lib/crypto: x86/aes-cbc: Add AES-NI optimization

Optimize the crypto library's AES-CBC and AES-CBC-CTS support with
AES-NI, bringing their performance on par with the "cbc-aes-aesni" and
"cts-cbc-aes-aesni" skcipher algorithms they will supersede.

The new assembly functions are written from scratch to fit well into the
crypto library.  However, they are functionally very similar to the
functions in arch/x86/crypto/aesni-intel_asm.S that they will supersede
and are intended to provide parity with those -- including supporting
32-bit mode, having the inner loops do 4 AES blocks per iteration, etc.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://patch.msgid.link/20260927224418.109759-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers 2026-09-27 15:42:56 -07:00
parent d825a5f349
commit 100d14f3f2
3 changed files with 323 additions and 2 deletions

View File

@ -625,7 +625,7 @@ static struct skcipher_alg skcipher_algs[] = {
{
.base.cra_name = "cbc(aes)",
.base.cra_driver_name = "cbc-aes-lib",
.base.cra_priority = 110,
.base.cra_priority = IS_ENABLED(CONFIG_X86) ? 300 : 110,
.base.cra_blocksize = AES_BLOCK_SIZE,
.base.cra_ctxsize = sizeof(struct aes_key),
.base.cra_module = THIS_MODULE,
@ -652,7 +652,7 @@ static struct skcipher_alg skcipher_algs[] = {
{
.base.cra_name = "cts(cbc(aes))",
.base.cra_driver_name = "cts-cbc-aes-lib",
.base.cra_priority = 110,
.base.cra_priority = IS_ENABLED(CONFIG_X86) ? 300 : 110,
.base.cra_blocksize = AES_BLOCK_SIZE,
.base.cra_ctxsize = sizeof(struct aes_key),
.base.cra_module = THIS_MODULE,

View File

@ -57,6 +57,14 @@
// The AES round constants, used during key expansion
.long 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
.Lcts_permute_table:
.byte 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80
.byte 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80
.byte 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07
.byte 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
.byte 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80
.byte 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80
.text
// In 32-bit mode, push certain callee-saved GPRs and optionally load function
@ -402,3 +410,227 @@ SYM_FUNC_END(aes_ecb_encrypt_aesni)
SYM_FUNC_START(aes_ecb_decrypt_aesni)
_ecb_crypt 0
SYM_FUNC_END(aes_ecb_decrypt_aesni)
// void aes_cbc_encrypt_aesni(u8 *dst, const u8 *src, long nblocks,
// u8 iv[AES_BLOCK_SIZE],
// const struct aes_enckey *key);
//
// This assumes nblocks > 0.
SYM_FUNC_START(aes_cbc_encrypt_aesni)
// Arguments
.set DST, ARG0
.set SRC, ARG1
.set NBLOCKS, ARG2
.set IV_PTR, ARG3
.set KEY, ARG4
// Other local variables
#ifdef __x86_64__
.set RNDKEY_PTR, %r9
#else
.set RNDKEY_PTR, IV_PTR // IV_PTR is clobbered and reloaded later
#endif
.set NROUNDS, TMP_32
.set AESDATA0, %xmm0
.set PTEXT, %xmm1
_prologue uses_arg3=2, uses_arg4=2
movdqu (IV_PTR), AESDATA0
.p2align 5
.Lcbc_enc_loop:
movdqu (SRC), PTEXT
pxor PTEXT, AESDATA0
_do_aes 1, 0
movdqu AESDATA0, (DST)
add $16, SRC
add $16, DST
dec NBLOCKS
jnz .Lcbc_enc_loop
// Store the next IV. On 32-bit, reload IV_PTR from stack first.
_reload_arg3
movdqu AESDATA0, (IV_PTR)
_epilogue
SYM_FUNC_END(aes_cbc_encrypt_aesni)
// void aes_cbc_decrypt_aesni(u8 *dst, const u8 *src, long nblocks,
// u8 iv[AES_BLOCK_SIZE], const struct aes_key *key);
SYM_FUNC_START(aes_cbc_decrypt_aesni)
// Arguments
.set DST, ARG0
.set SRC, ARG1
.set NBLOCKS, ARG2
.set NBLOCKS32, ARG2_32 // Used for improved code density
.set IV_PTR, ARG3
.set KEY, ARG4
// Other local variables
#ifdef __x86_64__
.set RNDKEY_PTR, %r9
#else
.set RNDKEY_PTR, IV_PTR // IV_PTR is clobbered and reloaded later
#endif
.set NROUNDS, TMP_32
.set AESDATA0, %xmm0
.set AESDATA1, %xmm1
.set AESDATA2, %xmm2
.set AESDATA3, %xmm3
.set RNDKEY, %xmm4
.set IV, %xmm5
.set CTEXT0, %xmm6
.set CTEXT1, %xmm7
#ifdef __x86_64__
.set CTEXT2, %xmm8
.set CTEXT3, %xmm9
#endif
_prologue uses_arg3=2, uses_arg4=2
movdqu (IV_PTR), IV
sub $4, NBLOCKS
jl .Lcbc_dec_loop4_done
.p2align 5
.Lcbc_dec_loop4:
movdqu 0(SRC), AESDATA0
movdqu 16(SRC), AESDATA1
movdqu 32(SRC), AESDATA2
movdqu 48(SRC), AESDATA3
movdqa AESDATA0, CTEXT0
movdqa AESDATA1, CTEXT1
#ifdef __x86_64__
movdqa AESDATA2, CTEXT2
movdqa AESDATA3, CTEXT3
#endif
_do_aes 0, 0,1,2,3
pxor IV, AESDATA0
pxor CTEXT0, AESDATA1
pxor CTEXT1, AESDATA2
#ifdef __x86_64__
pxor CTEXT2, AESDATA3
movdqa CTEXT3, IV
#else
movdqu 32(SRC), CTEXT0
pxor CTEXT0, AESDATA3
movdqu 48(SRC), IV
#endif
movdqu AESDATA0, 0(DST)
movdqu AESDATA1, 16(DST)
movdqu AESDATA2, 32(DST)
movdqu AESDATA3, 48(DST)
add $64, SRC
add $64, DST
sub $4, NBLOCKS
jge .Lcbc_dec_loop4
.Lcbc_dec_loop4_done:
add $4, NBLOCKS32
jz .Lcbc_dec_done
.Lcbc_dec_loop1:
movdqu (SRC), AESDATA0
movdqa AESDATA0, CTEXT0
_do_aes 0, 0
pxor IV, AESDATA0
movdqa CTEXT0, IV
movdqu AESDATA0, (DST)
add $16, SRC
add $16, DST
dec NBLOCKS32
jnz .Lcbc_dec_loop1
.Lcbc_dec_done:
// Store the next IV. On 32-bit, reload IV_PTR from stack first.
_reload_arg3
movdqu IV, (IV_PTR)
_epilogue
SYM_FUNC_END(aes_cbc_decrypt_aesni)
.macro _aes_cbc_cts_crypt enc
.set DST, ARG0
.set SRC, ARG1
.set PN_LEN, ARG2
.set IV_PTR, ARG3
.set KEY, ARG4
.set RNDKEY_PTR, IV_PTR // Temporary register for _do_aes
.set NROUNDS, TMP_32 // Temporary register for _do_aes
.set RSHIFT_MASK, %xmm0 // range(16-PN_LEN,16) + [0x80, 0x80, ...]
// Must be %xmm0 for pblendvb to work.
.set LSHIFT_MASK, %xmm1 // [0x80, 0x80, ...] + range(PN_LEN)
.set AESDATA0, %xmm2
.set AESDATA1, %xmm3
.set RNDKEY, %xmm4 // Temporary register for _do_aes
.set IV, %xmm5
_prologue uses_arg3=2, uses_arg4=2
// Load LSHIFT_MASK and RSHIFT_MASK.
lea RODATA(.Lcts_permute_table), TMP
movdqu (TMP,PN_LEN), LSHIFT_MASK
sub PN_LEN, TMP
movdqu 32(TMP), RSHIFT_MASK
// Load the IV, freeing up IV_PTR to reuse for RNDKEY_PTR.
movdqu (IV_PTR), IV
// Load the second-from-last source block (P[n-1] or C[n-1]) and
// AES-en/decrypt it. In the encryption case, XOR it with the IV first.
movdqu (SRC), AESDATA0
.if \enc
pxor IV, AESDATA0
.endif
_do_aes \enc, 0
// Load the last source block (P[n] or C[n]), left-aligned.
movdqu (SRC,PN_LEN), AESDATA1
.if \enc
// Right-align P[n], XOR it with the first AES output, and AES-encrypt
// the result. This gives C[n-1] in AESDATA1.
pshufb RSHIFT_MASK, AESDATA1
pxor AESDATA0, AESDATA1
_do_aes 1, 1
// Left-align the first AES output to get left-aligned C[n].
pshufb LSHIFT_MASK, AESDATA0
.else
// Save a copy of the first AES output in %xmm6 for later.
movdqa AESDATA0, %xmm6
// Left-align the first AES output and XOR it with the
// already-left-aligned C[n]. This gives the left-aligned P[n].
pshufb LSHIFT_MASK, AESDATA0
pxor AESDATA1, AESDATA0
// Right-align C[n], then use RSHIFT_MASK (in %xmm0 as pblendvb's
// implicit operand) as a blend mask to select C[n] and the remaining
// bytes from the first AES output, with the result in AESDATA1.
pshufb RSHIFT_MASK, AESDATA1
pblendvb %xmm6, AESDATA1
// AES-decrypt the result and XOR with the IV to get P[n-1] in AESDATA1.
_do_aes 0, 1
pxor IV, AESDATA1
.endif
// Store the left-aligned C[n] or P[n], then C[n-1] or P[n-1].
// Note that these stores may overlap.
movdqu AESDATA0, (DST,PN_LEN)
movdqu AESDATA1, (DST)
_epilogue
.endm
// void aes_cbc_cts_encrypt_aesni(u8 *dst, const u8 *src, long pn_len,
// const u8 iv[AES_BLOCK_SIZE],
// const struct aes_enckey *key);
// void aes_cbc_cts_decrypt_aesni(u8 *dst, const u8 *src, long pn_len,
// const u8 iv[AES_BLOCK_SIZE],
// const struct aes_key *key);
//
// Use the CS3 variant of ciphertext stealing to encrypt or decrypt the last two
// blocks in a message. The two blocks are located at src and consist of one
// full block of length 16 bytes and one possibly-partial block of length 1 <=
// pn_len <= 16 bytes. The output is written to dst, which may equal src.
SYM_FUNC_START(aes_cbc_cts_encrypt_aesni)
_aes_cbc_cts_crypt 1
SYM_FUNC_END(aes_cbc_cts_encrypt_aesni)
SYM_FUNC_START(aes_cbc_cts_decrypt_aesni)
_aes_cbc_cts_crypt 0
SYM_FUNC_END(aes_cbc_cts_decrypt_aesni)

View File

@ -116,6 +116,95 @@ static bool aes_ecb_decrypt_arch(u8 *dst, const u8 *src, size_t len,
}
#endif /* CONFIG_CRYPTO_LIB_AES_ECB */
#if IS_ENABLED(CONFIG_CRYPTO_LIB_AES_CBC)
void aes_cbc_encrypt_aesni(u8 *dst, const u8 *src, long nblocks,
u8 iv[AES_BLOCK_SIZE], const struct aes_enckey *key);
void aes_cbc_decrypt_aesni(u8 *dst, const u8 *src, long nblocks,
u8 iv[AES_BLOCK_SIZE], const struct aes_key *key);
void aes_cbc_cts_encrypt_aesni(u8 *dst, const u8 *src, long pn_len,
const u8 iv[AES_BLOCK_SIZE],
const struct aes_enckey *key);
void aes_cbc_cts_decrypt_aesni(u8 *dst, const u8 *src, long pn_len,
const u8 iv[AES_BLOCK_SIZE],
const struct aes_key *key);
/* len is always a positive multiple of AES_BLOCK_SIZE here. */
#define aes_cbc_encrypt_arch aes_cbc_encrypt_arch
static bool aes_cbc_encrypt_arch(u8 *dst, const u8 *src, size_t len,
u8 iv[AES_BLOCK_SIZE],
const struct aes_enckey *key)
{
if (!static_branch_likely(&have_aesni) || unlikely(!irq_fpu_usable()))
return false;
kernel_fpu_begin();
aes_cbc_encrypt_aesni(dst, src, len / AES_BLOCK_SIZE, iv, key);
kernel_fpu_end();
return true;
}
/* len is always a positive multiple of AES_BLOCK_SIZE here. */
#define aes_cbc_decrypt_arch aes_cbc_decrypt_arch
static bool aes_cbc_decrypt_arch(u8 *dst, const u8 *src, size_t len,
u8 iv[AES_BLOCK_SIZE],
const struct aes_key *key)
{
if (!static_branch_likely(&have_aesni) || unlikely(!irq_fpu_usable()))
return false;
kernel_fpu_begin();
aes_cbc_decrypt_aesni(dst, src, len / AES_BLOCK_SIZE, iv, key);
kernel_fpu_end();
return true;
}
/* len can be any value greater than AES_BLOCK_SIZE here. */
#define aes_cbc_cts_encrypt_arch aes_cbc_cts_encrypt_arch
static bool aes_cbc_cts_encrypt_arch(u8 *dst, const u8 *src, size_t len,
u8 iv[AES_BLOCK_SIZE],
const struct aes_enckey *key)
{
const size_t cbc_blocks = (len - AES_BLOCK_SIZE - 1) / AES_BLOCK_SIZE;
const size_t pn_len = ((len - 1) % AES_BLOCK_SIZE) + 1;
if (!static_branch_likely(&have_aesni) || unlikely(!irq_fpu_usable()))
return false;
kernel_fpu_begin();
if (cbc_blocks) {
aes_cbc_encrypt_aesni(dst, src, cbc_blocks, iv, key);
dst += cbc_blocks * AES_BLOCK_SIZE;
src += cbc_blocks * AES_BLOCK_SIZE;
}
/* Encrypt the last 17 to 32 bytes. */
aes_cbc_cts_encrypt_aesni(dst, src, pn_len, iv, key);
kernel_fpu_end();
return true;
}
/* len can be any value greater than AES_BLOCK_SIZE here. */
#define aes_cbc_cts_decrypt_arch aes_cbc_cts_decrypt_arch
static bool aes_cbc_cts_decrypt_arch(u8 *dst, const u8 *src, size_t len,
u8 iv[AES_BLOCK_SIZE],
const struct aes_key *key)
{
const size_t cbc_blocks = (len - AES_BLOCK_SIZE - 1) / AES_BLOCK_SIZE;
const size_t pn_len = ((len - 1) % AES_BLOCK_SIZE) + 1;
if (!static_branch_likely(&have_aesni) || unlikely(!irq_fpu_usable()))
return false;
kernel_fpu_begin();
if (cbc_blocks) {
aes_cbc_decrypt_aesni(dst, src, cbc_blocks, iv, key);
dst += cbc_blocks * AES_BLOCK_SIZE;
src += cbc_blocks * AES_BLOCK_SIZE;
}
/* Decrypt the last 17 to 32 bytes. */
aes_cbc_cts_decrypt_aesni(dst, src, pn_len, iv, key);
kernel_fpu_end();
return true;
}
#endif /* CONFIG_CRYPTO_LIB_AES_CBC */
#define aes_mod_init_arch aes_mod_init_arch
static void aes_mod_init_arch(void)
{