Merge tag 'for-linus-20170825' of git://git.infradead.org/linux-mtd

[mirror_ubuntu-artful-kernel.git] / include / linux / sched / signal.h

#ifndef _LINUX_SCHED_SIGNAL_H
#define _LINUX_SCHED_SIGNAL_H

#include <linux/rculist.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/sched/jobctl.h>
#include <linux/sched/task.h>
#include <linux/cred.h>

/*
 * Types defining task->signal and task->sighand and APIs using them:
 */

struct sighand_struct {
        atomic_t                count;
        struct k_sigaction      action[_NSIG];
        spinlock_t              siglock;
        wait_queue_head_t       signalfd_wqh;
};

/*
 * Per-process accounting stats:
 */
struct pacct_struct {
        int                     ac_flag;
        long                    ac_exitcode;
        unsigned long           ac_mem;
        u64                     ac_utime, ac_stime;
        unsigned long           ac_minflt, ac_majflt;
};

struct cpu_itimer {
        u64 expires;
        u64 incr;
};

/*
 * This is the atomic variant of task_cputime, which can be used for
 * storing and updating task_cputime statistics without locking.
 */
struct task_cputime_atomic {
        atomic64_t utime;
        atomic64_t stime;
        atomic64_t sum_exec_runtime;
};

#define INIT_CPUTIME_ATOMIC \
        (struct task_cputime_atomic) {                          \
                .utime = ATOMIC64_INIT(0),                      \
                .stime = ATOMIC64_INIT(0),                      \
                .sum_exec_runtime = ATOMIC64_INIT(0),           \
        }
/**
 * struct thread_group_cputimer - thread group interval timer counts
 * @cputime_atomic:     atomic thread group interval timers.
 * @running:            true when there are timers running and
 *                      @cputime_atomic receives updates.
 * @checking_timer:     true when a thread in the group is in the
 *                      process of checking for thread group timers.
 *
 * This structure contains the version of task_cputime, above, that is
 * used for thread group CPU timer calculations.
 */
struct thread_group_cputimer {
        struct task_cputime_atomic cputime_atomic;
        bool running;
        bool checking_timer;
};

/*
 * NOTE! "signal_struct" does not have its own
 * locking, because a shared signal_struct always
 * implies a shared sighand_struct, so locking
 * sighand_struct is always a proper superset of
 * the locking of signal_struct.
 */
struct signal_struct {
        atomic_t                sigcnt;
        atomic_t                live;
        int                     nr_threads;
        struct list_head        thread_head;

        wait_queue_head_t       wait_chldexit;  /* for wait4() */

        /* current thread group signal load-balancing target: */
        struct task_struct      *curr_target;

        /* shared signal handling: */
        struct sigpending       shared_pending;

        /* thread group exit support */
        int                     group_exit_code;
        /* overloaded:
         * - notify group_exit_task when ->count is equal to notify_count
         * - everyone except group_exit_task is stopped during signal delivery
         *   of fatal signals, group_exit_task processes the signal.
         */
        int                     notify_count;
        struct task_struct      *group_exit_task;

        /* thread group stop support, overloads group_exit_code too */
        int                     group_stop_count;
        unsigned int            flags; /* see SIGNAL_* flags below */

        /*
         * PR_SET_CHILD_SUBREAPER marks a process, like a service
         * manager, to re-parent orphan (double-forking) child processes
         * to this process instead of 'init'. The service manager is
         * able to receive SIGCHLD signals and is able to investigate
         * the process until it calls wait(). All children of this
         * process will inherit a flag if they should look for a
         * child_subreaper process at exit.
         */
        unsigned int            is_child_subreaper:1;
        unsigned int            has_child_subreaper:1;

#ifdef CONFIG_POSIX_TIMERS

        /* POSIX.1b Interval Timers */
        int                     posix_timer_id;
        struct list_head        posix_timers;

        /* ITIMER_REAL timer for the process */
        struct hrtimer real_timer;
        ktime_t it_real_incr;

        /*
         * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
         * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
         * values are defined to 0 and 1 respectively
         */
        struct cpu_itimer it[2];

        /*
         * Thread group totals for process CPU timers.
         * See thread_group_cputimer(), et al, for details.
         */
        struct thread_group_cputimer cputimer;

        /* Earliest-expiration cache. */
        struct task_cputime cputime_expires;

        struct list_head cpu_timers[3];

#endif

        struct pid *leader_pid;

#ifdef CONFIG_NO_HZ_FULL
        atomic_t tick_dep_mask;
#endif

        struct pid *tty_old_pgrp;

        /* boolean value for session group leader */
        int leader;

        struct tty_struct *tty; /* NULL if no tty */

#ifdef CONFIG_SCHED_AUTOGROUP
        struct autogroup *autogroup;
#endif
        /*
         * Cumulative resource counters for dead threads in the group,
         * and for reaped dead child processes forked by this group.
         * Live threads maintain their own counters and add to these
         * in __exit_signal, except for the group leader.
         */
        seqlock_t stats_lock;
        u64 utime, stime, cutime, cstime;
        u64 gtime;
        u64 cgtime;
        struct prev_cputime prev_cputime;
        unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
        unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
        unsigned long inblock, oublock, cinblock, coublock;
        unsigned long maxrss, cmaxrss;
        struct task_io_accounting ioac;

        /*
         * Cumulative ns of schedule CPU time fo dead threads in the
         * group, not including a zombie group leader, (This only differs
         * from jiffies_to_ns(utime + stime) if sched_clock uses something
         * other than jiffies.)
         */
        unsigned long long sum_sched_runtime;

        /*
         * We don't bother to synchronize most readers of this at all,
         * because there is no reader checking a limit that actually needs
         * to get both rlim_cur and rlim_max atomically, and either one
         * alone is a single word that can safely be read normally.
         * getrlimit/setrlimit use task_lock(current->group_leader) to
         * protect this instead of the siglock, because they really
         * have no need to disable irqs.
         */
        struct rlimit rlim[RLIM_NLIMITS];

#ifdef CONFIG_BSD_PROCESS_ACCT
        struct pacct_struct pacct;      /* per-process accounting information */
#endif
#ifdef CONFIG_TASKSTATS
        struct taskstats *stats;
#endif
#ifdef CONFIG_AUDIT
        unsigned audit_tty;
        struct tty_audit_buf *tty_audit_buf;
#endif

        /*
         * Thread is the potential origin of an oom condition; kill first on
         * oom
         */
        bool oom_flag_origin;
        short oom_score_adj;            /* OOM kill score adjustment */
        short oom_score_adj_min;        /* OOM kill score adjustment min value.
                                         * Only settable by CAP_SYS_RESOURCE. */
        struct mm_struct *oom_mm;       /* recorded mm when the thread group got
                                         * killed by the oom killer */

        struct mutex cred_guard_mutex;  /* guard against foreign influences on
                                         * credential calculations
                                         * (notably. ptrace) */
} __randomize_layout;

/*
 * Bits in flags field of signal_struct.
 */
#define SIGNAL_STOP_STOPPED     0x00000001 /* job control stop in effect */
#define SIGNAL_STOP_CONTINUED   0x00000002 /* SIGCONT since WCONTINUED reap */
#define SIGNAL_GROUP_EXIT       0x00000004 /* group exit in progress */
#define SIGNAL_GROUP_COREDUMP   0x00000008 /* coredump in progress */
/*
 * Pending notifications to parent.
 */
#define SIGNAL_CLD_STOPPED      0x00000010
#define SIGNAL_CLD_CONTINUED    0x00000020
#define SIGNAL_CLD_MASK         (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)

#define SIGNAL_UNKILLABLE       0x00000040 /* for init: ignore fatal signals */

#define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
                          SIGNAL_STOP_CONTINUED)

static inline void signal_set_stop_flags(struct signal_struct *sig,
                                         unsigned int flags)
{
        WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
        sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
}

/* If true, all threads except ->group_exit_task have pending SIGKILL */
static inline int signal_group_exit(const struct signal_struct *sig)
{
        return  (sig->flags & SIGNAL_GROUP_EXIT) ||
                (sig->group_exit_task != NULL);
}

extern void flush_signals(struct task_struct *);
extern void ignore_signals(struct task_struct *);
extern void flush_signal_handlers(struct task_struct *, int force_default);
extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);

static inline int kernel_dequeue_signal(siginfo_t *info)
{
        struct task_struct *tsk = current;
        siginfo_t __info;
        int ret;

        spin_lock_irq(&tsk->sighand->siglock);
        ret = dequeue_signal(tsk, &tsk->blocked, info ?: &__info);
        spin_unlock_irq(&tsk->sighand->siglock);

        return ret;
}

static inline void kernel_signal_stop(void)
{
        spin_lock_irq(&current->sighand->siglock);
        if (current->jobctl & JOBCTL_STOP_DEQUEUED)
                __set_current_state(TASK_STOPPED);
        spin_unlock_irq(&current->sighand->siglock);

        schedule();
}
extern int send_sig_info(int, struct siginfo *, struct task_struct *);
extern int force_sigsegv(int, struct task_struct *);
extern int force_sig_info(int, struct siginfo *, struct task_struct *);
extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);
extern int kill_pid_info_as_cred(int, struct siginfo *, struct pid *,
                                const struct cred *, u32);
extern int kill_pgrp(struct pid *pid, int sig, int priv);
extern int kill_pid(struct pid *pid, int sig, int priv);
extern __must_check bool do_notify_parent(struct task_struct *, int);
extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
extern void force_sig(int, struct task_struct *);
extern int send_sig(int, struct task_struct *, int);
extern int zap_other_threads(struct task_struct *p);
extern struct sigqueue *sigqueue_alloc(void);
extern void sigqueue_free(struct sigqueue *);
extern int send_sigqueue(struct sigqueue *,  struct task_struct *, int group);
extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);

static inline int restart_syscall(void)
{
        set_tsk_thread_flag(current, TIF_SIGPENDING);
        return -ERESTARTNOINTR;
}

static inline int signal_pending(struct task_struct *p)
{
        return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
}

static inline int __fatal_signal_pending(struct task_struct *p)
{
        return unlikely(sigismember(&p->pending.signal, SIGKILL));
}

static inline int fatal_signal_pending(struct task_struct *p)
{
        return signal_pending(p) && __fatal_signal_pending(p);
}

static inline int signal_pending_state(long state, struct task_struct *p)
{
        if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
                return 0;
        if (!signal_pending(p))
                return 0;

        return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
}

/*
 * Reevaluate whether the task has signals pending delivery.
 * Wake the task if so.
 * This is required every time the blocked sigset_t changes.
 * callers must hold sighand->siglock.
 */
extern void recalc_sigpending_and_wake(struct task_struct *t);
extern void recalc_sigpending(void);

extern void signal_wake_up_state(struct task_struct *t, unsigned int state);

static inline void signal_wake_up(struct task_struct *t, bool resume)
{
        signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
}
static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
{
        signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
}

#ifdef TIF_RESTORE_SIGMASK
/*
 * Legacy restore_sigmask accessors.  These are inefficient on
 * SMP architectures because they require atomic operations.
 */

/**
 * set_restore_sigmask() - make sure saved_sigmask processing gets done
 *
 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
 * will run before returning to user mode, to process the flag.  For
 * all callers, TIF_SIGPENDING is already set or it's no harm to set
 * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
 * arch code will notice on return to user mode, in case those bits
 * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
 */
static inline void set_restore_sigmask(void)
{
        set_thread_flag(TIF_RESTORE_SIGMASK);
        WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_restore_sigmask(void)
{
        clear_thread_flag(TIF_RESTORE_SIGMASK);
}
static inline bool test_restore_sigmask(void)
{
        return test_thread_flag(TIF_RESTORE_SIGMASK);
}
static inline bool test_and_clear_restore_sigmask(void)
{
        return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
}

#else   /* TIF_RESTORE_SIGMASK */

/* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
static inline void set_restore_sigmask(void)
{
        current->restore_sigmask = true;
        WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_restore_sigmask(void)
{
        current->restore_sigmask = false;
}
static inline bool test_restore_sigmask(void)
{
        return current->restore_sigmask;
}
static inline bool test_and_clear_restore_sigmask(void)
{
        if (!current->restore_sigmask)
                return false;
        current->restore_sigmask = false;
        return true;
}
#endif

static inline void restore_saved_sigmask(void)
{
        if (test_and_clear_restore_sigmask())
                __set_current_blocked(&current->saved_sigmask);
}

static inline sigset_t *sigmask_to_save(void)
{
        sigset_t *res = &current->blocked;
        if (unlikely(test_restore_sigmask()))
                res = &current->saved_sigmask;
        return res;
}

static inline int kill_cad_pid(int sig, int priv)
{
        return kill_pid(cad_pid, sig, priv);
}

/* These can be the second arg to send_sig_info/send_group_sig_info.  */
#define SEND_SIG_NOINFO ((struct siginfo *) 0)
#define SEND_SIG_PRIV   ((struct siginfo *) 1)
#define SEND_SIG_FORCED ((struct siginfo *) 2)

/*
 * True if we are on the alternate signal stack.
 */
static inline int on_sig_stack(unsigned long sp)
{
        /*
         * If the signal stack is SS_AUTODISARM then, by construction, we
         * can't be on the signal stack unless user code deliberately set
         * SS_AUTODISARM when we were already on it.
         *
         * This improves reliability: if user state gets corrupted such that
         * the stack pointer points very close to the end of the signal stack,
         * then this check will enable the signal to be handled anyway.
         */
        if (current->sas_ss_flags & SS_AUTODISARM)
                return 0;

#ifdef CONFIG_STACK_GROWSUP
        return sp >= current->sas_ss_sp &&
                sp - current->sas_ss_sp < current->sas_ss_size;
#else
        return sp > current->sas_ss_sp &&
                sp - current->sas_ss_sp <= current->sas_ss_size;
#endif
}

static inline int sas_ss_flags(unsigned long sp)
{
        if (!current->sas_ss_size)
                return SS_DISABLE;

        return on_sig_stack(sp) ? SS_ONSTACK : 0;
}

static inline void sas_ss_reset(struct task_struct *p)
{
        p->sas_ss_sp = 0;
        p->sas_ss_size = 0;
        p->sas_ss_flags = SS_DISABLE;
}

static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
{
        if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
#ifdef CONFIG_STACK_GROWSUP
                return current->sas_ss_sp;
#else
                return current->sas_ss_sp + current->sas_ss_size;
#endif
        return sp;
}

extern void __cleanup_sighand(struct sighand_struct *);
extern void flush_itimer_signals(void);

#define tasklist_empty() \
        list_empty(&init_task.tasks)

#define next_task(p) \
        list_entry_rcu((p)->tasks.next, struct task_struct, tasks)

#define for_each_process(p) \
        for (p = &init_task ; (p = next_task(p)) != &init_task ; )

extern bool current_is_single_threaded(void);

/*
 * Careful: do_each_thread/while_each_thread is a double loop so
 *          'break' will not work as expected - use goto instead.
 */
#define do_each_thread(g, t) \
        for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do

#define while_each_thread(g, t) \
        while ((t = next_thread(t)) != g)

#define __for_each_thread(signal, t)    \
        list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)

#define for_each_thread(p, t)           \
        __for_each_thread((p)->signal, t)

/* Careful: this is a double loop, 'break' won't work as expected. */
#define for_each_process_thread(p, t)   \
        for_each_process(p) for_each_thread(p, t)

typedef int (*proc_visitor)(struct task_struct *p, void *data);
void walk_process_tree(struct task_struct *top, proc_visitor, void *);

static inline int get_nr_threads(struct task_struct *tsk)
{
        return tsk->signal->nr_threads;
}

static inline bool thread_group_leader(struct task_struct *p)
{
        return p->exit_signal >= 0;
}

/* Do to the insanities of de_thread it is possible for a process
 * to have the pid of the thread group leader without actually being
 * the thread group leader.  For iteration through the pids in proc
 * all we care about is that we have a task with the appropriate
 * pid, we don't actually care if we have the right task.
 */
static inline bool has_group_leader_pid(struct task_struct *p)
{
        return task_pid(p) == p->signal->leader_pid;
}

static inline
bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
{
        return p1->signal == p2->signal;
}

static inline struct task_struct *next_thread(const struct task_struct *p)
{
        return list_entry_rcu(p->thread_group.next,
                              struct task_struct, thread_group);
}

static inline int thread_group_empty(struct task_struct *p)
{
        return list_empty(&p->thread_group);
}

#define delay_group_leader(p) \
                (thread_group_leader(p) && !thread_group_empty(p))

extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
                                                        unsigned long *flags);

static inline struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
                                                       unsigned long *flags)
{
        struct sighand_struct *ret;

        ret = __lock_task_sighand(tsk, flags);
        (void)__cond_lock(&tsk->sighand->siglock, ret);
        return ret;
}

static inline void unlock_task_sighand(struct task_struct *tsk,
                                                unsigned long *flags)
{
        spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
}

static inline unsigned long task_rlimit(const struct task_struct *tsk,
                unsigned int limit)
{
        return READ_ONCE(tsk->signal->rlim[limit].rlim_cur);
}

static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
                unsigned int limit)
{
        return READ_ONCE(tsk->signal->rlim[limit].rlim_max);
}

static inline unsigned long rlimit(unsigned int limit)
{
        return task_rlimit(current, limit);
}

static inline unsigned long rlimit_max(unsigned int limit)
{
        return task_rlimit_max(current, limit);
}

#endif /* _LINUX_SCHED_SIGNAL_H */