Merge branch 'ptrace' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc

* 'ptrace' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc: (39 commits)
  ptrace: do_wait(traced_leader_killed_by_mt_exec) can block forever
  ptrace: fix ptrace_signal() && STOP_DEQUEUED interaction
  connector: add an event for monitoring process tracers
  ptrace: dont send SIGSTOP on auto-attach if PT_SEIZED
  ptrace: mv send-SIGSTOP from do_fork() to ptrace_init_task()
  ptrace_init_task: initialize child->jobctl explicitly
  has_stopped_jobs: s/task_is_stopped/SIGNAL_STOP_STOPPED/
  ptrace: make former thread ID available via PTRACE_GETEVENTMSG after PTRACE_EVENT_EXEC stop
  ptrace: wait_consider_task: s/same_thread_group/ptrace_reparented/
  ptrace: kill real_parent_is_ptracer() in in favor of ptrace_reparented()
  ptrace: ptrace_reparented() should check same_thread_group()
  redefine thread_group_leader() as exit_signal >= 0
  do not change dead_task->exit_signal
  kill task_detached()
  reparent_leader: check EXIT_DEAD instead of task_detached()
  make do_notify_parent() __must_check, update the callers
  __ptrace_detach: avoid task_detached(), check do_notify_parent()
  kill tracehook_notify_death()
  make do_notify_parent() return bool
  ptrace: s/tracehook_tracer_task()/ptrace_parent()/
  ...

17 files changed, 674 insertions, 708 deletions

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index a65d2e82f61d..a63d34c3611e 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -331,7 +331,7 @@ void __kprobes do_per_trap(struct pt_regs *regs)
 {
         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
                 return;
-        if (tracehook_consider_fatal_signal(current, SIGTRAP))
+        if (current->ptrace)
                 force_sig(SIGTRAP, current);
 }
 
@@ -425,7 +425,7 @@ static void __kprobes illegal_op(struct pt_regs *regs, long pgm_int_code,
                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
                         return;
                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
-                        if (tracehook_consider_fatal_signal(current, SIGTRAP))
+                        if (current->ptrace)
                                 force_sig(SIGTRAP, current);
                         else
                                 signal = SIGILL;
diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 2b46a7efa0ac..281902d3f7ec 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -28,6 +28,7 @@
 #include <linux/init.h>
 #include <linux/connector.h>
 #include <linux/gfp.h>
+#include <linux/ptrace.h>
 #include <asm/atomic.h>
 #include <asm/unaligned.h>
 
@@ -166,6 +167,40 @@ void proc_sid_connector(struct task_struct *task)
         cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
 }
 
+void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
+{
+        struct cn_msg *msg;
+        struct proc_event *ev;
+        struct timespec ts;
+        __u8 buffer[CN_PROC_MSG_SIZE];
+        struct task_struct *tracer;
+
+        if (atomic_read(&proc_event_num_listeners) < 1)
+                return;
+
+        msg = (struct cn_msg *)buffer;
+        ev = (struct proc_event *)msg->data;
+        get_seq(&msg->seq, &ev->cpu);
+        ktime_get_ts(&ts); /* get high res monotonic timestamp */
+        put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
+        ev->what = PROC_EVENT_PTRACE;
+        ev->event_data.ptrace.process_pid  = task->pid;
+        ev->event_data.ptrace.process_tgid = task->tgid;
+        if (ptrace_id == PTRACE_ATTACH) {
+                ev->event_data.ptrace.tracer_pid  = current->pid;
+                ev->event_data.ptrace.tracer_tgid = current->tgid;
+        } else if (ptrace_id == PTRACE_DETACH) {
+                ev->event_data.ptrace.tracer_pid  = 0;
+                ev->event_data.ptrace.tracer_tgid = 0;
+        } else
+                return;
+
+        memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+        msg->ack = 0; /* not used */
+        msg->len = sizeof(*ev);
+        cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
+}
+
 void proc_exit_connector(struct task_struct *task)
 {
         struct cn_msg *msg;
diff --git a/fs/exec.c b/fs/exec.c
index 6075a1e727ae..d9576f261815 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -963,9 +963,18 @@ static int de_thread(struct task_struct *tsk)
                 leader->group_leader = tsk;
 
                 tsk->exit_signal = SIGCHLD;
+                leader->exit_signal = -1;
 
                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
                 leader->exit_state = EXIT_DEAD;
+
+                /*
+                 * We are going to release_task()->ptrace_unlink() silently,
+                 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
+                 * the tracer wont't block again waiting for this thread.
+                 */
+                if (unlikely(leader->ptrace))
+                        __wake_up_parent(leader, leader->parent);
                 write_unlock_irq(&tasklist_lock);
 
                 release_task(leader);
@@ -1225,7 +1234,12 @@ int check_unsafe_exec(struct linux_binprm *bprm)
         unsigned n_fs;
         int res = 0;
 
-        bprm->unsafe = tracehook_unsafe_exec(p);
+        if (p->ptrace) {
+                if (p->ptrace & PT_PTRACE_CAP)
+                        bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
+                else
+                        bprm->unsafe |= LSM_UNSAFE_PTRACE;
+        }
 
         n_fs = 1;
         spin_lock(&p->fs->lock);
@@ -1353,6 +1367,7 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
         unsigned int depth = bprm->recursion_depth;
         int try,retval;
         struct linux_binfmt *fmt;
+        pid_t old_pid;
 
         retval = security_bprm_check(bprm);
         if (retval)
@@ -1362,6 +1377,11 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
         if (retval)
                 return retval;
 
+        /* Need to fetch pid before load_binary changes it */
+        rcu_read_lock();
+        old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
+        rcu_read_unlock();
+
         retval = -ENOENT;
         for (try=0; try<2; try++) {
                 read_lock(&binfmt_lock);
@@ -1381,7 +1401,8 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
                         bprm->recursion_depth = depth;
                         if (retval >= 0) {
                                 if (depth == 0)
-                                        tracehook_report_exec(fmt, bprm, regs);
+                                        ptrace_event(PTRACE_EVENT_EXEC,
+                                                        old_pid);
                                 put_binfmt(fmt);
                                 allow_write_access(bprm->file);
                                 if (bprm->file)
@@ -1769,7 +1790,7 @@ static int zap_process(struct task_struct *start, int exit_code)
 
         t = start;
         do {
-                task_clear_group_stop_pending(t);
+                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
                 if (t != current && t->mm) {
                         sigaddset(&t->pending.signal, SIGKILL);
                         signal_wake_up(t, 1);
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 9b45ee84fbcc..3a1dafd228d1 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -172,7 +172,7 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
                 task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
         tpid = 0;
         if (pid_alive(p)) {
-                struct task_struct *tracer = tracehook_tracer_task(p);
+                struct task_struct *tracer = ptrace_parent(p);
                 if (tracer)
                         tpid = task_pid_nr_ns(tracer, ns);
         }
diff --git a/fs/proc/base.c b/fs/proc/base.c
index fc5bc2767692..c47719aaadef 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -216,7 +216,7 @@ static struct mm_struct *__check_mem_permission(struct task_struct *task)
         if (task_is_stopped_or_traced(task)) {
                 int match;
                 rcu_read_lock();
-                match = (tracehook_tracer_task(task) == current);
+                match = (ptrace_parent(task) == current);
                 rcu_read_unlock();
                 if (match && ptrace_may_access(task, PTRACE_MODE_ATTACH))
                         return mm;
diff --git a/include/linux/cn_proc.h b/include/linux/cn_proc.h
index 47dac5ea8d3a..12c517b51ca2 100644
--- a/include/linux/cn_proc.h
+++ b/include/linux/cn_proc.h
@@ -53,6 +53,7 @@ struct proc_event {
                 PROC_EVENT_UID  = 0x00000004,
                 PROC_EVENT_GID  = 0x00000040,
                 PROC_EVENT_SID  = 0x00000080,
+                PROC_EVENT_PTRACE = 0x00000100,
                 /* "next" should be 0x00000400 */
                 /* "last" is the last process event: exit */
                 PROC_EVENT_EXIT = 0x80000000
@@ -95,6 +96,13 @@ struct proc_event {
                         __kernel_pid_t process_tgid;
                 } sid;
 
+                struct ptrace_proc_event {
+                        __kernel_pid_t process_pid;
+                        __kernel_pid_t process_tgid;
+                        __kernel_pid_t tracer_pid;
+                        __kernel_pid_t tracer_tgid;
+                } ptrace;
+
                 struct exit_proc_event {
                         __kernel_pid_t process_pid;
                         __kernel_pid_t process_tgid;
@@ -109,6 +117,7 @@ void proc_fork_connector(struct task_struct *task);
 void proc_exec_connector(struct task_struct *task);
 void proc_id_connector(struct task_struct *task, int which_id);
 void proc_sid_connector(struct task_struct *task);
+void proc_ptrace_connector(struct task_struct *task, int which_id);
 void proc_exit_connector(struct task_struct *task);
 #else
 static inline void proc_fork_connector(struct task_struct *task)
@@ -124,6 +133,10 @@ static inline void proc_id_connector(struct task_struct *task,
 static inline void proc_sid_connector(struct task_struct *task)
 {}
 
+static inline void proc_ptrace_connector(struct task_struct *task,
+                                         int ptrace_id)
+{}
+
 static inline void proc_exit_connector(struct task_struct *task)
 {}
 #endif  /* CONFIG_PROC_EVENTS */
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 9178d5cc0b01..800f113bea66 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -47,6 +47,13 @@
 #define PTRACE_GETREGSET        0x4204
 #define PTRACE_SETREGSET        0x4205
 
+#define PTRACE_SEIZE            0x4206
+#define PTRACE_INTERRUPT        0x4207
+#define PTRACE_LISTEN           0x4208
+
+/* flags in @data for PTRACE_SEIZE */
+#define PTRACE_SEIZE_DEVEL      0x80000000 /* temp flag for development */
+
 /* options set using PTRACE_SETOPTIONS */
 #define PTRACE_O_TRACESYSGOOD   0x00000001
 #define PTRACE_O_TRACEFORK      0x00000002
@@ -65,6 +72,7 @@
 #define PTRACE_EVENT_EXEC       4
 #define PTRACE_EVENT_VFORK_DONE 5
 #define PTRACE_EVENT_EXIT       6
+#define PTRACE_EVENT_STOP       7
 
 #include <asm/ptrace.h>
 
@@ -77,16 +85,22 @@
  * flags.  When the a task is stopped the ptracer owns task->ptrace.
  */
 
+#define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
 #define PT_PTRACED      0x00000001
 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
 #define PT_TRACESYSGOOD 0x00000004
 #define PT_PTRACE_CAP   0x00000008      /* ptracer can follow suid-exec */
-#define PT_TRACE_FORK   0x00000010
-#define PT_TRACE_VFORK  0x00000020
-#define PT_TRACE_CLONE  0x00000040
-#define PT_TRACE_EXEC   0x00000080
-#define PT_TRACE_VFORK_DONE     0x00000100
-#define PT_TRACE_EXIT   0x00000200
+
+/* PT_TRACE_* event enable flags */
+#define PT_EVENT_FLAG_SHIFT     4
+#define PT_EVENT_FLAG(event)    (1 << (PT_EVENT_FLAG_SHIFT + (event) - 1))
+
+#define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
+#define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
+#define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
+#define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
+#define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
+#define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
 
 #define PT_TRACE_MASK   0x000003f4
 
@@ -105,7 +119,7 @@ extern long arch_ptrace(struct task_struct *child, long request,
 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
 extern void ptrace_disable(struct task_struct *);
-extern int ptrace_check_attach(struct task_struct *task, int kill);
+extern int ptrace_check_attach(struct task_struct *task, bool ignore_state);
 extern int ptrace_request(struct task_struct *child, long request,
                           unsigned long addr, unsigned long data);
 extern void ptrace_notify(int exit_code);
@@ -122,7 +136,7 @@ extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
 
 static inline int ptrace_reparented(struct task_struct *child)
 {
-        return child->real_parent != child->parent;
+        return !same_thread_group(child->real_parent, child->parent);
 }
 
 static inline void ptrace_unlink(struct task_struct *child)
@@ -137,36 +151,56 @@ int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
                             unsigned long data);
 
 /**
- * task_ptrace - return %PT_* flags that apply to a task
- * @task:       pointer to &task_struct in question
+ * ptrace_parent - return the task that is tracing the given task
+ * @task: task to consider
  *
- * Returns the %PT_* flags that apply to @task.
+ * Returns %NULL if no one is tracing @task, or the &struct task_struct
+ * pointer to its tracer.
+ *
+ * Must called under rcu_read_lock().  The pointer returned might be kept
+ * live only by RCU.  During exec, this may be called with task_lock() held
+ * on @task, still held from when check_unsafe_exec() was called.
  */
-static inline int task_ptrace(struct task_struct *task)
+static inline struct task_struct *ptrace_parent(struct task_struct *task)
 {
-        return task->ptrace;
+        if (unlikely(task->ptrace))
+                return rcu_dereference(task->parent);
+        return NULL;
+}
+
+/**
+ * ptrace_event_enabled - test whether a ptrace event is enabled
+ * @task: ptracee of interest
+ * @event: %PTRACE_EVENT_* to test
+ *
+ * Test whether @event is enabled for ptracee @task.
+ *
+ * Returns %true if @event is enabled, %false otherwise.
+ */
+static inline bool ptrace_event_enabled(struct task_struct *task, int event)
+{
+        return task->ptrace & PT_EVENT_FLAG(event);
 }
 
 /**
  * ptrace_event - possibly stop for a ptrace event notification
- * @mask:       %PT_* bit to check in @current->ptrace
- * @event:      %PTRACE_EVENT_* value to report if @mask is set
+ * @event:      %PTRACE_EVENT_* value to report
  * @message:    value for %PTRACE_GETEVENTMSG to return
  *
- * This checks the @mask bit to see if ptrace wants stops for this event.
- * If so we stop, reporting @event and @message to the ptrace parent.
- *
- * Returns nonzero if we did a ptrace notification, zero if not.
+ * Check whether @event is enabled and, if so, report @event and @message
+ * to the ptrace parent.
  *
  * Called without locks.
  */
-static inline int ptrace_event(int mask, int event, unsigned long message)
+static inline void ptrace_event(int event, unsigned long message)
 {
-        if (mask && likely(!(current->ptrace & mask)))
-                return 0;
-        current->ptrace_message = message;
-        ptrace_notify((event << 8) | SIGTRAP);
-        return 1;
+        if (unlikely(ptrace_event_enabled(current, event))) {
+                current->ptrace_message = message;
+                ptrace_notify((event << 8) | SIGTRAP);
+        } else if (event == PTRACE_EVENT_EXEC && unlikely(current->ptrace)) {
+                /* legacy EXEC report via SIGTRAP */
+                send_sig(SIGTRAP, current, 0);
+        }
 }
 
 /**
@@ -183,16 +217,24 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 {
         INIT_LIST_HEAD(&child->ptrace_entry);
         INIT_LIST_HEAD(&child->ptraced);
-        child->parent = child->real_parent;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+        atomic_set(&child->ptrace_bp_refcnt, 1);
+#endif
+        child->jobctl = 0;
         child->ptrace = 0;
-        if (unlikely(ptrace) && (current->ptrace & PT_PTRACED)) {
+        child->parent = child->real_parent;
+
+        if (unlikely(ptrace) && current->ptrace) {
                 child->ptrace = current->ptrace;
                 __ptrace_link(child, current->parent);
-        }
 
-#ifdef CONFIG_HAVE_HW_BREAKPOINT
-        atomic_set(&child->ptrace_bp_refcnt, 1);
-#endif
+                if (child->ptrace & PT_SEIZED)
+                        task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
+                else
+                        sigaddset(&child->pending.signal, SIGSTOP);
+
+                set_tsk_thread_flag(child, TIF_SIGPENDING);
+        }
 }
 
 /**
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 14a6c7b545de..f6ef727ee4fc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1292,7 +1292,7 @@ struct task_struct {
         int exit_state;
         int exit_code, exit_signal;
         int pdeath_signal;  /*  The signal sent when the parent dies  */
-        unsigned int group_stop;        /* GROUP_STOP_*, siglock protected */
+        unsigned int jobctl;    /* JOBCTL_*, siglock protected */
         /* ??? */
         unsigned int personality;
         unsigned did_exec:1;
@@ -1813,15 +1813,34 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 #define used_math() tsk_used_math(current)
 
 /*
- * task->group_stop flags
+ * task->jobctl flags
  */
-#define GROUP_STOP_SIGMASK      0xffff    /* signr of the last group stop */
-#define GROUP_STOP_PENDING      (1 << 16) /* task should stop for group stop */
-#define GROUP_STOP_CONSUME      (1 << 17) /* consume group stop count */
-#define GROUP_STOP_TRAPPING     (1 << 18) /* switching from STOPPED to TRACED */
-#define GROUP_STOP_DEQUEUED     (1 << 19) /* stop signal dequeued */
-
-extern void task_clear_group_stop_pending(struct task_struct *task);
+#define JOBCTL_STOP_SIGMASK     0xffff  /* signr of the last group stop */
+
+#define JOBCTL_STOP_DEQUEUED_BIT 16     /* stop signal dequeued */
+#define JOBCTL_STOP_PENDING_BIT 17      /* task should stop for group stop */
+#define JOBCTL_STOP_CONSUME_BIT 18      /* consume group stop count */
+#define JOBCTL_TRAP_STOP_BIT    19      /* trap for STOP */
+#define JOBCTL_TRAP_NOTIFY_BIT  20      /* trap for NOTIFY */
+#define JOBCTL_TRAPPING_BIT     21      /* switching to TRACED */
+#define JOBCTL_LISTENING_BIT    22      /* ptracer is listening for events */
+
+#define JOBCTL_STOP_DEQUEUED    (1 << JOBCTL_STOP_DEQUEUED_BIT)
+#define JOBCTL_STOP_PENDING     (1 << JOBCTL_STOP_PENDING_BIT)
+#define JOBCTL_STOP_CONSUME     (1 << JOBCTL_STOP_CONSUME_BIT)
+#define JOBCTL_TRAP_STOP        (1 << JOBCTL_TRAP_STOP_BIT)
+#define JOBCTL_TRAP_NOTIFY      (1 << JOBCTL_TRAP_NOTIFY_BIT)
+#define JOBCTL_TRAPPING         (1 << JOBCTL_TRAPPING_BIT)
+#define JOBCTL_LISTENING        (1 << JOBCTL_LISTENING_BIT)
+
+#define JOBCTL_TRAP_MASK        (JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY)
+#define JOBCTL_PENDING_MASK     (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK)
+
+extern bool task_set_jobctl_pending(struct task_struct *task,
+                                    unsigned int mask);
+extern void task_clear_jobctl_trapping(struct task_struct *task);
+extern void task_clear_jobctl_pending(struct task_struct *task,
+                                      unsigned int mask);
 
 #ifdef CONFIG_PREEMPT_RCU
 
@@ -2136,7 +2155,7 @@ static inline int dequeue_signal_lock(struct task_struct *tsk, sigset_t *mask, s
         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 
         return ret;
-}       
+}
 
 extern void block_all_signals(int (*notifier)(void *priv), void *priv,
                               sigset_t *mask);
@@ -2151,7 +2170,7 @@ extern int kill_pid_info_as_uid(int, struct siginfo *, struct pid *, uid_t, uid_
 extern int kill_pgrp(struct pid *pid, int sig, int priv);
 extern int kill_pid(struct pid *pid, int sig, int priv);
 extern int kill_proc_info(int, struct siginfo *, pid_t);
-extern int do_notify_parent(struct task_struct *, int);
+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);
@@ -2275,8 +2294,10 @@ static inline int get_nr_threads(struct task_struct *tsk)
         return tsk->signal->nr_threads;
 }
 
-/* de_thread depends on thread_group_leader not being a pid based check */
-#define thread_group_leader(p)  (p == p->group_leader)
+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
@@ -2309,11 +2330,6 @@ static inline int thread_group_empty(struct task_struct *p)
 #define delay_group_leader(p) \
                 (thread_group_leader(p) && !thread_group_empty(p))
 
-static inline int task_detached(struct task_struct *p)
-{
-        return p->exit_signal == -1;
-}
-
 /*
  * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
  * subscriptions and synchronises with wait4().  Also used in procfs.  Also
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index e95f5236611f..a71a2927a6a0 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -51,27 +51,12 @@
 #include <linux/security.h>
 struct linux_binprm;
 
-/**
- * tracehook_expect_breakpoints - guess if task memory might be touched
- * @task:               current task, making a new mapping
- *
- * Return nonzero if @task is expected to want breakpoint insertion in
- * its memory at some point.  A zero return is no guarantee it won't
- * be done, but this is a hint that it's known to be likely.
- *
- * May be called with @task->mm->mmap_sem held for writing.
- */
-static inline int tracehook_expect_breakpoints(struct task_struct *task)
-{
-        return (task_ptrace(task) & PT_PTRACED) != 0;
-}
-
 /*
  * ptrace report for syscall entry and exit looks identical.
  */
 static inline void ptrace_report_syscall(struct pt_regs *regs)
 {
-        int ptrace = task_ptrace(current);
+        int ptrace = current->ptrace;
 
         if (!(ptrace & PT_PTRACED))
                 return;
@@ -145,229 +130,6 @@ static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
 }
 
 /**
- * tracehook_unsafe_exec - check for exec declared unsafe due to tracing
- * @task:               current task doing exec
- *
- * Return %LSM_UNSAFE_* bits applied to an exec because of tracing.
- *
- * @task->signal->cred_guard_mutex is held by the caller through the do_execve().
- */
-static inline int tracehook_unsafe_exec(struct task_struct *task)
-{
-        int unsafe = 0;
-        int ptrace = task_ptrace(task);
-        if (ptrace & PT_PTRACED) {
-                if (ptrace & PT_PTRACE_CAP)
-                        unsafe |= LSM_UNSAFE_PTRACE_CAP;
-                else
-                        unsafe |= LSM_UNSAFE_PTRACE;
-        }
-        return unsafe;
-}
-
-/**
- * tracehook_tracer_task - return the task that is tracing the given task
- * @tsk:                task to consider
- *
- * Returns NULL if no one is tracing @task, or the &struct task_struct
- * pointer to its tracer.
- *
- * Must called under rcu_read_lock().  The pointer returned might be kept
- * live only by RCU.  During exec, this may be called with task_lock()
- * held on @task, still held from when tracehook_unsafe_exec() was called.
- */
-static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk)
-{
-        if (task_ptrace(tsk) & PT_PTRACED)
-                return rcu_dereference(tsk->parent);
-        return NULL;
-}
-
-/**
- * tracehook_report_exec - a successful exec was completed
- * @fmt:                &struct linux_binfmt that performed the exec
- * @bprm:               &struct linux_binprm containing exec details
- * @regs:               user-mode register state
- *
- * An exec just completed, we are shortly going to return to user mode.
- * The freshly initialized register state can be seen and changed in @regs.
- * The name, file and other pointers in @bprm are still on hand to be
- * inspected, but will be freed as soon as this returns.
- *
- * Called with no locks, but with some kernel resources held live
- * and a reference on @fmt->module.
- */
-static inline void tracehook_report_exec(struct linux_binfmt *fmt,
-                                         struct linux_binprm *bprm,
-                                         struct pt_regs *regs)
-{
-        if (!ptrace_event(PT_TRACE_EXEC, PTRACE_EVENT_EXEC, 0) &&
-            unlikely(task_ptrace(current) & PT_PTRACED))
-                send_sig(SIGTRAP, current, 0);
-}
-
-/**
- * tracehook_report_exit - task has begun to exit
- * @exit_code:          pointer to value destined for @current->exit_code
- *
- * @exit_code points to the value passed to do_exit(), which tracing
- * might change here.  This is almost the first thing in do_exit(),
- * before freeing any resources or setting the %PF_EXITING flag.
- *
- * Called with no locks held.
- */
-static inline void tracehook_report_exit(long *exit_code)
-{
-        ptrace_event(PT_TRACE_EXIT, PTRACE_EVENT_EXIT, *exit_code);
-}
-
-/**
- * tracehook_prepare_clone - prepare for new child to be cloned
- * @clone_flags:        %CLONE_* flags from clone/fork/vfork system call
- *
- * This is called before a new user task is to be cloned.
- * Its return value will be passed to tracehook_finish_clone().
- *
- * Called with no locks held.
- */
-static inline int tracehook_prepare_clone(unsigned clone_flags)
-{
-        if (clone_flags & CLONE_UNTRACED)
-                return 0;
-
-        if (clone_flags & CLONE_VFORK) {
-                if (current->ptrace & PT_TRACE_VFORK)
-                        return PTRACE_EVENT_VFORK;
-        } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
-                if (current->ptrace & PT_TRACE_CLONE)
-                        return PTRACE_EVENT_CLONE;
-        } else if (current->ptrace & PT_TRACE_FORK)
-                return PTRACE_EVENT_FORK;
-
-        return 0;
-}
-
-/**
- * tracehook_finish_clone - new child created and being attached
- * @child:              new child task
- * @clone_flags:        %CLONE_* flags from clone/fork/vfork system call
- * @trace:              return value from tracehook_prepare_clone()
- *
- * This is called immediately after adding @child to its parent's children list.
- * The @trace value is that returned by tracehook_prepare_clone().
- *
- * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
- */
-static inline void tracehook_finish_clone(struct task_struct *child,
-                                          unsigned long clone_flags, int trace)
-{
-        ptrace_init_task(child, (clone_flags & CLONE_PTRACE) || trace);
-}
-
-/**
- * tracehook_report_clone - in parent, new child is about to start running
- * @regs:               parent's user register state
- * @clone_flags:        flags from parent's system call
- * @pid:                new child's PID in the parent's namespace
- * @child:              new child task
- *
- * Called after a child is set up, but before it has been started running.
- * This is not a good place to block, because the child has not started
- * yet.  Suspend the child here if desired, and then block in
- * tracehook_report_clone_complete().  This must prevent the child from
- * self-reaping if tracehook_report_clone_complete() uses the @child
- * pointer; otherwise it might have died and been released by the time
- * tracehook_report_clone_complete() is called.
- *
- * Called with no locks held, but the child cannot run until this returns.
- */
-static inline void tracehook_report_clone(struct pt_regs *regs,
-                                          unsigned long clone_flags,
-                                          pid_t pid, struct task_struct *child)
-{
-        if (unlikely(task_ptrace(child))) {
-                /*
-                 * It doesn't matter who attached/attaching to this
-                 * task, the pending SIGSTOP is right in any case.
-                 */
-                sigaddset(&child->pending.signal, SIGSTOP);
-                set_tsk_thread_flag(child, TIF_SIGPENDING);
-        }
-}
-
-/**
- * tracehook_report_clone_complete - new child is running
- * @trace:              return value from tracehook_prepare_clone()
- * @regs:               parent's user register state
- * @clone_flags:        flags from parent's system call
- * @pid:                new child's PID in the parent's namespace
- * @child:              child task, already running
- *
- * This is called just after the child has started running.  This is
- * just before the clone/fork syscall returns, or blocks for vfork
- * child completion if @clone_flags has the %CLONE_VFORK bit set.
- * The @child pointer may be invalid if a self-reaping child died and
- * tracehook_report_clone() took no action to prevent it from self-reaping.
- *
- * Called with no locks held.
- */
-static inline void tracehook_report_clone_complete(int trace,
-                                                   struct pt_regs *regs,
-                                                   unsigned long clone_flags,
-                                                   pid_t pid,
-                                                   struct task_struct *child)
-{
-        if (unlikely(trace))
-                ptrace_event(0, trace, pid);
-}
-
-/**
- * tracehook_report_vfork_done - vfork parent's child has exited or exec'd
- * @child:              child task, already running
- * @pid:                new child's PID in the parent's namespace
- *
- * Called after a %CLONE_VFORK parent has waited for the child to complete.
- * The clone/vfork system call will return immediately after this.
- * The @child pointer may be invalid if a self-reaping child died and
- * tracehook_report_clone() took no action to prevent it from self-reaping.
- *
- * Called with no locks held.
- */
-static inline void tracehook_report_vfork_done(struct task_struct *child,
-                                               pid_t pid)
-{
-        ptrace_event(PT_TRACE_VFORK_DONE, PTRACE_EVENT_VFORK_DONE, pid);
-}
-
-/**
- * tracehook_prepare_release_task - task is being reaped, clean up tracing
- * @task:               task in %EXIT_DEAD state
- *
- * This is called in release_task() just before @task gets finally reaped
- * and freed.  This would be the ideal place to remove and clean up any
- * tracing-related state for @task.
- *
- * Called with no locks held.
- */
-static inline void tracehook_prepare_release_task(struct task_struct *task)
-{
-}
-
-/**
- * tracehook_finish_release_task - final tracing clean-up
- * @task:               task in %EXIT_DEAD state
- *
- * This is called in release_task() when @task is being in the middle of
- * being reaped.  After this, there must be no tracing entanglements.
- *
- * Called with write_lock_irq(&tasklist_lock) held.
- */
-static inline void tracehook_finish_release_task(struct task_struct *task)
-{
-        ptrace_release_task(task);
-}
-
-/**
  * tracehook_signal_handler - signal handler setup is complete
  * @sig:                number of signal being delivered
  * @info:               siginfo_t of signal being delivered
@@ -390,151 +152,6 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info,
                 ptrace_notify(SIGTRAP);
 }
 
-/**
- * tracehook_consider_ignored_signal - suppress short-circuit of ignored signal
- * @task:               task receiving the signal
- * @sig:                signal number being sent
- *
- * Return zero iff tracing doesn't care to examine this ignored signal,
- * so it can short-circuit normal delivery and never even get queued.
- *
- * Called with @task->sighand->siglock held.
- */
-static inline int tracehook_consider_ignored_signal(struct task_struct *task,
-                                                    int sig)
-{
-        return (task_ptrace(task) & PT_PTRACED) != 0;
-}
-
-/**
- * tracehook_consider_fatal_signal - suppress special handling of fatal signal
- * @task:               task receiving the signal
- * @sig:                signal number being sent
- *
- * Return nonzero to prevent special handling of this termination signal.
- * Normally handler for signal is %SIG_DFL.  It can be %SIG_IGN if @sig is
- * ignored, in which case force_sig() is about to reset it to %SIG_DFL.
- * When this returns zero, this signal might cause a quick termination
- * that does not give the debugger a chance to intercept the signal.
- *
- * Called with or without @task->sighand->siglock held.
- */
-static inline int tracehook_consider_fatal_signal(struct task_struct *task,
-                                                  int sig)
-{
-        return (task_ptrace(task) & PT_PTRACED) != 0;
-}
-
-/**
- * tracehook_force_sigpending - let tracing force signal_pending(current) on
- *
- * Called when recomputing our signal_pending() flag.  Return nonzero
- * to force the signal_pending() flag on, so that tracehook_get_signal()
- * will be called before the next return to user mode.
- *
- * Called with @current->sighand->siglock held.
- */
-static inline int tracehook_force_sigpending(void)
-{
-        return 0;
-}
-
-/**
- * tracehook_get_signal - deliver synthetic signal to traced task
- * @task:               @current
- * @regs:               task_pt_regs(@current)
- * @info:               details of synthetic signal
- * @return_ka:          sigaction for synthetic signal
- *
- * Return zero to check for a real pending signal normally.
- * Return -1 after releasing the siglock to repeat the check.
- * Return a signal number to induce an artificial signal delivery,
- * setting *@info and *@return_ka to specify its details and behavior.
- *
- * The @return_ka->sa_handler value controls the disposition of the
- * signal, no matter the signal number.  For %SIG_DFL, the return value
- * is a representative signal to indicate the behavior (e.g. %SIGTERM
- * for death, %SIGQUIT for core dump, %SIGSTOP for job control stop,
- * %SIGTSTP for stop unless in an orphaned pgrp), but the signal number
- * reported will be @info->si_signo instead.
- *
- * Called with @task->sighand->siglock held, before dequeuing pending signals.
- */
-static inline int tracehook_get_signal(struct task_struct *task,
-                                       struct pt_regs *regs,
-                                       siginfo_t *info,
-                                       struct k_sigaction *return_ka)
-{
-        return 0;
-}
-
-/**
- * tracehook_finish_jctl - report about return from job control stop
- *
- * This is called by do_signal_stop() after wakeup.
- */
-static inline void tracehook_finish_jctl(void)
-{
-}
-
-#define DEATH_REAP                      -1
-#define DEATH_DELAYED_GROUP_LEADER      -2
-
-/**
- * tracehook_notify_death - task is dead, ready to notify parent
- * @task:               @current task now exiting
- * @death_cookie:       value to pass to tracehook_report_death()
- * @group_dead:         nonzero if this was the last thread in the group to die
- *
- * A return value >= 0 means call do_notify_parent() with that signal
- * number.  Negative return value can be %DEATH_REAP to self-reap right
- * now, or %DEATH_DELAYED_GROUP_LEADER to a zombie without notifying our
- * parent.  Note that a return value of 0 means a do_notify_parent() call
- * that sends no signal, but still wakes up a parent blocked in wait*().
- *
- * Called with write_lock_irq(&tasklist_lock) held.
- */
-static inline int tracehook_notify_death(struct task_struct *task,
-                                         void **death_cookie, int group_dead)
-{
-        if (task_detached(task))
-                return task->ptrace ? SIGCHLD : DEATH_REAP;
-
-        /*
-         * If something other than our normal parent is ptracing us, then
-         * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
-         * only has special meaning to our real parent.
-         */
-        if (thread_group_empty(task) && !ptrace_reparented(task))
-                return task->exit_signal;
-
-        return task->ptrace ? SIGCHLD : DEATH_DELAYED_GROUP_LEADER;
-}
-
-/**
- * tracehook_report_death - task is dead and ready to be reaped
- * @task:               @current task now exiting
- * @signal:             return value from tracheook_notify_death()
- * @death_cookie:       value passed back from tracehook_notify_death()
- * @group_dead:         nonzero if this was the last thread in the group to die
- *
- * Thread has just become a zombie or is about to self-reap.  If positive,
- * @signal is the signal number just sent to the parent (usually %SIGCHLD).
- * If @signal is %DEATH_REAP, this thread will self-reap.  If @signal is
- * %DEATH_DELAYED_GROUP_LEADER, this is a delayed_group_leader() zombie.
- * The @death_cookie was passed back by tracehook_notify_death().
- *
- * If normal reaping is not inhibited, @task->exit_state might be changing
- * in parallel.
- *
- * Called without locks.
- */
-static inline void tracehook_report_death(struct task_struct *task,
-                                          int signal, void *death_cookie,
-                                          int group_dead)
-{
-}
-
 #ifdef TIF_NOTIFY_RESUME
 /**
  * set_notify_resume - cause tracehook_notify_resume() to be called
diff --git a/kernel/exit.c b/kernel/exit.c
index f2b321bae440..73bb192a3d32 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -169,7 +169,6 @@ void release_task(struct task_struct * p)
         struct task_struct *leader;
         int zap_leader;
 repeat:
-        tracehook_prepare_release_task(p);
         /* don't need to get the RCU readlock here - the process is dead and
          * can't be modifying its own credentials. But shut RCU-lockdep up */
         rcu_read_lock();
@@ -179,7 +178,7 @@ repeat:
         proc_flush_task(p);
 
         write_lock_irq(&tasklist_lock);
-        tracehook_finish_release_task(p);
+        ptrace_release_task(p);
         __exit_signal(p);
 
         /*
@@ -190,22 +189,12 @@ repeat:
         zap_leader = 0;
         leader = p->group_leader;
         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
-                BUG_ON(task_detached(leader));
-                do_notify_parent(leader, leader->exit_signal);
                 /*
                  * If we were the last child thread and the leader has
                  * exited already, and the leader's parent ignores SIGCHLD,
                  * then we are the one who should release the leader.
-                 *
-                 * do_notify_parent() will have marked it self-reaping in
-                 * that case.
-                 */
-                zap_leader = task_detached(leader);
-
-                /*
-                 * This maintains the invariant that release_task()
-                 * only runs on a task in EXIT_DEAD, just for sanity.
                  */
+                zap_leader = do_notify_parent(leader, leader->exit_signal);
                 if (zap_leader)
                         leader->exit_state = EXIT_DEAD;
         }
@@ -277,18 +266,16 @@ int is_current_pgrp_orphaned(void)
         return retval;
 }
 
-static int has_stopped_jobs(struct pid *pgrp)
+static bool has_stopped_jobs(struct pid *pgrp)
 {
-        int retval = 0;
         struct task_struct *p;
 
         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
-                if (!task_is_stopped(p))
-                        continue;
-                retval = 1;
-                break;
+                if (p->signal->flags & SIGNAL_STOP_STOPPED)
+                        return true;
         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
-        return retval;
+
+        return false;
 }
 
 /*
@@ -751,7 +738,7 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
 {
         list_move_tail(&p->sibling, &p->real_parent->children);
 
-        if (task_detached(p))
+        if (p->exit_state == EXIT_DEAD)
                 return;
         /*
          * If this is a threaded reparent there is no need to
@@ -764,10 +751,9 @@ static void reparent_leader(struct task_struct *father, struct task_struct *p,
         p->exit_signal = SIGCHLD;
 
         /* If it has exited notify the new parent about this child's death. */
-        if (!task_ptrace(p) &&
+        if (!p->ptrace &&
             p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
-                do_notify_parent(p, p->exit_signal);
-                if (task_detached(p)) {
+                if (do_notify_parent(p, p->exit_signal)) {
                         p->exit_state = EXIT_DEAD;
                         list_move_tail(&p->sibling, dead);
                 }
@@ -794,7 +780,7 @@ static void forget_original_parent(struct task_struct *father)
                 do {
                         t->real_parent = reaper;
                         if (t->parent == father) {
-                                BUG_ON(task_ptrace(t));
+                                BUG_ON(t->ptrace);
                                 t->parent = t->real_parent;
                         }
                         if (t->pdeath_signal)
@@ -819,8 +805,7 @@ static void forget_original_parent(struct task_struct *father)
  */
 static void exit_notify(struct task_struct *tsk, int group_dead)
 {
-        int signal;
-        void *cookie;
+        bool autoreap;
 
         /*
          * This does two things:
@@ -851,26 +836,33 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
          * we have changed execution domain as these two values started
          * the same after a fork.
          */
-        if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
+        if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD &&
             (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
              tsk->self_exec_id != tsk->parent_exec_id))
                 tsk->exit_signal = SIGCHLD;
 
-        signal = tracehook_notify_death(tsk, &cookie, group_dead);
-        if (signal >= 0)
-                signal = do_notify_parent(tsk, signal);
+        if (unlikely(tsk->ptrace)) {
+                int sig = thread_group_leader(tsk) &&
+                                thread_group_empty(tsk) &&
+                                !ptrace_reparented(tsk) ?
+                        tsk->exit_signal : SIGCHLD;
+                autoreap = do_notify_parent(tsk, sig);
+        } else if (thread_group_leader(tsk)) {
+                autoreap = thread_group_empty(tsk) &&
+                        do_notify_parent(tsk, tsk->exit_signal);
+        } else {
+                autoreap = true;
+        }
 
-        tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
+        tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
 
         /* mt-exec, de_thread() is waiting for group leader */
         if (unlikely(tsk->signal->notify_count < 0))
                 wake_up_process(tsk->signal->group_exit_task);
         write_unlock_irq(&tasklist_lock);
 
-        tracehook_report_death(tsk, signal, cookie, group_dead);
-
         /* If the process is dead, release it - nobody will wait for it */
-        if (signal == DEATH_REAP)
+        if (autoreap)
                 release_task(tsk);
 }
 
@@ -923,7 +915,7 @@ NORET_TYPE void do_exit(long code)
          */
         set_fs(USER_DS);
 
-        tracehook_report_exit(&code);
+        ptrace_event(PTRACE_EVENT_EXIT, code);
 
         validate_creds_for_do_exit(tsk);
 
@@ -1235,9 +1227,9 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
         traced = ptrace_reparented(p);
         /*
          * It can be ptraced but not reparented, check
-         * !task_detached() to filter out sub-threads.
+         * thread_group_leader() to filter out sub-threads.
          */
-        if (likely(!traced) && likely(!task_detached(p))) {
+        if (likely(!traced) && thread_group_leader(p)) {
                 struct signal_struct *psig;
                 struct signal_struct *sig;
                 unsigned long maxrss;
@@ -1345,16 +1337,13 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
                 /* We dropped tasklist, ptracer could die and untrace */
                 ptrace_unlink(p);
                 /*
-                 * If this is not a detached task, notify the parent.
-                 * If it's still not detached after that, don't release
-                 * it now.
+                 * If this is not a sub-thread, notify the parent.
+                 * If parent wants a zombie, don't release it now.
                  */
-                if (!task_detached(p)) {
-                        do_notify_parent(p, p->exit_signal);
-                        if (!task_detached(p)) {
-                                p->exit_state = EXIT_ZOMBIE;
-                                p = NULL;
-                        }
+                if (thread_group_leader(p) &&
+                    !do_notify_parent(p, p->exit_signal)) {
+                        p->exit_state = EXIT_ZOMBIE;
+                        p = NULL;
                 }
                 write_unlock_irq(&tasklist_lock);
         }
@@ -1367,7 +1356,8 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 static int *task_stopped_code(struct task_struct *p, bool ptrace)
 {
         if (ptrace) {
-                if (task_is_stopped_or_traced(p))
+                if (task_is_stopped_or_traced(p) &&
+                    !(p->jobctl & JOBCTL_LISTENING))
                         return &p->exit_code;
         } else {
                 if (p->signal->flags & SIGNAL_STOP_STOPPED)
@@ -1563,7 +1553,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
                  * Notification and reaping will be cascaded to the real
                  * parent when the ptracer detaches.
                  */
-                if (likely(!ptrace) && unlikely(task_ptrace(p))) {
+                if (likely(!ptrace) && unlikely(p->ptrace)) {
                         /* it will become visible, clear notask_error */
                         wo->notask_error = 0;
                         return 0;
@@ -1606,8 +1596,7 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
                  * own children, it should create a separate process which
                  * takes the role of real parent.
                  */
-                if (likely(!ptrace) && task_ptrace(p) &&
-                    same_thread_group(p->parent, p->real_parent))
+                if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p))
                         return 0;
 
                 /*
diff --git a/kernel/fork.c b/kernel/fork.c
index 0276c30401a0..4d4117e01504 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -37,7 +37,6 @@
 #include <linux/swap.h>
 #include <linux/syscalls.h>
 #include <linux/jiffies.h>
-#include <linux/tracehook.h>
 #include <linux/futex.h>
 #include <linux/compat.h>
 #include <linux/kthread.h>
@@ -1340,7 +1339,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         }
 
         if (likely(p->pid)) {
-                tracehook_finish_clone(p, clone_flags, trace);
+                ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
 
                 if (thread_group_leader(p)) {
                         if (is_child_reaper(pid))
@@ -1481,10 +1480,22 @@ long do_fork(unsigned long clone_flags,
         }
 
         /*
-         * When called from kernel_thread, don't do user tracing stuff.
+         * Determine whether and which event to report to ptracer.  When
+         * called from kernel_thread or CLONE_UNTRACED is explicitly
+         * requested, no event is reported; otherwise, report if the event
+         * for the type of forking is enabled.
          */
-        if (likely(user_mode(regs)))
-                trace = tracehook_prepare_clone(clone_flags);
+        if (likely(user_mode(regs)) && !(clone_flags & CLONE_UNTRACED)) {
+                if (clone_flags & CLONE_VFORK)
+                        trace = PTRACE_EVENT_VFORK;
+                else if ((clone_flags & CSIGNAL) != SIGCHLD)
+                        trace = PTRACE_EVENT_CLONE;
+                else
+                        trace = PTRACE_EVENT_FORK;
+
+                if (likely(!ptrace_event_enabled(current, trace)))
+                        trace = 0;
+        }
 
         p = copy_process(clone_flags, stack_start, regs, stack_size,
                          child_tidptr, NULL, trace);
@@ -1508,26 +1519,26 @@ long do_fork(unsigned long clone_flags,
                 }
 
                 audit_finish_fork(p);
-                tracehook_report_clone(regs, clone_flags, nr, p);
 
                 /*
                  * We set PF_STARTING at creation in case tracing wants to
                  * use this to distinguish a fully live task from one that
-                 * hasn't gotten to tracehook_report_clone() yet.  Now we
-                 * clear it and set the child going.
+                 * hasn't finished SIGSTOP raising yet.  Now we clear it
+                 * and set the child going.
                  */
                 p->flags &= ~PF_STARTING;
 
                 wake_up_new_task(p);
 
-                tracehook_report_clone_complete(trace, regs,
-                                                clone_flags, nr, p);
+                /* forking complete and child started to run, tell ptracer */
+                if (unlikely(trace))
+                        ptrace_event(trace, nr);
 
                 if (clone_flags & CLONE_VFORK) {
                         freezer_do_not_count();
                         wait_for_completion(&vfork);
                         freezer_count();
-                        tracehook_report_vfork_done(p, nr);
+                        ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
                 }
         } else {
                 nr = PTR_ERR(p);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 2df115790cd9..9de3ecfd20f9 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -23,8 +23,15 @@
 #include <linux/uaccess.h>
 #include <linux/regset.h>
 #include <linux/hw_breakpoint.h>
+#include <linux/cn_proc.h>
 
 
+static int ptrace_trapping_sleep_fn(void *flags)
+{
+        schedule();
+        return 0;
+}
+
 /*
  * ptrace a task: make the debugger its new parent and
  * move it to the ptrace list.
@@ -77,13 +84,20 @@ void __ptrace_unlink(struct task_struct *child)
         spin_lock(&child->sighand->siglock);
 
         /*
-         * Reinstate GROUP_STOP_PENDING if group stop is in effect and
+         * Clear all pending traps and TRAPPING.  TRAPPING should be
+         * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
+         */
+        task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
+        task_clear_jobctl_trapping(child);
+
+        /*
+         * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
          * @child isn't dead.
          */
         if (!(child->flags & PF_EXITING) &&
             (child->signal->flags & SIGNAL_STOP_STOPPED ||
              child->signal->group_stop_count))
-                child->group_stop |= GROUP_STOP_PENDING;
+                child->jobctl |= JOBCTL_STOP_PENDING;
 
         /*
          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
@@ -91,16 +105,30 @@ void __ptrace_unlink(struct task_struct *child)
          * is in TASK_TRACED; otherwise, we might unduly disrupt
          * TASK_KILLABLE sleeps.
          */
-        if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
+        if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
                 signal_wake_up(child, task_is_traced(child));
 
         spin_unlock(&child->sighand->siglock);
 }
 
-/*
- * Check that we have indeed attached to the thing..
+/**
+ * ptrace_check_attach - check whether ptracee is ready for ptrace operation
+ * @child: ptracee to check for
+ * @ignore_state: don't check whether @child is currently %TASK_TRACED
+ *
+ * Check whether @child is being ptraced by %current and ready for further
+ * ptrace operations.  If @ignore_state is %false, @child also should be in
+ * %TASK_TRACED state and on return the child is guaranteed to be traced
+ * and not executing.  If @ignore_state is %true, @child can be in any
+ * state.
+ *
+ * CONTEXT:
+ * Grabs and releases tasklist_lock and @child->sighand->siglock.
+ *
+ * RETURNS:
+ * 0 on success, -ESRCH if %child is not ready.
  */
-int ptrace_check_attach(struct task_struct *child, int kill)
+int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 {
         int ret = -ESRCH;
 
@@ -119,13 +147,14 @@ int ptrace_check_attach(struct task_struct *child, int kill)
                  */
                 spin_lock_irq(&child->sighand->siglock);
                 WARN_ON_ONCE(task_is_stopped(child));
-                if (task_is_traced(child) || kill)
+                if (ignore_state || (task_is_traced(child) &&
+                                     !(child->jobctl & JOBCTL_LISTENING)))
                         ret = 0;
                 spin_unlock_irq(&child->sighand->siglock);
         }
         read_unlock(&tasklist_lock);
 
-        if (!ret && !kill)
+        if (!ret && !ignore_state)
                 ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 
         /* All systems go.. */
@@ -182,11 +211,28 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
         return !err;
 }
 
-static int ptrace_attach(struct task_struct *task)
+static int ptrace_attach(struct task_struct *task, long request,
+                         unsigned long flags)
 {
-        bool wait_trap = false;
+        bool seize = (request == PTRACE_SEIZE);
         int retval;
 
+        /*
+         * SEIZE will enable new ptrace behaviors which will be implemented
+         * gradually.  SEIZE_DEVEL is used to prevent applications
+         * expecting full SEIZE behaviors trapping on kernel commits which
+         * are still in the process of implementing them.
+         *
+         * Only test programs for new ptrace behaviors being implemented
+         * should set SEIZE_DEVEL.  If unset, SEIZE will fail with -EIO.
+         *
+         * Once SEIZE behaviors are completely implemented, this flag and
+         * the following test will be removed.
+         */
+        retval = -EIO;
+        if (seize && !(flags & PTRACE_SEIZE_DEVEL))
+                goto out;
+
         audit_ptrace(task);
 
         retval = -EPERM;
@@ -218,16 +264,21 @@ static int ptrace_attach(struct task_struct *task)
                 goto unlock_tasklist;
 
         task->ptrace = PT_PTRACED;
+        if (seize)
+                task->ptrace |= PT_SEIZED;
         if (task_ns_capable(task, CAP_SYS_PTRACE))
                 task->ptrace |= PT_PTRACE_CAP;
 
         __ptrace_link(task, current);
-        send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+
+        /* SEIZE doesn't trap tracee on attach */
+        if (!seize)
+                send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 
         spin_lock(&task->sighand->siglock);
 
         /*
-         * If the task is already STOPPED, set GROUP_STOP_PENDING and
+         * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
          * will be cleared if the child completes the transition or any
          * event which clears the group stop states happens.  We'll wait
@@ -243,11 +294,9 @@ static int ptrace_attach(struct task_struct *task)
          * The following task_is_stopped() test is safe as both transitions
          * in and out of STOPPED are protected by siglock.
          */
-        if (task_is_stopped(task)) {
-                task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
+        if (task_is_stopped(task) &&
+            task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
                 signal_wake_up(task, 1);
-                wait_trap = true;
-        }
 
         spin_unlock(&task->sighand->siglock);
 
@@ -257,9 +306,12 @@ unlock_tasklist:
 unlock_creds:
         mutex_unlock(&task->signal->cred_guard_mutex);
 out:
-        if (wait_trap)
-                wait_event(current->signal->wait_chldexit,
-                           !(task->group_stop & GROUP_STOP_TRAPPING));
+        if (!retval) {
+                wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
+                            ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
+                proc_ptrace_connector(task, PTRACE_ATTACH);
+        }
+
         return retval;
 }
 
@@ -322,25 +374,27 @@ static int ignoring_children(struct sighand_struct *sigh)
  */
 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 {
+        bool dead;
+
         __ptrace_unlink(p);
 
-        if (p->exit_state == EXIT_ZOMBIE) {
-                if (!task_detached(p) && thread_group_empty(p)) {
-                        if (!same_thread_group(p->real_parent, tracer))
-                                do_notify_parent(p, p->exit_signal);
-                        else if (ignoring_children(tracer->sighand)) {
-                                __wake_up_parent(p, tracer);
-                                p->exit_signal = -1;
-                        }
-                }
-                if (task_detached(p)) {
-                        /* Mark it as in the process of being reaped. */
-                        p->exit_state = EXIT_DEAD;
-                        return true;
+        if (p->exit_state != EXIT_ZOMBIE)
+                return false;
+
+        dead = !thread_group_leader(p);
+
+        if (!dead && thread_group_empty(p)) {
+                if (!same_thread_group(p->real_parent, tracer))
+                        dead = do_notify_parent(p, p->exit_signal);
+                else if (ignoring_children(tracer->sighand)) {
+                        __wake_up_parent(p, tracer);
+                        dead = true;
                 }
         }
-
-        return false;
+        /* Mark it as in the process of being reaped. */
+        if (dead)
+                p->exit_state = EXIT_DEAD;
+        return dead;
 }
 
 static int ptrace_detach(struct task_struct *child, unsigned int data)
@@ -365,6 +419,7 @@ static int ptrace_detach(struct task_struct *child, unsigned int data)
         }
         write_unlock_irq(&tasklist_lock);
 
+        proc_ptrace_connector(child, PTRACE_DETACH);
         if (unlikely(dead))
                 release_task(child);
 
@@ -611,10 +666,12 @@ static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 int ptrace_request(struct task_struct *child, long request,
                    unsigned long addr, unsigned long data)
 {
+        bool seized = child->ptrace & PT_SEIZED;
         int ret = -EIO;
-        siginfo_t siginfo;
+        siginfo_t siginfo, *si;
         void __user *datavp = (void __user *) data;
         unsigned long __user *datalp = datavp;
+        unsigned long flags;
 
         switch (request) {
         case PTRACE_PEEKTEXT:
@@ -647,6 +704,62 @@ int ptrace_request(struct task_struct *child, long request,
                         ret = ptrace_setsiginfo(child, &siginfo);
                 break;
 
+        case PTRACE_INTERRUPT:
+                /*
+                 * Stop tracee without any side-effect on signal or job
+                 * control.  At least one trap is guaranteed to happen
+                 * after this request.  If @child is already trapped, the
+                 * current trap is not disturbed and another trap will
+                 * happen after the current trap is ended with PTRACE_CONT.
+                 *
+                 * The actual trap might not be PTRACE_EVENT_STOP trap but
+                 * the pending condition is cleared regardless.
+                 */
+                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
+                        break;
+
+                /*
+                 * INTERRUPT doesn't disturb existing trap sans one
+                 * exception.  If ptracer issued LISTEN for the current
+                 * STOP, this INTERRUPT should clear LISTEN and re-trap
+                 * tracee into STOP.
+                 */
+                if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
+                        signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
+
+                unlock_task_sighand(child, &flags);
+                ret = 0;
+                break;
+
+        case PTRACE_LISTEN:
+                /*
+                 * Listen for events.  Tracee must be in STOP.  It's not
+                 * resumed per-se but is not considered to be in TRACED by
+                 * wait(2) or ptrace(2).  If an async event (e.g. group
+                 * stop state change) happens, tracee will enter STOP trap
+                 * again.  Alternatively, ptracer can issue INTERRUPT to
+                 * finish listening and re-trap tracee into STOP.
+                 */
+                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
+                        break;
+
+                si = child->last_siginfo;
+                if (unlikely(!si || si->si_code >> 8 != PTRACE_EVENT_STOP))
+                        break;
+
+                child->jobctl |= JOBCTL_LISTENING;
+
+                /*
+                 * If NOTIFY is set, it means event happened between start
+                 * of this trap and now.  Trigger re-trap immediately.
+                 */
+                if (child->jobctl & JOBCTL_TRAP_NOTIFY)
+                        signal_wake_up(child, true);
+
+                unlock_task_sighand(child, &flags);
+                ret = 0;
+                break;
+
         case PTRACE_DETACH:      /* detach a process that was attached. */
                 ret = ptrace_detach(child, data);
                 break;
@@ -761,8 +874,8 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
                 goto out;
         }
 
-        if (request == PTRACE_ATTACH) {
-                ret = ptrace_attach(child);
+        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
+                ret = ptrace_attach(child, request, data);
                 /*
                  * Some architectures need to do book-keeping after
                  * a ptrace attach.
@@ -772,7 +885,8 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
                 goto out_put_task_struct;
         }
 
-        ret = ptrace_check_attach(child, request == PTRACE_KILL);
+        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
+                                  request == PTRACE_INTERRUPT);
         if (ret < 0)
                 goto out_put_task_struct;
 
@@ -903,8 +1017,8 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
                 goto out;
         }
 
-        if (request == PTRACE_ATTACH) {
-                ret = ptrace_attach(child);
+        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
+                ret = ptrace_attach(child, request, data);
                 /*
                  * Some architectures need to do book-keeping after
                  * a ptrace attach.
@@ -914,7 +1028,8 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
                 goto out_put_task_struct;
         }
 
-        ret = ptrace_check_attach(child, request == PTRACE_KILL);
+        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
+                                  request == PTRACE_INTERRUPT);
         if (!ret)
                 ret = compat_arch_ptrace(child, request, addr, data);
 
diff --git a/kernel/signal.c b/kernel/signal.c
index 415d85d6f6c6..d7f70aed1cc0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -87,7 +87,7 @@ static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
         /*
          * Tracers may want to know about even ignored signals.
          */
-        return !tracehook_consider_ignored_signal(t, sig);
+        return !t->ptrace;
 }
 
 /*
@@ -124,7 +124,7 @@ static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
 
 static int recalc_sigpending_tsk(struct task_struct *t)
 {
-        if ((t->group_stop & GROUP_STOP_PENDING) ||
+        if ((t->jobctl & JOBCTL_PENDING_MASK) ||
             PENDING(&t->pending, &t->blocked) ||
             PENDING(&t->signal->shared_pending, &t->blocked)) {
                 set_tsk_thread_flag(t, TIF_SIGPENDING);
@@ -150,9 +150,7 @@ void recalc_sigpending_and_wake(struct task_struct *t)
 
 void recalc_sigpending(void)
 {
-        if (unlikely(tracehook_force_sigpending()))
-                set_thread_flag(TIF_SIGPENDING);
-        else if (!recalc_sigpending_tsk(current) && !freezing(current))
+        if (!recalc_sigpending_tsk(current) && !freezing(current))
                 clear_thread_flag(TIF_SIGPENDING);
 
 }
@@ -224,47 +222,93 @@ static inline void print_dropped_signal(int sig)
 }
 
 /**
- * task_clear_group_stop_trapping - clear group stop trapping bit
+ * task_set_jobctl_pending - set jobctl pending bits
  * @task: target task
+ * @mask: pending bits to set
  *
- * If GROUP_STOP_TRAPPING is set, a ptracer is waiting for us.  Clear it
- * and wake up the ptracer.  Note that we don't need any further locking.
- * @task->siglock guarantees that @task->parent points to the ptracer.
+ * Clear @mask from @task->jobctl.  @mask must be subset of
+ * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
+ * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
+ * cleared.  If @task is already being killed or exiting, this function
+ * becomes noop.
+ *
+ * CONTEXT:
+ * Must be called with @task->sighand->siglock held.
+ *
+ * RETURNS:
+ * %true if @mask is set, %false if made noop because @task was dying.
+ */
+bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
+{
+        BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
+                        JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
+        BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
+
+        if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
+                return false;
+
+        if (mask & JOBCTL_STOP_SIGMASK)
+                task->jobctl &= ~JOBCTL_STOP_SIGMASK;
+
+        task->jobctl |= mask;
+        return true;
+}
+
+/**
+ * task_clear_jobctl_trapping - clear jobctl trapping bit
+ * @task: target task
+ *
+ * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
+ * Clear it and wake up the ptracer.  Note that we don't need any further
+ * locking.  @task->siglock guarantees that @task->parent points to the
+ * ptracer.
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  */
-static void task_clear_group_stop_trapping(struct task_struct *task)
+void task_clear_jobctl_trapping(struct task_struct *task)
 {
-        if (unlikely(task->group_stop & GROUP_STOP_TRAPPING)) {
-                task->group_stop &= ~GROUP_STOP_TRAPPING;
-                __wake_up_sync_key(&task->parent->signal->wait_chldexit,
-                                   TASK_UNINTERRUPTIBLE, 1, task);
+        if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
+                task->jobctl &= ~JOBCTL_TRAPPING;
+                wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
         }
 }
 
 /**
- * task_clear_group_stop_pending - clear pending group stop
+ * task_clear_jobctl_pending - clear jobctl pending bits
  * @task: target task
+ * @mask: pending bits to clear
+ *
+ * Clear @mask from @task->jobctl.  @mask must be subset of
+ * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
+ * STOP bits are cleared together.
  *
- * Clear group stop states for @task.
+ * If clearing of @mask leaves no stop or trap pending, this function calls
+ * task_clear_jobctl_trapping().
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  */
-void task_clear_group_stop_pending(struct task_struct *task)
+void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
 {
-        task->group_stop &= ~(GROUP_STOP_PENDING | GROUP_STOP_CONSUME |
-                              GROUP_STOP_DEQUEUED);
+        BUG_ON(mask & ~JOBCTL_PENDING_MASK);
+
+        if (mask & JOBCTL_STOP_PENDING)
+                mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
+
+        task->jobctl &= ~mask;
+
+        if (!(task->jobctl & JOBCTL_PENDING_MASK))
+                task_clear_jobctl_trapping(task);
 }
 
 /**
  * task_participate_group_stop - participate in a group stop
  * @task: task participating in a group stop
  *
- * @task has GROUP_STOP_PENDING set and is participating in a group stop.
+ * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
  * Group stop states are cleared and the group stop count is consumed if
- * %GROUP_STOP_CONSUME was set.  If the consumption completes the group
+ * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
  * stop, the appropriate %SIGNAL_* flags are set.
  *
  * CONTEXT:
@@ -277,11 +321,11 @@ void task_clear_group_stop_pending(struct task_struct *task)
 static bool task_participate_group_stop(struct task_struct *task)
 {
         struct signal_struct *sig = task->signal;
-        bool consume = task->group_stop & GROUP_STOP_CONSUME;
+        bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
 
-        WARN_ON_ONCE(!(task->group_stop & GROUP_STOP_PENDING));
+        WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
 
-        task_clear_group_stop_pending(task);
+        task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
 
         if (!consume)
                 return false;
@@ -449,7 +493,8 @@ int unhandled_signal(struct task_struct *tsk, int sig)
                 return 1;
         if (handler != SIG_IGN && handler != SIG_DFL)
                 return 0;
-        return !tracehook_consider_fatal_signal(tsk, sig);
+        /* if ptraced, let the tracer determine */
+        return !tsk->ptrace;
 }
 
 /*
@@ -604,7 +649,7 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
                  * is to alert stop-signal processing code when another
                  * processor has come along and cleared the flag.
                  */
-                current->group_stop |= GROUP_STOP_DEQUEUED;
+                current->jobctl |= JOBCTL_STOP_DEQUEUED;
         }
         if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
                 /*
@@ -773,6 +818,32 @@ static int check_kill_permission(int sig, struct siginfo *info,
         return security_task_kill(t, info, sig, 0);
 }
 
+/**
+ * ptrace_trap_notify - schedule trap to notify ptracer
+ * @t: tracee wanting to notify tracer
+ *
+ * This function schedules sticky ptrace trap which is cleared on the next
+ * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
+ * ptracer.
+ *
+ * If @t is running, STOP trap will be taken.  If trapped for STOP and
+ * ptracer is listening for events, tracee is woken up so that it can
+ * re-trap for the new event.  If trapped otherwise, STOP trap will be
+ * eventually taken without returning to userland after the existing traps
+ * are finished by PTRACE_CONT.
+ *
+ * CONTEXT:
+ * Must be called with @task->sighand->siglock held.
+ */
+static void ptrace_trap_notify(struct task_struct *t)
+{
+        WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
+        assert_spin_locked(&t->sighand->siglock);
+
+        task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
+        signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
+}
+
 /*
  * Handle magic process-wide effects of stop/continue signals. Unlike
  * the signal actions, these happen immediately at signal-generation
@@ -809,9 +880,12 @@ static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
                 rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
                 t = p;
                 do {
-                        task_clear_group_stop_pending(t);
+                        task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
                         rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
-                        wake_up_state(t, __TASK_STOPPED);
+                        if (likely(!(t->ptrace & PT_SEIZED)))
+                                wake_up_state(t, __TASK_STOPPED);
+                        else
+                                ptrace_trap_notify(t);
                 } while_each_thread(p, t);
 
                 /*
@@ -908,8 +982,7 @@ static void complete_signal(int sig, struct task_struct *p, int group)
         if (sig_fatal(p, sig) &&
             !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
             !sigismember(&t->real_blocked, sig) &&
-            (sig == SIGKILL ||
-             !tracehook_consider_fatal_signal(t, sig))) {
+            (sig == SIGKILL || !t->ptrace)) {
                 /*
                  * This signal will be fatal to the whole group.
                  */
@@ -925,7 +998,7 @@ static void complete_signal(int sig, struct task_struct *p, int group)
                         signal->group_stop_count = 0;
                         t = p;
                         do {
-                                task_clear_group_stop_pending(t);
+                                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
                                 sigaddset(&t->pending.signal, SIGKILL);
                                 signal_wake_up(t, 1);
                         } while_each_thread(p, t);
@@ -1160,7 +1233,7 @@ int zap_other_threads(struct task_struct *p)
         p->signal->group_stop_count = 0;
 
         while_each_thread(p, t) {
-                task_clear_group_stop_pending(t);
+                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
                 count++;
 
                 /* Don't bother with already dead threads */
@@ -1511,22 +1584,22 @@ ret:
  * Let a parent know about the death of a child.
  * For a stopped/continued status change, use do_notify_parent_cldstop instead.
  *
- * Returns -1 if our parent ignored us and so we've switched to
- * self-reaping, or else @sig.
+ * Returns true if our parent ignored us and so we've switched to
+ * self-reaping.
  */
-int do_notify_parent(struct task_struct *tsk, int sig)
+bool do_notify_parent(struct task_struct *tsk, int sig)
 {
         struct siginfo info;
         unsigned long flags;
         struct sighand_struct *psig;
-        int ret = sig;
+        bool autoreap = false;
 
         BUG_ON(sig == -1);
 
         /* do_notify_parent_cldstop should have been called instead.  */
         BUG_ON(task_is_stopped_or_traced(tsk));
 
-        BUG_ON(!task_ptrace(tsk) &&
+        BUG_ON(!tsk->ptrace &&
                (tsk->group_leader != tsk || !thread_group_empty(tsk)));
 
         info.si_signo = sig;
@@ -1565,7 +1638,7 @@ int do_notify_parent(struct task_struct *tsk, int sig)
 
         psig = tsk->parent->sighand;
         spin_lock_irqsave(&psig->siglock, flags);
-        if (!task_ptrace(tsk) && sig == SIGCHLD &&
+        if (!tsk->ptrace && sig == SIGCHLD &&
             (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
              (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
                 /*
@@ -1583,16 +1656,16 @@ int do_notify_parent(struct task_struct *tsk, int sig)
                  * is implementation-defined: we do (if you don't want
                  * it, just use SIG_IGN instead).
                  */
-                ret = tsk->exit_signal = -1;
+                autoreap = true;
                 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
-                        sig = -1;
+                        sig = 0;
         }
-        if (valid_signal(sig) && sig > 0)
+        if (valid_signal(sig) && sig)
                 __group_send_sig_info(sig, &info, tsk->parent);
         __wake_up_parent(tsk, tsk->parent);
         spin_unlock_irqrestore(&psig->siglock, flags);
 
-        return ret;
+        return autoreap;
 }
 
 /**
@@ -1665,7 +1738,7 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
 
 static inline int may_ptrace_stop(void)
 {
-        if (!likely(task_ptrace(current)))
+        if (!likely(current->ptrace))
                 return 0;
         /*
          * Are we in the middle of do_coredump?
@@ -1694,15 +1767,6 @@ static int sigkill_pending(struct task_struct *tsk)
 }
 
 /*
- * Test whether the target task of the usual cldstop notification - the
- * real_parent of @child - is in the same group as the ptracer.
- */
-static bool real_parent_is_ptracer(struct task_struct *child)
-{
-        return same_thread_group(child->parent, child->real_parent);
-}
-
-/*
  * This must be called with current->sighand->siglock held.
  *
  * This should be the path for all ptrace stops.
@@ -1739,31 +1803,34 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
         }
 
         /*
-         * If @why is CLD_STOPPED, we're trapping to participate in a group
-         * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
-         * while siglock was released for the arch hook, PENDING could be
-         * clear now.  We act as if SIGCONT is received after TASK_TRACED
-         * is entered - ignore it.
+         * We're committing to trapping.  TRACED should be visible before
+         * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
+         * Also, transition to TRACED and updates to ->jobctl should be
+         * atomic with respect to siglock and should be done after the arch
+         * hook as siglock is released and regrabbed across it.
          */
-        if (why == CLD_STOPPED && (current->group_stop & GROUP_STOP_PENDING))
-                gstop_done = task_participate_group_stop(current);
+        set_current_state(TASK_TRACED);
 
         current->last_siginfo = info;
         current->exit_code = exit_code;
 
         /*
-         * TRACED should be visible before TRAPPING is cleared; otherwise,
-         * the tracer might fail do_wait().
+         * If @why is CLD_STOPPED, we're trapping to participate in a group
+         * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
+         * across siglock relocks since INTERRUPT was scheduled, PENDING
+         * could be clear now.  We act as if SIGCONT is received after
+         * TASK_TRACED is entered - ignore it.
          */
-        set_current_state(TASK_TRACED);
+        if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
+                gstop_done = task_participate_group_stop(current);
 
-        /*
-         * We're committing to trapping.  Clearing GROUP_STOP_TRAPPING and
-         * transition to TASK_TRACED should be atomic with respect to
-         * siglock.  This hsould be done after the arch hook as siglock is
-         * released and regrabbed across it.
-         */
-        task_clear_group_stop_trapping(current);
+        /* any trap clears pending STOP trap, STOP trap clears NOTIFY */
+        task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
+        if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
+                task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
+
+        /* entering a trap, clear TRAPPING */
+        task_clear_jobctl_trapping(current);
 
         spin_unlock_irq(&current->sighand->siglock);
         read_lock(&tasklist_lock);
@@ -1779,7 +1846,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
                  * separately unless they're gonna be duplicates.
                  */
                 do_notify_parent_cldstop(current, true, why);
-                if (gstop_done && !real_parent_is_ptracer(current))
+                if (gstop_done && ptrace_reparented(current))
                         do_notify_parent_cldstop(current, false, why);
 
                 /*
@@ -1799,9 +1866,9 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
                  *
                  * If @gstop_done, the ptracer went away between group stop
                  * completion and here.  During detach, it would have set
-                 * GROUP_STOP_PENDING on us and we'll re-enter TASK_STOPPED
-                 * in do_signal_stop() on return, so notifying the real
-                 * parent of the group stop completion is enough.
+                 * JOBCTL_STOP_PENDING on us and we'll re-enter
+                 * TASK_STOPPED in do_signal_stop() on return, so notifying
+                 * the real parent of the group stop completion is enough.
                  */
                 if (gstop_done)
                         do_notify_parent_cldstop(current, false, why);
@@ -1827,6 +1894,9 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
         spin_lock_irq(&current->sighand->siglock);
         current->last_siginfo = NULL;
 
+        /* LISTENING can be set only during STOP traps, clear it */
+        current->jobctl &= ~JOBCTL_LISTENING;
+
         /*
          * Queued signals ignored us while we were stopped for tracing.
          * So check for any that we should take before resuming user mode.
@@ -1835,44 +1905,66 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
         recalc_sigpending_tsk(current);
 }
 
-void ptrace_notify(int exit_code)
+static void ptrace_do_notify(int signr, int exit_code, int why)
 {
         siginfo_t info;
 
-        BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
-
         memset(&info, 0, sizeof info);
-        info.si_signo = SIGTRAP;
+        info.si_signo = signr;
         info.si_code = exit_code;
         info.si_pid = task_pid_vnr(current);
         info.si_uid = current_uid();
 
         /* Let the debugger run.  */
+        ptrace_stop(exit_code, why, 1, &info);
+}
+
+void ptrace_notify(int exit_code)
+{
+        BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
+
         spin_lock_irq(&current->sighand->siglock);
-        ptrace_stop(exit_code, CLD_TRAPPED, 1, &info);
+        ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
         spin_unlock_irq(&current->sighand->siglock);
 }
 
-/*
- * This performs the stopping for SIGSTOP and other stop signals.
- * We have to stop all threads in the thread group.
- * Returns non-zero if we've actually stopped and released the siglock.
- * Returns zero if we didn't stop and still hold the siglock.
+/**
+ * do_signal_stop - handle group stop for SIGSTOP and other stop signals
+ * @signr: signr causing group stop if initiating
+ *
+ * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
+ * and participate in it.  If already set, participate in the existing
+ * group stop.  If participated in a group stop (and thus slept), %true is
+ * returned with siglock released.
+ *
+ * If ptraced, this function doesn't handle stop itself.  Instead,
+ * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
+ * untouched.  The caller must ensure that INTERRUPT trap handling takes
+ * places afterwards.
+ *
+ * CONTEXT:
+ * Must be called with @current->sighand->siglock held, which is released
+ * on %true return.
+ *
+ * RETURNS:
+ * %false if group stop is already cancelled or ptrace trap is scheduled.
+ * %true if participated in group stop.
  */
-static int do_signal_stop(int signr)
+static bool do_signal_stop(int signr)
+        __releases(&current->sighand->siglock)
 {
         struct signal_struct *sig = current->signal;
 
-        if (!(current->group_stop & GROUP_STOP_PENDING)) {
-                unsigned int gstop = GROUP_STOP_PENDING | GROUP_STOP_CONSUME;
+        if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
+                unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
                 struct task_struct *t;
 
-                /* signr will be recorded in task->group_stop for retries */
-                WARN_ON_ONCE(signr & ~GROUP_STOP_SIGMASK);
+                /* signr will be recorded in task->jobctl for retries */
+                WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
 
-                if (!likely(current->group_stop & GROUP_STOP_DEQUEUED) ||
+                if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
                     unlikely(signal_group_exit(sig)))
-                        return 0;
+                        return false;
                 /*
                  * There is no group stop already in progress.  We must
                  * initiate one now.
@@ -1895,28 +1987,32 @@ static int do_signal_stop(int signr)
                 if (!(sig->flags & SIGNAL_STOP_STOPPED))
                         sig->group_exit_code = signr;
                 else
-                        WARN_ON_ONCE(!task_ptrace(current));
+                        WARN_ON_ONCE(!current->ptrace);
+
+                sig->group_stop_count = 0;
+
+                if (task_set_jobctl_pending(current, signr | gstop))
+                        sig->group_stop_count++;
 
-                current->group_stop &= ~GROUP_STOP_SIGMASK;
-                current->group_stop |= signr | gstop;
-                sig->group_stop_count = 1;
                 for (t = next_thread(current); t != current;
                      t = next_thread(t)) {
-                        t->group_stop &= ~GROUP_STOP_SIGMASK;
                         /*
                          * Setting state to TASK_STOPPED for a group
                          * stop is always done with the siglock held,
                          * so this check has no races.
                          */
-                        if (!(t->flags & PF_EXITING) && !task_is_stopped(t)) {
-                                t->group_stop |= signr | gstop;
+                        if (!task_is_stopped(t) &&
+                            task_set_jobctl_pending(t, signr | gstop)) {
                                 sig->group_stop_count++;
-                                signal_wake_up(t, 0);
+                                if (likely(!(t->ptrace & PT_SEIZED)))
+                                        signal_wake_up(t, 0);
+                                else
+                                        ptrace_trap_notify(t);
                         }
                 }
         }
-retry:
-        if (likely(!task_ptrace(current))) {
+
+        if (likely(!current->ptrace)) {
                 int notify = 0;
 
                 /*
@@ -1947,43 +2043,65 @@ retry:
 
                 /* Now we don't run again until woken by SIGCONT or SIGKILL */
                 schedule();
-
-                spin_lock_irq(&current->sighand->siglock);
+                return true;
         } else {
-                ptrace_stop(current->group_stop & GROUP_STOP_SIGMASK,
-                            CLD_STOPPED, 0, NULL);
-                current->exit_code = 0;
+                /*
+                 * While ptraced, group stop is handled by STOP trap.
+                 * Schedule it and let the caller deal with it.
+                 */
+                task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
+                return false;
         }
+}
 
-        /*
-         * GROUP_STOP_PENDING could be set if another group stop has
-         * started since being woken up or ptrace wants us to transit
-         * between TASK_STOPPED and TRACED.  Retry group stop.
-         */
-        if (current->group_stop & GROUP_STOP_PENDING) {
-                WARN_ON_ONCE(!(current->group_stop & GROUP_STOP_SIGMASK));
-                goto retry;
+/**
+ * do_jobctl_trap - take care of ptrace jobctl traps
+ *
+ * When PT_SEIZED, it's used for both group stop and explicit
+ * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
+ * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
+ * the stop signal; otherwise, %SIGTRAP.
+ *
+ * When !PT_SEIZED, it's used only for group stop trap with stop signal
+ * number as exit_code and no siginfo.
+ *
+ * CONTEXT:
+ * Must be called with @current->sighand->siglock held, which may be
+ * released and re-acquired before returning with intervening sleep.
+ */
+static void do_jobctl_trap(void)
+{
+        struct signal_struct *signal = current->signal;
+        int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
+
+        if (current->ptrace & PT_SEIZED) {
+                if (!signal->group_stop_count &&
+                    !(signal->flags & SIGNAL_STOP_STOPPED))
+                        signr = SIGTRAP;
+                WARN_ON_ONCE(!signr);
+                ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
+                                 CLD_STOPPED);
+        } else {
+                WARN_ON_ONCE(!signr);
+                ptrace_stop(signr, CLD_STOPPED, 0, NULL);
+                current->exit_code = 0;
         }
-
-        /* PTRACE_ATTACH might have raced with task killing, clear trapping */
-        task_clear_group_stop_trapping(current);
-
-        spin_unlock_irq(&current->sighand->siglock);
-
-        tracehook_finish_jctl();
-
-        return 1;
 }
 
 static int ptrace_signal(int signr, siginfo_t *info,
                          struct pt_regs *regs, void *cookie)
 {
-        if (!task_ptrace(current))
-                return signr;
-
         ptrace_signal_deliver(regs, cookie);
-
-        /* Let the debugger run.  */
+        /*
+         * We do not check sig_kernel_stop(signr) but set this marker
+         * unconditionally because we do not know whether debugger will
+         * change signr. This flag has no meaning unless we are going
+         * to stop after return from ptrace_stop(). In this case it will
+         * be checked in do_signal_stop(), we should only stop if it was
+         * not cleared by SIGCONT while we were sleeping. See also the
+         * comment in dequeue_signal().
+         */
+        current->jobctl |= JOBCTL_STOP_DEQUEUED;
         ptrace_stop(signr, CLD_TRAPPED, 0, info);
 
         /* We're back.  Did the debugger cancel the sig?  */
@@ -2039,7 +2157,6 @@ relock:
          * the CLD_ si_code into SIGNAL_CLD_MASK bits.
          */
         if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
-                struct task_struct *leader;
                 int why;
 
                 if (signal->flags & SIGNAL_CLD_CONTINUED)
@@ -2060,13 +2177,11 @@ relock:
                  * a duplicate.
                  */
                 read_lock(&tasklist_lock);
-
                 do_notify_parent_cldstop(current, false, why);
 
-                leader = current->group_leader;
-                if (task_ptrace(leader) && !real_parent_is_ptracer(leader))
-                        do_notify_parent_cldstop(leader, true, why);
-
+                if (ptrace_reparented(current->group_leader))
+                        do_notify_parent_cldstop(current->group_leader,
+                                                true, why);
                 read_unlock(&tasklist_lock);
 
                 goto relock;
@@ -2074,37 +2189,31 @@ relock:
 
         for (;;) {
                 struct k_sigaction *ka;
-                /*
-                 * Tracing can induce an artificial signal and choose sigaction.
-                 * The return value in @signr determines the default action,
-                 * but @info->si_signo is the signal number we will report.
-                 */
-                signr = tracehook_get_signal(current, regs, info, return_ka);
-                if (unlikely(signr < 0))
+
+                if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
+                    do_signal_stop(0))
                         goto relock;
-                if (unlikely(signr != 0))
-                        ka = return_ka;
-                else {
-                        if (unlikely(current->group_stop &
-                                     GROUP_STOP_PENDING) && do_signal_stop(0))
-                                goto relock;
 
-                        signr = dequeue_signal(current, &current->blocked,
-                                               info);
+                if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
+                        do_jobctl_trap();
+                        spin_unlock_irq(&sighand->siglock);
+                        goto relock;
+                }
 
-                        if (!signr)
-                                break; /* will return 0 */
+                signr = dequeue_signal(current, &current->blocked, info);
 
-                        if (signr != SIGKILL) {
-                                signr = ptrace_signal(signr, info,
-                                                      regs, cookie);
-                                if (!signr)
-                                        continue;
-                        }
+                if (!signr)
+                        break; /* will return 0 */
 
-                        ka = &sighand->action[signr-1];
+                if (unlikely(current->ptrace) && signr != SIGKILL) {
+                        signr = ptrace_signal(signr, info,
+                                              regs, cookie);
+                        if (!signr)
+                                continue;
                 }
 
+                ka = &sighand->action[signr-1];
+
                 /* Trace actually delivered signals. */
                 trace_signal_deliver(signr, info, ka);
 
@@ -2260,7 +2369,7 @@ void exit_signals(struct task_struct *tsk)
         signotset(&unblocked);
         retarget_shared_pending(tsk, &unblocked);
 
-        if (unlikely(tsk->group_stop & GROUP_STOP_PENDING) &&
+        if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
             task_participate_group_stop(tsk))
                 group_stop = CLD_STOPPED;
 out:
diff --git a/mm/nommu.c b/mm/nommu.c
index 9edc897a3970..5c5c2d4b1807 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -22,7 +22,6 @@
 #include <linux/pagemap.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
-#include <linux/tracehook.h>
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
 #include <linux/mount.h>
@@ -1087,7 +1086,7 @@ static unsigned long determine_vm_flags(struct file *file,
          * it's being traced - otherwise breakpoints set in it may interfere
          * with another untraced process
          */
-        if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
+        if ((flags & MAP_PRIVATE) && current->ptrace)
                 vm_flags &= ~VM_MAYSHARE;
 
         return vm_flags;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index e4b0991ca351..b0be989d4365 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -339,8 +339,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
                                  * then wait for it to finish before killing
                                  * some other task unnecessarily.
                                  */
-                                if (!(task_ptrace(p->group_leader) &
-                                                        PT_TRACE_EXIT))
+                                if (!(p->group_leader->ptrace & PT_TRACE_EXIT))
                                         return ERR_PTR(-1UL);
                         }
                 }
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index c825c6e0b636..7312bf9f7afc 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -67,7 +67,7 @@ static int may_change_ptraced_domain(struct task_struct *task,
         int error = 0;
 
         rcu_read_lock();
-        tracer = tracehook_tracer_task(task);
+        tracer = ptrace_parent(task);
         if (tracer) {
                 /* released below */
                 cred = get_task_cred(tracer);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 20219ef5439a..422515509f3d 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2053,7 +2053,7 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
                         u32 ptsid = 0;
 
                         rcu_read_lock();
-                        tracer = tracehook_tracer_task(current);
+                        tracer = ptrace_parent(current);
                         if (likely(tracer != NULL)) {
                                 sec = __task_cred(tracer)->security;
                                 ptsid = sec->sid;
@@ -5319,7 +5319,7 @@ static int selinux_setprocattr(struct task_struct *p,
                    Otherwise, leave SID unchanged and fail. */
                 ptsid = 0;
                 task_lock(p);
-                tracer = tracehook_tracer_task(p);
+                tracer = ptrace_parent(p);
                 if (tracer)
                         ptsid = task_sid(tracer);
                 task_unlock(p);