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// 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 || !cpu_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");
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