Currently, we rely on the generic CTS chaining mode wrapper to
instantiate the cts(cbc(aes)) skcipher. Due to the high performance
of the ARMv8 Crypto Extensions AES instructions (~1 cycles per byte),
any overhead in the chaining mode layers is amplified, and so it pays
off considerably to fold the CTS handling into the core algorithm.
On Cortex-A53, this results in a ~50% speedup for smaller block sizes.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
Raw performance numbers after the patch.
arch/arm64/crypto/aes-glue.c | 142 ++++++++++++++++++++
arch/arm64/crypto/aes-modes.S | 73 ++++++++++
2 files changed, 215 insertions(+)
diff --git a/arch/arm64/crypto/aes-glue.c b/arch/arm64/crypto/aes-glue.c
index adcb83eb683c..0860feedbafe 100644
--- a/arch/arm64/crypto/aes-glue.c
+++ b/arch/arm64/crypto/aes-glue.c
@@ -15,6 +15,7 @@
#include <crypto/internal/hash.h>
#include <crypto/internal/simd.h>
#include <crypto/internal/skcipher.h>
+#include <crypto/scatterwalk.h>
#include <linux/module.h>
#include <linux/cpufeature.h>
#include <crypto/xts.h>
@@ -31,6 +32,8 @@
#define aes_ecb_decrypt ce_aes_ecb_decrypt
#define aes_cbc_encrypt ce_aes_cbc_encrypt
#define aes_cbc_decrypt ce_aes_cbc_decrypt
+#define aes_cbc_cts_encrypt ce_aes_cbc_cts_encrypt
+#define aes_cbc_cts_decrypt ce_aes_cbc_cts_decrypt
#define aes_ctr_encrypt ce_aes_ctr_encrypt
#define aes_xts_encrypt ce_aes_xts_encrypt
#define aes_xts_decrypt ce_aes_xts_decrypt
@@ -45,6 +48,8 @@ MODULE_DESCRIPTION("AES-ECB/CBC/CTR/XTS using ARMv8 Crypto Extensions");
#define aes_ecb_decrypt neon_aes_ecb_decrypt
#define aes_cbc_encrypt neon_aes_cbc_encrypt
#define aes_cbc_decrypt neon_aes_cbc_decrypt
+#define aes_cbc_cts_encrypt neon_aes_cbc_cts_encrypt
+#define aes_cbc_cts_decrypt neon_aes_cbc_cts_decrypt
#define aes_ctr_encrypt neon_aes_ctr_encrypt
#define aes_xts_encrypt neon_aes_xts_encrypt
#define aes_xts_decrypt neon_aes_xts_decrypt
@@ -73,6 +78,11 @@ asmlinkage void aes_cbc_encrypt(u8 out[], u8 const in[], u8 const rk[],
asmlinkage void aes_cbc_decrypt(u8 out[], u8 const in[], u8 const rk[],
int rounds, int blocks, u8 iv[]);
+asmlinkage void aes_cbc_cts_encrypt(u8 out[], u8 const in[], u8 const rk[],
+ int rounds, int bytes, u8 iv[]);
+asmlinkage void aes_cbc_cts_decrypt(u8 out[], u8 const in[], u8 const rk[],
+ int rounds, int bytes, u8 iv[]);
+
asmlinkage void aes_ctr_encrypt(u8 out[], u8 const in[], u8 const rk[],
int rounds, int blocks, u8 ctr[]);
@@ -209,6 +219,120 @@ static int cbc_decrypt(struct skcipher_request *req)
return err;
}
+static int cts_cbc_encrypt(struct skcipher_request *req)
+{
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+ int err, rounds = 6 + ctx->key_length / 4;
+ int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2;
+ struct skcipher_request subreq = *req;
+ struct scatterlist sg_src[2], sg_dst[2];
+ struct scatterlist *src = req->src, *dst = req->dst;
+ struct skcipher_walk walk;
+ unsigned int blocks;
+
+ if (req->cryptlen == AES_BLOCK_SIZE)
+ cbc_blocks = 1;
+
+ if (cbc_blocks > 0) {
+ skcipher_request_set_crypt(&subreq, req->src, req->dst,
+ cbc_blocks * AES_BLOCK_SIZE,
+ req->iv);
+ err = skcipher_walk_virt(&walk, &subreq, false);
+
+ while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) {
+ kernel_neon_begin();
+ aes_cbc_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
+ (u8 *)ctx->key_enc, rounds, blocks,
+ walk.iv);
+ kernel_neon_end();
+ err = skcipher_walk_done(&walk,
+ walk.nbytes % AES_BLOCK_SIZE);
+ }
+ if (err)
+ return err;
+
+ if (req->cryptlen == AES_BLOCK_SIZE)
+ return 0;
+
+ src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen);
+ dst = scatterwalk_ffwd(sg_dst, req->dst, subreq.cryptlen);
+ }
+
+ /* handle ciphertext stealing */
+ skcipher_request_set_crypt(&subreq, src, dst,
+ req->cryptlen - cbc_blocks * AES_BLOCK_SIZE,
+ req->iv);
+
+ err = skcipher_walk_virt(&walk, &subreq, false);
+ if (err)
+ return err;
+
+ kernel_neon_begin();
+ aes_cbc_cts_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
+ (u8 *)ctx->key_enc, rounds, walk.nbytes, walk.iv);
+ kernel_neon_end();
+
+ return skcipher_walk_done(&walk, 0);
+}
+
+static int cts_cbc_decrypt(struct skcipher_request *req)
+{
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+ int err, rounds = 6 + ctx->key_length / 4;
+ int cbc_blocks = DIV_ROUND_UP(req->cryptlen, AES_BLOCK_SIZE) - 2;
+ struct skcipher_request subreq = *req;
+ struct scatterlist sg_src[2], sg_dst[2];
+ struct scatterlist *src = req->src, *dst = req->dst;
+ struct skcipher_walk walk;
+ unsigned int blocks;
+
+ if (req->cryptlen == AES_BLOCK_SIZE)
+ cbc_blocks = 1;
+
+ if (cbc_blocks > 0) {
+ skcipher_request_set_crypt(&subreq, req->src, req->dst,
+ cbc_blocks * AES_BLOCK_SIZE,
+ req->iv);
+ err = skcipher_walk_virt(&walk, &subreq, false);
+
+ while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) {
+ kernel_neon_begin();
+ aes_cbc_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
+ (u8 *)ctx->key_dec, rounds, blocks,
+ walk.iv);
+ kernel_neon_end();
+ err = skcipher_walk_done(&walk,
+ walk.nbytes % AES_BLOCK_SIZE);
+ }
+ if (err)
+ return err;
+
+ if (req->cryptlen == AES_BLOCK_SIZE)
+ return 0;
+
+ src = scatterwalk_ffwd(sg_src, req->src, subreq.cryptlen);
+ dst = scatterwalk_ffwd(sg_dst, req->dst, subreq.cryptlen);
+ }
+
+ /* handle ciphertext stealing */
+ skcipher_request_set_crypt(&subreq, src, dst,
+ req->cryptlen - cbc_blocks * AES_BLOCK_SIZE,
+ req->iv);
+
+ err = skcipher_walk_virt(&walk, &subreq, false);
+ if (err)
+ return err;
+
+ kernel_neon_begin();
+ aes_cbc_cts_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
+ (u8 *)ctx->key_dec, rounds, walk.nbytes, walk.iv);
+ kernel_neon_end();
+
+ return skcipher_walk_done(&walk, 0);
+}
+
static int ctr_encrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
@@ -334,6 +458,24 @@ static struct skcipher_alg aes_algs[] = { {
.setkey = skcipher_aes_setkey,
.encrypt = cbc_encrypt,
.decrypt = cbc_decrypt,
+}, {
+ .base = {
+ .cra_name = "__cts(cbc(aes))",
+ .cra_driver_name = "__cts-cbc-aes-" MODE,
+ .cra_priority = PRIO,
+ .cra_flags = CRYPTO_ALG_INTERNAL,
+ .cra_blocksize = 1,
+ .cra_ctxsize = sizeof(struct crypto_aes_ctx),
+ .cra_module = THIS_MODULE,
+ },
+ .min_keysize = AES_MIN_KEY_SIZE,
+ .max_keysize = AES_MAX_KEY_SIZE,
+ .ivsize = AES_BLOCK_SIZE,
+ .chunksize = AES_BLOCK_SIZE,
+ .walksize = 2 * AES_BLOCK_SIZE,
+ .setkey = skcipher_aes_setkey,
+ .encrypt = cts_cbc_encrypt,
+ .decrypt = cts_cbc_decrypt,
}, {
.base = {
.cra_name = "__ctr(aes)",
diff --git a/arch/arm64/crypto/aes-modes.S b/arch/arm64/crypto/aes-modes.S
index 483a7130cf0e..61bab20de8da 100644
--- a/arch/arm64/crypto/aes-modes.S
+++ b/arch/arm64/crypto/aes-modes.S
@@ -205,6 +205,79 @@ AES_ENTRY(aes_cbc_decrypt)
ret
AES_ENDPROC(aes_cbc_decrypt)
+ /*
+ * aes_cbc_cts_encrypt(u8 out[], u8 const in[], u8 const rk[],
+ * int rounds, int bytes, u8 iv[])
+ * aes_cbc_cts_decrypt(u8 out[], u8 const in[], u8 const rk[],
+ * int rounds, int bytes, u8 iv[])
+ */
+
+AES_ENTRY(aes_cbc_cts_encrypt)
+ adr x8, .Lcts_permute_table + 48
+ sub x9, x8, x4
+ sub x4, x4, #16
+ sub x8, x8, #48
+ add x8, x8, x4
+ ld1 {v6.16b}, [x9]
+ ld1 {v7.16b}, [x8]
+
+ ld1 {v4.16b}, [x5] /* get iv */
+ enc_prepare w3, x2, x6
+
+ ld1 {v0.16b}, [x1], x4 /* overlapping loads */
+ ld1 {v1.16b}, [x1]
+
+ eor v0.16b, v0.16b, v4.16b /* xor with iv */
+ tbl v1.16b, {v1.16b}, v6.16b
+ encrypt_block v0, w3, x2, x6, w7
+
+ eor v1.16b, v1.16b, v0.16b
+ tbl v0.16b, {v0.16b}, v7.16b
+ encrypt_block v1, w3, x2, x6, w7
+
+ add x4, x0, x4
+ st1 {v0.16b}, [x4] /* overlapping stores */
+ st1 {v1.16b}, [x0]
+ ret
+AES_ENDPROC(aes_cbc_cts_encrypt)
+
+AES_ENTRY(aes_cbc_cts_decrypt)
+ adr x8, .Lcts_permute_table + 48
+ sub x9, x8, x4
+ sub x4, x4, #16
+ sub x8, x8, #48
+ add x8, x8, x4
+ ld1 {v6.16b}, [x9]
+ ld1 {v7.16b}, [x8]
+
+ ld1 {v4.16b}, [x5] /* get iv */
+ dec_prepare w3, x2, x6
+
+ ld1 {v0.16b}, [x1], x4 /* overlapping loads */
+ ld1 {v1.16b}, [x1]
+
+ tbl v2.16b, {v1.16b}, v6.16b
+ decrypt_block v0, w3, x2, x6, w7
+ eor v2.16b, v2.16b, v0.16b
+
+ tbx v0.16b, {v1.16b}, v6.16b
+ tbl v2.16b, {v2.16b}, v7.16b
+ decrypt_block v0, w3, x2, x6, w7
+ eor v0.16b, v0.16b, v4.16b /* xor with iv */
+
+ add x4, x0, x4
+ st1 {v2.16b}, [x4] /* overlapping stores */
+ st1 {v0.16b}, [x0]
+ ret
+AES_ENDPROC(aes_cbc_cts_decrypt)
+
+.Lcts_permute_table:
+ .byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+ .byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+ .byte 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7
+ .byte 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf
+ .byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+ .byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
/*
* aes_ctr_encrypt(u8 out[], u8 const in[], u8 const rk[], int rounds,
--
2.18.0
Cortex-A53 @ 1 GHz
BEFORE:
testing speed of async cts(cbc(aes)) (cts(cbc-aes-ce)) encryption
0 (128 bit key, 16 byte blocks): 1407866 ops in 1 secs ( 22525856 bytes)
1 (128 bit key, 64 byte blocks): 466814 ops in 1 secs ( 29876096 bytes)
2 (128 bit key, 256 byte blocks): 401023 ops in 1 secs (102661888 bytes)
3 (128 bit key, 1024 byte blocks): 258238 ops in 1 secs (264435712 bytes)
4 (128 bit key, 8192 byte blocks): 57905 ops in 1 secs (474357760 bytes)
5 (192 bit key, 16 byte blocks): 1388333 ops in 1 secs ( 22213328 bytes)
6 (192 bit key, 64 byte blocks): 448595 ops in 1 secs ( 28710080 bytes)
7 (192 bit key, 256 byte blocks): 376951 ops in 1 secs ( 96499456 bytes)
8 (192 bit key, 1024 byte blocks): 231635 ops in 1 secs (237194240 bytes)
9 (192 bit key, 8192 byte blocks): 43345 ops in 1 secs (355082240 bytes)
10 (256 bit key, 16 byte blocks): 1370820 ops in 1 secs ( 21933120 bytes)
11 (256 bit key, 64 byte blocks): 452352 ops in 1 secs ( 28950528 bytes)
12 (256 bit key, 256 byte blocks): 376506 ops in 1 secs ( 96385536 bytes)
13 (256 bit key, 1024 byte blocks): 223219 ops in 1 secs (228576256 bytes)
14 (256 bit key, 8192 byte blocks): 44874 ops in 1 secs (367607808 bytes)
testing speed of async cts(cbc(aes)) (cts(cbc-aes-ce)) decryption
0 (128 bit key, 16 byte blocks): 1402795 ops in 1 secs ( 22444720 bytes)
1 (128 bit key, 64 byte blocks): 403300 ops in 1 secs ( 25811200 bytes)
2 (128 bit key, 256 byte blocks): 367710 ops in 1 secs ( 94133760 bytes)
3 (128 bit key, 1024 byte blocks): 269118 ops in 1 secs (275576832 bytes)
4 (128 bit key, 8192 byte blocks): 74706 ops in 1 secs (611991552 bytes)
5 (192 bit key, 16 byte blocks): 1381390 ops in 1 secs ( 22102240 bytes)
6 (192 bit key, 64 byte blocks): 388555 ops in 1 secs ( 24867520 bytes)
7 (192 bit key, 256 byte blocks): 350282 ops in 1 secs ( 89672192 bytes)
8 (192 bit key, 1024 byte blocks): 251268 ops in 1 secs (257298432 bytes)
9 (192 bit key, 8192 byte blocks): 56535 ops in 1 secs (463134720 bytes)
10 (256 bit key, 16 byte blocks): 1364334 ops in 1 secs ( 21829344 bytes)
11 (256 bit key, 64 byte blocks): 392610 ops in 1 secs ( 25127040 bytes)
12 (256 bit key, 256 byte blocks): 351150 ops in 1 secs ( 89894400 bytes)
13 (256 bit key, 1024 byte blocks): 247455 ops in 1 secs (253393920 bytes)
14 (256 bit key, 8192 byte blocks): 62530 ops in 1 secs (512245760 bytes)
AFTER:
testing speed of async cts(cbc(aes)) (cts-cbc-aes-ce) encryption
0 (128 bit key, 16 byte blocks): 1380568 ops in 1 secs ( 22089088 bytes)
1 (128 bit key, 64 byte blocks): 692731 ops in 1 secs ( 44334784 bytes)
2 (128 bit key, 256 byte blocks): 556393 ops in 1 secs (142436608 bytes)
3 (128 bit key, 1024 byte blocks): 314635 ops in 1 secs (322186240 bytes)
4 (128 bit key, 8192 byte blocks): 57550 ops in 1 secs (471449600 bytes)
5 (192 bit key, 16 byte blocks): 1367027 ops in 1 secs ( 21872432 bytes)
6 (192 bit key, 64 byte blocks): 675058 ops in 1 secs ( 43203712 bytes)
7 (192 bit key, 256 byte blocks): 523177 ops in 1 secs (133933312 bytes)
8 (192 bit key, 1024 byte blocks): 279235 ops in 1 secs (285936640 bytes)
9 (192 bit key, 8192 byte blocks): 46316 ops in 1 secs (379420672 bytes)
10 (256 bit key, 16 byte blocks): 1353576 ops in 1 secs ( 21657216 bytes)
11 (256 bit key, 64 byte blocks): 664523 ops in 1 secs ( 42529472 bytes)
12 (256 bit key, 256 byte blocks): 508141 ops in 1 secs (130084096 bytes)
13 (256 bit key, 1024 byte blocks): 264386 ops in 1 secs (270731264 bytes)
14 (256 bit key, 8192 byte blocks): 47224 ops in 1 secs (386859008 bytes)
testing speed of async cts(cbc(aes)) (cts-cbc-aes-ce) decryption
0 (128 bit key, 16 byte blocks): 1388553 ops in 1 secs ( 22216848 bytes)
1 (128 bit key, 64 byte blocks): 688402 ops in 1 secs ( 44057728 bytes)
2 (128 bit key, 256 byte blocks): 589268 ops in 1 secs (150852608 bytes)
3 (128 bit key, 1024 byte blocks): 372238 ops in 1 secs (381171712 bytes)
4 (128 bit key, 8192 byte blocks): 75691 ops in 1 secs (620060672 bytes)
5 (192 bit key, 16 byte blocks): 1366220 ops in 1 secs ( 21859520 bytes)
6 (192 bit key, 64 byte blocks): 666889 ops in 1 secs ( 42680896 bytes)
7 (192 bit key, 256 byte blocks): 561809 ops in 1 secs (143823104 bytes)
8 (192 bit key, 1024 byte blocks): 344117 ops in 1 secs (352375808 bytes)
9 (192 bit key, 8192 byte blocks): 63150 ops in 1 secs (517324800 bytes)
10 (256 bit key, 16 byte blocks): 1349266 ops in 1 secs ( 21588256 bytes)
11 (256 bit key, 64 byte blocks): 661056 ops in 1 secs ( 42307584 bytes)
12 (256 bit key, 256 byte blocks): 550261 ops in 1 secs (140866816 bytes)
13 (256 bit key, 1024 byte blocks): 332947 ops in 1 secs (340937728 bytes)
14 (256 bit key, 8192 byte blocks): 68759 ops in 1 secs (563273728 bytes)
