diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index c74abfc4c7e8c013879a5f0840cb319286fee51d..dae6d85520fbe5acca66bee5dd8d489fc264786d 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -154,6 +154,28 @@ static inline int ptrace_event(int mask, int event, unsigned long message)
return 1;
}
+/**
+ * ptrace_init_task - initialize ptrace state for a new child
+ * @child: new child task
+ * @ptrace: true if child should be ptrace'd by parent's tracer
+ *
+ * This is called immediately after adding @child to its parent's children
+ * list. @ptrace is false in the normal case, and true to ptrace @child.
+ *
+ * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
+ */
+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;
+ child->ptrace = 0;
+ if (unlikely(ptrace)) {
+ child->ptrace = current->ptrace;
+ __ptrace_link(child, current->parent);
+ }
+}
+
#ifndef force_successful_syscall_return
/*
* System call handlers that, upon successful completion, need to return a
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 967ab473afbccf476751d510621bb4123bdaa4a8..3ebc58b597665a798c8ed97cf995a0dbfff37514 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -110,4 +110,104 @@ 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_clone_prepare()
+ *
+ * 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
+ * @trace: return value from tracehook_clone_prepare()
+ * @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.
+ * The @trace value is that returned by tracehook_clone_prepare().
+ * This is not a good place to block, because the child has not started yet.
+ * Suspend the child here if desired, and block in tracehook_clone_complete().
+ * This must prevent the child from self-reaping if tracehook_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(int trace, struct pt_regs *regs,
+ unsigned long clone_flags,
+ pid_t pid, struct task_struct *child)
+{
+ if (unlikely(trace)) {
+ /*
+ * The child starts up with an immediate SIGSTOP.
+ */
+ 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_clone_prepare()
+ * @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);
+}
+
#endif /* <linux/tracehook.h> */
diff --git a/kernel/fork.c b/kernel/fork.c
index 80e83e459b17f28625e485b80392189b63b4a172..b42f8ed23611703400788dccb525e1c9b5240134 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -37,6 +37,7 @@
#include <linux/swap.h>
#include <linux/syscalls.h>
#include <linux/jiffies.h>
+#include <linux/tracehook.h>
#include <linux/futex.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/rcupdate.h>
@@ -865,8 +866,7 @@ static void copy_flags(unsigned long clone_flags, struct task_struct *p)
new_flags &= ~PF_SUPERPRIV;
new_flags |= PF_FORKNOEXEC;
- if (!(clone_flags & CLONE_PTRACE))
- p->ptrace = 0;
+ new_flags |= PF_STARTING;
p->flags = new_flags;
clear_freeze_flag(p);
}
@@ -907,7 +907,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
struct pt_regs *regs,
unsigned long stack_size,
int __user *child_tidptr,
- struct pid *pid)
+ struct pid *pid,
+ int trace)
{
int retval;
struct task_struct *p;
@@ -1163,8 +1164,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
*/
p->group_leader = p;
INIT_LIST_HEAD(&p->thread_group);
- INIT_LIST_HEAD(&p->ptrace_entry);
- INIT_LIST_HEAD(&p->ptraced);
/* Now that the task is set up, run cgroup callbacks if
* necessary. We need to run them before the task is visible
@@ -1195,7 +1194,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->real_parent = current->real_parent;
else
p->real_parent = current;
- p->parent = p->real_parent;
spin_lock(¤t->sighand->siglock);
@@ -1237,8 +1235,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
if (likely(p->pid)) {
list_add_tail(&p->sibling, &p->real_parent->children);
- if (unlikely(p->ptrace & PT_PTRACED))
- __ptrace_link(p, current->parent);
+ tracehook_finish_clone(p, clone_flags, trace);
if (thread_group_leader(p)) {
if (clone_flags & CLONE_NEWPID)
@@ -1323,29 +1320,13 @@ struct task_struct * __cpuinit fork_idle(int cpu)
struct pt_regs regs;
task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
- &init_struct_pid);
+ &init_struct_pid, 0);
if (!IS_ERR(task))
init_idle(task, cpu);
return task;
}
-static int fork_traceflag(unsigned clone_flags)
-{
- if (clone_flags & CLONE_UNTRACED)
- return 0;
- else 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;
-}
-
/*
* Ok, this is the main fork-routine.
*
@@ -1380,14 +1361,14 @@ long do_fork(unsigned long clone_flags,
}
}
- if (unlikely(current->ptrace)) {
- trace = fork_traceflag (clone_flags);
- if (trace)
- clone_flags |= CLONE_PTRACE;
- }
+ /*
+ * When called from kernel_thread, don't do user tracing stuff.
+ */
+ if (likely(user_mode(regs)))
+ trace = tracehook_prepare_clone(clone_flags);
p = copy_process(clone_flags, stack_start, regs, stack_size,
- child_tidptr, NULL);
+ child_tidptr, NULL, trace);
/*
* Do this prior waking up the new thread - the thread pointer
* might get invalid after that point, if the thread exits quickly.
@@ -1405,24 +1386,30 @@ long do_fork(unsigned long clone_flags,
init_completion(&vfork);
}
- if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
+ tracehook_report_clone(trace, 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.
+ */
+ p->flags &= ~PF_STARTING;
+
+ if (unlikely(clone_flags & CLONE_STOPPED)) {
/*
* We'll start up with an immediate SIGSTOP.
*/
sigaddset(&p->pending.signal, SIGSTOP);
set_tsk_thread_flag(p, TIF_SIGPENDING);
- }
-
- if (!(clone_flags & CLONE_STOPPED))
- wake_up_new_task(p, clone_flags);
- else
__set_task_state(p, TASK_STOPPED);
-
- if (unlikely (trace)) {
- current->ptrace_message = nr;
- ptrace_notify ((trace << 8) | SIGTRAP);
+ } else {
+ wake_up_new_task(p, clone_flags);
}
+ tracehook_report_clone_complete(trace, regs,
+ clone_flags, nr, p);
+
if (clone_flags & CLONE_VFORK) {
freezer_do_not_count();
wait_for_completion(&vfork);