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-rw-r--r--kernel/signal.c107
1 files changed, 75 insertions, 32 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 38602738866e..368a34c25bbf 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -32,7 +32,7 @@
#include <linux/signal.h>
#include <linux/signalfd.h>
#include <linux/ratelimit.h>
-#include <linux/tracehook.h>
+#include <linux/task_work.h>
#include <linux/capability.h>
#include <linux/freezer.h>
#include <linux/pid_namespace.h>
@@ -1308,6 +1308,43 @@ enum sig_handler {
};
/*
+ * On some archictectures, PREEMPT_RT has to delay sending a signal from a
+ * trap since it cannot enable preemption, and the signal code's
+ * spin_locks turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME
+ * which will send the signal on exit of the trap.
+ */
+#ifdef CONFIG_RT_DELAYED_SIGNALS
+static inline bool force_sig_delayed(struct kernel_siginfo *info,
+ struct task_struct *t)
+{
+ if (!in_atomic())
+ return false;
+
+ if (WARN_ON_ONCE(t->forced_info.si_signo))
+ return true;
+
+ if (is_si_special(info)) {
+ WARN_ON_ONCE(info != SEND_SIG_PRIV);
+ t->forced_info.si_signo = info->si_signo;
+ t->forced_info.si_errno = 0;
+ t->forced_info.si_code = SI_KERNEL;
+ t->forced_info.si_pid = 0;
+ t->forced_info.si_uid = 0;
+ } else {
+ t->forced_info = *info;
+ }
+ set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
+ return true;
+}
+#else
+static inline bool force_sig_delayed(struct kernel_siginfo *info,
+ struct task_struct *t)
+{
+ return false;
+}
+#endif
+
+/*
* Force a signal that the process can't ignore: if necessary
* we unblock the signal and change any SIG_IGN to SIG_DFL.
*
@@ -1327,6 +1364,9 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
struct k_sigaction *action;
int sig = info->si_signo;
+ if (force_sig_delayed(info, t))
+ return 0;
+
spin_lock_irqsave(&t->sighand->siglock, flags);
action = &t->sighand->action[sig-1];
ignored = action->sa.sa_handler == SIG_IGN;
@@ -1342,9 +1382,10 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
}
/*
* Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
- * debugging to leave init killable.
+ * debugging to leave init killable. But HANDLER_EXIT is always fatal.
*/
- if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
+ if (action->sa.sa_handler == SIG_DFL &&
+ (!t->ptrace || (handler == HANDLER_EXIT)))
t->signal->flags &= ~SIGNAL_UNKILLABLE;
ret = send_signal(sig, info, t, PIDTYPE_PID);
spin_unlock_irqrestore(&t->sighand->siglock, flags);
@@ -2188,14 +2229,17 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
* That makes it a way to test a stopped process for
* being ptrace-stopped vs being job-control-stopped.
*
- * If we actually decide not to stop at all because the tracer
- * is gone, we keep current->exit_code unless clear_code.
+ * Returns the signal the ptracer requested the code resume
+ * with. If the code did not stop because the tracer is gone,
+ * the stop signal remains unchanged unless clear_code.
*/
-static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t *info)
+static int ptrace_stop(int exit_code, int why, int clear_code,
+ unsigned long message, kernel_siginfo_t *info)
__releases(&current->sighand->siglock)
__acquires(&current->sighand->siglock)
{
bool gstop_done = false;
+ bool read_code = true;
if (arch_ptrace_stop_needed()) {
/*
@@ -2237,6 +2281,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
*/
smp_wmb();
+ current->ptrace_message = message;
current->last_siginfo = info;
current->exit_code = exit_code;
@@ -2303,8 +2348,9 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
/* tasklist protects us from ptrace_freeze_traced() */
__set_current_state(TASK_RUNNING);
+ read_code = false;
if (clear_code)
- current->exit_code = 0;
+ exit_code = 0;
read_unlock(&tasklist_lock);
}
@@ -2314,7 +2360,11 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
* any signal-sending on another CPU that wants to examine it.
*/
spin_lock_irq(&current->sighand->siglock);
+ if (read_code)
+ exit_code = current->exit_code;
current->last_siginfo = NULL;
+ current->ptrace_message = 0;
+ current->exit_code = 0;
/* LISTENING can be set only during STOP traps, clear it */
current->jobctl &= ~JOBCTL_LISTENING;
@@ -2325,9 +2375,10 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
* This sets TIF_SIGPENDING, but never clears it.
*/
recalc_sigpending_tsk(current);
+ return exit_code;
}
-static void ptrace_do_notify(int signr, int exit_code, int why)
+static int ptrace_do_notify(int signr, int exit_code, int why, unsigned long message)
{
kernel_siginfo_t info;
@@ -2338,18 +2389,21 @@ static void ptrace_do_notify(int signr, int exit_code, int why)
info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
/* Let the debugger run. */
- ptrace_stop(exit_code, why, 1, &info);
+ return ptrace_stop(exit_code, why, 1, message, &info);
}
-void ptrace_notify(int exit_code)
+int ptrace_notify(int exit_code, unsigned long message)
{
+ int signr;
+
BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
- if (unlikely(current->task_works))
+ if (unlikely(task_work_pending(current)))
task_work_run();
spin_lock_irq(&current->sighand->siglock);
- ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
+ signr = ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED, message);
spin_unlock_irq(&current->sighand->siglock);
+ return signr;
}
/**
@@ -2504,11 +2558,10 @@ static void do_jobctl_trap(void)
signr = SIGTRAP;
WARN_ON_ONCE(!signr);
ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
- CLD_STOPPED);
+ CLD_STOPPED, 0);
} else {
WARN_ON_ONCE(!signr);
- ptrace_stop(signr, CLD_STOPPED, 0, NULL);
- current->exit_code = 0;
+ ptrace_stop(signr, CLD_STOPPED, 0, 0, NULL);
}
}
@@ -2561,15 +2614,12 @@ static int ptrace_signal(int signr, kernel_siginfo_t *info, enum pid_type type)
* comment in dequeue_signal().
*/
current->jobctl |= JOBCTL_STOP_DEQUEUED;
- ptrace_stop(signr, CLD_TRAPPED, 0, info);
+ signr = ptrace_stop(signr, CLD_TRAPPED, 0, 0, info);
/* We're back. Did the debugger cancel the sig? */
- signr = current->exit_code;
if (signr == 0)
return signr;
- current->exit_code = 0;
-
/*
* Update the siginfo structure if the signal has
* changed. If the debugger wanted something
@@ -2626,20 +2676,12 @@ bool get_signal(struct ksignal *ksig)
struct signal_struct *signal = current->signal;
int signr;
- if (unlikely(current->task_works))
+ clear_notify_signal();
+ if (unlikely(task_work_pending(current)))
task_work_run();
- /*
- * For non-generic architectures, check for TIF_NOTIFY_SIGNAL so
- * that the arch handlers don't all have to do it. If we get here
- * without TIF_SIGPENDING, just exit after running signal work.
- */
- if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
- if (test_thread_flag(TIF_NOTIFY_SIGNAL))
- tracehook_notify_signal();
- if (!task_sigpending(current))
- return false;
- }
+ if (!task_sigpending(current))
+ return false;
if (unlikely(uprobe_deny_signal()))
return false;
@@ -2898,7 +2940,8 @@ static void signal_delivered(struct ksignal *ksig, int stepping)
set_current_blocked(&blocked);
if (current->sas_ss_flags & SS_AUTODISARM)
sas_ss_reset(current);
- tracehook_signal_handler(stepping);
+ if (stepping)
+ ptrace_notify(SIGTRAP, 0);
}
void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
generated by cgit v1.2.3 (git 2.0.4) at 2025-12-10 18:13:09 +0000