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 
136 #ifdef CONFIG_POSIX_TIMERS
137 
138 	/* POSIX.1b Interval Timers */
139 	unsigned int		timer_create_restore_ids:1;
140 	atomic_t		next_posix_timer_id;
141 	struct hlist_head	posix_timers;
142 	struct hlist_head	ignored_posix_timers;
143 
144 	/* ITIMER_REAL timer for the process */
145 	struct hrtimer real_timer;
146 	ktime_t it_real_incr;
147 
148 	/*
149 	 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
150 	 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
151 	 * values are defined to 0 and 1 respectively
152 	 */
153 	struct cpu_itimer it[2];
154 
155 	/*
156 	 * Thread group totals for process CPU timers.
157 	 * See thread_group_cputimer(), et al, for details.
158 	 */
159 	struct thread_group_cputimer cputimer;
160 
161 #endif
162 	/* Empty if CONFIG_POSIX_TIMERS=n */
163 	struct posix_cputimers posix_cputimers;
164 
165 	/* PID/PID hash table linkage. */
166 	struct pid *pids[PIDTYPE_MAX];
167 
168 #ifdef CONFIG_NO_HZ_FULL
169 	atomic_t tick_dep_mask;
170 #endif
171 
172 	struct pid *tty_old_pgrp;
173 
174 	/* boolean value for session group leader */
175 	int leader;
176 
177 	struct tty_struct *tty; /* NULL if no tty */
178 
179 #ifdef CONFIG_SCHED_AUTOGROUP
180 	struct autogroup *autogroup;
181 #endif
182 	/*
183 	 * Cumulative resource counters for dead threads in the group,
184 	 * and for reaped dead child processes forked by this group.
185 	 * Live threads maintain their own counters and add to these
186 	 * in __exit_signal, except for the group leader.
187 	 */
188 	seqlock_t stats_lock;
189 	u64 utime, stime, cutime, cstime;
190 	u64 gtime;
191 	u64 cgtime;
192 	struct prev_cputime prev_cputime;
193 	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
194 	unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
195 	unsigned long inblock, oublock, cinblock, coublock;
196 	unsigned long maxrss, cmaxrss;
197 	struct task_io_accounting ioac;
198 
199 	/*
200 	 * Cumulative ns of schedule CPU time fo dead threads in the
201 	 * group, not including a zombie group leader, (This only differs
202 	 * from jiffies_to_ns(utime + stime) if sched_clock uses something
203 	 * other than jiffies.)
204 	 */
205 	unsigned long long sum_sched_runtime;
206 
207 	/*
208 	 * We don't bother to synchronize most readers of this at all,
209 	 * because there is no reader checking a limit that actually needs
210 	 * to get both rlim_cur and rlim_max atomically, and either one
211 	 * alone is a single word that can safely be read normally.
212 	 * getrlimit/setrlimit use task_lock(current->group_leader) to
213 	 * protect this instead of the siglock, because they really
214 	 * have no need to disable irqs.
215 	 */
216 	struct rlimit rlim[RLIM_NLIMITS];
217 
218 #ifdef CONFIG_BSD_PROCESS_ACCT
219 	struct pacct_struct pacct;	/* per-process accounting information */
220 #endif
221 #ifdef CONFIG_TASKSTATS
222 	struct taskstats *stats;
223 #endif
224 #ifdef CONFIG_AUDIT
225 	unsigned audit_tty;
226 	struct tty_audit_buf *tty_audit_buf;
227 #endif
228 
229 	/*
230 	 * Thread is the potential origin of an oom condition; kill first on
231 	 * oom
232 	 */
233 	bool oom_flag_origin;
234 	short oom_score_adj;		/* OOM kill score adjustment */
235 	short oom_score_adj_min;	/* OOM kill score adjustment min value.
236 					 * Only settable by CAP_SYS_RESOURCE. */
237 	struct mm_struct *oom_mm;	/* recorded mm when the thread group got
238 					 * killed by the oom killer */
239 
240 	struct mutex cred_guard_mutex;	/* guard against foreign influences on
241 					 * credential calculations
242 					 * (notably. ptrace)
243 					 * Deprecated do not use in new code.
244 					 * Use exec_update_lock instead.
245 					 */
246 	struct rw_semaphore exec_update_lock;	/* Held while task_struct is
247 						 * being updated during exec,
248 						 * and may have inconsistent
249 						 * permissions.
250 						 */
251 } __randomize_layout;
252 
253 /*
254  * Bits in flags field of signal_struct.
255  */
256 #define SIGNAL_STOP_STOPPED	0x00000001 /* job control stop in effect */
257 #define SIGNAL_STOP_CONTINUED	0x00000002 /* SIGCONT since WCONTINUED reap */
258 #define SIGNAL_GROUP_EXIT	0x00000004 /* group exit in progress */
259 /*
260  * Pending notifications to parent.
261  */
262 #define SIGNAL_CLD_STOPPED	0x00000010
263 #define SIGNAL_CLD_CONTINUED	0x00000020
264 #define SIGNAL_CLD_MASK		(SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
265 
266 #define SIGNAL_UNKILLABLE	0x00000040 /* for init: ignore fatal signals */
267 
268 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
269 			  SIGNAL_STOP_CONTINUED)
270 
signal_set_stop_flags(struct signal_struct * sig,unsigned int flags)271 static inline void signal_set_stop_flags(struct signal_struct *sig,
272 					 unsigned int flags)
273 {
274 	WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
275 	sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
276 }
277 
278 extern void flush_signals(struct task_struct *);
279 extern void ignore_signals(struct task_struct *);
280 extern void flush_signal_handlers(struct task_struct *, int force_default);
281 extern int dequeue_signal(sigset_t *mask, kernel_siginfo_t *info, enum pid_type *type);
282 
kernel_dequeue_signal(void)283 static inline int kernel_dequeue_signal(void)
284 {
285 	struct task_struct *task = current;
286 	kernel_siginfo_t __info;
287 	enum pid_type __type;
288 	int ret;
289 
290 	spin_lock_irq(&task->sighand->siglock);
291 	ret = dequeue_signal(&task->blocked, &__info, &__type);
292 	spin_unlock_irq(&task->sighand->siglock);
293 
294 	return ret;
295 }
296 
kernel_signal_stop(void)297 static inline void kernel_signal_stop(void)
298 {
299 	spin_lock_irq(&current->sighand->siglock);
300 	if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
301 		current->jobctl |= JOBCTL_STOPPED;
302 		set_special_state(TASK_STOPPED);
303 	}
304 	spin_unlock_irq(&current->sighand->siglock);
305 
306 	schedule();
307 }
308 
309 int force_sig_fault_to_task(int sig, int code, void __user *addr,
310 			    struct task_struct *t);
311 int force_sig_fault(int sig, int code, void __user *addr);
312 int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t);
313 
314 int force_sig_mceerr(int code, void __user *, short);
315 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
316 
317 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
318 int force_sig_pkuerr(void __user *addr, u32 pkey);
319 int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
320 
321 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
322 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
323 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
324 			struct task_struct *t);
325 int force_sig_seccomp(int syscall, int reason, bool force_coredump);
326 
327 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
328 extern void force_sigsegv(int sig);
329 extern int force_sig_info(struct kernel_siginfo *);
330 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
331 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
332 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
333 				const struct cred *);
334 extern int kill_pgrp(struct pid *pid, int sig, int priv);
335 extern int kill_pid(struct pid *pid, int sig, int priv);
336 extern __must_check bool do_notify_parent(struct task_struct *, int);
337 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
338 extern void force_sig(int);
339 extern void force_fatal_sig(int);
340 extern void force_exit_sig(int);
341 extern int send_sig(int, struct task_struct *, int);
342 extern int zap_other_threads(struct task_struct *p);
343 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
344 
clear_notify_signal(void)345 static inline void clear_notify_signal(void)
346 {
347 	clear_thread_flag(TIF_NOTIFY_SIGNAL);
348 	smp_mb__after_atomic();
349 }
350 
351 /*
352  * Returns 'true' if kick_process() is needed to force a transition from
353  * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
354  */
__set_notify_signal(struct task_struct * task)355 static inline bool __set_notify_signal(struct task_struct *task)
356 {
357 	return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
358 	       !wake_up_state(task, TASK_INTERRUPTIBLE);
359 }
360 
361 /*
362  * Called to break out of interruptible wait loops, and enter the
363  * exit_to_user_mode_loop().
364  */
set_notify_signal(struct task_struct * task)365 static inline void set_notify_signal(struct task_struct *task)
366 {
367 	if (__set_notify_signal(task))
368 		kick_process(task);
369 }
370 
restart_syscall(void)371 static inline int restart_syscall(void)
372 {
373 	set_tsk_thread_flag(current, TIF_SIGPENDING);
374 	return -ERESTARTNOINTR;
375 }
376 
task_sigpending(struct task_struct * p)377 static inline int task_sigpending(struct task_struct *p)
378 {
379 	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
380 }
381 
signal_pending(struct task_struct * p)382 static inline int signal_pending(struct task_struct *p)
383 {
384 	/*
385 	 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
386 	 * behavior in terms of ensuring that we break out of wait loops
387 	 * so that notify signal callbacks can be processed.
388 	 */
389 	if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
390 		return 1;
391 	return task_sigpending(p);
392 }
393 
__fatal_signal_pending(struct task_struct * p)394 static inline int __fatal_signal_pending(struct task_struct *p)
395 {
396 	return unlikely(sigismember(&p->pending.signal, SIGKILL));
397 }
398 
fatal_signal_pending(struct task_struct * p)399 static inline int fatal_signal_pending(struct task_struct *p)
400 {
401 	return task_sigpending(p) && __fatal_signal_pending(p);
402 }
403 
signal_pending_state(unsigned int state,struct task_struct * p)404 static inline int signal_pending_state(unsigned int state, struct task_struct *p)
405 {
406 	if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
407 		return 0;
408 	if (!signal_pending(p))
409 		return 0;
410 
411 	return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
412 }
413 
414 /*
415  * This should only be used in fault handlers to decide whether we
416  * should stop the current fault routine to handle the signals
417  * instead, especially with the case where we've got interrupted with
418  * a VM_FAULT_RETRY.
419  */
fault_signal_pending(vm_fault_t fault_flags,struct pt_regs * regs)420 static inline bool fault_signal_pending(vm_fault_t fault_flags,
421 					struct pt_regs *regs)
422 {
423 	return unlikely((fault_flags & VM_FAULT_RETRY) &&
424 			(fatal_signal_pending(current) ||
425 			 (user_mode(regs) && signal_pending(current))));
426 }
427 
428 /*
429  * Reevaluate whether the task has signals pending delivery.
430  * Wake the task if so.
431  * This is required every time the blocked sigset_t changes.
432  * callers must hold sighand->siglock.
433  */
434 extern void recalc_sigpending(void);
435 extern void calculate_sigpending(void);
436 
437 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
438 
signal_wake_up(struct task_struct * t,bool fatal)439 static inline void signal_wake_up(struct task_struct *t, bool fatal)
440 {
441 	unsigned int state = 0;
442 	if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
443 		t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
444 		state = TASK_WAKEKILL | __TASK_TRACED;
445 	}
446 	signal_wake_up_state(t, state);
447 }
ptrace_signal_wake_up(struct task_struct * t,bool resume)448 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
449 {
450 	unsigned int state = 0;
451 	if (resume) {
452 		t->jobctl &= ~JOBCTL_TRACED;
453 		state = __TASK_TRACED;
454 	}
455 	signal_wake_up_state(t, state);
456 }
457 
458 void task_join_group_stop(struct task_struct *task);
459 
460 #ifdef TIF_RESTORE_SIGMASK
461 /*
462  * Legacy restore_sigmask accessors.  These are inefficient on
463  * SMP architectures because they require atomic operations.
464  */
465 
466 /**
467  * set_restore_sigmask() - make sure saved_sigmask processing gets done
468  *
469  * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
470  * will run before returning to user mode, to process the flag.  For
471  * all callers, TIF_SIGPENDING is already set or it's no harm to set
472  * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
473  * arch code will notice on return to user mode, in case those bits
474  * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
475  * signal code always gets run when TIF_RESTORE_SIGMASK is set.
476  */
set_restore_sigmask(void)477 static inline void set_restore_sigmask(void)
478 {
479 	set_thread_flag(TIF_RESTORE_SIGMASK);
480 }
481 
clear_tsk_restore_sigmask(struct task_struct * task)482 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
483 {
484 	clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
485 }
486 
clear_restore_sigmask(void)487 static inline void clear_restore_sigmask(void)
488 {
489 	clear_thread_flag(TIF_RESTORE_SIGMASK);
490 }
test_tsk_restore_sigmask(struct task_struct * task)491 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
492 {
493 	return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
494 }
test_restore_sigmask(void)495 static inline bool test_restore_sigmask(void)
496 {
497 	return test_thread_flag(TIF_RESTORE_SIGMASK);
498 }
test_and_clear_restore_sigmask(void)499 static inline bool test_and_clear_restore_sigmask(void)
500 {
501 	return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
502 }
503 
504 #else	/* TIF_RESTORE_SIGMASK */
505 
506 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
set_restore_sigmask(void)507 static inline void set_restore_sigmask(void)
508 {
509 	current->restore_sigmask = true;
510 }
clear_tsk_restore_sigmask(struct task_struct * task)511 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
512 {
513 	task->restore_sigmask = false;
514 }
clear_restore_sigmask(void)515 static inline void clear_restore_sigmask(void)
516 {
517 	current->restore_sigmask = false;
518 }
test_restore_sigmask(void)519 static inline bool test_restore_sigmask(void)
520 {
521 	return current->restore_sigmask;
522 }
test_tsk_restore_sigmask(struct task_struct * task)523 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
524 {
525 	return task->restore_sigmask;
526 }
test_and_clear_restore_sigmask(void)527 static inline bool test_and_clear_restore_sigmask(void)
528 {
529 	if (!current->restore_sigmask)
530 		return false;
531 	current->restore_sigmask = false;
532 	return true;
533 }
534 #endif
535 
restore_saved_sigmask(void)536 static inline void restore_saved_sigmask(void)
537 {
538 	if (test_and_clear_restore_sigmask())
539 		__set_current_blocked(&current->saved_sigmask);
540 }
541 
542 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
543 
restore_saved_sigmask_unless(bool interrupted)544 static inline void restore_saved_sigmask_unless(bool interrupted)
545 {
546 	if (interrupted)
547 		WARN_ON(!signal_pending(current));
548 	else
549 		restore_saved_sigmask();
550 }
551 
sigmask_to_save(void)552 static inline sigset_t *sigmask_to_save(void)
553 {
554 	sigset_t *res = &current->blocked;
555 	if (unlikely(test_restore_sigmask()))
556 		res = &current->saved_sigmask;
557 	return res;
558 }
559 
kill_cad_pid(int sig,int priv)560 static inline int kill_cad_pid(int sig, int priv)
561 {
562 	return kill_pid(cad_pid, sig, priv);
563 }
564 
565 /* These can be the second arg to send_sig_info/send_group_sig_info.  */
566 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
567 #define SEND_SIG_PRIV	((struct kernel_siginfo *) 1)
568 
__on_sig_stack(unsigned long sp)569 static inline int __on_sig_stack(unsigned long sp)
570 {
571 #ifdef CONFIG_STACK_GROWSUP
572 	return sp >= current->sas_ss_sp &&
573 		sp - current->sas_ss_sp < current->sas_ss_size;
574 #else
575 	return sp > current->sas_ss_sp &&
576 		sp - current->sas_ss_sp <= current->sas_ss_size;
577 #endif
578 }
579 
580 /*
581  * True if we are on the alternate signal stack.
582  */
on_sig_stack(unsigned long sp)583 static inline int on_sig_stack(unsigned long sp)
584 {
585 	/*
586 	 * If the signal stack is SS_AUTODISARM then, by construction, we
587 	 * can't be on the signal stack unless user code deliberately set
588 	 * SS_AUTODISARM when we were already on it.
589 	 *
590 	 * This improves reliability: if user state gets corrupted such that
591 	 * the stack pointer points very close to the end of the signal stack,
592 	 * then this check will enable the signal to be handled anyway.
593 	 */
594 	if (current->sas_ss_flags & SS_AUTODISARM)
595 		return 0;
596 
597 	return __on_sig_stack(sp);
598 }
599 
sas_ss_flags(unsigned long sp)600 static inline int sas_ss_flags(unsigned long sp)
601 {
602 	if (!current->sas_ss_size)
603 		return SS_DISABLE;
604 
605 	return on_sig_stack(sp) ? SS_ONSTACK : 0;
606 }
607 
sas_ss_reset(struct task_struct * p)608 static inline void sas_ss_reset(struct task_struct *p)
609 {
610 	p->sas_ss_sp = 0;
611 	p->sas_ss_size = 0;
612 	p->sas_ss_flags = SS_DISABLE;
613 }
614 
sigsp(unsigned long sp,struct ksignal * ksig)615 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
616 {
617 	if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
618 #ifdef CONFIG_STACK_GROWSUP
619 		return current->sas_ss_sp;
620 #else
621 		return current->sas_ss_sp + current->sas_ss_size;
622 #endif
623 	return sp;
624 }
625 
626 extern void __cleanup_sighand(struct sighand_struct *);
627 extern void flush_itimer_signals(void);
628 
629 #define tasklist_empty() \
630 	list_empty(&init_task.tasks)
631 
632 #define next_task(p) \
633 	list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
634 
635 #define for_each_process(p) \
636 	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
637 
638 extern bool current_is_single_threaded(void);
639 
640 /*
641  * Without tasklist/siglock it is only rcu-safe if g can't exit/exec,
642  * otherwise next_thread(t) will never reach g after list_del_rcu(g).
643  */
644 #define while_each_thread(g, t) \
645 	while ((t = next_thread(t)) != g)
646 
647 #define for_other_threads(p, t)	\
648 	for (t = p; (t = next_thread(t)) != p; )
649 
650 #define __for_each_thread(signal, t)	\
651 	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node, \
652 		lockdep_is_held(&tasklist_lock))
653 
654 #define for_each_thread(p, t)		\
655 	__for_each_thread((p)->signal, t)
656 
657 /* Careful: this is a double loop, 'break' won't work as expected. */
658 #define for_each_process_thread(p, t)	\
659 	for_each_process(p) for_each_thread(p, t)
660 
661 typedef int (*proc_visitor)(struct task_struct *p, void *data);
662 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
663 
664 static inline
task_pid_type(struct task_struct * task,enum pid_type type)665 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
666 {
667 	struct pid *pid;
668 	if (type == PIDTYPE_PID)
669 		pid = task_pid(task);
670 	else
671 		pid = task->signal->pids[type];
672 	return pid;
673 }
674 
task_tgid(struct task_struct * task)675 static inline struct pid *task_tgid(struct task_struct *task)
676 {
677 	return task->signal->pids[PIDTYPE_TGID];
678 }
679 
680 /*
681  * Without tasklist or RCU lock it is not safe to dereference
682  * the result of task_pgrp/task_session even if task == current,
683  * we can race with another thread doing sys_setsid/sys_setpgid.
684  */
task_pgrp(struct task_struct * task)685 static inline struct pid *task_pgrp(struct task_struct *task)
686 {
687 	return task->signal->pids[PIDTYPE_PGID];
688 }
689 
task_session(struct task_struct * task)690 static inline struct pid *task_session(struct task_struct *task)
691 {
692 	return task->signal->pids[PIDTYPE_SID];
693 }
694 
get_nr_threads(struct task_struct * task)695 static inline int get_nr_threads(struct task_struct *task)
696 {
697 	return task->signal->nr_threads;
698 }
699 
thread_group_leader(struct task_struct * p)700 static inline bool thread_group_leader(struct task_struct *p)
701 {
702 	return p->exit_signal >= 0;
703 }
704 
705 static inline
same_thread_group(struct task_struct * p1,struct task_struct * p2)706 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
707 {
708 	return p1->signal == p2->signal;
709 }
710 
711 /*
712  * returns NULL if p is the last thread in the thread group
713  */
__next_thread(struct task_struct * p)714 static inline struct task_struct *__next_thread(struct task_struct *p)
715 {
716 	return list_next_or_null_rcu(&p->signal->thread_head,
717 					&p->thread_node,
718 					struct task_struct,
719 					thread_node);
720 }
721 
next_thread(struct task_struct * p)722 static inline struct task_struct *next_thread(struct task_struct *p)
723 {
724 	return __next_thread(p) ?: p->group_leader;
725 }
726 
thread_group_empty(struct task_struct * p)727 static inline int thread_group_empty(struct task_struct *p)
728 {
729 	return thread_group_leader(p) &&
730 	       list_is_last(&p->thread_node, &p->signal->thread_head);
731 }
732 
733 #define delay_group_leader(p) \
734 		(thread_group_leader(p) && !thread_group_empty(p))
735 
736 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
737 							unsigned long *flags);
738 
lock_task_sighand(struct task_struct * task,unsigned long * flags)739 static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
740 						       unsigned long *flags)
741 {
742 	struct sighand_struct *ret;
743 
744 	ret = __lock_task_sighand(task, flags);
745 	(void)__cond_lock(&task->sighand->siglock, ret);
746 	return ret;
747 }
748 
unlock_task_sighand(struct task_struct * task,unsigned long * flags)749 static inline void unlock_task_sighand(struct task_struct *task,
750 						unsigned long *flags)
751 {
752 	spin_unlock_irqrestore(&task->sighand->siglock, *flags);
753 }
754 
755 #ifdef CONFIG_LOCKDEP
756 extern void lockdep_assert_task_sighand_held(struct task_struct *task);
757 #else
lockdep_assert_task_sighand_held(struct task_struct * task)758 static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
759 #endif
760 
task_rlimit(const struct task_struct * task,unsigned int limit)761 static inline unsigned long task_rlimit(const struct task_struct *task,
762 		unsigned int limit)
763 {
764 	return READ_ONCE(task->signal->rlim[limit].rlim_cur);
765 }
766 
task_rlimit_max(const struct task_struct * task,unsigned int limit)767 static inline unsigned long task_rlimit_max(const struct task_struct *task,
768 		unsigned int limit)
769 {
770 	return READ_ONCE(task->signal->rlim[limit].rlim_max);
771 }
772 
rlimit(unsigned int limit)773 static inline unsigned long rlimit(unsigned int limit)
774 {
775 	return task_rlimit(current, limit);
776 }
777 
rlimit_max(unsigned int limit)778 static inline unsigned long rlimit_max(unsigned int limit)
779 {
780 	return task_rlimit_max(current, limit);
781 }
782 
783 #endif /* _LINUX_SCHED_SIGNAL_H */
784