1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * s390 ChaCha stream cipher. 4 * 5 * Copyright IBM Corp. 2021 6 */ 7 8 #define KMSG_COMPONENT "chacha_s390" 9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt 10 11 #include <crypto/internal/chacha.h> 12 #include <crypto/internal/skcipher.h> 13 #include <crypto/algapi.h> 14 #include <linux/cpufeature.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/sizes.h> 18 #include <asm/fpu/api.h> 19 #include "chacha-s390.h" 20 21 static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src, 22 unsigned int nbytes, const u32 *key, 23 u32 *counter) 24 { 25 struct kernel_fpu vxstate; 26 27 kernel_fpu_begin(&vxstate, KERNEL_VXR); 28 chacha20_vx(dst, src, nbytes, key, counter); 29 kernel_fpu_end(&vxstate, KERNEL_VXR); 30 31 *counter += round_up(nbytes, CHACHA_BLOCK_SIZE) / CHACHA_BLOCK_SIZE; 32 } 33 34 static int chacha20_s390(struct skcipher_request *req) 35 { 36 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 37 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); 38 u32 state[CHACHA_STATE_WORDS] __aligned(16); 39 struct skcipher_walk walk; 40 unsigned int nbytes; 41 int rc; 42 43 rc = skcipher_walk_virt(&walk, req, false); 44 chacha_init_generic(state, ctx->key, req->iv); 45 46 while (walk.nbytes > 0) { 47 nbytes = walk.nbytes; 48 if (nbytes < walk.total) 49 nbytes = round_down(nbytes, walk.stride); 50 51 if (nbytes <= CHACHA_BLOCK_SIZE) { 52 chacha_crypt_generic(state, walk.dst.virt.addr, 53 walk.src.virt.addr, nbytes, 54 ctx->nrounds); 55 } else { 56 chacha20_crypt_s390(state, walk.dst.virt.addr, 57 walk.src.virt.addr, nbytes, 58 &state[4], &state[12]); 59 } 60 rc = skcipher_walk_done(&walk, walk.nbytes - nbytes); 61 } 62 return rc; 63 } 64 65 static struct skcipher_alg chacha_algs[] = { 66 { 67 .base.cra_name = "chacha20", 68 .base.cra_driver_name = "chacha20-s390", 69 .base.cra_priority = 900, 70 .base.cra_blocksize = 1, 71 .base.cra_ctxsize = sizeof(struct chacha_ctx), 72 .base.cra_module = THIS_MODULE, 73 74 .min_keysize = CHACHA_KEY_SIZE, 75 .max_keysize = CHACHA_KEY_SIZE, 76 .ivsize = CHACHA_IV_SIZE, 77 .chunksize = CHACHA_BLOCK_SIZE, 78 .setkey = chacha20_setkey, 79 .encrypt = chacha20_s390, 80 .decrypt = chacha20_s390, 81 } 82 }; 83 84 static int __init chacha_mod_init(void) 85 { 86 return crypto_register_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)); 87 } 88 89 static void __exit chacha_mod_fini(void) 90 { 91 crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)); 92 } 93 94 module_cpu_feature_match(VXRS, chacha_mod_init); 95 module_exit(chacha_mod_fini); 96 97 MODULE_DESCRIPTION("ChaCha20 stream cipher"); 98 MODULE_LICENSE("GPL v2"); 99 100 MODULE_ALIAS_CRYPTO("chacha20"); 101