linux-kernel - [PATCH] crypto: caam - add a test for the RNG

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Date:   Mon, 12 Jun 2023 10:28:42 +0200
From:   meenakshi.aggarwal@....com
To:     horia.geanta@....com, V.sethi@....com, pankaj.gupta@....com,
        gaurav.jain@....com, herbert@...dor.apana.org.au,
        davem@...emloft.net, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     "Victoria Milhoan (b42089)" <vicki.milhoan@...escale.com>,
        Dan Douglass <dan.douglass@....com>,
        Vipul Kumar <vipul_kumar@...tor.com>,
        Meenakshi Aggarwal <meenakshi.aggarwal@....com>
Subject: [PATCH] crypto: caam - add a test for the RNG

From: "Victoria Milhoan (b42089)" <vicki.milhoan@...escale.com>

CAAM includes a Random Number Generator.  This change adds
a kernel configuration option to test the RNG's capabilities via the
hw_random framework.

Signed-off-by: Victoria Milhoan <vicki.milhoan@...escale.com>
Signed-off-by: Dan Douglass <dan.douglass@....com>
Signed-off-by: Vipul Kumar <vipul_kumar@...tor.com>
Signed-off-by: Horia Geantă <horia.geanta@....com>
Signed-off-by: Meenakshi Aggarwal <meenakshi.aggarwal@....com>
---
 drivers/crypto/caam/Kconfig   |  9 +++++++
 drivers/crypto/caam/caamrng.c | 48 +++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/crypto/caam/Kconfig b/drivers/crypto/caam/Kconfig
index ec6a9e6ad4d2..c631f99e415f 100644
--- a/drivers/crypto/caam/Kconfig
+++ b/drivers/crypto/caam/Kconfig
@@ -162,6 +162,15 @@ config CRYPTO_DEV_FSL_CAAM_PRNG_API
 config CRYPTO_DEV_FSL_CAAM_BLOB_GEN
 	bool
 
+config CRYPTO_DEV_FSL_CAAM_RNG_TEST
+	bool "Test caam rng"
+	select CRYPTO_DEV_FSL_CAAM_RNG_API
+	help
+	  Selecting this will enable a self-test to run for the
+	  caam RNG.
+	  This test is several minutes long and executes
+	  just before the RNG is registered with the hw_random API.
+
 endif # CRYPTO_DEV_FSL_CAAM_JR
 
 endif # CRYPTO_DEV_FSL_CAAM
diff --git a/drivers/crypto/caam/caamrng.c b/drivers/crypto/caam/caamrng.c
index 50eb55da45c2..b3d14a7f4dd1 100644
--- a/drivers/crypto/caam/caamrng.c
+++ b/drivers/crypto/caam/caamrng.c
@@ -172,6 +172,50 @@ static void caam_cleanup(struct hwrng *rng)
 	kfifo_free(&ctx->fifo);
 }
 
+#ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_TEST
+static inline void test_len(struct hwrng *rng, size_t len, bool wait)
+{
+	u8 *buf;
+	int read_len;
+	struct caam_rng_ctx *ctx = to_caam_rng_ctx(rng);
+	struct device *dev = ctx->ctrldev;
+
+	buf = kcalloc(CAAM_RNG_MAX_FIFO_STORE_SIZE, sizeof(u8), GFP_KERNEL);
+
+	while (len > 0) {
+		read_len = rng->read(rng, buf, len, wait);
+
+		if (read_len < 0 || (read_len == 0 && wait)) {
+			dev_err(dev, "RNG Read FAILED received %d bytes\n",
+				read_len);
+			kfree(buf);
+			return;
+		}
+
+		print_hex_dump_debug("random bytes@: ",
+			DUMP_PREFIX_ADDRESS, 16, 4,
+			buf, read_len, 1);
+
+		len = len - read_len;
+	}
+
+	kfree(buf);
+}
+
+static inline void test_mode_once(struct hwrng *rng, bool wait)
+{
+	test_len(rng, 32, wait);
+	test_len(rng, 64, wait);
+	test_len(rng, 128, wait);
+}
+
+static void self_test(struct hwrng *rng)
+{
+	pr_info("Executing RNG SELF-TEST with wait\n");
+	test_mode_once(rng, true);
+}
+#endif
+
 static int caam_init(struct hwrng *rng)
 {
 	struct caam_rng_ctx *ctx = to_caam_rng_ctx(rng);
@@ -258,6 +302,10 @@ int caam_rng_init(struct device *ctrldev)
 		return ret;
 	}
 
+#ifdef CONFIG_CRYPTO_DEV_FSL_CAAM_RNG_TEST
+	self_test(&ctx->rng);
+#endif
+
 	devres_close_group(ctrldev, caam_rng_init);
 	return 0;
 }
-- 
2.25.1