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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* POLYVAL library functions, x86_64 optimized
*
* Copyright 2025 Google LLC
*/
#include <asm/fpu/api.h>
#include <linux/cpufeature.h>
#define NUM_H_POWERS 8
static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_pclmul_avx);
asmlinkage void polyval_mul_pclmul_avx(struct polyval_elem *a,
const struct polyval_elem *b);
asmlinkage void polyval_blocks_pclmul_avx(struct polyval_elem *acc,
const struct polyval_key *key,
const u8 *data, size_t nblocks);
static void polyval_preparekey_arch(struct polyval_key *key,
const u8 raw_key[POLYVAL_BLOCK_SIZE])
{
static_assert(ARRAY_SIZE(key->h_powers) == NUM_H_POWERS);
memcpy(&key->h_powers[NUM_H_POWERS - 1], raw_key, POLYVAL_BLOCK_SIZE);
if (static_branch_likely(&have_pclmul_avx) && irq_fpu_usable()) {
kernel_fpu_begin();
for (int i = NUM_H_POWERS - 2; i >= 0; i--) {
key->h_powers[i] = key->h_powers[i + 1];
polyval_mul_pclmul_avx(
&key->h_powers[i],
&key->h_powers[NUM_H_POWERS - 1]);
}
kernel_fpu_end();
} else {
for (int i = NUM_H_POWERS - 2; i >= 0; i--) {
key->h_powers[i] = key->h_powers[i + 1];
polyval_mul_generic(&key->h_powers[i],
&key->h_powers[NUM_H_POWERS - 1]);
}
}
}
static void polyval_mul_arch(struct polyval_elem *acc,
const struct polyval_key *key)
{
if (static_branch_likely(&have_pclmul_avx) && irq_fpu_usable()) {
kernel_fpu_begin();
polyval_mul_pclmul_avx(acc, &key->h_powers[NUM_H_POWERS - 1]);
kernel_fpu_end();
} else {
polyval_mul_generic(acc, &key->h_powers[NUM_H_POWERS - 1]);
}
}
static void polyval_blocks_arch(struct polyval_elem *acc,
const struct polyval_key *key,
const u8 *data, size_t nblocks)
{
if (static_branch_likely(&have_pclmul_avx) && irq_fpu_usable()) {
do {
/* Allow rescheduling every 4 KiB. */
size_t n = min_t(size_t, nblocks,
4096 / POLYVAL_BLOCK_SIZE);
kernel_fpu_begin();
polyval_blocks_pclmul_avx(acc, key, data, n);
kernel_fpu_end();
data += n * POLYVAL_BLOCK_SIZE;
nblocks -= n;
} while (nblocks);
} else {
polyval_blocks_generic(acc, &key->h_powers[NUM_H_POWERS - 1],
data, nblocks);
}
}
#define polyval_mod_init_arch polyval_mod_init_arch
static void polyval_mod_init_arch(void)
{
if (boot_cpu_has(X86_FEATURE_PCLMULQDQ) &&
boot_cpu_has(X86_FEATURE_AVX))
static_branch_enable(&have_pclmul_avx);
}
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