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The kernel_fpu structure has a quite large size of 520 bytes. In order to reduce stack footprint introduce several kernel fpu structures with different and also smaller sizes. This way every kernel fpu user must use the correct variant. A compile time check verifies that the correct variant is used. There are several users which use only 16 instead of all 32 vector registers. For those users the new kernel_fpu_16 structure with a size of only 266 bytes can be used. Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
131 lines
3.5 KiB
C
131 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* s390 ChaCha stream cipher.
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*
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* Copyright IBM Corp. 2021
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*/
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#define KMSG_COMPONENT "chacha_s390"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <crypto/internal/chacha.h>
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#include <crypto/internal/skcipher.h>
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#include <crypto/algapi.h>
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#include <linux/cpufeature.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sizes.h>
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#include <asm/fpu.h>
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#include "chacha-s390.h"
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static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src,
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unsigned int nbytes, const u32 *key,
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u32 *counter)
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{
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DECLARE_KERNEL_FPU_ONSTACK32(vxstate);
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kernel_fpu_begin(&vxstate, KERNEL_VXR);
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chacha20_vx(dst, src, nbytes, key, counter);
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kernel_fpu_end(&vxstate, KERNEL_VXR);
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*counter += round_up(nbytes, CHACHA_BLOCK_SIZE) / CHACHA_BLOCK_SIZE;
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}
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static int chacha20_s390(struct skcipher_request *req)
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
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u32 state[CHACHA_STATE_WORDS] __aligned(16);
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struct skcipher_walk walk;
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unsigned int nbytes;
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int rc;
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rc = skcipher_walk_virt(&walk, req, false);
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chacha_init_generic(state, ctx->key, req->iv);
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while (walk.nbytes > 0) {
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nbytes = walk.nbytes;
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if (nbytes < walk.total)
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nbytes = round_down(nbytes, walk.stride);
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if (nbytes <= CHACHA_BLOCK_SIZE) {
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chacha_crypt_generic(state, walk.dst.virt.addr,
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walk.src.virt.addr, nbytes,
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ctx->nrounds);
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} else {
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chacha20_crypt_s390(state, walk.dst.virt.addr,
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walk.src.virt.addr, nbytes,
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&state[4], &state[12]);
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}
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rc = skcipher_walk_done(&walk, walk.nbytes - nbytes);
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}
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return rc;
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}
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void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
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{
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/* TODO: implement hchacha_block_arch() in assembly */
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hchacha_block_generic(state, stream, nrounds);
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}
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EXPORT_SYMBOL(hchacha_block_arch);
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void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
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{
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chacha_init_generic(state, key, iv);
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}
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EXPORT_SYMBOL(chacha_init_arch);
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void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds)
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{
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/* s390 chacha20 implementation has 20 rounds hard-coded,
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* it cannot handle a block of data or less, but otherwise
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* it can handle data of arbitrary size
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*/
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if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20 || !cpu_has_vx())
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chacha_crypt_generic(state, dst, src, bytes, nrounds);
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else
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chacha20_crypt_s390(state, dst, src, bytes,
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&state[4], &state[12]);
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}
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EXPORT_SYMBOL(chacha_crypt_arch);
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static struct skcipher_alg chacha_algs[] = {
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{
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.base.cra_name = "chacha20",
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.base.cra_driver_name = "chacha20-s390",
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.base.cra_priority = 900,
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.base.cra_blocksize = 1,
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.base.cra_ctxsize = sizeof(struct chacha_ctx),
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.base.cra_module = THIS_MODULE,
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.min_keysize = CHACHA_KEY_SIZE,
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.max_keysize = CHACHA_KEY_SIZE,
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.ivsize = CHACHA_IV_SIZE,
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.chunksize = CHACHA_BLOCK_SIZE,
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.setkey = chacha20_setkey,
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.encrypt = chacha20_s390,
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.decrypt = chacha20_s390,
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}
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};
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static int __init chacha_mod_init(void)
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{
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return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
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crypto_register_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)) : 0;
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}
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static void __exit chacha_mod_fini(void)
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{
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if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER))
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crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs));
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}
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module_cpu_feature_match(S390_CPU_FEATURE_VXRS, chacha_mod_init);
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module_exit(chacha_mod_fini);
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MODULE_DESCRIPTION("ChaCha20 stream cipher");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS_CRYPTO("chacha20");
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