1 files changed, 60 insertions, 0 deletions
diff --git a/tools/perf/tests/workloads/datasym.c b/tools/perf/tests/workloads/datasym.c
new file mode 100644
index 000000000000..1d0b7d64e1ba
--- /dev/null
+++ b/tools/perf/tests/workloads/datasym.c
@@ -0,0 +1,60 @@
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+#include <linux/compiler.h>
+#include "../tests.h"
+
+typedef struct _buf {
+	char data1;
+	char reserved[55];
+	char data2;
+} buf __attribute__((aligned(64)));
+
+/* volatile to try to avoid the compiler seeing reserved as unused. */
+static volatile buf workload_datasym_buf1 = {
+	/* to have this in the data section */
+	.reserved[0] = 1,
+};
+
+static volatile sig_atomic_t done;
+
+static void sighandler(int sig __maybe_unused)
+{
+	done = 1;
+}
+
+static int datasym(int argc, const char **argv)
+{
+	int sec = 1;
+
+	if (argc > 0)
+		sec = atoi(argv[0]);
+
+	signal(SIGINT, sighandler);
+	signal(SIGALRM, sighandler);
+	alarm(sec);
+
+	while (!done) {
+		workload_datasym_buf1.data1++;
+		if (workload_datasym_buf1.data1 == 123) {
+			/*
+			 * Add some 'noise' in the loop to work around errata
+			 * 1694299 on Arm N1.
+			 *
+			 * Bias exists in SPE sampling which can cause the load
+			 * and store instructions to be skipped entirely. This
+			 * comes and goes randomly depending on the offset the
+			 * linker places the datasym loop at in the Perf binary.
+			 * With an extra branch in the middle of the loop that
+			 * isn't always taken, the instruction stream is no
+			 * longer a continuous repeating pattern that interacts
+			 * badly with the bias.
+			 */
+			workload_datasym_buf1.data1++;
+		}
+		workload_datasym_buf1.data2 += workload_datasym_buf1.data1;
+	}
+	return 0;
+}
+
+DEFINE_WORKLOAD(datasym);