[patch V4 16/36] rseq: Provide tracepoint wrappers for inline code

Thomas Gleixner
2025-09-08T21:32:00Z

Provide tracepoint wrappers for the upcoming RSEQ exit to user space inline
fast path, so that the header can be safely included by code which defines
actual trace points.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
V4: Fix the fallback stub
V3: Get rid of one indentation level - Mathieu
---
include/linux/rseq_entry.h | 28 ++++++++++++++++++++++++++++
kernel/rseq.c | 17 +++++++++++++++++
2 files changed, 45 insertions(+)

--- a/include/linux/rseq_entry.h
+++ b/include/linux/rseq_entry.h
@@ -5,6 +5,34 @@
#ifdef CONFIG_RSEQ
#include <linux/rseq.h>

+#include <linux/tracepoint-defs.h>
+
+#ifdef CONFIG_TRACEPOINTS
+DECLARE_TRACEPOINT(rseq_update);
+DECLARE_TRACEPOINT(rseq_ip_fixup);
+void __rseq_trace_update(struct task_struct *t);
+void __rseq_trace_ip_fixup(unsigned long ip, unsigned long start_ip,
+ unsigned long offset, unsigned long abort_ip);
+
+static inline void rseq_trace_update(struct task_struct *t, struct rseq_ids *ids)
+{
+ if (tracepoint_enabled(rseq_update) && ids)
+ __rseq_trace_update(t);
+}
+
+static inline void rseq_trace_ip_fixup(unsigned long ip, unsigned long start_ip,
+ unsigned long offset, unsigned long abort_ip)
+{
+ if (tracepoint_enabled(rseq_ip_fixup))
+ __rseq_trace_ip_fixup(ip, start_ip, offset, abort_ip);
+}
+
+#else /* CONFIG_TRACEPOINT */
+static inline void rseq_trace_update(struct task_struct *t, struct rseq_ids *ids) { }
+static inline void rseq_trace_ip_fixup(unsigned long ip, unsigned long start_ip,
+ unsigned long offset, unsigned long abort_ip) { }
+#endif /* !CONFIG_TRACEPOINT */
+
static __always_inline void rseq_note_user_irq_entry(void)
{
if (IS_ENABLED(CONFIG_GENERIC_IRQ_ENTRY))
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -91,6 +91,23 @@
RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL | \
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE)

+#ifdef CONFIG_TRACEPOINTS
+/*
+ * Out of line, so the actual update functions can be in a header to be
+ * inlined into the exit to user code.
+ */
+void __rseq_trace_update(struct task_struct *t)
+{
+ trace_rseq_update(t);
+}
+
+void __rseq_trace_ip_fixup(unsigned long ip, unsigned long start_ip,
+ unsigned long offset, unsigned long abort_ip)
+{
+ trace_rseq_ip_fixup(ip, start_ip, offset, abort_ip);
+}
+#endif /* CONFIG_TRACEPOINTS */
+
#ifdef CONFIG_DEBUG_RSEQ
static struct rseq *rseq_kernel_fields(struct task_struct *t)
{