1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * ChaCha stream cipher (s390 optimized)
4 *
5 * Copyright IBM Corp. 2021
6 */
7
8 #include <linux/cpufeature.h>
9 #include <linux/export.h>
10 #include <linux/kernel.h>
11 #include <linux/sizes.h>
12 #include <asm/fpu.h>
13 #include "chacha-s390.h"
14
15 #define hchacha_block_arch hchacha_block_generic /* not implemented yet */
16
chacha_crypt_arch(struct chacha_state * state,u8 * dst,const u8 * src,unsigned int bytes,int nrounds)17 static void chacha_crypt_arch(struct chacha_state *state, u8 *dst,
18 const u8 *src, unsigned int bytes, int nrounds)
19 {
20 /* s390 chacha20 implementation has 20 rounds hard-coded,
21 * it cannot handle a block of data or less, but otherwise
22 * it can handle data of arbitrary size
23 */
24 if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20 || !cpu_has_vx()) {
25 chacha_crypt_generic(state, dst, src, bytes, nrounds);
26 } else {
27 DECLARE_KERNEL_FPU_ONSTACK32(vxstate);
28
29 kernel_fpu_begin(&vxstate, KERNEL_VXR);
30 chacha20_vx(dst, src, bytes, &state->x[4], &state->x[12]);
31 kernel_fpu_end(&vxstate, KERNEL_VXR);
32
33 state->x[12] += round_up(bytes, CHACHA_BLOCK_SIZE) /
34 CHACHA_BLOCK_SIZE;
35 }
36 }
37