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>
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>
18 * Types defining task->signal and task->sighand and APIs using them:
21 struct sighand_struct {
24 wait_queue_head_t signalfd_wqh;
25 struct k_sigaction action[_NSIG];
29 * Per-process accounting stats:
35 u64 ac_utime, ac_stime;
36 unsigned long ac_minflt, ac_majflt;
45 * This is the atomic variant of task_cputime, which can be used for
46 * storing and updating task_cputime statistics without locking.
48 struct task_cputime_atomic {
51 atomic64_t sum_exec_runtime;
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), \
61 * struct thread_group_cputimer - thread group interval timer counts
62 * @cputime_atomic: atomic thread group interval timers.
64 * This structure contains the version of task_cputime, above, that is
65 * used for thread group CPU timer calculations.
67 struct thread_group_cputimer {
68 struct task_cputime_atomic cputime_atomic;
71 struct multiprocess_signals {
73 struct hlist_node node;
77 struct task_struct *task;
78 struct core_thread *next;
83 struct core_thread dumper;
84 struct completion startup;
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.
94 struct signal_struct {
99 struct list_head thread_head;
101 wait_queue_head_t wait_chldexit; /* for wait4() */
103 /* current thread group signal load-balancing target: */
104 struct task_struct *curr_target;
106 /* shared signal handling: */
107 struct sigpending shared_pending;
109 /* For collecting multiprocess signals during fork */
110 struct hlist_head multiprocess;
112 /* thread group exit support */
114 /* notify group_exec_task when notify_count is less or equal to 0 */
116 struct task_struct *group_exec_task;
118 /* thread group stop support, overloads group_exit_code too */
119 int group_stop_count;
120 unsigned int flags; /* see SIGNAL_* flags below */
122 struct core_state *core_state; /* coredumping support */
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.
133 unsigned int is_child_subreaper:1;
134 unsigned int has_child_subreaper:1;
136 #ifdef CONFIG_POSIX_TIMERS
138 /* POSIX.1b Interval Timers */
139 unsigned int next_posix_timer_id;
140 struct list_head posix_timers;
142 /* ITIMER_REAL timer for the process */
143 struct hrtimer real_timer;
144 ktime_t it_real_incr;
147 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
148 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
149 * values are defined to 0 and 1 respectively
151 struct cpu_itimer it[2];
154 * Thread group totals for process CPU timers.
155 * See thread_group_cputimer(), et al, for details.
157 struct thread_group_cputimer cputimer;
160 /* Empty if CONFIG_POSIX_TIMERS=n */
161 struct posix_cputimers posix_cputimers;
163 /* PID/PID hash table linkage. */
164 struct pid *pids[PIDTYPE_MAX];
166 #ifdef CONFIG_NO_HZ_FULL
167 atomic_t tick_dep_mask;
170 struct pid *tty_old_pgrp;
172 /* boolean value for session group leader */
175 struct tty_struct *tty; /* NULL if no tty */
177 #ifdef CONFIG_SCHED_AUTOGROUP
178 struct autogroup *autogroup;
181 * Cumulative resource counters for dead threads in the group,
182 * and for reaped dead child processes forked by this group.
183 * Live threads maintain their own counters and add to these
184 * in __exit_signal, except for the group leader.
186 seqlock_t stats_lock;
187 u64 utime, stime, cutime, cstime;
190 struct prev_cputime prev_cputime;
191 unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
192 unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
193 unsigned long inblock, oublock, cinblock, coublock;
194 unsigned long maxrss, cmaxrss;
195 struct task_io_accounting ioac;
198 * Cumulative ns of schedule CPU time fo dead threads in the
199 * group, not including a zombie group leader, (This only differs
200 * from jiffies_to_ns(utime + stime) if sched_clock uses something
201 * other than jiffies.)
203 unsigned long long sum_sched_runtime;
206 * We don't bother to synchronize most readers of this at all,
207 * because there is no reader checking a limit that actually needs
208 * to get both rlim_cur and rlim_max atomically, and either one
209 * alone is a single word that can safely be read normally.
210 * getrlimit/setrlimit use task_lock(current->group_leader) to
211 * protect this instead of the siglock, because they really
212 * have no need to disable irqs.
214 struct rlimit rlim[RLIM_NLIMITS];
216 #ifdef CONFIG_BSD_PROCESS_ACCT
217 struct pacct_struct pacct; /* per-process accounting information */
219 #ifdef CONFIG_TASKSTATS
220 struct taskstats *stats;
224 struct tty_audit_buf *tty_audit_buf;
228 * Thread is the potential origin of an oom condition; kill first on
231 bool oom_flag_origin;
232 short oom_score_adj; /* OOM kill score adjustment */
233 short oom_score_adj_min; /* OOM kill score adjustment min value.
234 * Only settable by CAP_SYS_RESOURCE. */
235 struct mm_struct *oom_mm; /* recorded mm when the thread group got
236 * killed by the oom killer */
238 struct mutex cred_guard_mutex; /* guard against foreign influences on
239 * credential calculations
241 * Deprecated do not use in new code.
242 * Use exec_update_lock instead.
244 struct rw_semaphore exec_update_lock; /* Held while task_struct is
245 * being updated during exec,
246 * and may have inconsistent
249 } __randomize_layout;
252 * Bits in flags field of signal_struct.
254 #define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
255 #define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
256 #define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
258 * Pending notifications to parent.
260 #define SIGNAL_CLD_STOPPED 0x00000010
261 #define SIGNAL_CLD_CONTINUED 0x00000020
262 #define SIGNAL_CLD_MASK (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
264 #define SIGNAL_UNKILLABLE 0x00000040 /* for init: ignore fatal signals */
266 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
267 SIGNAL_STOP_CONTINUED)
269 static inline void signal_set_stop_flags(struct signal_struct *sig,
272 WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
273 sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
276 extern void flush_signals(struct task_struct *);
277 extern void ignore_signals(struct task_struct *);
278 extern void flush_signal_handlers(struct task_struct *, int force_default);
279 extern int dequeue_signal(struct task_struct *task, sigset_t *mask,
280 kernel_siginfo_t *info, enum pid_type *type);
282 static inline int kernel_dequeue_signal(void)
284 struct task_struct *task = current;
285 kernel_siginfo_t __info;
286 enum pid_type __type;
289 spin_lock_irq(&task->sighand->siglock);
290 ret = dequeue_signal(task, &task->blocked, &__info, &__type);
291 spin_unlock_irq(&task->sighand->siglock);
296 static inline void kernel_signal_stop(void)
298 spin_lock_irq(¤t->sighand->siglock);
299 if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
300 current->jobctl |= JOBCTL_STOPPED;
301 set_special_state(TASK_STOPPED);
303 spin_unlock_irq(¤t->sighand->siglock);
308 int force_sig_fault_to_task(int sig, int code, void __user *addr,
309 struct task_struct *t);
310 int force_sig_fault(int sig, int code, void __user *addr);
311 int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t);
313 int force_sig_mceerr(int code, void __user *, short);
314 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
316 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
317 int force_sig_pkuerr(void __user *addr, u32 pkey);
318 int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
320 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
321 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
322 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
323 struct task_struct *t);
324 int force_sig_seccomp(int syscall, int reason, bool force_coredump);
326 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
327 extern void force_sigsegv(int sig);
328 extern int force_sig_info(struct kernel_siginfo *);
329 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
330 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
331 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
332 const struct cred *);
333 extern int kill_pgrp(struct pid *pid, int sig, int priv);
334 extern int kill_pid(struct pid *pid, int sig, int priv);
335 extern __must_check bool do_notify_parent(struct task_struct *, int);
336 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
337 extern void force_sig(int);
338 extern void force_fatal_sig(int);
339 extern void force_exit_sig(int);
340 extern int send_sig(int, struct task_struct *, int);
341 extern int zap_other_threads(struct task_struct *p);
342 extern struct sigqueue *sigqueue_alloc(void);
343 extern void sigqueue_free(struct sigqueue *);
344 extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
345 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
347 static inline void clear_notify_signal(void)
349 clear_thread_flag(TIF_NOTIFY_SIGNAL);
350 smp_mb__after_atomic();
354 * Returns 'true' if kick_process() is needed to force a transition from
355 * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
357 static inline bool __set_notify_signal(struct task_struct *task)
359 return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
360 !wake_up_state(task, TASK_INTERRUPTIBLE);
364 * Called to break out of interruptible wait loops, and enter the
365 * exit_to_user_mode_loop().
367 static inline void set_notify_signal(struct task_struct *task)
369 if (__set_notify_signal(task))
373 static inline int restart_syscall(void)
375 set_tsk_thread_flag(current, TIF_SIGPENDING);
376 return -ERESTARTNOINTR;
379 static inline int task_sigpending(struct task_struct *p)
381 return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
384 static inline int signal_pending(struct task_struct *p)
387 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
388 * behavior in terms of ensuring that we break out of wait loops
389 * so that notify signal callbacks can be processed.
391 if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
393 return task_sigpending(p);
396 static inline int __fatal_signal_pending(struct task_struct *p)
398 return unlikely(sigismember(&p->pending.signal, SIGKILL));
401 static inline int fatal_signal_pending(struct task_struct *p)
403 return task_sigpending(p) && __fatal_signal_pending(p);
406 static inline int signal_pending_state(unsigned int state, struct task_struct *p)
408 if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
410 if (!signal_pending(p))
413 return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
417 * This should only be used in fault handlers to decide whether we
418 * should stop the current fault routine to handle the signals
419 * instead, especially with the case where we've got interrupted with
422 static inline bool fault_signal_pending(vm_fault_t fault_flags,
423 struct pt_regs *regs)
425 return unlikely((fault_flags & VM_FAULT_RETRY) &&
426 (fatal_signal_pending(current) ||
427 (user_mode(regs) && signal_pending(current))));
431 * Reevaluate whether the task has signals pending delivery.
432 * Wake the task if so.
433 * This is required every time the blocked sigset_t changes.
434 * callers must hold sighand->siglock.
436 extern void recalc_sigpending(void);
437 extern void calculate_sigpending(void);
439 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
441 static inline void signal_wake_up(struct task_struct *t, bool fatal)
443 unsigned int state = 0;
444 if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
445 t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
446 state = TASK_WAKEKILL | __TASK_TRACED;
448 signal_wake_up_state(t, state);
450 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
452 unsigned int state = 0;
454 t->jobctl &= ~JOBCTL_TRACED;
455 state = __TASK_TRACED;
457 signal_wake_up_state(t, state);
460 void task_join_group_stop(struct task_struct *task);
462 #ifdef TIF_RESTORE_SIGMASK
464 * Legacy restore_sigmask accessors. These are inefficient on
465 * SMP architectures because they require atomic operations.
469 * set_restore_sigmask() - make sure saved_sigmask processing gets done
471 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
472 * will run before returning to user mode, to process the flag. For
473 * all callers, TIF_SIGPENDING is already set or it's no harm to set
474 * it. TIF_RESTORE_SIGMASK need not be in the set of bits that the
475 * arch code will notice on return to user mode, in case those bits
476 * are scarce. We set TIF_SIGPENDING here to ensure that the arch
477 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
479 static inline void set_restore_sigmask(void)
481 set_thread_flag(TIF_RESTORE_SIGMASK);
484 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
486 clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
489 static inline void clear_restore_sigmask(void)
491 clear_thread_flag(TIF_RESTORE_SIGMASK);
493 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
495 return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
497 static inline bool test_restore_sigmask(void)
499 return test_thread_flag(TIF_RESTORE_SIGMASK);
501 static inline bool test_and_clear_restore_sigmask(void)
503 return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
506 #else /* TIF_RESTORE_SIGMASK */
508 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
509 static inline void set_restore_sigmask(void)
511 current->restore_sigmask = true;
513 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
515 task->restore_sigmask = false;
517 static inline void clear_restore_sigmask(void)
519 current->restore_sigmask = false;
521 static inline bool test_restore_sigmask(void)
523 return current->restore_sigmask;
525 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
527 return task->restore_sigmask;
529 static inline bool test_and_clear_restore_sigmask(void)
531 if (!current->restore_sigmask)
533 current->restore_sigmask = false;
538 static inline void restore_saved_sigmask(void)
540 if (test_and_clear_restore_sigmask())
541 __set_current_blocked(¤t->saved_sigmask);
544 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
546 static inline void restore_saved_sigmask_unless(bool interrupted)
549 WARN_ON(!signal_pending(current));
551 restore_saved_sigmask();
554 static inline sigset_t *sigmask_to_save(void)
556 sigset_t *res = ¤t->blocked;
557 if (unlikely(test_restore_sigmask()))
558 res = ¤t->saved_sigmask;
562 static inline int kill_cad_pid(int sig, int priv)
564 return kill_pid(cad_pid, sig, priv);
567 /* These can be the second arg to send_sig_info/send_group_sig_info. */
568 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
569 #define SEND_SIG_PRIV ((struct kernel_siginfo *) 1)
571 static inline int __on_sig_stack(unsigned long sp)
573 #ifdef CONFIG_STACK_GROWSUP
574 return sp >= current->sas_ss_sp &&
575 sp - current->sas_ss_sp < current->sas_ss_size;
577 return sp > current->sas_ss_sp &&
578 sp - current->sas_ss_sp <= current->sas_ss_size;
583 * True if we are on the alternate signal stack.
585 static inline int on_sig_stack(unsigned long sp)
588 * If the signal stack is SS_AUTODISARM then, by construction, we
589 * can't be on the signal stack unless user code deliberately set
590 * SS_AUTODISARM when we were already on it.
592 * This improves reliability: if user state gets corrupted such that
593 * the stack pointer points very close to the end of the signal stack,
594 * then this check will enable the signal to be handled anyway.
596 if (current->sas_ss_flags & SS_AUTODISARM)
599 return __on_sig_stack(sp);
602 static inline int sas_ss_flags(unsigned long sp)
604 if (!current->sas_ss_size)
607 return on_sig_stack(sp) ? SS_ONSTACK : 0;
610 static inline void sas_ss_reset(struct task_struct *p)
614 p->sas_ss_flags = SS_DISABLE;
617 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
619 if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
620 #ifdef CONFIG_STACK_GROWSUP
621 return current->sas_ss_sp;
623 return current->sas_ss_sp + current->sas_ss_size;
628 extern void __cleanup_sighand(struct sighand_struct *);
629 extern void flush_itimer_signals(void);
631 #define tasklist_empty() \
632 list_empty(&init_task.tasks)
634 #define next_task(p) \
635 list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
637 #define for_each_process(p) \
638 for (p = &init_task ; (p = next_task(p)) != &init_task ; )
640 extern bool current_is_single_threaded(void);
643 * Without tasklist/siglock it is only rcu-safe if g can't exit/exec,
644 * otherwise next_thread(t) will never reach g after list_del_rcu(g).
646 #define while_each_thread(g, t) \
647 while ((t = next_thread(t)) != g)
649 #define for_other_threads(p, t) \
650 for (t = p; (t = next_thread(t)) != p; )
652 #define __for_each_thread(signal, t) \
653 list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node, \
654 lockdep_is_held(&tasklist_lock))
656 #define for_each_thread(p, t) \
657 __for_each_thread((p)->signal, t)
659 /* Careful: this is a double loop, 'break' won't work as expected. */
660 #define for_each_process_thread(p, t) \
661 for_each_process(p) for_each_thread(p, t)
663 typedef int (*proc_visitor)(struct task_struct *p, void *data);
664 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
667 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
670 if (type == PIDTYPE_PID)
671 pid = task_pid(task);
673 pid = task->signal->pids[type];
677 static inline struct pid *task_tgid(struct task_struct *task)
679 return task->signal->pids[PIDTYPE_TGID];
683 * Without tasklist or RCU lock it is not safe to dereference
684 * the result of task_pgrp/task_session even if task == current,
685 * we can race with another thread doing sys_setsid/sys_setpgid.
687 static inline struct pid *task_pgrp(struct task_struct *task)
689 return task->signal->pids[PIDTYPE_PGID];
692 static inline struct pid *task_session(struct task_struct *task)
694 return task->signal->pids[PIDTYPE_SID];
697 static inline int get_nr_threads(struct task_struct *task)
699 return task->signal->nr_threads;
702 static inline bool thread_group_leader(struct task_struct *p)
704 return p->exit_signal >= 0;
708 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
710 return p1->signal == p2->signal;
714 * returns NULL if p is the last thread in the thread group
716 static inline struct task_struct *__next_thread(struct task_struct *p)
718 return list_next_or_null_rcu(&p->signal->thread_head,
724 static inline struct task_struct *next_thread(struct task_struct *p)
726 return __next_thread(p) ?: p->group_leader;
729 static inline int thread_group_empty(struct task_struct *p)
731 return thread_group_leader(p) &&
732 list_is_last(&p->thread_node, &p->signal->thread_head);
735 #define delay_group_leader(p) \
736 (thread_group_leader(p) && !thread_group_empty(p))
738 extern bool thread_group_exited(struct pid *pid);
740 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
741 unsigned long *flags);
743 static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
744 unsigned long *flags)
746 struct sighand_struct *ret;
748 ret = __lock_task_sighand(task, flags);
749 (void)__cond_lock(&task->sighand->siglock, ret);
753 static inline void unlock_task_sighand(struct task_struct *task,
754 unsigned long *flags)
756 spin_unlock_irqrestore(&task->sighand->siglock, *flags);
759 #ifdef CONFIG_LOCKDEP
760 extern void lockdep_assert_task_sighand_held(struct task_struct *task);
762 static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
765 static inline unsigned long task_rlimit(const struct task_struct *task,
768 return READ_ONCE(task->signal->rlim[limit].rlim_cur);
771 static inline unsigned long task_rlimit_max(const struct task_struct *task,
774 return READ_ONCE(task->signal->rlim[limit].rlim_max);
777 static inline unsigned long rlimit(unsigned int limit)
779 return task_rlimit(current, limit);
782 static inline unsigned long rlimit_max(unsigned int limit)
784 return task_rlimit_max(current, limit);
787 #endif /* _LINUX_SCHED_SIGNAL_H */