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		next_posix_timer_id;
140  	struct hlist_head	posix_timers;
141  
142  	/* ITIMER_REAL timer for the process */
143  	struct hrtimer real_timer;
144  	ktime_t it_real_incr;
145  
146  	/*
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
150  	 */
151  	struct cpu_itimer it[2];
152  
153  	/*
154  	 * Thread group totals for process CPU timers.
155  	 * See thread_group_cputimer(), et al, for details.
156  	 */
157  	struct thread_group_cputimer cputimer;
158  
159  #endif
160  	/* Empty if CONFIG_POSIX_TIMERS=n */
161  	struct posix_cputimers posix_cputimers;
162  
163  	/* PID/PID hash table linkage. */
164  	struct pid *pids[PIDTYPE_MAX];
165  
166  #ifdef CONFIG_NO_HZ_FULL
167  	atomic_t tick_dep_mask;
168  #endif
169  
170  	struct pid *tty_old_pgrp;
171  
172  	/* boolean value for session group leader */
173  	int leader;
174  
175  	struct tty_struct *tty; /* NULL if no tty */
176  
177  #ifdef CONFIG_SCHED_AUTOGROUP
178  	struct autogroup *autogroup;
179  #endif
180  	/*
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.
185  	 */
186  	seqlock_t stats_lock;
187  	u64 utime, stime, cutime, cstime;
188  	u64 gtime;
189  	u64 cgtime;
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;
196  
197  	/*
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.)
202  	 */
203  	unsigned long long sum_sched_runtime;
204  
205  	/*
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.
213  	 */
214  	struct rlimit rlim[RLIM_NLIMITS];
215  
216  #ifdef CONFIG_BSD_PROCESS_ACCT
217  	struct pacct_struct pacct;	/* per-process accounting information */
218  #endif
219  #ifdef CONFIG_TASKSTATS
220  	struct taskstats *stats;
221  #endif
222  #ifdef CONFIG_AUDIT
223  	unsigned audit_tty;
224  	struct tty_audit_buf *tty_audit_buf;
225  #endif
226  
227  	/*
228  	 * Thread is the potential origin of an oom condition; kill first on
229  	 * oom
230  	 */
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 */
237  
238  	struct mutex cred_guard_mutex;	/* guard against foreign influences on
239  					 * credential calculations
240  					 * (notably. ptrace)
241  					 * Deprecated do not use in new code.
242  					 * Use exec_update_lock instead.
243  					 */
244  	struct rw_semaphore exec_update_lock;	/* Held while task_struct is
245  						 * being updated during exec,
246  						 * and may have inconsistent
247  						 * permissions.
248  						 */
249  } __randomize_layout;
250  
251  /*
252   * Bits in flags field of signal_struct.
253   */
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 */
257  /*
258   * Pending notifications to parent.
259   */
260  #define SIGNAL_CLD_STOPPED	0x00000010
261  #define SIGNAL_CLD_CONTINUED	0x00000020
262  #define SIGNAL_CLD_MASK		(SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
263  
264  #define SIGNAL_UNKILLABLE	0x00000040 /* for init: ignore fatal signals */
265  
266  #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
267  			  SIGNAL_STOP_CONTINUED)
268  
signal_set_stop_flags(struct signal_struct * sig,unsigned int flags)269  static inline void signal_set_stop_flags(struct signal_struct *sig,
270  					 unsigned int flags)
271  {
272  	WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
273  	sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
274  }
275  
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(sigset_t *mask, kernel_siginfo_t *info, enum pid_type *type);
280  
kernel_dequeue_signal(void)281  static inline int kernel_dequeue_signal(void)
282  {
283  	struct task_struct *task = current;
284  	kernel_siginfo_t __info;
285  	enum pid_type __type;
286  	int ret;
287  
288  	spin_lock_irq(&task->sighand->siglock);
289  	ret = dequeue_signal(&task->blocked, &__info, &__type);
290  	spin_unlock_irq(&task->sighand->siglock);
291  
292  	return ret;
293  }
294  
kernel_signal_stop(void)295  static inline void kernel_signal_stop(void)
296  {
297  	spin_lock_irq(&current->sighand->siglock);
298  	if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
299  		current->jobctl |= JOBCTL_STOPPED;
300  		set_special_state(TASK_STOPPED);
301  	}
302  	spin_unlock_irq(&current->sighand->siglock);
303  
304  	schedule();
305  }
306  
307  int force_sig_fault_to_task(int sig, int code, void __user *addr,
308  			    struct task_struct *t);
309  int force_sig_fault(int sig, int code, void __user *addr);
310  int send_sig_fault(int sig, int code, void __user *addr, struct task_struct *t);
311  
312  int force_sig_mceerr(int code, void __user *, short);
313  int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
314  
315  int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
316  int force_sig_pkuerr(void __user *addr, u32 pkey);
317  int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
318  
319  int force_sig_ptrace_errno_trap(int errno, void __user *addr);
320  int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
321  int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
322  			struct task_struct *t);
323  int force_sig_seccomp(int syscall, int reason, bool force_coredump);
324  
325  extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
326  extern void force_sigsegv(int sig);
327  extern int force_sig_info(struct kernel_siginfo *);
328  extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
329  extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
330  extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
331  				const struct cred *);
332  extern int kill_pgrp(struct pid *pid, int sig, int priv);
333  extern int kill_pid(struct pid *pid, int sig, int priv);
334  extern __must_check bool do_notify_parent(struct task_struct *, int);
335  extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
336  extern void force_sig(int);
337  extern void force_fatal_sig(int);
338  extern void force_exit_sig(int);
339  extern int send_sig(int, struct task_struct *, int);
340  extern int zap_other_threads(struct task_struct *p);
341  extern struct sigqueue *sigqueue_alloc(void);
342  extern void sigqueue_free(struct sigqueue *);
343  extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
344  extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
345  
clear_notify_signal(void)346  static inline void clear_notify_signal(void)
347  {
348  	clear_thread_flag(TIF_NOTIFY_SIGNAL);
349  	smp_mb__after_atomic();
350  }
351  
352  /*
353   * Returns 'true' if kick_process() is needed to force a transition from
354   * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
355   */
__set_notify_signal(struct task_struct * task)356  static inline bool __set_notify_signal(struct task_struct *task)
357  {
358  	return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
359  	       !wake_up_state(task, TASK_INTERRUPTIBLE);
360  }
361  
362  /*
363   * Called to break out of interruptible wait loops, and enter the
364   * exit_to_user_mode_loop().
365   */
set_notify_signal(struct task_struct * task)366  static inline void set_notify_signal(struct task_struct *task)
367  {
368  	if (__set_notify_signal(task))
369  		kick_process(task);
370  }
371  
restart_syscall(void)372  static inline int restart_syscall(void)
373  {
374  	set_tsk_thread_flag(current, TIF_SIGPENDING);
375  	return -ERESTARTNOINTR;
376  }
377  
task_sigpending(struct task_struct * p)378  static inline int task_sigpending(struct task_struct *p)
379  {
380  	return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
381  }
382  
signal_pending(struct task_struct * p)383  static inline int signal_pending(struct task_struct *p)
384  {
385  	/*
386  	 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
387  	 * behavior in terms of ensuring that we break out of wait loops
388  	 * so that notify signal callbacks can be processed.
389  	 */
390  	if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
391  		return 1;
392  	return task_sigpending(p);
393  }
394  
__fatal_signal_pending(struct task_struct * p)395  static inline int __fatal_signal_pending(struct task_struct *p)
396  {
397  	return unlikely(sigismember(&p->pending.signal, SIGKILL));
398  }
399  
fatal_signal_pending(struct task_struct * p)400  static inline int fatal_signal_pending(struct task_struct *p)
401  {
402  	return task_sigpending(p) && __fatal_signal_pending(p);
403  }
404  
signal_pending_state(unsigned int state,struct task_struct * p)405  static inline int signal_pending_state(unsigned int state, struct task_struct *p)
406  {
407  	if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
408  		return 0;
409  	if (!signal_pending(p))
410  		return 0;
411  
412  	return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
413  }
414  
415  /*
416   * This should only be used in fault handlers to decide whether we
417   * should stop the current fault routine to handle the signals
418   * instead, especially with the case where we've got interrupted with
419   * a VM_FAULT_RETRY.
420   */
fault_signal_pending(vm_fault_t fault_flags,struct pt_regs * regs)421  static inline bool fault_signal_pending(vm_fault_t fault_flags,
422  					struct pt_regs *regs)
423  {
424  	return unlikely((fault_flags & VM_FAULT_RETRY) &&
425  			(fatal_signal_pending(current) ||
426  			 (user_mode(regs) && signal_pending(current))));
427  }
428  
429  /*
430   * Reevaluate whether the task has signals pending delivery.
431   * Wake the task if so.
432   * This is required every time the blocked sigset_t changes.
433   * callers must hold sighand->siglock.
434   */
435  extern void recalc_sigpending(void);
436  extern void calculate_sigpending(void);
437  
438  extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
439  
signal_wake_up(struct task_struct * t,bool fatal)440  static inline void signal_wake_up(struct task_struct *t, bool fatal)
441  {
442  	unsigned int state = 0;
443  	if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
444  		t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
445  		state = TASK_WAKEKILL | __TASK_TRACED;
446  	}
447  	signal_wake_up_state(t, state);
448  }
ptrace_signal_wake_up(struct task_struct * t,bool resume)449  static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
450  {
451  	unsigned int state = 0;
452  	if (resume) {
453  		t->jobctl &= ~JOBCTL_TRACED;
454  		state = __TASK_TRACED;
455  	}
456  	signal_wake_up_state(t, state);
457  }
458  
459  void task_join_group_stop(struct task_struct *task);
460  
461  #ifdef TIF_RESTORE_SIGMASK
462  /*
463   * Legacy restore_sigmask accessors.  These are inefficient on
464   * SMP architectures because they require atomic operations.
465   */
466  
467  /**
468   * set_restore_sigmask() - make sure saved_sigmask processing gets done
469   *
470   * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
471   * will run before returning to user mode, to process the flag.  For
472   * all callers, TIF_SIGPENDING is already set or it's no harm to set
473   * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
474   * arch code will notice on return to user mode, in case those bits
475   * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
476   * signal code always gets run when TIF_RESTORE_SIGMASK is set.
477   */
set_restore_sigmask(void)478  static inline void set_restore_sigmask(void)
479  {
480  	set_thread_flag(TIF_RESTORE_SIGMASK);
481  }
482  
clear_tsk_restore_sigmask(struct task_struct * task)483  static inline void clear_tsk_restore_sigmask(struct task_struct *task)
484  {
485  	clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
486  }
487  
clear_restore_sigmask(void)488  static inline void clear_restore_sigmask(void)
489  {
490  	clear_thread_flag(TIF_RESTORE_SIGMASK);
491  }
test_tsk_restore_sigmask(struct task_struct * task)492  static inline bool test_tsk_restore_sigmask(struct task_struct *task)
493  {
494  	return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
495  }
test_restore_sigmask(void)496  static inline bool test_restore_sigmask(void)
497  {
498  	return test_thread_flag(TIF_RESTORE_SIGMASK);
499  }
test_and_clear_restore_sigmask(void)500  static inline bool test_and_clear_restore_sigmask(void)
501  {
502  	return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
503  }
504  
505  #else	/* TIF_RESTORE_SIGMASK */
506  
507  /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
set_restore_sigmask(void)508  static inline void set_restore_sigmask(void)
509  {
510  	current->restore_sigmask = true;
511  }
clear_tsk_restore_sigmask(struct task_struct * task)512  static inline void clear_tsk_restore_sigmask(struct task_struct *task)
513  {
514  	task->restore_sigmask = false;
515  }
clear_restore_sigmask(void)516  static inline void clear_restore_sigmask(void)
517  {
518  	current->restore_sigmask = false;
519  }
test_restore_sigmask(void)520  static inline bool test_restore_sigmask(void)
521  {
522  	return current->restore_sigmask;
523  }
test_tsk_restore_sigmask(struct task_struct * task)524  static inline bool test_tsk_restore_sigmask(struct task_struct *task)
525  {
526  	return task->restore_sigmask;
527  }
test_and_clear_restore_sigmask(void)528  static inline bool test_and_clear_restore_sigmask(void)
529  {
530  	if (!current->restore_sigmask)
531  		return false;
532  	current->restore_sigmask = false;
533  	return true;
534  }
535  #endif
536  
restore_saved_sigmask(void)537  static inline void restore_saved_sigmask(void)
538  {
539  	if (test_and_clear_restore_sigmask())
540  		__set_current_blocked(&current->saved_sigmask);
541  }
542  
543  extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
544  
restore_saved_sigmask_unless(bool interrupted)545  static inline void restore_saved_sigmask_unless(bool interrupted)
546  {
547  	if (interrupted)
548  		WARN_ON(!signal_pending(current));
549  	else
550  		restore_saved_sigmask();
551  }
552  
sigmask_to_save(void)553  static inline sigset_t *sigmask_to_save(void)
554  {
555  	sigset_t *res = &current->blocked;
556  	if (unlikely(test_restore_sigmask()))
557  		res = &current->saved_sigmask;
558  	return res;
559  }
560  
kill_cad_pid(int sig,int priv)561  static inline int kill_cad_pid(int sig, int priv)
562  {
563  	return kill_pid(cad_pid, sig, priv);
564  }
565  
566  /* These can be the second arg to send_sig_info/send_group_sig_info.  */
567  #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
568  #define SEND_SIG_PRIV	((struct kernel_siginfo *) 1)
569  
__on_sig_stack(unsigned long sp)570  static inline int __on_sig_stack(unsigned long sp)
571  {
572  #ifdef CONFIG_STACK_GROWSUP
573  	return sp >= current->sas_ss_sp &&
574  		sp - current->sas_ss_sp < current->sas_ss_size;
575  #else
576  	return sp > current->sas_ss_sp &&
577  		sp - current->sas_ss_sp <= current->sas_ss_size;
578  #endif
579  }
580  
581  /*
582   * True if we are on the alternate signal stack.
583   */
on_sig_stack(unsigned long sp)584  static inline int on_sig_stack(unsigned long sp)
585  {
586  	/*
587  	 * If the signal stack is SS_AUTODISARM then, by construction, we
588  	 * can't be on the signal stack unless user code deliberately set
589  	 * SS_AUTODISARM when we were already on it.
590  	 *
591  	 * This improves reliability: if user state gets corrupted such that
592  	 * the stack pointer points very close to the end of the signal stack,
593  	 * then this check will enable the signal to be handled anyway.
594  	 */
595  	if (current->sas_ss_flags & SS_AUTODISARM)
596  		return 0;
597  
598  	return __on_sig_stack(sp);
599  }
600  
sas_ss_flags(unsigned long sp)601  static inline int sas_ss_flags(unsigned long sp)
602  {
603  	if (!current->sas_ss_size)
604  		return SS_DISABLE;
605  
606  	return on_sig_stack(sp) ? SS_ONSTACK : 0;
607  }
608  
sas_ss_reset(struct task_struct * p)609  static inline void sas_ss_reset(struct task_struct *p)
610  {
611  	p->sas_ss_sp = 0;
612  	p->sas_ss_size = 0;
613  	p->sas_ss_flags = SS_DISABLE;
614  }
615  
sigsp(unsigned long sp,struct ksignal * ksig)616  static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
617  {
618  	if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
619  #ifdef CONFIG_STACK_GROWSUP
620  		return current->sas_ss_sp;
621  #else
622  		return current->sas_ss_sp + current->sas_ss_size;
623  #endif
624  	return sp;
625  }
626  
627  extern void __cleanup_sighand(struct sighand_struct *);
628  extern void flush_itimer_signals(void);
629  
630  #define tasklist_empty() \
631  	list_empty(&init_task.tasks)
632  
633  #define next_task(p) \
634  	list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
635  
636  #define for_each_process(p) \
637  	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
638  
639  extern bool current_is_single_threaded(void);
640  
641  /*
642   * Without tasklist/siglock it is only rcu-safe if g can't exit/exec,
643   * otherwise next_thread(t) will never reach g after list_del_rcu(g).
644   */
645  #define while_each_thread(g, t) \
646  	while ((t = next_thread(t)) != g)
647  
648  #define for_other_threads(p, t)	\
649  	for (t = p; (t = next_thread(t)) != p; )
650  
651  #define __for_each_thread(signal, t)	\
652  	list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node, \
653  		lockdep_is_held(&tasklist_lock))
654  
655  #define for_each_thread(p, t)		\
656  	__for_each_thread((p)->signal, t)
657  
658  /* Careful: this is a double loop, 'break' won't work as expected. */
659  #define for_each_process_thread(p, t)	\
660  	for_each_process(p) for_each_thread(p, t)
661  
662  typedef int (*proc_visitor)(struct task_struct *p, void *data);
663  void walk_process_tree(struct task_struct *top, proc_visitor, void *);
664  
665  static inline
task_pid_type(struct task_struct * task,enum pid_type type)666  struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
667  {
668  	struct pid *pid;
669  	if (type == PIDTYPE_PID)
670  		pid = task_pid(task);
671  	else
672  		pid = task->signal->pids[type];
673  	return pid;
674  }
675  
task_tgid(struct task_struct * task)676  static inline struct pid *task_tgid(struct task_struct *task)
677  {
678  	return task->signal->pids[PIDTYPE_TGID];
679  }
680  
681  /*
682   * Without tasklist or RCU lock it is not safe to dereference
683   * the result of task_pgrp/task_session even if task == current,
684   * we can race with another thread doing sys_setsid/sys_setpgid.
685   */
task_pgrp(struct task_struct * task)686  static inline struct pid *task_pgrp(struct task_struct *task)
687  {
688  	return task->signal->pids[PIDTYPE_PGID];
689  }
690  
task_session(struct task_struct * task)691  static inline struct pid *task_session(struct task_struct *task)
692  {
693  	return task->signal->pids[PIDTYPE_SID];
694  }
695  
get_nr_threads(struct task_struct * task)696  static inline int get_nr_threads(struct task_struct *task)
697  {
698  	return task->signal->nr_threads;
699  }
700  
thread_group_leader(struct task_struct * p)701  static inline bool thread_group_leader(struct task_struct *p)
702  {
703  	return p->exit_signal >= 0;
704  }
705  
706  static inline
same_thread_group(struct task_struct * p1,struct task_struct * p2)707  bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
708  {
709  	return p1->signal == p2->signal;
710  }
711  
712  /*
713   * returns NULL if p is the last thread in the thread group
714   */
__next_thread(struct task_struct * p)715  static inline struct task_struct *__next_thread(struct task_struct *p)
716  {
717  	return list_next_or_null_rcu(&p->signal->thread_head,
718  					&p->thread_node,
719  					struct task_struct,
720  					thread_node);
721  }
722  
next_thread(struct task_struct * p)723  static inline struct task_struct *next_thread(struct task_struct *p)
724  {
725  	return __next_thread(p) ?: p->group_leader;
726  }
727  
thread_group_empty(struct task_struct * p)728  static inline int thread_group_empty(struct task_struct *p)
729  {
730  	return thread_group_leader(p) &&
731  	       list_is_last(&p->thread_node, &p->signal->thread_head);
732  }
733  
734  #define delay_group_leader(p) \
735  		(thread_group_leader(p) && !thread_group_empty(p))
736  
737  extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
738  							unsigned long *flags);
739  
lock_task_sighand(struct task_struct * task,unsigned long * flags)740  static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
741  						       unsigned long *flags)
742  {
743  	struct sighand_struct *ret;
744  
745  	ret = __lock_task_sighand(task, flags);
746  	(void)__cond_lock(&task->sighand->siglock, ret);
747  	return ret;
748  }
749  
unlock_task_sighand(struct task_struct * task,unsigned long * flags)750  static inline void unlock_task_sighand(struct task_struct *task,
751  						unsigned long *flags)
752  {
753  	spin_unlock_irqrestore(&task->sighand->siglock, *flags);
754  }
755  
756  #ifdef CONFIG_LOCKDEP
757  extern void lockdep_assert_task_sighand_held(struct task_struct *task);
758  #else
lockdep_assert_task_sighand_held(struct task_struct * task)759  static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
760  #endif
761  
task_rlimit(const struct task_struct * task,unsigned int limit)762  static inline unsigned long task_rlimit(const struct task_struct *task,
763  		unsigned int limit)
764  {
765  	return READ_ONCE(task->signal->rlim[limit].rlim_cur);
766  }
767  
task_rlimit_max(const struct task_struct * task,unsigned int limit)768  static inline unsigned long task_rlimit_max(const struct task_struct *task,
769  		unsigned int limit)
770  {
771  	return READ_ONCE(task->signal->rlim[limit].rlim_max);
772  }
773  
rlimit(unsigned int limit)774  static inline unsigned long rlimit(unsigned int limit)
775  {
776  	return task_rlimit(current, limit);
777  }
778  
rlimit_max(unsigned int limit)779  static inline unsigned long rlimit_max(unsigned int limit)
780  {
781  	return task_rlimit_max(current, limit);
782  }
783  
784  #endif /* _LINUX_SCHED_SIGNAL_H */
785