1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCHED_SIGNAL_H
3 #define _LINUX_SCHED_SIGNAL_H
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>
13 * Types defining task->signal and task->sighand and APIs using them:
16 struct sighand_struct {
18 struct k_sigaction action[_NSIG];
20 wait_queue_head_t signalfd_wqh;
24 * Per-process accounting stats:
30 u64 ac_utime, ac_stime;
31 unsigned long ac_minflt, ac_majflt;
40 * This is the atomic variant of task_cputime, which can be used for
41 * storing and updating task_cputime statistics without locking.
43 struct task_cputime_atomic {
46 atomic64_t sum_exec_runtime;
49 #define INIT_CPUTIME_ATOMIC \
50 (struct task_cputime_atomic) { \
51 .utime = ATOMIC64_INIT(0), \
52 .stime = ATOMIC64_INIT(0), \
53 .sum_exec_runtime = ATOMIC64_INIT(0), \
56 * struct thread_group_cputimer - thread group interval timer counts
57 * @cputime_atomic: atomic thread group interval timers.
58 * @running: true when there are timers running and
59 * @cputime_atomic receives updates.
60 * @checking_timer: true when a thread in the group is in the
61 * process of checking for thread group timers.
63 * This structure contains the version of task_cputime, above, that is
64 * used for thread group CPU timer calculations.
66 struct thread_group_cputimer {
67 struct task_cputime_atomic cputime_atomic;
73 * NOTE! "signal_struct" does not have its own
74 * locking, because a shared signal_struct always
75 * implies a shared sighand_struct, so locking
76 * sighand_struct is always a proper superset of
77 * the locking of signal_struct.
79 struct signal_struct {
83 struct list_head thread_head;
85 wait_queue_head_t wait_chldexit; /* for wait4() */
87 /* current thread group signal load-balancing target: */
88 struct task_struct *curr_target;
90 /* shared signal handling: */
91 struct sigpending shared_pending;
93 /* thread group exit support */
96 * - notify group_exit_task when ->count is equal to notify_count
97 * - everyone except group_exit_task is stopped during signal delivery
98 * of fatal signals, group_exit_task processes the signal.
101 struct task_struct *group_exit_task;
103 /* thread group stop support, overloads group_exit_code too */
104 int group_stop_count;
105 unsigned int flags; /* see SIGNAL_* flags below */
108 * PR_SET_CHILD_SUBREAPER marks a process, like a service
109 * manager, to re-parent orphan (double-forking) child processes
110 * to this process instead of 'init'. The service manager is
111 * able to receive SIGCHLD signals and is able to investigate
112 * the process until it calls wait(). All children of this
113 * process will inherit a flag if they should look for a
114 * child_subreaper process at exit.
116 unsigned int is_child_subreaper:1;
117 unsigned int has_child_subreaper:1;
119 #ifdef CONFIG_POSIX_TIMERS
121 /* POSIX.1b Interval Timers */
123 struct list_head posix_timers;
125 /* ITIMER_REAL timer for the process */
126 struct hrtimer real_timer;
127 ktime_t it_real_incr;
130 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
131 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
132 * values are defined to 0 and 1 respectively
134 struct cpu_itimer it[2];
137 * Thread group totals for process CPU timers.
138 * See thread_group_cputimer(), et al, for details.
140 struct thread_group_cputimer cputimer;
142 /* Earliest-expiration cache. */
143 struct task_cputime cputime_expires;
145 struct list_head cpu_timers[3];
149 struct pid *leader_pid;
151 #ifdef CONFIG_NO_HZ_FULL
152 atomic_t tick_dep_mask;
155 struct pid *tty_old_pgrp;
157 /* boolean value for session group leader */
160 struct tty_struct *tty; /* NULL if no tty */
162 #ifdef CONFIG_SCHED_AUTOGROUP
163 struct autogroup *autogroup;
166 * Cumulative resource counters for dead threads in the group,
167 * and for reaped dead child processes forked by this group.
168 * Live threads maintain their own counters and add to these
169 * in __exit_signal, except for the group leader.
171 seqlock_t stats_lock;
172 u64 utime, stime, cutime, cstime;
175 struct prev_cputime prev_cputime;
176 unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
177 unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
178 unsigned long inblock, oublock, cinblock, coublock;
179 unsigned long maxrss, cmaxrss;
180 struct task_io_accounting ioac;
183 * Cumulative ns of schedule CPU time fo dead threads in the
184 * group, not including a zombie group leader, (This only differs
185 * from jiffies_to_ns(utime + stime) if sched_clock uses something
186 * other than jiffies.)
188 unsigned long long sum_sched_runtime;
191 * We don't bother to synchronize most readers of this at all,
192 * because there is no reader checking a limit that actually needs
193 * to get both rlim_cur and rlim_max atomically, and either one
194 * alone is a single word that can safely be read normally.
195 * getrlimit/setrlimit use task_lock(current->group_leader) to
196 * protect this instead of the siglock, because they really
197 * have no need to disable irqs.
199 struct rlimit rlim[RLIM_NLIMITS];
201 #ifdef CONFIG_BSD_PROCESS_ACCT
202 struct pacct_struct pacct; /* per-process accounting information */
204 #ifdef CONFIG_TASKSTATS
205 struct taskstats *stats;
209 struct tty_audit_buf *tty_audit_buf;
213 * Thread is the potential origin of an oom condition; kill first on
216 bool oom_flag_origin;
217 short oom_score_adj; /* OOM kill score adjustment */
218 short oom_score_adj_min; /* OOM kill score adjustment min value.
219 * Only settable by CAP_SYS_RESOURCE. */
220 struct mm_struct *oom_mm; /* recorded mm when the thread group got
221 * killed by the oom killer */
223 struct mutex cred_guard_mutex; /* guard against foreign influences on
224 * credential calculations
225 * (notably. ptrace) */
226 } __randomize_layout;
229 * Bits in flags field of signal_struct.
231 #define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
232 #define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
233 #define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
234 #define SIGNAL_GROUP_COREDUMP 0x00000008 /* coredump in progress */
236 * Pending notifications to parent.
238 #define SIGNAL_CLD_STOPPED 0x00000010
239 #define SIGNAL_CLD_CONTINUED 0x00000020
240 #define SIGNAL_CLD_MASK (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
242 #define SIGNAL_UNKILLABLE 0x00000040 /* for init: ignore fatal signals */
244 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
245 SIGNAL_STOP_CONTINUED)
247 static inline void signal_set_stop_flags(struct signal_struct *sig,
250 WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
251 sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
254 /* If true, all threads except ->group_exit_task have pending SIGKILL */
255 static inline int signal_group_exit(const struct signal_struct *sig)
257 return (sig->flags & SIGNAL_GROUP_EXIT) ||
258 (sig->group_exit_task != NULL);
261 extern void flush_signals(struct task_struct *);
262 extern void ignore_signals(struct task_struct *);
263 extern void flush_signal_handlers(struct task_struct *, int force_default);
264 extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);
266 static inline int kernel_dequeue_signal(siginfo_t *info)
268 struct task_struct *tsk = current;
272 spin_lock_irq(&tsk->sighand->siglock);
273 ret = dequeue_signal(tsk, &tsk->blocked, info ?: &__info);
274 spin_unlock_irq(&tsk->sighand->siglock);
279 static inline void kernel_signal_stop(void)
281 spin_lock_irq(¤t->sighand->siglock);
282 if (current->jobctl & JOBCTL_STOP_DEQUEUED)
283 set_special_state(TASK_STOPPED);
284 spin_unlock_irq(¤t->sighand->siglock);
288 extern int send_sig_info(int, struct siginfo *, struct task_struct *);
289 extern int force_sigsegv(int, struct task_struct *);
290 extern int force_sig_info(int, struct siginfo *, struct task_struct *);
291 extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
292 extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);
293 extern int kill_pid_info_as_cred(int, struct siginfo *, struct pid *,
294 const struct cred *, u32);
295 extern int kill_pgrp(struct pid *pid, int sig, int priv);
296 extern int kill_pid(struct pid *pid, int sig, int priv);
297 extern __must_check bool do_notify_parent(struct task_struct *, int);
298 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
299 extern void force_sig(int, struct task_struct *);
300 extern int send_sig(int, struct task_struct *, int);
301 extern int zap_other_threads(struct task_struct *p);
302 extern struct sigqueue *sigqueue_alloc(void);
303 extern void sigqueue_free(struct sigqueue *);
304 extern int send_sigqueue(struct sigqueue *, struct task_struct *, int group);
305 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
307 static inline int restart_syscall(void)
309 set_tsk_thread_flag(current, TIF_SIGPENDING);
310 return -ERESTARTNOINTR;
313 static inline int signal_pending(struct task_struct *p)
315 return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
318 static inline int __fatal_signal_pending(struct task_struct *p)
320 return unlikely(sigismember(&p->pending.signal, SIGKILL));
323 static inline int fatal_signal_pending(struct task_struct *p)
325 return signal_pending(p) && __fatal_signal_pending(p);
328 static inline int signal_pending_state(long state, struct task_struct *p)
330 if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
332 if (!signal_pending(p))
335 return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
339 * Reevaluate whether the task has signals pending delivery.
340 * Wake the task if so.
341 * This is required every time the blocked sigset_t changes.
342 * callers must hold sighand->siglock.
344 extern void recalc_sigpending_and_wake(struct task_struct *t);
345 extern void recalc_sigpending(void);
347 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
349 static inline void signal_wake_up(struct task_struct *t, bool resume)
351 signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
353 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
355 signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
358 #ifdef TIF_RESTORE_SIGMASK
360 * Legacy restore_sigmask accessors. These are inefficient on
361 * SMP architectures because they require atomic operations.
365 * set_restore_sigmask() - make sure saved_sigmask processing gets done
367 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
368 * will run before returning to user mode, to process the flag. For
369 * all callers, TIF_SIGPENDING is already set or it's no harm to set
370 * it. TIF_RESTORE_SIGMASK need not be in the set of bits that the
371 * arch code will notice on return to user mode, in case those bits
372 * are scarce. We set TIF_SIGPENDING here to ensure that the arch
373 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
375 static inline void set_restore_sigmask(void)
377 set_thread_flag(TIF_RESTORE_SIGMASK);
378 WARN_ON(!test_thread_flag(TIF_SIGPENDING));
381 static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
383 clear_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
386 static inline void clear_restore_sigmask(void)
388 clear_thread_flag(TIF_RESTORE_SIGMASK);
390 static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
392 return test_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
394 static inline bool test_restore_sigmask(void)
396 return test_thread_flag(TIF_RESTORE_SIGMASK);
398 static inline bool test_and_clear_restore_sigmask(void)
400 return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
403 #else /* TIF_RESTORE_SIGMASK */
405 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
406 static inline void set_restore_sigmask(void)
408 current->restore_sigmask = true;
409 WARN_ON(!test_thread_flag(TIF_SIGPENDING));
411 static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
413 tsk->restore_sigmask = false;
415 static inline void clear_restore_sigmask(void)
417 current->restore_sigmask = false;
419 static inline bool test_restore_sigmask(void)
421 return current->restore_sigmask;
423 static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
425 return tsk->restore_sigmask;
427 static inline bool test_and_clear_restore_sigmask(void)
429 if (!current->restore_sigmask)
431 current->restore_sigmask = false;
436 static inline void restore_saved_sigmask(void)
438 if (test_and_clear_restore_sigmask())
439 __set_current_blocked(¤t->saved_sigmask);
442 static inline sigset_t *sigmask_to_save(void)
444 sigset_t *res = ¤t->blocked;
445 if (unlikely(test_restore_sigmask()))
446 res = ¤t->saved_sigmask;
450 static inline int kill_cad_pid(int sig, int priv)
452 return kill_pid(cad_pid, sig, priv);
455 /* These can be the second arg to send_sig_info/send_group_sig_info. */
456 #define SEND_SIG_NOINFO ((struct siginfo *) 0)
457 #define SEND_SIG_PRIV ((struct siginfo *) 1)
458 #define SEND_SIG_FORCED ((struct siginfo *) 2)
461 * True if we are on the alternate signal stack.
463 static inline int on_sig_stack(unsigned long sp)
466 * If the signal stack is SS_AUTODISARM then, by construction, we
467 * can't be on the signal stack unless user code deliberately set
468 * SS_AUTODISARM when we were already on it.
470 * This improves reliability: if user state gets corrupted such that
471 * the stack pointer points very close to the end of the signal stack,
472 * then this check will enable the signal to be handled anyway.
474 if (current->sas_ss_flags & SS_AUTODISARM)
477 #ifdef CONFIG_STACK_GROWSUP
478 return sp >= current->sas_ss_sp &&
479 sp - current->sas_ss_sp < current->sas_ss_size;
481 return sp > current->sas_ss_sp &&
482 sp - current->sas_ss_sp <= current->sas_ss_size;
486 static inline int sas_ss_flags(unsigned long sp)
488 if (!current->sas_ss_size)
491 return on_sig_stack(sp) ? SS_ONSTACK : 0;
494 static inline void sas_ss_reset(struct task_struct *p)
498 p->sas_ss_flags = SS_DISABLE;
501 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
503 if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
504 #ifdef CONFIG_STACK_GROWSUP
505 return current->sas_ss_sp;
507 return current->sas_ss_sp + current->sas_ss_size;
512 extern void __cleanup_sighand(struct sighand_struct *);
513 extern void flush_itimer_signals(void);
515 #define tasklist_empty() \
516 list_empty(&init_task.tasks)
518 #define next_task(p) \
519 list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
521 #define for_each_process(p) \
522 for (p = &init_task ; (p = next_task(p)) != &init_task ; )
524 extern bool current_is_single_threaded(void);
527 * Careful: do_each_thread/while_each_thread is a double loop so
528 * 'break' will not work as expected - use goto instead.
530 #define do_each_thread(g, t) \
531 for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
533 #define while_each_thread(g, t) \
534 while ((t = next_thread(t)) != g)
536 #define __for_each_thread(signal, t) \
537 list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
539 #define for_each_thread(p, t) \
540 __for_each_thread((p)->signal, t)
542 /* Careful: this is a double loop, 'break' won't work as expected. */
543 #define for_each_process_thread(p, t) \
544 for_each_process(p) for_each_thread(p, t)
546 typedef int (*proc_visitor)(struct task_struct *p, void *data);
547 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
549 static inline int get_nr_threads(struct task_struct *tsk)
551 return tsk->signal->nr_threads;
554 static inline bool thread_group_leader(struct task_struct *p)
556 return p->exit_signal >= 0;
559 /* Do to the insanities of de_thread it is possible for a process
560 * to have the pid of the thread group leader without actually being
561 * the thread group leader. For iteration through the pids in proc
562 * all we care about is that we have a task with the appropriate
563 * pid, we don't actually care if we have the right task.
565 static inline bool has_group_leader_pid(struct task_struct *p)
567 return task_pid(p) == p->signal->leader_pid;
571 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
573 return p1->signal == p2->signal;
576 static inline struct task_struct *next_thread(const struct task_struct *p)
578 return list_entry_rcu(p->thread_group.next,
579 struct task_struct, thread_group);
582 static inline int thread_group_empty(struct task_struct *p)
584 return list_empty(&p->thread_group);
587 #define delay_group_leader(p) \
588 (thread_group_leader(p) && !thread_group_empty(p))
590 extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
591 unsigned long *flags);
593 static inline struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
594 unsigned long *flags)
596 struct sighand_struct *ret;
598 ret = __lock_task_sighand(tsk, flags);
599 (void)__cond_lock(&tsk->sighand->siglock, ret);
603 static inline void unlock_task_sighand(struct task_struct *tsk,
604 unsigned long *flags)
606 spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
609 static inline unsigned long task_rlimit(const struct task_struct *tsk,
612 return READ_ONCE(tsk->signal->rlim[limit].rlim_cur);
615 static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
618 return READ_ONCE(tsk->signal->rlim[limit].rlim_max);
621 static inline unsigned long rlimit(unsigned int limit)
623 return task_rlimit(current, limit);
626 static inline unsigned long rlimit_max(unsigned int limit)
628 return task_rlimit_max(current, limit);
631 #endif /* _LINUX_SCHED_SIGNAL_H */