test: Add rng_benchmark test

BRANCH=none
BUG=b:246836252
TEST=./test/run_device_tests.py --board bloonchipper -t rng_benchmark
TEST=./test/run_device_tests.py --board dartmonkey -t rng_benchmark

Signed-off-by: Andrea Grandi <agrandi@google.com>
Change-Id: Ib1a2a4b0fc8e3d55022e94727417c38e5e94359b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4019773
Reviewed-by: Bobby Casey <bobbycasey@google.com>
Code-Coverage: Zoss <zoss-cl-coverage@prod.google.com>
Reviewed-by: Tom Hughes <tomhughes@chromium.org>

1 files changed, 81 insertions, 0 deletions

diff --git a/test/rng_benchmark.cc b/test/rng_benchmark.cc
new file mode 100644
index 0000000000..2e47b8ea27
--- /dev/null
+++ b/test/rng_benchmark.cc
@@ -0,0 +1,81 @@
+/* Copyright 2022 The ChromiumOS Authors
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Measure performance of the hardware True Random Number Generator (TRNG)
+ * compared to the std::rand().
+ */
+
+#include "benchmark.h"
+
+#include "console.h"
+#include <array>
+#include <cstdint>
+#include <cstdlib>
+
+extern "C" {
+#include "test_util.h"
+#include "trng.h"
+}
+
+test_static int test_rng()
+{
+	constexpr int num_iterations = 100;
+	Benchmark benchmark({ .num_iterations = num_iterations });
+	std::array<uint32_t, num_iterations> trng_out;
+	std::array<int, num_iterations> rand_out;
+
+	// Try the hardware true random number generator
+	trng_out.fill(0);
+
+	trng_init();
+	auto result = benchmark.run("trng", [&trng_out]() {
+		static int i = 0;
+		trng_out[i++] = trng_rand();
+	});
+	trng_exit();
+
+	TEST_ASSERT(result.has_value());
+	for (int i = 0; i < trng_out.size() - 1; ++i) {
+		TEST_NE(trng_out[i], trng_out[i + 1], "%d");
+		cflush();
+	}
+
+	// Repeat the test by turning the TNRG on and off at each iteration
+	trng_out.fill(0);
+	result = benchmark.run("trng_on_off", [&trng_out]() {
+		trng_init();
+		static int i = 0;
+		trng_out[i++] = trng_rand();
+		trng_exit();
+	});
+
+	TEST_ASSERT(result.has_value());
+	for (int i = 0; i < trng_out.size() - 1; ++i) {
+		TEST_NE(trng_out[i], trng_out[i + 1], "%d");
+		cflush();
+	}
+
+	// Repeat the test using std::rand() for comparison
+	rand_out.fill(0);
+	result = benchmark.run("std::rand", [&rand_out]() {
+		static int i = 0;
+		rand_out[i++] = std::rand();
+	});
+
+	TEST_ASSERT(result.has_value());
+	for (int i = 0; i < rand_out.size() - 1; ++i) {
+		TEST_NE(rand_out[i], rand_out[i + 1], "%d");
+		cflush();
+	}
+
+	benchmark.print_results();
+	return EC_SUCCESS;
+}
+
+void run_test(int argc, const char **argv)
+{
+	test_reset();
+	RUN_TEST(test_rng);
+	test_print_result();
+}
\ No newline at end of file