Skip to content

Commit

Permalink
crypto: arm/chacha20 - refactor to allow varying number of rounds
Browse files Browse the repository at this point in the history 
In preparation for adding XChaCha12 support, rename/refactor the NEON
implementation of ChaCha20 to support different numbers of rounds.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
  • Loading branch information
Eric Biggers authored and Herbert Xu committed Nov 20, 2018
1 parent d97a943 commit 3cc2151
Show file tree
Hide file tree
Showing 3 changed files with 56 additions and 48 deletions.
4 changes: 2 additions & 2 deletions arch/arm/crypto/Makefile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ obj-$(CONFIG_CRYPTO_SHA1_ARM) += sha1-arm.o
obj-$(CONFIG_CRYPTO_SHA1_ARM_NEON) += sha1-arm-neon.o
obj-$(CONFIG_CRYPTO_SHA256_ARM) += sha256-arm.o
obj-$(CONFIG_CRYPTO_SHA512_ARM) += sha512-arm.o
obj-$(CONFIG_CRYPTO_CHACHA20_NEON) += chacha20-neon.o
obj-$(CONFIG_CRYPTO_CHACHA20_NEON) += chacha-neon.o

ce-obj-$(CONFIG_CRYPTO_AES_ARM_CE) += aes-arm-ce.o
ce-obj-$(CONFIG_CRYPTO_SHA1_ARM_CE) += sha1-arm-ce.o
Expand Down Expand Up @@ -52,7 +52,7 @@ aes-arm-ce-y := aes-ce-core.o aes-ce-glue.o
ghash-arm-ce-y := ghash-ce-core.o ghash-ce-glue.o
crct10dif-arm-ce-y := crct10dif-ce-core.o crct10dif-ce-glue.o
crc32-arm-ce-y:= crc32-ce-core.o crc32-ce-glue.o
chacha20-neon-y := chacha20-neon-core.o chacha20-neon-glue.o
chacha-neon-y := chacha-neon-core.o chacha-neon-glue.o

ifdef REGENERATE_ARM_CRYPTO
quiet_cmd_perl = PERL $@
Expand Down
44 changes: 24 additions & 20 deletions arch/arm/crypto/chacha20-neon-core.S → arch/arm/crypto/chacha-neon-core.S
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* ChaCha20 256-bit cipher algorithm, RFC7539, ARM NEON functions
* ChaCha/XChaCha NEON helper functions
*
* Copyright (C) 2016 Linaro, Ltd. <ard.biesheuvel@linaro.org>
*
Expand Down Expand Up @@ -27,9 +27,9 @@
* (d) vtbl.8 + vtbl.8 (multiple of 8 bits rotations only,
* needs index vector)
*
* ChaCha20 has 16, 12, 8, and 7-bit rotations. For the 12 and 7-bit
* rotations, the only choices are (a) and (b). We use (a) since it takes
* two-thirds the cycles of (b) on both Cortex-A7 and Cortex-A53.
* ChaCha has 16, 12, 8, and 7-bit rotations. For the 12 and 7-bit rotations,
* the only choices are (a) and (b). We use (a) since it takes two-thirds the
* cycles of (b) on both Cortex-A7 and Cortex-A53.
*
* For the 16-bit rotation, we use vrev32.16 since it's consistently fastest
* and doesn't need a temporary register.
Expand All @@ -53,18 +53,19 @@
.align 5

/*
* chacha20_permute - permute one block
* chacha_permute - permute one block
*
* Permute one 64-byte block where the state matrix is stored in the four NEON
* registers q0-q3. It performs matrix operations on four words in parallel,
* but requires shuffling to rearrange the words after each round.
*
* The round count is given in r3.
*
* Clobbers: r3, ip, q4-q5
*/
chacha20_permute:
chacha_permute:

adr ip, .Lrol8_table
mov r3, #10
vld1.8 {d10}, [ip, :64]

.Ldoubleround:
Expand Down Expand Up @@ -128,16 +129,17 @@ chacha20_permute:
// x3 = shuffle32(x3, MASK(0, 3, 2, 1))
vext.8 q3, q3, q3, #4

subs r3, r3, #1
subs r3, r3, #2
bne .Ldoubleround

bx lr
ENDPROC(chacha20_permute)
ENDPROC(chacha_permute)

ENTRY(chacha20_block_xor_neon)
ENTRY(chacha_block_xor_neon)
// r0: Input state matrix, s
// r1: 1 data block output, o
// r2: 1 data block input, i
// r3: nrounds
push {lr}

// x0..3 = s0..3
Expand All @@ -150,7 +152,7 @@ ENTRY(chacha20_block_xor_neon)
vmov q10, q2
vmov q11, q3

bl chacha20_permute
bl chacha_permute

add ip, r2, #0x20
vld1.8 {q4-q5}, [r2]
Expand All @@ -177,30 +179,32 @@ ENTRY(chacha20_block_xor_neon)
vst1.8 {q2-q3}, [ip]

pop {pc}
ENDPROC(chacha20_block_xor_neon)
ENDPROC(chacha_block_xor_neon)

ENTRY(hchacha20_block_neon)
ENTRY(hchacha_block_neon)
// r0: Input state matrix, s
// r1: output (8 32-bit words)
// r2: nrounds
push {lr}

vld1.32 {q0-q1}, [r0]!
vld1.32 {q2-q3}, [r0]

bl chacha20_permute
mov r3, r2
bl chacha_permute

vst1.32 {q0}, [r1]!
vst1.32 {q3}, [r1]

pop {pc}
ENDPROC(hchacha20_block_neon)
ENDPROC(hchacha_block_neon)

.align 4
.Lctrinc: .word 0, 1, 2, 3
.Lrol8_table: .byte 3, 0, 1, 2, 7, 4, 5, 6

.align 5
ENTRY(chacha20_4block_xor_neon)
ENTRY(chacha_4block_xor_neon)
push {r4-r5}
mov r4, sp // preserve the stack pointer
sub ip, sp, #0x20 // allocate a 32 byte buffer
Expand All @@ -210,9 +214,10 @@ ENTRY(chacha20_4block_xor_neon)
// r0: Input state matrix, s
// r1: 4 data blocks output, o
// r2: 4 data blocks input, i
// r3: nrounds

//
// This function encrypts four consecutive ChaCha20 blocks by loading
// This function encrypts four consecutive ChaCha blocks by loading
// the state matrix in NEON registers four times. The algorithm performs
// each operation on the corresponding word of each state matrix, hence
// requires no word shuffling. The words are re-interleaved before the
Expand Down Expand Up @@ -245,7 +250,6 @@ ENTRY(chacha20_4block_xor_neon)
vdup.32 q0, d0[0]

adr ip, .Lrol8_table
mov r3, #10
b 1f

.Ldoubleround4:
Expand Down Expand Up @@ -443,7 +447,7 @@ ENTRY(chacha20_4block_xor_neon)
vsri.u32 q5, q8, #25
vsri.u32 q6, q9, #25

subs r3, r3, #1
subs r3, r3, #2
bne .Ldoubleround4

// x0..7[0-3] are in q0-q7, x10..15[0-3] are in q10-q15.
Expand Down Expand Up @@ -553,4 +557,4 @@ ENTRY(chacha20_4block_xor_neon)

pop {r4-r5}
bx lr
ENDPROC(chacha20_4block_xor_neon)
ENDPROC(chacha_4block_xor_neon)
56 changes: 30 additions & 26 deletions arch/arm/crypto/chacha20-neon-glue.c → arch/arm/crypto/chacha-neon-glue.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,38 +28,40 @@
#include <asm/neon.h>
#include <asm/simd.h>

asmlinkage void chacha20_block_xor_neon(u32 *state, u8 *dst, const u8 *src);
asmlinkage void chacha20_4block_xor_neon(u32 *state, u8 *dst, const u8 *src);
asmlinkage void hchacha20_block_neon(const u32 *state, u32 *out);

static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
asmlinkage void chacha_block_xor_neon(const u32 *state, u8 *dst, const u8 *src,
int nrounds);
asmlinkage void chacha_4block_xor_neon(const u32 *state, u8 *dst, const u8 *src,
int nrounds);
asmlinkage void hchacha_block_neon(const u32 *state, u32 *out, int nrounds);

static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes, int nrounds)
{
u8 buf[CHACHA_BLOCK_SIZE];

while (bytes >= CHACHA_BLOCK_SIZE * 4) {
chacha20_4block_xor_neon(state, dst, src);
chacha_4block_xor_neon(state, dst, src, nrounds);
bytes -= CHACHA_BLOCK_SIZE * 4;
src += CHACHA_BLOCK_SIZE * 4;
dst += CHACHA_BLOCK_SIZE * 4;
state[12] += 4;
}
while (bytes >= CHACHA_BLOCK_SIZE) {
chacha20_block_xor_neon(state, dst, src);
chacha_block_xor_neon(state, dst, src, nrounds);
bytes -= CHACHA_BLOCK_SIZE;
src += CHACHA_BLOCK_SIZE;
dst += CHACHA_BLOCK_SIZE;
state[12]++;
}
if (bytes) {
memcpy(buf, src, bytes);
chacha20_block_xor_neon(state, buf, buf);
chacha_block_xor_neon(state, buf, buf, nrounds);
memcpy(dst, buf, bytes);
}
}

static int chacha20_neon_stream_xor(struct skcipher_request *req,
struct chacha_ctx *ctx, u8 *iv)
static int chacha_neon_stream_xor(struct skcipher_request *req,
struct chacha_ctx *ctx, u8 *iv)
{
struct skcipher_walk walk;
u32 state[16];
Expand All @@ -76,27 +78,27 @@ static int chacha20_neon_stream_xor(struct skcipher_request *req,
nbytes = round_down(nbytes, walk.stride);

kernel_neon_begin();
chacha20_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
nbytes);
chacha_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
nbytes, ctx->nrounds);
kernel_neon_end();
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}

return err;
}

static int chacha20_neon(struct skcipher_request *req)
static int chacha_neon(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);

if (req->cryptlen <= CHACHA_BLOCK_SIZE || !may_use_simd())
return crypto_chacha_crypt(req);

return chacha20_neon_stream_xor(req, ctx, req->iv);
return chacha_neon_stream_xor(req, ctx, req->iv);
}

static int xchacha20_neon(struct skcipher_request *req)
static int xchacha_neon(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
Expand All @@ -110,12 +112,13 @@ static int xchacha20_neon(struct skcipher_request *req)
crypto_chacha_init(state, ctx, req->iv);

kernel_neon_begin();
hchacha20_block_neon(state, subctx.key);
hchacha_block_neon(state, subctx.key, ctx->nrounds);
kernel_neon_end();
subctx.nrounds = ctx->nrounds;

memcpy(&real_iv[0], req->iv + 24, 8);
memcpy(&real_iv[8], req->iv + 16, 8);
return chacha20_neon_stream_xor(req, &subctx, real_iv);
return chacha_neon_stream_xor(req, &subctx, real_iv);
}

static struct skcipher_alg algs[] = {
Expand All @@ -133,8 +136,8 @@ static struct skcipher_alg algs[] = {
.chunksize = CHACHA_BLOCK_SIZE,
.walksize = 4 * CHACHA_BLOCK_SIZE,
.setkey = crypto_chacha20_setkey,
.encrypt = chacha20_neon,
.decrypt = chacha20_neon,
.encrypt = chacha_neon,
.decrypt = chacha_neon,
}, {
.base.cra_name = "xchacha20",
.base.cra_driver_name = "xchacha20-neon",
Expand All @@ -149,27 +152,28 @@ static struct skcipher_alg algs[] = {
.chunksize = CHACHA_BLOCK_SIZE,
.walksize = 4 * CHACHA_BLOCK_SIZE,
.setkey = crypto_chacha20_setkey,
.encrypt = xchacha20_neon,
.decrypt = xchacha20_neon,
.encrypt = xchacha_neon,
.decrypt = xchacha_neon,
}
};

static int __init chacha20_simd_mod_init(void)
static int __init chacha_simd_mod_init(void)
{
if (!(elf_hwcap & HWCAP_NEON))
return -ENODEV;

return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
}

static void __exit chacha20_simd_mod_fini(void)
static void __exit chacha_simd_mod_fini(void)
{
crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
}

module_init(chacha20_simd_mod_init);
module_exit(chacha20_simd_mod_fini);
module_init(chacha_simd_mod_init);
module_exit(chacha_simd_mod_fini);

MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (NEON accelerated)");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("chacha20");
Expand Down

0 comments on commit 3cc2151

Please sign in to comment.