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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* AES block cipher using AES-NI instructions
*
* Copyright 2026 Google LLC
*/
#include <asm/fpu/api.h>
static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_aes);
void aes128_expandkey_aesni(u32 rndkeys[], u32 *inv_rndkeys,
const u8 in_key[AES_KEYSIZE_128]);
void aes256_expandkey_aesni(u32 rndkeys[], u32 *inv_rndkeys,
const u8 in_key[AES_KEYSIZE_256]);
void aes_encrypt_aesni(const u32 rndkeys[], int nrounds,
u8 out[AES_BLOCK_SIZE], const u8 in[AES_BLOCK_SIZE]);
void aes_decrypt_aesni(const u32 inv_rndkeys[], int nrounds,
u8 out[AES_BLOCK_SIZE], const u8 in[AES_BLOCK_SIZE]);
/*
* Expand an AES key using AES-NI if supported and usable or generic code
* otherwise. The expanded key format is compatible between the two cases. The
* outputs are @k->rndkeys (required) and @inv_k->inv_rndkeys (optional).
*
* We could just always use the generic key expansion code. AES key expansion
* is usually less performance-critical than AES en/decryption. However,
* there's still *some* value in speed here, as well as in non-key-dependent
* execution time which AES-NI provides. So, do use AES-NI to expand AES-128
* and AES-256 keys. (Don't bother with AES-192, as it's almost never used.)
*/
static void aes_preparekey_arch(union aes_enckey_arch *k,
union aes_invkey_arch *inv_k,
const u8 *in_key, int key_len, int nrounds)
{
u32 *rndkeys = k->rndkeys;
u32 *inv_rndkeys = inv_k ? inv_k->inv_rndkeys : NULL;
if (static_branch_likely(&have_aes) && key_len != AES_KEYSIZE_192 &&
irq_fpu_usable()) {
kernel_fpu_begin();
if (key_len == AES_KEYSIZE_128)
aes128_expandkey_aesni(rndkeys, inv_rndkeys, in_key);
else
aes256_expandkey_aesni(rndkeys, inv_rndkeys, in_key);
kernel_fpu_end();
} else {
aes_expandkey_generic(rndkeys, inv_rndkeys, in_key, key_len);
}
}
static void aes_encrypt_arch(const struct aes_enckey *key,
u8 out[AES_BLOCK_SIZE],
const u8 in[AES_BLOCK_SIZE])
{
if (static_branch_likely(&have_aes) && irq_fpu_usable()) {
kernel_fpu_begin();
aes_encrypt_aesni(key->k.rndkeys, key->nrounds, out, in);
kernel_fpu_end();
} else {
aes_encrypt_generic(key->k.rndkeys, key->nrounds, out, in);
}
}
static void aes_decrypt_arch(const struct aes_key *key,
u8 out[AES_BLOCK_SIZE],
const u8 in[AES_BLOCK_SIZE])
{
if (static_branch_likely(&have_aes) && irq_fpu_usable()) {
kernel_fpu_begin();
aes_decrypt_aesni(key->inv_k.inv_rndkeys, key->nrounds,
out, in);
kernel_fpu_end();
} else {
aes_decrypt_generic(key->inv_k.inv_rndkeys, key->nrounds,
out, in);
}
}
#define aes_mod_init_arch aes_mod_init_arch
static void aes_mod_init_arch(void)
{
if (boot_cpu_has(X86_FEATURE_AES))
static_branch_enable(&have_aes);
}
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