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/posix-timers.h>
13 #include <linux/mm_types.h>
14 #include <asm/ptrace.h>
17 * Types defining task->signal and task->sighand and APIs using them:
20 struct sighand_struct {
23 wait_queue_head_t signalfd_wqh;
24 struct k_sigaction action[_NSIG];
28 * Per-process accounting stats:
34 u64 ac_utime, ac_stime;
35 unsigned long ac_minflt, ac_majflt;
44 * This is the atomic variant of task_cputime, which can be used for
45 * storing and updating task_cputime statistics without locking.
47 struct task_cputime_atomic {
50 atomic64_t sum_exec_runtime;
53 #define INIT_CPUTIME_ATOMIC \
54 (struct task_cputime_atomic) { \
55 .utime = ATOMIC64_INIT(0), \
56 .stime = ATOMIC64_INIT(0), \
57 .sum_exec_runtime = ATOMIC64_INIT(0), \
60 * struct thread_group_cputimer - thread group interval timer counts
61 * @cputime_atomic: atomic thread group interval 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;
70 struct multiprocess_signals {
72 struct hlist_node node;
76 * NOTE! "signal_struct" does not have its own
77 * locking, because a shared signal_struct always
78 * implies a shared sighand_struct, so locking
79 * sighand_struct is always a proper superset of
80 * the locking of signal_struct.
82 struct signal_struct {
86 struct list_head thread_head;
88 wait_queue_head_t wait_chldexit; /* for wait4() */
90 /* current thread group signal load-balancing target: */
91 struct task_struct *curr_target;
93 /* shared signal handling: */
94 struct sigpending shared_pending;
96 /* For collecting multiprocess signals during fork */
97 struct hlist_head multiprocess;
99 /* thread group exit support */
102 * - notify group_exit_task when ->count is equal to notify_count
103 * - everyone except group_exit_task is stopped during signal delivery
104 * of fatal signals, group_exit_task processes the signal.
107 struct task_struct *group_exit_task;
109 /* thread group stop support, overloads group_exit_code too */
110 int group_stop_count;
111 unsigned int flags; /* see SIGNAL_* flags below */
114 * PR_SET_CHILD_SUBREAPER marks a process, like a service
115 * manager, to re-parent orphan (double-forking) child processes
116 * to this process instead of 'init'. The service manager is
117 * able to receive SIGCHLD signals and is able to investigate
118 * the process until it calls wait(). All children of this
119 * process will inherit a flag if they should look for a
120 * child_subreaper process at exit.
122 unsigned int is_child_subreaper:1;
123 unsigned int has_child_subreaper:1;
125 #ifdef CONFIG_POSIX_TIMERS
127 /* POSIX.1b Interval Timers */
129 struct list_head posix_timers;
131 /* ITIMER_REAL timer for the process */
132 struct hrtimer real_timer;
133 ktime_t it_real_incr;
136 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
137 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
138 * values are defined to 0 and 1 respectively
140 struct cpu_itimer it[2];
143 * Thread group totals for process CPU timers.
144 * See thread_group_cputimer(), et al, for details.
146 struct thread_group_cputimer cputimer;
149 /* Empty if CONFIG_POSIX_TIMERS=n */
150 struct posix_cputimers posix_cputimers;
152 /* PID/PID hash table linkage. */
153 struct pid *pids[PIDTYPE_MAX];
155 #ifdef CONFIG_NO_HZ_FULL
156 atomic_t tick_dep_mask;
159 struct pid *tty_old_pgrp;
161 /* boolean value for session group leader */
164 struct tty_struct *tty; /* NULL if no tty */
166 #ifdef CONFIG_SCHED_AUTOGROUP
167 struct autogroup *autogroup;
170 * Cumulative resource counters for dead threads in the group,
171 * and for reaped dead child processes forked by this group.
172 * Live threads maintain their own counters and add to these
173 * in __exit_signal, except for the group leader.
175 seqlock_t stats_lock;
176 u64 utime, stime, cutime, cstime;
179 struct prev_cputime prev_cputime;
180 unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
181 unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
182 unsigned long inblock, oublock, cinblock, coublock;
183 unsigned long maxrss, cmaxrss;
184 struct task_io_accounting ioac;
187 * Cumulative ns of schedule CPU time fo dead threads in the
188 * group, not including a zombie group leader, (This only differs
189 * from jiffies_to_ns(utime + stime) if sched_clock uses something
190 * other than jiffies.)
192 unsigned long long sum_sched_runtime;
195 * We don't bother to synchronize most readers of this at all,
196 * because there is no reader checking a limit that actually needs
197 * to get both rlim_cur and rlim_max atomically, and either one
198 * alone is a single word that can safely be read normally.
199 * getrlimit/setrlimit use task_lock(current->group_leader) to
200 * protect this instead of the siglock, because they really
201 * have no need to disable irqs.
203 struct rlimit rlim[RLIM_NLIMITS];
205 #ifdef CONFIG_BSD_PROCESS_ACCT
206 struct pacct_struct pacct; /* per-process accounting information */
208 #ifdef CONFIG_TASKSTATS
209 struct taskstats *stats;
213 struct tty_audit_buf *tty_audit_buf;
217 * Thread is the potential origin of an oom condition; kill first on
220 bool oom_flag_origin;
221 short oom_score_adj; /* OOM kill score adjustment */
222 short oom_score_adj_min; /* OOM kill score adjustment min value.
223 * Only settable by CAP_SYS_RESOURCE. */
224 struct mm_struct *oom_mm; /* recorded mm when the thread group got
225 * killed by the oom killer */
227 struct mutex cred_guard_mutex; /* guard against foreign influences on
228 * credential calculations
230 * Deprecated do not use in new code.
231 * Use exec_update_lock instead.
233 struct rw_semaphore exec_update_lock; /* Held while task_struct is
234 * being updated during exec,
235 * and may have inconsistent
238 } __randomize_layout;
241 * Bits in flags field of signal_struct.
243 #define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
244 #define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
245 #define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
246 #define SIGNAL_GROUP_COREDUMP 0x00000008 /* coredump in progress */
248 * Pending notifications to parent.
250 #define SIGNAL_CLD_STOPPED 0x00000010
251 #define SIGNAL_CLD_CONTINUED 0x00000020
252 #define SIGNAL_CLD_MASK (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
254 #define SIGNAL_UNKILLABLE 0x00000040 /* for init: ignore fatal signals */
256 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
257 SIGNAL_STOP_CONTINUED)
259 static inline void signal_set_stop_flags(struct signal_struct *sig,
262 WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
263 sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
266 /* If true, all threads except ->group_exit_task have pending SIGKILL */
267 static inline int signal_group_exit(const struct signal_struct *sig)
269 return (sig->flags & SIGNAL_GROUP_EXIT) ||
270 (sig->group_exit_task != NULL);
273 extern void flush_signals(struct task_struct *);
274 extern void ignore_signals(struct task_struct *);
275 extern void flush_signal_handlers(struct task_struct *, int force_default);
276 extern int dequeue_signal(struct task_struct *task,
277 sigset_t *mask, kernel_siginfo_t *info);
279 static inline int kernel_dequeue_signal(void)
281 struct task_struct *task = current;
282 kernel_siginfo_t __info;
285 spin_lock_irq(&task->sighand->siglock);
286 ret = dequeue_signal(task, &task->blocked, &__info);
287 spin_unlock_irq(&task->sighand->siglock);
292 static inline void kernel_signal_stop(void)
294 spin_lock_irq(¤t->sighand->siglock);
295 if (current->jobctl & JOBCTL_STOP_DEQUEUED)
296 set_special_state(TASK_STOPPED);
297 spin_unlock_irq(¤t->sighand->siglock);
302 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
304 # define ___ARCH_SI_IA64(_a1, _a2, _a3)
307 int force_sig_fault_to_task(int sig, int code, void __user *addr
308 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
309 , struct task_struct *t);
310 int force_sig_fault(int sig, int code, void __user *addr
311 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
312 int send_sig_fault(int sig, int code, void __user *addr
313 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
314 , struct task_struct *t);
316 int force_sig_mceerr(int code, void __user *, short);
317 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
319 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
320 int force_sig_pkuerr(void __user *addr, u32 pkey);
321 int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
323 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
324 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
325 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
326 struct task_struct *t);
328 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
329 extern void force_sigsegv(int sig);
330 extern int force_sig_info(struct kernel_siginfo *);
331 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
332 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
333 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
334 const struct cred *);
335 extern int kill_pgrp(struct pid *pid, int sig, int priv);
336 extern int kill_pid(struct pid *pid, int sig, int priv);
337 extern __must_check bool do_notify_parent(struct task_struct *, int);
338 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
339 extern void force_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 int restart_syscall(void)
349 set_tsk_thread_flag(current, TIF_SIGPENDING);
350 return -ERESTARTNOINTR;
353 static inline int task_sigpending(struct task_struct *p)
355 return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
358 static inline int signal_pending(struct task_struct *p)
361 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
362 * behavior in terms of ensuring that we break out of wait loops
363 * so that notify signal callbacks can be processed.
365 if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
367 return task_sigpending(p);
370 static inline int __fatal_signal_pending(struct task_struct *p)
372 return unlikely(sigismember(&p->pending.signal, SIGKILL));
375 static inline int fatal_signal_pending(struct task_struct *p)
377 return task_sigpending(p) && __fatal_signal_pending(p);
380 static inline int signal_pending_state(unsigned int state, struct task_struct *p)
382 if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
384 if (!signal_pending(p))
387 return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
391 * This should only be used in fault handlers to decide whether we
392 * should stop the current fault routine to handle the signals
393 * instead, especially with the case where we've got interrupted with
396 static inline bool fault_signal_pending(vm_fault_t fault_flags,
397 struct pt_regs *regs)
399 return unlikely((fault_flags & VM_FAULT_RETRY) &&
400 (fatal_signal_pending(current) ||
401 (user_mode(regs) && signal_pending(current))));
405 * Reevaluate whether the task has signals pending delivery.
406 * Wake the task if so.
407 * This is required every time the blocked sigset_t changes.
408 * callers must hold sighand->siglock.
410 extern void recalc_sigpending_and_wake(struct task_struct *t);
411 extern void recalc_sigpending(void);
412 extern void calculate_sigpending(void);
414 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
416 static inline void signal_wake_up(struct task_struct *t, bool resume)
418 signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
420 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
422 signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
425 void task_join_group_stop(struct task_struct *task);
427 #ifdef TIF_RESTORE_SIGMASK
429 * Legacy restore_sigmask accessors. These are inefficient on
430 * SMP architectures because they require atomic operations.
434 * set_restore_sigmask() - make sure saved_sigmask processing gets done
436 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
437 * will run before returning to user mode, to process the flag. For
438 * all callers, TIF_SIGPENDING is already set or it's no harm to set
439 * it. TIF_RESTORE_SIGMASK need not be in the set of bits that the
440 * arch code will notice on return to user mode, in case those bits
441 * are scarce. We set TIF_SIGPENDING here to ensure that the arch
442 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
444 static inline void set_restore_sigmask(void)
446 set_thread_flag(TIF_RESTORE_SIGMASK);
449 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
451 clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
454 static inline void clear_restore_sigmask(void)
456 clear_thread_flag(TIF_RESTORE_SIGMASK);
458 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
460 return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
462 static inline bool test_restore_sigmask(void)
464 return test_thread_flag(TIF_RESTORE_SIGMASK);
466 static inline bool test_and_clear_restore_sigmask(void)
468 return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
471 #else /* TIF_RESTORE_SIGMASK */
473 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
474 static inline void set_restore_sigmask(void)
476 current->restore_sigmask = true;
478 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
480 task->restore_sigmask = false;
482 static inline void clear_restore_sigmask(void)
484 current->restore_sigmask = false;
486 static inline bool test_restore_sigmask(void)
488 return current->restore_sigmask;
490 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
492 return task->restore_sigmask;
494 static inline bool test_and_clear_restore_sigmask(void)
496 if (!current->restore_sigmask)
498 current->restore_sigmask = false;
503 static inline void restore_saved_sigmask(void)
505 if (test_and_clear_restore_sigmask())
506 __set_current_blocked(¤t->saved_sigmask);
509 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
511 static inline void restore_saved_sigmask_unless(bool interrupted)
514 WARN_ON(!signal_pending(current));
516 restore_saved_sigmask();
519 static inline sigset_t *sigmask_to_save(void)
521 sigset_t *res = ¤t->blocked;
522 if (unlikely(test_restore_sigmask()))
523 res = ¤t->saved_sigmask;
527 static inline int kill_cad_pid(int sig, int priv)
529 return kill_pid(cad_pid, sig, priv);
532 /* These can be the second arg to send_sig_info/send_group_sig_info. */
533 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
534 #define SEND_SIG_PRIV ((struct kernel_siginfo *) 1)
536 static inline int __on_sig_stack(unsigned long sp)
538 #ifdef CONFIG_STACK_GROWSUP
539 return sp >= current->sas_ss_sp &&
540 sp - current->sas_ss_sp < current->sas_ss_size;
542 return sp > current->sas_ss_sp &&
543 sp - current->sas_ss_sp <= current->sas_ss_size;
548 * True if we are on the alternate signal stack.
550 static inline int on_sig_stack(unsigned long sp)
553 * If the signal stack is SS_AUTODISARM then, by construction, we
554 * can't be on the signal stack unless user code deliberately set
555 * SS_AUTODISARM when we were already on it.
557 * This improves reliability: if user state gets corrupted such that
558 * the stack pointer points very close to the end of the signal stack,
559 * then this check will enable the signal to be handled anyway.
561 if (current->sas_ss_flags & SS_AUTODISARM)
564 return __on_sig_stack(sp);
567 static inline int sas_ss_flags(unsigned long sp)
569 if (!current->sas_ss_size)
572 return on_sig_stack(sp) ? SS_ONSTACK : 0;
575 static inline void sas_ss_reset(struct task_struct *p)
579 p->sas_ss_flags = SS_DISABLE;
582 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
584 if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
585 #ifdef CONFIG_STACK_GROWSUP
586 return current->sas_ss_sp;
588 return current->sas_ss_sp + current->sas_ss_size;
593 extern void __cleanup_sighand(struct sighand_struct *);
594 extern void flush_itimer_signals(void);
596 #define tasklist_empty() \
597 list_empty(&init_task.tasks)
599 #define next_task(p) \
600 list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
602 #define for_each_process(p) \
603 for (p = &init_task ; (p = next_task(p)) != &init_task ; )
605 extern bool current_is_single_threaded(void);
608 * Careful: do_each_thread/while_each_thread is a double loop so
609 * 'break' will not work as expected - use goto instead.
611 #define do_each_thread(g, t) \
612 for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
614 #define while_each_thread(g, t) \
615 while ((t = next_thread(t)) != g)
617 #define __for_each_thread(signal, t) \
618 list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
620 #define for_each_thread(p, t) \
621 __for_each_thread((p)->signal, t)
623 /* Careful: this is a double loop, 'break' won't work as expected. */
624 #define for_each_process_thread(p, t) \
625 for_each_process(p) for_each_thread(p, t)
627 typedef int (*proc_visitor)(struct task_struct *p, void *data);
628 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
631 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
634 if (type == PIDTYPE_PID)
635 pid = task_pid(task);
637 pid = task->signal->pids[type];
641 static inline struct pid *task_tgid(struct task_struct *task)
643 return task->signal->pids[PIDTYPE_TGID];
647 * Without tasklist or RCU lock it is not safe to dereference
648 * the result of task_pgrp/task_session even if task == current,
649 * we can race with another thread doing sys_setsid/sys_setpgid.
651 static inline struct pid *task_pgrp(struct task_struct *task)
653 return task->signal->pids[PIDTYPE_PGID];
656 static inline struct pid *task_session(struct task_struct *task)
658 return task->signal->pids[PIDTYPE_SID];
661 static inline int get_nr_threads(struct task_struct *task)
663 return task->signal->nr_threads;
666 static inline bool thread_group_leader(struct task_struct *p)
668 return p->exit_signal >= 0;
672 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
674 return p1->signal == p2->signal;
677 static inline struct task_struct *next_thread(const struct task_struct *p)
679 return list_entry_rcu(p->thread_group.next,
680 struct task_struct, thread_group);
683 static inline int thread_group_empty(struct task_struct *p)
685 return list_empty(&p->thread_group);
688 #define delay_group_leader(p) \
689 (thread_group_leader(p) && !thread_group_empty(p))
691 extern bool thread_group_exited(struct pid *pid);
693 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
694 unsigned long *flags);
696 static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
697 unsigned long *flags)
699 struct sighand_struct *ret;
701 ret = __lock_task_sighand(task, flags);
702 (void)__cond_lock(&task->sighand->siglock, ret);
706 static inline void unlock_task_sighand(struct task_struct *task,
707 unsigned long *flags)
709 spin_unlock_irqrestore(&task->sighand->siglock, *flags);
712 #ifdef CONFIG_LOCKDEP
713 extern void lockdep_assert_task_sighand_held(struct task_struct *task);
715 static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
718 static inline unsigned long task_rlimit(const struct task_struct *task,
721 return READ_ONCE(task->signal->rlim[limit].rlim_cur);
724 static inline unsigned long task_rlimit_max(const struct task_struct *task,
727 return READ_ONCE(task->signal->rlim[limit].rlim_max);
730 static inline unsigned long rlimit(unsigned int limit)
732 return task_rlimit(current, limit);
735 static inline unsigned long rlimit_max(unsigned int limit)
737 return task_rlimit_max(current, limit);
740 #endif /* _LINUX_SCHED_SIGNAL_H */