void)
533 {
534 	if (!current->restore_sigmask)
535 		return false;
536 	current->restore_sigmask = false;
537 	return true;
538 }
539 #endif
540 
restore_saved_sigmask(void)541 static inline void restore_saved_sigmask(void)
542 {
543 	if (test_and_clear_restore_sigmask())
544 		__set_current_blocked(&current->saved_sigmask);
545 }
546 
547 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
548 
restore_saved_sigmask_unless(bool interrupted)549 static inline void restore_saved_sigmask_unless(bool interrupted)
550 {
551 	if (interrupted)
552 		WARN_ON(!signal_pending(current));
553 	else
554 		restore_saved_sigmask();
555 }
556 
sigmask_to_save(void)557 static inline sigset_t *sigmask_to_save(void)
558 {
559 	sigset_t *res = &current->blocked;
560 	if (unlikely(test_restore_sigmask()))
561 		res = &current->saved_sigmask;
562 	return res;
563 }
564 
kill_cad_pid(int sig,int priv)565 static inline int kill_cad_pid(int sig, int priv)
566 {
567 	return kill_pid(cad_pid, sig, priv);
568 }
569 
570 /* These can be the second arg to send_sig_info/send_group_sig_info.  */
571 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
572 #define SEND_SIG_PRIV	((struct kernel_siginfo *) 1)
573 
__on_sig_stack(unsigned long sp)574 static inline int __on_sig_stack(unsigned long sp)
575 {
576 #ifdef CONFIG_STACK_GROWSUP
577 	return sp >= current->sas_ss_sp &&
578 		sp - current->sas_ss_sp < current->sas_ss_size;
579 #else
580 	return sp > current->sas_ss_sp &&
581 		sp - current->sas_ss_sp <= current->sas_ss_size;
582 #endif
583 }
584 
585 /*
586  * True if we are on the alternate signal stack.
587  */
on_sig_stack(unsigned long sp)588 static inline int on_sig_stack(unsigned long sp)
589 {
590 	/*
591 	 * If the signal stack is SS_AUTODISARM then, by construction, we
592 	 * can't be on the signal stack unless user code deliberately set
593 	 * SS_AUTODISARM when we were already on it.
594 	 *
595 	 * This improves reliability: if user state gets corrupted such that
596 	 * the stack pointer points very close to the end of the signal stack,
597 	 * then this check will enable the signal to be handled anyway.
598 	 */
599 	if (current->sas_ss_flags & SS_AUTODISARM)
600 		return 0;
601 
602 	return __on_sig_stack(sp);
603 }
604 
sas_ss_flags(unsigned long sp)605 static inline int sas_ss_flags(unsigned long sp)
606 {
607 	if (!current->sas_ss_size)
608 		return SS_DISABLE;
609 
610 	return on_sig_stack(sp) ? SS_ONSTACK : 0;
611 }
612 
sas_ss_reset(struct task_struct * p)613 static inline void sas_ss_reset(struct task_struct *p)
614 {
615 	p->sas_ss_sp = 0;
616 	p->sas_ss_size = 0;
617 	p->sas_ss_flags = SS_DISABLE;
618 }
619 
sigsp(unsigned long sp,struct ksignal * ksig)620 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
621 {
622 	if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
623 #ifdef CONFIG_STACK_GROWSUP
624 		return current->sas_ss_sp;
625 #else
626 		return current->sas_ss_sp + current->sas_ss_size;
627 #endif
628 	return sp;
629 }
630 
631 extern void __cleanup_sighand(struct sighand_struct *);
632 extern void flush_itimer_signals(void);
633 
634 #define tasklist_empty() \
635 	list_empty(&init_task.tasks)
636 
637 #define next_task(p) \
638 	list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
639 
640 #define for_each_process(p) \
641 	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
642 
643 extern bool current_is_single_threaded(void);
644 
645 /*
646  * Without tasklist/siglock it is only rcu-safe if g can't exit/exec,
647  * otherwise next_thread(t) will never reach g after list_del_rcu(g).
648  */
649 #define while_each_thread(g, t) \
650 	while ((t = next_thread(t)) != g)
651 
652 #define for_other_threads(p, t)	\
653 	for (t = p; (t = next_thread(t)) != p; )
654 
655 #define __for_each_thread(signal, t)	\
656 	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node, \
657 		lockdep_is_held(&tasklist_lock))
658 
659 #define for_each_thread(p, t)		\
660 	__for_each_thread((p)->signal, t)
661 
662 /* Careful: this is a double loop, 'break' won't work as expected. */
663 #define for_each_process_thread(p, t)	\
664 	for_each_process(p) for_each_thread(p, t)
665 
666 typedef int (*proc_visitor)(struct task_struct *p, void *data);
667 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
668 
669 static inline
task_pid_type(struct task_struct * task,enum pid_type type)670 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
671 {
672 	struct pid *pid;
673 	if (type == PIDTYPE_PID)
674 		pid = task_pid(task);
675 	else
676 		pid = task->signal->pids[type];
677 	return pid;
678 }
679 
task_tgid(struct task_struct * task)680 static inline struct pid *task_tgid(struct task_struct *task)
681 {
682 	return task->signal->pids[PIDTYPE_TGID];
683 }
684 
685 /*
686  * Without tasklist or RCU lock it is not safe to dereference
687  * the result of task_pgrp/task_session even if task == current,
688  * we can race with another thread doing sys_setsid/sys_setpgid.
689  */
task_pgrp(struct task_struct * task)690 static inline struct pid *task_pgrp(struct task_struct *task)
691 {
692 	return task->signal->pids[PIDTYPE_PGID];
693 }
694 
task_session(struct task_struct * task)695 static inline struct pid *task_session(struct task_struct *task)
696 {
697 	return task->signal->pids[PIDTYPE_SID];
698 }
699 
get_nr_threads(struct task_struct * task)700 static inline int get_nr_threads(struct task_struct *task)
701 {
702 	return task->signal->nr_threads;
703 }
704 
thread_group_leader(struct task_struct * p)705 static inline bool thread_group_leader(struct task_struct *p)
706 {
707 	return p->exit_signal >= 0;
708 }
709 
710 static inline
same_thread_group(struct task_struct * p1,struct task_struct * p2)711 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
712 {
713 	return p1->signal == p2->signal;
714 }
715 
716 /*
717  * returns NULL if p is the last thread in the thread group
718  */
__next_thread(struct task_struct * p)719 static inline struct task_struct *__next_thread(struct task_struct *p)
720 {
721 	return list_next_or_null_rcu(&p->signal->thread_head,
722 					&p->thread_node,
723 					struct task_struct,
724 					thread_node);
725 }
726 
next_thread(struct task_struct * p)727 static inline struct task_struct *next_thread(struct task_struct *p)
728 {
729 	return __next_thread(p) ?: p->group_leader;
730 }
731 
thread_group_empty(struct task_struct * p)732 static inline int thread_group_empty(struct task_struct *p)
733 {
734 	return thread_group_leader(p) &&
735 	       list_is_last(&p->thread_node, &p->signal->thread_head);
736 }
737 
738 #define delay_group_leader(p) \
739 		(thread_group_leader(p) && !thread_group_empty(p))
740 
741 extern struct sighand_struct *lock_task_sighand(struct task_struct *task,
742 						unsigned long *flags)
743 	__cond_acquires(nonnull, &task->sighand->siglock);
744 
unlock_task_sighand(struct task_struct * task,unsigned long * flags)745 static inline void unlock_task_sighand(struct task_struct *task,
746 						unsigned long *flags)
747 	__releases(&task->sighand->siglock)
748 {
749 	spin_unlock_irqrestore(&task->sighand->siglock, *flags);
750 }
751 
752 #ifdef CONFIG_LOCKDEP
753 extern void lockdep_assert_task_sighand_held(struct task_struct *task);
754 #else
lockdep_assert_task_sighand_held(struct task_struct * task)755 static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
756 #endif
757 
task_rlimit(const struct task_struct * task,unsigned int limit)758 static inline unsigned long task_rlimit(const struct task_struct *task,
759 		unsigned int limit)
760 {
761 	return READ_ONCE(task->signal->rlim[limit].rlim_cur);
762 }
763 
task_rlimit_max(const struct task_struct * task,unsigned int limit)764 static inline unsigned long task_rlimit_max(const struct task_struct *task,
765 		unsigned int limit)
766 {
767 	return READ_ONCE(task->signal->rlim[limit].rlim_max);
768 }
769 
rlimit(unsigned int limit)770 static inline unsigned long rlimit(unsigned int limit)
771 {
772 	return task_rlimit(current, limit);
773 }
774 
rlimit_max(unsigned int limit)775 static inline unsigned long rlimit_max(unsigned int limit)
776 {
777 	return task_rlimit_max(current, limit);
778 }
779 
780 #endif /* _LINUX_SCHED_SIGNAL_H */
781