Merge tag 'core-rseq-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull rseq updates from Thomas Gleixner:
 "Two fixes for RSEQ:

   - Protect the event mask modification against the membarrier() IPI as
     otherwise the RmW operation is unprotected and events might be lost

   - Fix the weak symbol reference in rseq selftests

     The current weak RSEQ symbols definitions which were added to allow
     static linkage are not working correctly as they effectively
     re-define the glibc symbols leading to multiple versions of the
     symbols when compiled with -fno-common.

     Mark them as 'extern' to convert them from weak symbol definitions
     to weak symbol references. That works with static and dynamic
     linkage independent of -fcommon and -fno-common"

* tag 'core-rseq-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq/selftests: Use weak symbol reference, not definition, to link with glibc
  rseq: Protect event mask against membarrier IPI

1 files changed, 8 insertions, 3 deletions

diff --git a/include/linux/rseq.h b/include/linux/rseq.h
index a96fd345aa38..69553e7c14c1 100644
--- a/include/linux/rseq.h
+++ b/include/linux/rseq.h
@@ -7,6 +7,12 @@
 #include <linux/preempt.h>
 #include <linux/sched.h>
 
+#ifdef CONFIG_MEMBARRIER
+# define RSEQ_EVENT_GUARD	irq
+#else
+# define RSEQ_EVENT_GUARD	preempt
+#endif
+
 /*
  * Map the event mask on the user-space ABI enum rseq_cs_flags
  * for direct mask checks.
@@ -41,9 +47,8 @@ static inline void rseq_handle_notify_resume(struct ksignal *ksig,
 static inline void rseq_signal_deliver(struct ksignal *ksig,
 				       struct pt_regs *regs)
 {
-	preempt_disable();
-	__set_bit(RSEQ_EVENT_SIGNAL_BIT, &current->rseq_event_mask);
-	preempt_enable();
+	scoped_guard(RSEQ_EVENT_GUARD)
+		__set_bit(RSEQ_EVENT_SIGNAL_BIT, &current->rseq_event_mask);
 	rseq_handle_notify_resume(ksig, regs);
 }