linux-kernel - [patch V2 16/37] rseq: Provide tracepoint wrappers for inline code

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Message-ID: <20250823161654.292334353@linutronix.de>
Date: Sat, 23 Aug 2025 18:39:45 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Jens Axboe <axboe@...nel.dk>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Peter Zijlstra <peterz@...radead.org>,
 "Paul E. McKenney" <paulmck@...nel.org>,
 Boqun Feng <boqun.feng@...il.com>,
 Paolo Bonzini <pbonzini@...hat.com>,
 Sean Christopherson <seanjc@...gle.com>,
 Wei Liu <wei.liu@...nel.org>,
 Dexuan Cui <decui@...rosoft.com>,
 x86@...nel.org,
 Arnd Bergmann <arnd@...db.de>,
 Heiko Carstens <hca@...ux.ibm.com>,
 Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Sven Schnelle <svens@...ux.ibm.com>,
 Huacai Chen <chenhuacai@...nel.org>,
 Paul Walmsley <paul.walmsley@...ive.com>,
 Palmer Dabbelt <palmer@...belt.com>
Subject: [patch V2 16/37] rseq: Provide tracepoint wrappers for inline code

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@...utronix.de>
---
 include/linux/rseq_entry.h |   30 ++++++++++++++++++++++++++++++
 kernel/rseq.c              |   17 +++++++++++++++++
 2 files changed, 47 insertions(+)

--- a/include/linux/rseq_entry.h
+++ b/include/linux/rseq_entry.h
@@ -5,6 +5,36 @@
 #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)) {
+		if (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) { }
+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)
 {