selftests/rseq: Implement rseq numa node id field selftest

Test the NUMA node id extension rseq field. Compare it against the value
returned by the getcpu(2) system call while pinned on a specific core.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221122203932.231377-7-mathieu.desnoyers@efficios.com

1 files changed, 28 insertions, 0 deletions

diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h
index 95adc1e1b0db..fd17d0e54a1b 100644
--- a/tools/testing/selftests/rseq/rseq.h
+++ b/tools/testing/selftests/rseq/rseq.h
@@ -20,6 +20,15 @@
 #include "rseq-abi.h"
 #include "compiler.h"
 
+#ifndef rseq_sizeof_field
+#define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+#endif
+
+#ifndef rseq_offsetofend
+#define rseq_offsetofend(TYPE, MEMBER) \
+	(offsetof(TYPE, MEMBER)	+ rseq_sizeof_field(TYPE, MEMBER))
+#endif
+
 /*
  * Empty code injection macros, override when testing.
  * It is important to consider that the ASM injection macros need to be
@@ -129,6 +138,11 @@ int rseq_unregister_current_thread(void);
 int32_t rseq_fallback_current_cpu(void);
 
 /*
+ * Restartable sequence fallback for reading the current node number.
+ */
+int32_t rseq_fallback_current_node(void);
+
+/*
  * Values returned can be either the current CPU number, -1 (rseq is
  * uninitialized), or -2 (rseq initialization has failed).
  */
@@ -163,6 +177,20 @@ static inline uint32_t rseq_current_cpu(void)
 	return cpu;
 }
 
+static inline bool rseq_node_id_available(void)
+{
+	return (int) rseq_feature_size >= rseq_offsetofend(struct rseq_abi, node_id);
+}
+
+/*
+ * Current NUMA node number.
+ */
+static inline uint32_t rseq_current_node_id(void)
+{
+	assert(rseq_node_id_available());
+	return RSEQ_ACCESS_ONCE(rseq_get_abi()->node_id);
+}
+
 static inline void rseq_clear_rseq_cs(void)
 {
 	RSEQ_WRITE_ONCE(rseq_get_abi()->rseq_cs.arch.ptr, 0);