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>
15 * Types defining task->signal and task->sighand and APIs using them:
18 struct sighand_struct {
21 wait_queue_head_t signalfd_wqh;
22 struct k_sigaction action[_NSIG];
26 * Per-process accounting stats:
32 u64 ac_utime, ac_stime;
33 unsigned long ac_minflt, ac_majflt;
42 * This is the atomic variant of task_cputime, which can be used for
43 * storing and updating task_cputime statistics without locking.
45 struct task_cputime_atomic {
48 atomic64_t sum_exec_runtime;
51 #define INIT_CPUTIME_ATOMIC \
52 (struct task_cputime_atomic) { \
53 .utime = ATOMIC64_INIT(0), \
54 .stime = ATOMIC64_INIT(0), \
55 .sum_exec_runtime = ATOMIC64_INIT(0), \
58 * struct thread_group_cputimer - thread group interval timer counts
59 * @cputime_atomic: atomic thread group interval timers.
61 * This structure contains the version of task_cputime, above, that is
62 * used for thread group CPU timer calculations.
64 struct thread_group_cputimer {
65 struct task_cputime_atomic cputime_atomic;
68 struct multiprocess_signals {
70 struct hlist_node node;
74 * NOTE! "signal_struct" does not have its own
75 * locking, because a shared signal_struct always
76 * implies a shared sighand_struct, so locking
77 * sighand_struct is always a proper superset of
78 * the locking of signal_struct.
80 struct signal_struct {
84 struct list_head thread_head;
86 wait_queue_head_t wait_chldexit; /* for wait4() */
88 /* current thread group signal load-balancing target: */
89 struct task_struct *curr_target;
91 /* shared signal handling: */
92 struct sigpending shared_pending;
94 /* For collecting multiprocess signals during fork */
95 struct hlist_head multiprocess;
97 /* thread group exit support */
100 * - notify group_exit_task when ->count is equal to notify_count
101 * - everyone except group_exit_task is stopped during signal delivery
102 * of fatal signals, group_exit_task processes the signal.
105 struct task_struct *group_exit_task;
107 /* thread group stop support, overloads group_exit_code too */
108 int group_stop_count;
109 unsigned int flags; /* see SIGNAL_* flags below */
112 * PR_SET_CHILD_SUBREAPER marks a process, like a service
113 * manager, to re-parent orphan (double-forking) child processes
114 * to this process instead of 'init'. The service manager is
115 * able to receive SIGCHLD signals and is able to investigate
116 * the process until it calls wait(). All children of this
117 * process will inherit a flag if they should look for a
118 * child_subreaper process at exit.
120 unsigned int is_child_subreaper:1;
121 unsigned int has_child_subreaper:1;
123 #ifdef CONFIG_POSIX_TIMERS
125 /* POSIX.1b Interval Timers */
127 struct list_head posix_timers;
129 /* ITIMER_REAL timer for the process */
130 struct hrtimer real_timer;
131 ktime_t it_real_incr;
134 * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
135 * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
136 * values are defined to 0 and 1 respectively
138 struct cpu_itimer it[2];
141 * Thread group totals for process CPU timers.
142 * See thread_group_cputimer(), et al, for details.
144 struct thread_group_cputimer cputimer;
147 /* Empty if CONFIG_POSIX_TIMERS=n */
148 struct posix_cputimers posix_cputimers;
150 /* PID/PID hash table linkage. */
151 struct pid *pids[PIDTYPE_MAX];
153 #ifdef CONFIG_NO_HZ_FULL
154 atomic_t tick_dep_mask;
157 struct pid *tty_old_pgrp;
159 /* boolean value for session group leader */
162 struct tty_struct *tty; /* NULL if no tty */
164 #ifdef CONFIG_SCHED_AUTOGROUP
165 struct autogroup *autogroup;
168 * Cumulative resource counters for dead threads in the group,
169 * and for reaped dead child processes forked by this group.
170 * Live threads maintain their own counters and add to these
171 * in __exit_signal, except for the group leader.
173 seqlock_t stats_lock;
174 u64 utime, stime, cutime, cstime;
177 struct prev_cputime prev_cputime;
178 unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
179 unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
180 unsigned long inblock, oublock, cinblock, coublock;
181 unsigned long maxrss, cmaxrss;
182 struct task_io_accounting ioac;
185 * Cumulative ns of schedule CPU time fo dead threads in the
186 * group, not including a zombie group leader, (This only differs
187 * from jiffies_to_ns(utime + stime) if sched_clock uses something
188 * other than jiffies.)
190 unsigned long long sum_sched_runtime;
193 * We don't bother to synchronize most readers of this at all,
194 * because there is no reader checking a limit that actually needs
195 * to get both rlim_cur and rlim_max atomically, and either one
196 * alone is a single word that can safely be read normally.
197 * getrlimit/setrlimit use task_lock(current->group_leader) to
198 * protect this instead of the siglock, because they really
199 * have no need to disable irqs.
201 struct rlimit rlim[RLIM_NLIMITS];
203 #ifdef CONFIG_BSD_PROCESS_ACCT
204 struct pacct_struct pacct; /* per-process accounting information */
206 #ifdef CONFIG_TASKSTATS
207 struct taskstats *stats;
211 struct tty_audit_buf *tty_audit_buf;
215 * Thread is the potential origin of an oom condition; kill first on
218 bool oom_flag_origin;
219 short oom_score_adj; /* OOM kill score adjustment */
220 short oom_score_adj_min; /* OOM kill score adjustment min value.
221 * Only settable by CAP_SYS_RESOURCE. */
222 struct mm_struct *oom_mm; /* recorded mm when the thread group got
223 * killed by the oom killer */
225 struct mutex cred_guard_mutex; /* guard against foreign influences on
226 * credential calculations
227 * (notably. ptrace) */
228 } __randomize_layout;
231 * Bits in flags field of signal_struct.
233 #define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
234 #define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
235 #define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
236 #define SIGNAL_GROUP_COREDUMP 0x00000008 /* coredump in progress */
238 * Pending notifications to parent.
240 #define SIGNAL_CLD_STOPPED 0x00000010
241 #define SIGNAL_CLD_CONTINUED 0x00000020
242 #define SIGNAL_CLD_MASK (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
244 #define SIGNAL_UNKILLABLE 0x00000040 /* for init: ignore fatal signals */
246 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
247 SIGNAL_STOP_CONTINUED)
249 static inline void signal_set_stop_flags(struct signal_struct *sig,
252 WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
253 sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
256 /* If true, all threads except ->group_exit_task have pending SIGKILL */
257 static inline int signal_group_exit(const struct signal_struct *sig)
259 return (sig->flags & SIGNAL_GROUP_EXIT) ||
260 (sig->group_exit_task != NULL);
263 extern void flush_signals(struct task_struct *);
264 extern void ignore_signals(struct task_struct *);
265 extern void flush_signal_handlers(struct task_struct *, int force_default);
266 extern int dequeue_signal(struct task_struct *task,
267 sigset_t *mask, kernel_siginfo_t *info);
269 static inline int kernel_dequeue_signal(void)
271 struct task_struct *task = current;
272 kernel_siginfo_t __info;
275 spin_lock_irq(&task->sighand->siglock);
276 ret = dequeue_signal(task, &task->blocked, &__info);
277 spin_unlock_irq(&task->sighand->siglock);
282 static inline void kernel_signal_stop(void)
284 spin_lock_irq(¤t->sighand->siglock);
285 if (current->jobctl & JOBCTL_STOP_DEQUEUED)
286 set_special_state(TASK_STOPPED);
287 spin_unlock_irq(¤t->sighand->siglock);
291 #ifdef __ARCH_SI_TRAPNO
292 # define ___ARCH_SI_TRAPNO(_a1) , _a1
294 # define ___ARCH_SI_TRAPNO(_a1)
297 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
299 # define ___ARCH_SI_IA64(_a1, _a2, _a3)
302 int force_sig_fault_to_task(int sig, int code, void __user *addr
303 ___ARCH_SI_TRAPNO(int trapno)
304 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
305 , struct task_struct *t);
306 int force_sig_fault(int sig, int code, void __user *addr
307 ___ARCH_SI_TRAPNO(int trapno)
308 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
309 int send_sig_fault(int sig, int code, void __user *addr
310 ___ARCH_SI_TRAPNO(int trapno)
311 ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
312 , struct task_struct *t);
314 int force_sig_mceerr(int code, void __user *, short);
315 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
317 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
318 int force_sig_pkuerr(void __user *addr, u32 pkey);
320 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
322 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
323 extern void force_sigsegv(int sig);
324 extern int force_sig_info(struct kernel_siginfo *);
325 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
326 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
327 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
328 const struct cred *);
329 extern int kill_pgrp(struct pid *pid, int sig, int priv);
330 extern int kill_pid(struct pid *pid, int sig, int priv);
331 extern __must_check bool do_notify_parent(struct task_struct *, int);
332 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
333 extern void force_sig(int);
334 extern int send_sig(int, struct task_struct *, int);
335 extern int zap_other_threads(struct task_struct *p);
336 extern struct sigqueue *sigqueue_alloc(void);
337 extern void sigqueue_free(struct sigqueue *);
338 extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
339 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
341 static inline int restart_syscall(void)
343 set_tsk_thread_flag(current, TIF_SIGPENDING);
344 return -ERESTARTNOINTR;
347 static inline int signal_pending(struct task_struct *p)
349 return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
352 static inline int __fatal_signal_pending(struct task_struct *p)
354 return unlikely(sigismember(&p->pending.signal, SIGKILL));
357 static inline int fatal_signal_pending(struct task_struct *p)
359 return signal_pending(p) && __fatal_signal_pending(p);
362 static inline int signal_pending_state(long state, struct task_struct *p)
364 if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
366 if (!signal_pending(p))
369 return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
373 * Reevaluate whether the task has signals pending delivery.
374 * Wake the task if so.
375 * This is required every time the blocked sigset_t changes.
376 * callers must hold sighand->siglock.
378 extern void recalc_sigpending_and_wake(struct task_struct *t);
379 extern void recalc_sigpending(void);
380 extern void calculate_sigpending(void);
382 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
384 static inline void signal_wake_up(struct task_struct *t, bool resume)
386 signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
388 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
390 signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
393 void task_join_group_stop(struct task_struct *task);
395 #ifdef TIF_RESTORE_SIGMASK
397 * Legacy restore_sigmask accessors. These are inefficient on
398 * SMP architectures because they require atomic operations.
402 * set_restore_sigmask() - make sure saved_sigmask processing gets done
404 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
405 * will run before returning to user mode, to process the flag. For
406 * all callers, TIF_SIGPENDING is already set or it's no harm to set
407 * it. TIF_RESTORE_SIGMASK need not be in the set of bits that the
408 * arch code will notice on return to user mode, in case those bits
409 * are scarce. We set TIF_SIGPENDING here to ensure that the arch
410 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
412 static inline void set_restore_sigmask(void)
414 set_thread_flag(TIF_RESTORE_SIGMASK);
417 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
419 clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
422 static inline void clear_restore_sigmask(void)
424 clear_thread_flag(TIF_RESTORE_SIGMASK);
426 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
428 return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
430 static inline bool test_restore_sigmask(void)
432 return test_thread_flag(TIF_RESTORE_SIGMASK);
434 static inline bool test_and_clear_restore_sigmask(void)
436 return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
439 #else /* TIF_RESTORE_SIGMASK */
441 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
442 static inline void set_restore_sigmask(void)
444 current->restore_sigmask = true;
446 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
448 task->restore_sigmask = false;
450 static inline void clear_restore_sigmask(void)
452 current->restore_sigmask = false;
454 static inline bool test_restore_sigmask(void)
456 return current->restore_sigmask;
458 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
460 return task->restore_sigmask;
462 static inline bool test_and_clear_restore_sigmask(void)
464 if (!current->restore_sigmask)
466 current->restore_sigmask = false;
471 static inline void restore_saved_sigmask(void)
473 if (test_and_clear_restore_sigmask())
474 __set_current_blocked(¤t->saved_sigmask);
477 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
479 static inline void restore_saved_sigmask_unless(bool interrupted)
482 WARN_ON(!test_thread_flag(TIF_SIGPENDING));
484 restore_saved_sigmask();
487 static inline sigset_t *sigmask_to_save(void)
489 sigset_t *res = ¤t->blocked;
490 if (unlikely(test_restore_sigmask()))
491 res = ¤t->saved_sigmask;
495 static inline int kill_cad_pid(int sig, int priv)
497 return kill_pid(cad_pid, sig, priv);
500 /* These can be the second arg to send_sig_info/send_group_sig_info. */
501 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
502 #define SEND_SIG_PRIV ((struct kernel_siginfo *) 1)
505 * True if we are on the alternate signal stack.
507 static inline int on_sig_stack(unsigned long sp)
510 * If the signal stack is SS_AUTODISARM then, by construction, we
511 * can't be on the signal stack unless user code deliberately set
512 * SS_AUTODISARM when we were already on it.
514 * This improves reliability: if user state gets corrupted such that
515 * the stack pointer points very close to the end of the signal stack,
516 * then this check will enable the signal to be handled anyway.
518 if (current->sas_ss_flags & SS_AUTODISARM)
521 #ifdef CONFIG_STACK_GROWSUP
522 return sp >= current->sas_ss_sp &&
523 sp - current->sas_ss_sp < current->sas_ss_size;
525 return sp > current->sas_ss_sp &&
526 sp - current->sas_ss_sp <= current->sas_ss_size;
530 static inline int sas_ss_flags(unsigned long sp)
532 if (!current->sas_ss_size)
535 return on_sig_stack(sp) ? SS_ONSTACK : 0;
538 static inline void sas_ss_reset(struct task_struct *p)
542 p->sas_ss_flags = SS_DISABLE;
545 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
547 if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
548 #ifdef CONFIG_STACK_GROWSUP
549 return current->sas_ss_sp;
551 return current->sas_ss_sp + current->sas_ss_size;
556 extern void __cleanup_sighand(struct sighand_struct *);
557 extern void flush_itimer_signals(void);
559 #define tasklist_empty() \
560 list_empty(&init_task.tasks)
562 #define next_task(p) \
563 list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
565 #define for_each_process(p) \
566 for (p = &init_task ; (p = next_task(p)) != &init_task ; )
568 extern bool current_is_single_threaded(void);
571 * Careful: do_each_thread/while_each_thread is a double loop so
572 * 'break' will not work as expected - use goto instead.
574 #define do_each_thread(g, t) \
575 for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
577 #define while_each_thread(g, t) \
578 while ((t = next_thread(t)) != g)
580 #define __for_each_thread(signal, t) \
581 list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
583 #define for_each_thread(p, t) \
584 __for_each_thread((p)->signal, t)
586 /* Careful: this is a double loop, 'break' won't work as expected. */
587 #define for_each_process_thread(p, t) \
588 for_each_process(p) for_each_thread(p, t)
590 typedef int (*proc_visitor)(struct task_struct *p, void *data);
591 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
594 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
597 if (type == PIDTYPE_PID)
598 pid = task_pid(task);
600 pid = task->signal->pids[type];
604 static inline struct pid *task_tgid(struct task_struct *task)
606 return task->signal->pids[PIDTYPE_TGID];
610 * Without tasklist or RCU lock it is not safe to dereference
611 * the result of task_pgrp/task_session even if task == current,
612 * we can race with another thread doing sys_setsid/sys_setpgid.
614 static inline struct pid *task_pgrp(struct task_struct *task)
616 return task->signal->pids[PIDTYPE_PGID];
619 static inline struct pid *task_session(struct task_struct *task)
621 return task->signal->pids[PIDTYPE_SID];
624 static inline int get_nr_threads(struct task_struct *task)
626 return task->signal->nr_threads;
629 static inline bool thread_group_leader(struct task_struct *p)
631 return p->exit_signal >= 0;
634 /* Do to the insanities of de_thread it is possible for a process
635 * to have the pid of the thread group leader without actually being
636 * the thread group leader. For iteration through the pids in proc
637 * all we care about is that we have a task with the appropriate
638 * pid, we don't actually care if we have the right task.
640 static inline bool has_group_leader_pid(struct task_struct *p)
642 return task_pid(p) == task_tgid(p);
646 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
648 return p1->signal == p2->signal;
651 static inline struct task_struct *next_thread(const struct task_struct *p)
653 return list_entry_rcu(p->thread_group.next,
654 struct task_struct, thread_group);
657 static inline int thread_group_empty(struct task_struct *p)
659 return list_empty(&p->thread_group);
662 #define delay_group_leader(p) \
663 (thread_group_leader(p) && !thread_group_empty(p))
665 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
666 unsigned long *flags);
668 static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
669 unsigned long *flags)
671 struct sighand_struct *ret;
673 ret = __lock_task_sighand(task, flags);
674 (void)__cond_lock(&task->sighand->siglock, ret);
678 static inline void unlock_task_sighand(struct task_struct *task,
679 unsigned long *flags)
681 spin_unlock_irqrestore(&task->sighand->siglock, *flags);
684 static inline unsigned long task_rlimit(const struct task_struct *task,
687 return READ_ONCE(task->signal->rlim[limit].rlim_cur);
690 static inline unsigned long task_rlimit_max(const struct task_struct *task,
693 return READ_ONCE(task->signal->rlim[limit].rlim_max);
696 static inline unsigned long rlimit(unsigned int limit)
698 return task_rlimit(current, limit);
701 static inline unsigned long rlimit_max(unsigned int limit)
703 return task_rlimit_max(current, limit);
706 #endif /* _LINUX_SCHED_SIGNAL_H */