1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * POLYVAL library functions, x86_64 optimized
4 *
5 * Copyright 2025 Google LLC
6 */
7#include <asm/fpu/api.h>
8#include <linux/cpufeature.h>
9
10#define NUM_H_POWERS 8
11
12static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_pclmul_avx);
13
14asmlinkage void polyval_mul_pclmul_avx(struct polyval_elem *a,
15 const struct polyval_elem *b);
16asmlinkage void polyval_blocks_pclmul_avx(struct polyval_elem *acc,
17 const struct polyval_key *key,
18 const u8 *data, size_t nblocks);
19
20static void polyval_preparekey_arch(struct polyval_key *key,
21 const u8 raw_key[POLYVAL_BLOCK_SIZE])
22{
23 static_assert(ARRAY_SIZE(key->h_powers) == NUM_H_POWERS);
24 memcpy(&key->h_powers[NUM_H_POWERS - 1], raw_key, POLYVAL_BLOCK_SIZE);
25 if (static_branch_likely(&have_pclmul_avx) && irq_fpu_usable()) {
26 kernel_fpu_begin();
27 for (int i = NUM_H_POWERS - 2; i >= 0; i--) {
28 key->h_powers[i] = key->h_powers[i + 1];
29 polyval_mul_pclmul_avx(
30 a: &key->h_powers[i],
31 b: &key->h_powers[NUM_H_POWERS - 1]);
32 }
33 kernel_fpu_end();
34 } else {
35 for (int i = NUM_H_POWERS - 2; i >= 0; i--) {
36 key->h_powers[i] = key->h_powers[i + 1];
37 polyval_mul_generic(a: &key->h_powers[i],
38 b: &key->h_powers[NUM_H_POWERS - 1]);
39 }
40 }
41}
42
43static void polyval_mul_arch(struct polyval_elem *acc,
44 const struct polyval_key *key)
45{
46 if (static_branch_likely(&have_pclmul_avx) && irq_fpu_usable()) {
47 kernel_fpu_begin();
48 polyval_mul_pclmul_avx(a: acc, b: &key->h_powers[NUM_H_POWERS - 1]);
49 kernel_fpu_end();
50 } else {
51 polyval_mul_generic(a: acc, b: &key->h_powers[NUM_H_POWERS - 1]);
52 }
53}
54
55static void polyval_blocks_arch(struct polyval_elem *acc,
56 const struct polyval_key *key,
57 const u8 *data, size_t nblocks)
58{
59 if (static_branch_likely(&have_pclmul_avx) && irq_fpu_usable()) {
60 do {
61 /* Allow rescheduling every 4 KiB. */
62 size_t n = min_t(size_t, nblocks,
63 4096 / POLYVAL_BLOCK_SIZE);
64
65 kernel_fpu_begin();
66 polyval_blocks_pclmul_avx(acc, key, data, nblocks: n);
67 kernel_fpu_end();
68 data += n * POLYVAL_BLOCK_SIZE;
69 nblocks -= n;
70 } while (nblocks);
71 } else {
72 polyval_blocks_generic(acc, key: &key->h_powers[NUM_H_POWERS - 1],
73 data, nblocks);
74 }
75}
76
77#define polyval_mod_init_arch polyval_mod_init_arch
78static void polyval_mod_init_arch(void)
79{
80 if (boot_cpu_has(X86_FEATURE_PCLMULQDQ) &&
81 boot_cpu_has(X86_FEATURE_AVX))
82 static_branch_enable(&have_pclmul_avx);
83}
84

source code of linux/lib/crypto/x86/polyval.h