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

4 files changed, 58 insertions, 0 deletions

diff --git a/tools/testing/selftests/rseq/basic_test.c b/tools/testing/selftests/rseq/basic_test.c
index d8efbfb89193..295eea16466f 100644
--- a/tools/testing/selftests/rseq/basic_test.c
+++ b/tools/testing/selftests/rseq/basic_test.c
@@ -22,6 +22,8 @@ void test_cpu_pointer(void)
 	CPU_ZERO(&test_affinity);
 	for (i = 0; i < CPU_SETSIZE; i++) {
 		if (CPU_ISSET(i, &affinity)) {
+			int node;
+
 			CPU_SET(i, &test_affinity);
 			sched_setaffinity(0, sizeof(test_affinity),
 					&test_affinity);
@@ -29,6 +31,8 @@ void test_cpu_pointer(void)
 			assert(rseq_current_cpu() == i);
 			assert(rseq_current_cpu_raw() == i);
 			assert(rseq_cpu_start() == i);
+			node = rseq_fallback_current_node();
+			assert(rseq_current_node_id() == node);
 			CPU_CLR(i, &test_affinity);
 		}
 	}
diff --git a/tools/testing/selftests/rseq/rseq-abi.h b/tools/testing/selftests/rseq/rseq-abi.h
index 00ac846d85b0..a1faa9162d52 100644
--- a/tools/testing/selftests/rseq/rseq-abi.h
+++ b/tools/testing/selftests/rseq/rseq-abi.h
@@ -148,6 +148,14 @@ struct rseq_abi {
 	__u32 flags;
 
 	/*
+	 * Restartable sequences node_id field. Updated by the kernel. Read by
+	 * user-space with single-copy atomicity semantics. This field should
+	 * only be read by the thread which registered this data structure.
+	 * Aligned on 32-bit. Contains the current NUMA node ID.
+	 */
+	__u32 node_id;
+
+	/*
 	 * Flexible array member at end of structure, after last feature field.
 	 */
 	char end[];
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 1e8e3265bdbf..4e4aa006004c 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -79,6 +79,11 @@ static int sys_rseq(struct rseq_abi *rseq_abi, uint32_t rseq_len,
 	return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
 }
 
+static int sys_getcpu(unsigned *cpu, unsigned *node)
+{
+	return syscall(__NR_getcpu, cpu, node, NULL);
+}
+
 int rseq_available(void)
 {
 	int rc;
@@ -201,3 +206,16 @@ int32_t rseq_fallback_current_cpu(void)
 	}
 	return cpu;
 }
+
+int32_t rseq_fallback_current_node(void)
+{
+	uint32_t cpu_id, node_id;
+	int ret;
+
+	ret = sys_getcpu(&cpu_id, &node_id);
+	if (ret) {
+		perror("sys_getcpu()");
+		return ret;
+	}
+	return (int32_t) node_id;
+}
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);