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-rw-r--r--include/linux/sched.h6
-rw-r--r--kernel/ptrace.c12
-rw-r--r--kernel/signal.c90
3 files changed, 75 insertions, 33 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5157bd9..8bd84b8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1810,17 +1810,21 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
#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_TRAPPING_BIT 21 /* switching to TRACED */
#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_TRAPPING (1 << JOBCTL_TRAPPING_BIT)
-#define JOBCTL_PENDING_MASK JOBCTL_STOP_PENDING
+#define JOBCTL_TRAP_MASK JOBCTL_TRAP_STOP
+#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);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 7f05f3a..45a8a4c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -83,6 +83,13 @@ void __ptrace_unlink(struct task_struct *child)
spin_lock(&child->sighand->siglock);
/*
+ * 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.
*/
@@ -246,7 +253,7 @@ static int ptrace_attach(struct task_struct *task)
spin_lock(&task->sighand->siglock);
/*
- * If the task is already STOPPED, set JOBCTL_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
@@ -263,8 +270,7 @@ static int ptrace_attach(struct task_struct *task)
* in and out of STOPPED are protected by siglock.
*/
if (task_is_stopped(task) &&
- task_set_jobctl_pending(task,
- JOBCTL_STOP_PENDING | JOBCTL_TRAPPING))
+ task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
signal_wake_up(task, 1);
spin_unlock(&task->sighand->siglock);
diff --git a/kernel/signal.c b/kernel/signal.c
index c99b8b5..b5f55ca 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -266,7 +266,7 @@ bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
* CONTEXT:
* Must be called with @task->sighand->siglock held.
*/
-static void task_clear_jobctl_trapping(struct task_struct *task)
+void task_clear_jobctl_trapping(struct task_struct *task)
{
if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
task->jobctl &= ~JOBCTL_TRAPPING;
@@ -1790,13 +1790,16 @@ 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.
+ * 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.
*/
if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
gstop_done = task_participate_group_stop(current);
+ /* any trap clears pending STOP trap */
+ task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
+
/* entering a trap, clear TRAPPING */
task_clear_jobctl_trapping(current);
@@ -1888,13 +1891,30 @@ void ptrace_notify(int exit_code)
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;
@@ -1907,7 +1927,7 @@ static int do_signal_stop(int signr)
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.
@@ -1951,7 +1971,7 @@ static int do_signal_stop(int signr)
}
}
}
-retry:
+
if (likely(!task_ptrace(current))) {
int notify = 0;
@@ -1983,27 +2003,33 @@ 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->jobctl & JOBCTL_STOP_SIGMASK,
- CLD_STOPPED, 0, NULL);
- current->exit_code = 0;
- }
-
- /*
- * JOBCTL_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->jobctl & JOBCTL_STOP_PENDING) {
- WARN_ON_ONCE(!(current->jobctl & JOBCTL_STOP_SIGMASK));
- goto retry;
+ /*
+ * 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;
}
+}
- spin_unlock_irq(&current->sighand->siglock);
+/**
+ * do_jobctl_trap - take care of ptrace jobctl traps
+ *
+ * It is currently used only to trap for group stop while ptraced.
+ *
+ * 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)
+{
+ int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
- return 1;
+ WARN_ON_ONCE(!signr);
+ ptrace_stop(signr, CLD_STOPPED, 0, NULL);
+ current->exit_code = 0;
}
static int ptrace_signal(int signr, siginfo_t *info,
@@ -2110,6 +2136,12 @@ relock:
do_signal_stop(0))
goto relock;
+ if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
+ do_jobctl_trap();
+ spin_unlock_irq(&sighand->siglock);
+ goto relock;
+ }
+
signr = dequeue_signal(current, &current->blocked, info);
if (!signr)
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