xref: /linux/include/linux/sched/signal.h (revision 755fa5b4fb36627796af19932a432d343220ec63)
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 #ifdef CONFIG_CGROUPS
230 	struct rw_semaphore cgroup_threadgroup_rwsem;
231 #endif
232 
233 	/*
234 	 * Thread is the potential origin of an oom condition; kill first on
235 	 * oom
236 	 */
237 	bool oom_flag_origin;
238 	short oom_score_adj;		/* OOM kill score adjustment */
239 	short oom_score_adj_min;	/* OOM kill score adjustment min value.
240 					 * Only settable by CAP_SYS_RESOURCE. */
241 	struct mm_struct *oom_mm;	/* recorded mm when the thread group got
242 					 * killed by the oom killer */
243 
244 	struct mutex cred_guard_mutex;	/* guard against foreign influences on
245 					 * credential calculations
246 					 * (notably. ptrace)
247 					 * Deprecated do not use in new code.
248 					 * Use exec_update_lock instead.
249 					 */
250 	struct rw_semaphore exec_update_lock;	/* Held while task_struct is
251 						 * being updated during exec,
252 						 * and may have inconsistent
253 						 * permissions.
254 						 */
255 } __randomize_layout;
256 
257 /*
258  * Bits in flags field of signal_struct.
259  */
260 #define SIGNAL_STOP_STOPPED	0x00000001 /* job control stop in effect */
261 #define SIGNAL_STOP_CONTINUED	0x00000002 /* SIGCONT since WCONTINUED reap */
262 #define SIGNAL_GROUP_EXIT	0x00000004 /* group exit in progress */
263 /*
264  * Pending notifications to parent.
265  */
266 #define SIGNAL_CLD_STOPPED	0x00000010
267 #define SIGNAL_CLD_CONTINUED	0x00000020
268 #define SIGNAL_CLD_MASK		(SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
269 
270 #define SIGNAL_UNKILLABLE	0x00000040 /* for init: ignore fatal signals */
271 
272 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
273 			  SIGNAL_STOP_CONTINUED)
274 
signal_set_stop_flags(struct signal_struct * sig,unsigned int flags)275 static inline void signal_set_stop_flags(struct signal_struct *sig,
276 					 unsigned int flags)
277 {
278 	WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
279 	sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
280 }
281 
282 extern void flush_signals(struct task_struct *);
283 extern void ignore_signals(struct task_struct *);
284 extern void flush_signal_handlers(struct task_struct *, int force_default);
285 extern int dequeue_signal(sigset_t *mask, kernel_siginfo_t *info, enum pid_type *type);
286 
kernel_dequeue_signal(void)287 static inline int kernel_dequeue_signal(void)
288 {
289 	struct task_struct *task = current;
290 	kernel_siginfo_t __info;
291 	enum pid_type __type;
292 	int ret;
293 
294 	spin_lock_irq(&task->sighand->siglock);
295 	ret = dequeue_signal(&task->blocked, &__info, &__type);
296 	spin_unlock_irq(&task->sighand->siglock);
297 
298 	return ret;
299 }
300 
kernel_signal_stop(void)301 static inline void kernel_signal_stop(void)
302 {
303 	spin_lock_irq(&current->sighand->siglock);
304 	if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
305 		current->jobctl |= JOBCTL_STOPPED;
306 		set_special_state(TASK_STOPPED);
307 	}
308 	spin_unlock_irq(&current->sighand->siglock);
309 
310 	schedule();
311 }
312 
313 int force_sig_fault_to_task(int sig, int code, void __user *addr,
314 			    struct task_struct *t);
315 int force_sig_fault(int sig, int code, void __user *addr);
316 int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t);
317 
318 int force_sig_mceerr(int code, void __user *, short);
319 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
320 
321 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
322 int force_sig_pkuerr(void __user *addr, u32 pkey);
323 int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
324 
325 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
326 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
327 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
328 			struct task_struct *t);
329 int force_sig_seccomp(int syscall, int reason, bool force_coredump);
330 
331 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
332 extern void force_sigsegv(int sig);
333 extern int force_sig_info(struct kernel_siginfo *);
334 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
335 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
336 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
337 				const struct cred *);
338 extern int kill_pgrp(struct pid *pid, int sig, int priv);
339 extern int kill_pid(struct pid *pid, int sig, int priv);
340 extern __must_check bool do_notify_parent(struct task_struct *, int);
341 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
342 extern void force_sig(int);
343 extern void force_fatal_sig(int);
344 extern void force_exit_sig(int);
345 extern int send_sig(int, struct task_struct *, int);
346 extern int zap_other_threads(struct task_struct *p);
347 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
348 
clear_notify_signal(void)349 static inline void clear_notify_signal(void)
350 {
351 	clear_thread_flag(TIF_NOTIFY_SIGNAL);
352 	smp_mb__after_atomic();
353 }
354 
355 /*
356  * Returns 'true' if kick_process() is needed to force a transition from
357  * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
358  */
__set_notify_signal(struct task_struct * task)359 static inline bool __set_notify_signal(struct task_struct *task)
360 {
361 	return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
362 	       !wake_up_state(task, TASK_INTERRUPTIBLE);
363 }
364 
365 /*
366  * Called to break out of interruptible wait loops, and enter the
367  * exit_to_user_mode_loop().
368  */
set_notify_signal(struct task_struct * task)369 static inline void set_notify_signal(struct task_struct *task)
370 {
371 	if (__set_notify_signal(task))
372 		kick_process(task);
373 }
374 
restart_syscall(void)375 static inline int restart_syscall(void)
376 {
377 	set_tsk_thread_flag(current, TIF_SIGPENDING);
378 	return -ERESTARTNOINTR;
379 }
380 
task_sigpending(struct task_struct * p)381 static inline int task_sigpending(struct task_struct *p)
382 {
383 	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
384 }
385 
signal_pending(struct task_struct * p)386 static inline int signal_pending(struct task_struct *p)
387 {
388 	/*
389 	 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
390 	 * behavior in terms of ensuring that we break out of wait loops
391 	 * so that notify signal callbacks can be processed.
392 	 */
393 	if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
394 		return 1;
395 	return task_sigpending(p);
396 }
397 
__fatal_signal_pending(struct task_struct * p)398 static inline int __fatal_signal_pending(struct task_struct *p)
399 {
400 	return unlikely(sigismember(&p->pending.signal, SIGKILL));
401 }
402 
fatal_signal_pending(struct task_struct * p)403 static inline int fatal_signal_pending(struct task_struct *p)
404 {
405 	return task_sigpending(p) && __fatal_signal_pending(p);
406 }
407 
signal_pending_state(unsigned int state,struct task_struct * p)408 static inline int signal_pending_state(unsigned int state, struct task_struct *p)
409 {
410 	if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
411 		return 0;
412 	if (!signal_pending(p))
413 		return 0;
414 
415 	return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
416 }
417 
418 /*
419  * This should only be used in fault handlers to decide whether we
420  * should stop the current fault routine to handle the signals
421  * instead, especially with the case where we've got interrupted with
422  * a VM_FAULT_RETRY.
423  */
fault_signal_pending(vm_fault_t fault_flags,struct pt_regs * regs)424 static inline bool fault_signal_pending(vm_fault_t fault_flags,
425 					struct pt_regs *regs)
426 {
427 	return unlikely((fault_flags & VM_FAULT_RETRY) &&
428 			(fatal_signal_pending(current) ||
429 			 (user_mode(regs) && signal_pending(current))));
430 }
431 
432 /*
433  * Reevaluate whether the task has signals pending delivery.
434  * Wake the task if so.
435  * This is required every time the blocked sigset_t changes.
436  * callers must hold sighand->siglock.
437  */
438 extern void recalc_sigpending(void);
439 extern void calculate_sigpending(void);
440 
441 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
442 
signal_wake_up(struct task_struct * t,bool fatal)443 static inline void signal_wake_up(struct task_struct *t, bool fatal)
444 {
445 	unsigned int state = 0;
446 	if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
447 		t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
448 		state = TASK_WAKEKILL | __TASK_TRACED;
449 	}
450 	signal_wake_up_state(t, state);
451 }
ptrace_signal_wake_up(struct task_struct * t,bool resume)452 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
453 {
454 	unsigned int state = 0;
455 	if (resume) {
456 		t->jobctl &= ~JOBCTL_TRACED;
457 		state = __TASK_TRACED;
458 	}
459 	signal_wake_up_state(t, state);
460 }
461 
462 void task_join_group_stop(struct task_struct *task);
463 
464 #ifdef TIF_RESTORE_SIGMASK
465 /*
466  * Legacy restore_sigmask accessors.  These are inefficient on
467  * SMP architectures because they require atomic operations.
468  */
469 
470 /**
471  * set_restore_sigmask() - make sure saved_sigmask processing gets done
472  *
473  * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
474  * will run before returning to user mode, to process the flag.  For
475  * all callers, TIF_SIGPENDING is already set or it's no harm to set
476  * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
477  * arch code will notice on return to user mode, in case those bits
478  * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
479  * signal code always gets run when TIF_RESTORE_SIGMASK is set.
480  */
set_restore_sigmask(void)481 static inline void set_restore_sigmask(void)
482 {
483 	set_thread_flag(TIF_RESTORE_SIGMASK);
484 }
485 
clear_tsk_restore_sigmask(struct task_struct * task)486 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
487 {
488 	clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
489 }
490 
clear_restore_sigmask(void)491 static inline void clear_restore_sigmask(void)
492 {
493 	clear_thread_flag(TIF_RESTORE_SIGMASK);
494 }
test_tsk_restore_sigmask(struct task_struct * task)495 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
496 {
497 	return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
498 }
test_restore_sigmask(void)499 static inline bool test_restore_sigmask(void)
500 {
501 	return test_thread_flag(TIF_RESTORE_SIGMASK);
502 }
test_and_clear_restore_sigmask(void)503 static inline bool test_and_clear_restore_sigmask(void)
504 {
505 	return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
506 }
507 
508 #else	/* TIF_RESTORE_SIGMASK */
509 
510 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
set_restore_sigmask(void)511 static inline void set_restore_sigmask(void)
512 {
513 	current->restore_sigmask = true;
514 }
clear_tsk_restore_sigmask(struct task_struct * task)515 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
516 {
517 	task->restore_sigmask = false;
518 }
clear_restore_sigmask(void)519 static inline void clear_restore_sigmask(void)
520 {
521 	current->restore_sigmask = false;
522 }
test_restore_sigmask(void)523 static inline bool test_restore_sigmask(void)
524 {
525 	return current->restore_sigmask;
526 }
test_tsk_restore_sigmask(struct task_struct * task)527 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
528 {
529 	return task->restore_sigmask;
530 }
test_and_clear_restore_sigmask(void)531 static inline bool test_and_clear_restore_sigmask(void)
532 {
533 	if (!current->restore_sigmask)
534 		return false;
535 	current->restore_sigmask = false;
536 	return true;
537 }
538 #endif
539 
restore_saved_sigmask(void)540 static inline void restore_saved_sigmask(void)
541 {
542 	if (test_and_clear_restore_sigmask())
543 		__set_current_blocked(&current->saved_sigmask);
544 }
545 
546 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
547 
restore_saved_sigmask_unless(bool interrupted)548 static inline void restore_saved_sigmask_unless(bool interrupted)
549 {
550 	if (interrupted)
551 		WARN_ON(!signal_pending(current));
552 	else
553 		restore_saved_sigmask();
554 }
555 
sigmask_to_save(void)556 static inline sigset_t *sigmask_to_save(void)
557 {
558 	sigset_t *res = &current->blocked;
559 	if (unlikely(test_restore_sigmask()))
560 		res = &current->saved_sigmask;
561 	return res;
562 }
563 
kill_cad_pid(int sig,int priv)564 static inline int kill_cad_pid(int sig, int priv)
565 {
566 	return kill_pid(cad_pid, sig, priv);
567 }
568 
569 /* These can be the second arg to send_sig_info/send_group_sig_info.  */
570 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
571 #define SEND_SIG_PRIV	((struct kernel_siginfo *) 1)
572 
__on_sig_stack(unsigned long sp)573 static inline int __on_sig_stack(unsigned long sp)
574 {
575 #ifdef CONFIG_STACK_GROWSUP
576 	return sp >= current->sas_ss_sp &&
577 		sp - current->sas_ss_sp < current->sas_ss_size;
578 #else
579 	return sp > current->sas_ss_sp &&
580 		sp - current->sas_ss_sp <= current->sas_ss_size;
581 #endif
582 }
583 
584 /*
585  * True if we are on the alternate signal stack.
586  */
on_sig_stack(unsigned long sp)587 static inline int on_sig_stack(unsigned long sp)
588 {
589 	/*
590 	 * If the signal stack is SS_AUTODISARM then, by construction, we
591 	 * can't be on the signal stack unless user code deliberately set
592 	 * SS_AUTODISARM when we were already on it.
593 	 *
594 	 * This improves reliability: if user state gets corrupted such that
595 	 * the stack pointer points very close to the end of the signal stack,
596 	 * then this check will enable the signal to be handled anyway.
597 	 */
598 	if (current->sas_ss_flags & SS_AUTODISARM)
599 		return 0;
600 
601 	return __on_sig_stack(sp);
602 }
603 
sas_ss_flags(unsigned long sp)604 static inline int sas_ss_flags(unsigned long sp)
605 {
606 	if (!current->sas_ss_size)
607 		return SS_DISABLE;
608 
609 	return on_sig_stack(sp) ? SS_ONSTACK : 0;
610 }
611 
sas_ss_reset(struct task_struct * p)612 static inline void sas_ss_reset(struct task_struct *p)
613 {
614 	p->sas_ss_sp = 0;
615 	p->sas_ss_size = 0;
616 	p->sas_ss_flags = SS_DISABLE;
617 }
618 
sigsp(unsigned long sp,struct ksignal * ksig)619 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
620 {
621 	if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
622 #ifdef CONFIG_STACK_GROWSUP
623 		return current->sas_ss_sp;
624 #else
625 		return current->sas_ss_sp + current->sas_ss_size;
626 #endif
627 	return sp;
628 }
629 
630 extern void __cleanup_sighand(struct sighand_struct *);
631 extern void flush_itimer_signals(void);
632 
633 #define tasklist_empty() \
634 	list_empty(&init_task.tasks)
635 
636 #define next_task(p) \
637 	list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
638 
639 #define for_each_process(p) \
640 	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
641 
642 extern bool current_is_single_threaded(void);
643 
644 /*
645  * Without tasklist/siglock it is only rcu-safe if g can't exit/exec,
646  * otherwise next_thread(t) will never reach g after list_del_rcu(g).
647  */
648 #define while_each_thread(g, t) \
649 	while ((t = next_thread(t)) != g)
650 
651 #define for_other_threads(p, t)	\
652 	for (t = p; (t = next_thread(t)) != p; )
653 
654 #define __for_each_thread(signal, t)	\
655 	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node, \
656 		lockdep_is_held(&tasklist_lock))
657 
658 #define for_each_thread(p, t)		\
659 	__for_each_thread((p)->signal, t)
660 
661 /* Careful: this is a double loop, 'break' won't work as expected. */
662 #define for_each_process_thread(p, t)	\
663 	for_each_process(p) for_each_thread(p, t)
664 
665 typedef int (*proc_visitor)(struct task_struct *p, void *data);
666 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
667 
668 static inline
task_pid_type(struct task_struct * task,enum pid_type type)669 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
670 {
671 	struct pid *pid;
672 	if (type == PIDTYPE_PID)
673 		pid = task_pid(task);
674 	else
675 		pid = task->signal->pids[type];
676 	return pid;
677 }
678 
task_tgid(struct task_struct * task)679 static inline struct pid *task_tgid(struct task_struct *task)
680 {
681 	return task->signal->pids[PIDTYPE_TGID];
682 }
683 
684 /*
685  * Without tasklist or RCU lock it is not safe to dereference
686  * the result of task_pgrp/task_session even if task == current,
687  * we can race with another thread doing sys_setsid/sys_setpgid.
688  */
task_pgrp(struct task_struct * task)689 static inline struct pid *task_pgrp(struct task_struct *task)
690 {
691 	return task->signal->pids[PIDTYPE_PGID];
692 }
693 
task_session(struct task_struct * task)694 static inline struct pid *task_session(struct task_struct *task)
695 {
696 	return task->signal->pids[PIDTYPE_SID];
697 }
698 
get_nr_threads(struct task_struct * task)699 static inline int get_nr_threads(struct task_struct *task)
700 {
701 	return task->signal->nr_threads;
702 }
703 
thread_group_leader(struct task_struct * p)704 static inline bool thread_group_leader(struct task_struct *p)
705 {
706 	return p->exit_signal >= 0;
707 }
708 
709 static inline
same_thread_group(struct task_struct * p1,struct task_struct * p2)710 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
711 {
712 	return p1->signal == p2->signal;
713 }
714 
715 /*
716  * returns NULL if p is the last thread in the thread group
717  */
__next_thread(struct task_struct * p)718 static inline struct task_struct *__next_thread(struct task_struct *p)
719 {
720 	return list_next_or_null_rcu(&p->signal->thread_head,
721 					&p->thread_node,
722 					struct task_struct,
723 					thread_node);
724 }
725 
next_thread(struct task_struct * p)726 static inline struct task_struct *next_thread(struct task_struct *p)
727 {
728 	return __next_thread(p) ?: p->group_leader;
729 }
730 
thread_group_empty(struct task_struct * p)731 static inline int thread_group_empty(struct task_struct *p)
732 {
733 	return thread_group_leader(p) &&
734 	       list_is_last(&p->thread_node, &p->signal->thread_head);
735 }
736 
737 #define delay_group_leader(p) \
738 		(thread_group_leader(p) && !thread_group_empty(p))
739 
740 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
741 							unsigned long *flags);
742 
lock_task_sighand(struct task_struct * task,unsigned long * flags)743 static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
744 						       unsigned long *flags)
745 {
746 	struct sighand_struct *ret;
747 
748 	ret = __lock_task_sighand(task, flags);
749 	(void)__cond_lock(&task->sighand->siglock, ret);
750 	return ret;
751 }
752 
unlock_task_sighand(struct task_struct * task,unsigned long * flags)753 static inline void unlock_task_sighand(struct task_struct *task,
754 						unsigned long *flags)
755 {
756 	spin_unlock_irqrestore(&task->sighand->siglock, *flags);
757 }
758 
759 #ifdef CONFIG_LOCKDEP
760 extern void lockdep_assert_task_sighand_held(struct task_struct *task);
761 #else
lockdep_assert_task_sighand_held(struct task_struct * task)762 static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
763 #endif
764 
task_rlimit(const struct task_struct * task,unsigned int limit)765 static inline unsigned long task_rlimit(const struct task_struct *task,
766 		unsigned int limit)
767 {
768 	return READ_ONCE(task->signal->rlim[limit].rlim_cur);
769 }
770 
task_rlimit_max(const struct task_struct * task,unsigned int limit)771 static inline unsigned long task_rlimit_max(const struct task_struct *task,
772 		unsigned int limit)
773 {
774 	return READ_ONCE(task->signal->rlim[limit].rlim_max);
775 }
776 
rlimit(unsigned int limit)777 static inline unsigned long rlimit(unsigned int limit)
778 {
779 	return task_rlimit(current, limit);
780 }
781 
rlimit_max(unsigned int limit)782 static inline unsigned long rlimit_max(unsigned int limit)
783 {
784 	return task_rlimit_max(current, limit);
785 }
786 
787 #endif /* _LINUX_SCHED_SIGNAL_H */
788