1 files changed, 130 insertions, 0 deletions
diff --git a/arch/s390/crypto/chacha-glue.c b/arch/s390/crypto/chacha-glue.c
new file mode 100644
index 0000000000..5fae187f94
--- /dev/null
+++ b/arch/s390/crypto/chacha-glue.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * s390 ChaCha stream cipher.
+ *
+ * Copyright IBM Corp. 2021
+ */
+
+#define KMSG_COMPONENT "chacha_s390"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <crypto/internal/chacha.h>
+#include <crypto/internal/skcipher.h>
+#include <crypto/algapi.h>
+#include <linux/cpufeature.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sizes.h>
+#include <asm/fpu/api.h>
+#include "chacha-s390.h"
+
+static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src,
+				unsigned int nbytes, const u32 *key,
+				u32 *counter)
+{
+	struct kernel_fpu vxstate;
+
+	kernel_fpu_begin(&vxstate, KERNEL_VXR);
+	chacha20_vx(dst, src, nbytes, key, counter);
+	kernel_fpu_end(&vxstate, KERNEL_VXR);
+
+	*counter += round_up(nbytes, CHACHA_BLOCK_SIZE) / CHACHA_BLOCK_SIZE;
+}
+
+static int chacha20_s390(struct skcipher_request *req)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
+	u32 state[CHACHA_STATE_WORDS] __aligned(16);
+	struct skcipher_walk walk;
+	unsigned int nbytes;
+	int rc;
+
+	rc = skcipher_walk_virt(&walk, req, false);
+	chacha_init_generic(state, ctx->key, req->iv);
+
+	while (walk.nbytes > 0) {
+		nbytes = walk.nbytes;
+		if (nbytes < walk.total)
+			nbytes = round_down(nbytes, walk.stride);
+
+		if (nbytes <= CHACHA_BLOCK_SIZE) {
+			chacha_crypt_generic(state, walk.dst.virt.addr,
+					     walk.src.virt.addr, nbytes,
+					     ctx->nrounds);
+		} else {
+			chacha20_crypt_s390(state, walk.dst.virt.addr,
+					    walk.src.virt.addr, nbytes,
+					    &state[4], &state[12]);
+		}
+		rc = skcipher_walk_done(&walk, walk.nbytes - nbytes);
+	}
+	return rc;
+}
+
+void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
+{
+	/* TODO: implement hchacha_block_arch() in assembly */
+	hchacha_block_generic(state, stream, nrounds);
+}
+EXPORT_SYMBOL(hchacha_block_arch);
+
+void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
+{
+	chacha_init_generic(state, key, iv);
+}
+EXPORT_SYMBOL(chacha_init_arch);
+
+void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
+		       unsigned int bytes, int nrounds)
+{
+	/* s390 chacha20 implementation has 20 rounds hard-coded,
+	 * it cannot handle a block of data or less, but otherwise
+	 * it can handle data of arbitrary size
+	 */
+	if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20 || !MACHINE_HAS_VX)
+		chacha_crypt_generic(state, dst, src, bytes, nrounds);
+	else
+		chacha20_crypt_s390(state, dst, src, bytes,
+				    &state[4], &state[12]);
+}
+EXPORT_SYMBOL(chacha_crypt_arch);
+
+static struct skcipher_alg chacha_algs[] = {
+	{
+		.base.cra_name		= "chacha20",
+		.base.cra_driver_name	= "chacha20-s390",
+		.base.cra_priority	= 900,
+		.base.cra_blocksize	= 1,
+		.base.cra_ctxsize	= sizeof(struct chacha_ctx),
+		.base.cra_module	= THIS_MODULE,
+
+		.min_keysize		= CHACHA_KEY_SIZE,
+		.max_keysize		= CHACHA_KEY_SIZE,
+		.ivsize			= CHACHA_IV_SIZE,
+		.chunksize		= CHACHA_BLOCK_SIZE,
+		.setkey			= chacha20_setkey,
+		.encrypt		= chacha20_s390,
+		.decrypt		= chacha20_s390,
+	}
+};
+
+static int __init chacha_mod_init(void)
+{
+	return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
+		crypto_register_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)) : 0;
+}
+
+static void __exit chacha_mod_fini(void)
+{
+	if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER))
+		crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs));
+}
+
+module_cpu_feature_match(S390_CPU_FEATURE_VXRS, chacha_mod_init);
+module_exit(chacha_mod_fini);
+
+MODULE_DESCRIPTION("ChaCha20 stream cipher");
+MODULE_LICENSE("GPL v2");
+
+MODULE_ALIAS_CRYPTO("chacha20");