diff options
| -rw-r--r-- | include/linux/sched.h | 6 | ||||
| -rw-r--r-- | kernel/ptrace.c | 12 | ||||
| -rw-r--r-- | kernel/signal.c | 90 |
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(¤t->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(¤t->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(¤t->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(¤t->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, ¤t->blocked, info); if (!signr) |