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crypto: arm64/chacha20 - refactor to allow varying number of rounds
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In preparation for adding XChaCha12 support, rename/refactor the ARM64
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>
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Eric Biggers authored and Herbert Xu committed Dec 13, 2018
1 parent cc7cf99 commit 95a34b7
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Showing 3 changed files with 57 additions and 49 deletions.
4 changes: 2 additions & 2 deletions arch/arm64/crypto/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -50,8 +50,8 @@ sha256-arm64-y := sha256-glue.o sha256-core.o
obj-$(CONFIG_CRYPTO_SHA512_ARM64) += sha512-arm64.o
sha512-arm64-y := sha512-glue.o sha512-core.o

obj-$(CONFIG_CRYPTO_CHACHA20_NEON) += chacha20-neon.o
chacha20-neon-y := chacha20-neon-core.o chacha20-neon-glue.o
obj-$(CONFIG_CRYPTO_CHACHA20_NEON) += chacha-neon.o
chacha-neon-y := chacha-neon-core.o chacha-neon-glue.o

obj-$(CONFIG_CRYPTO_NHPOLY1305_NEON) += nhpoly1305-neon.o
nhpoly1305-neon-y := nh-neon-core.o nhpoly1305-neon-glue.o
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45 changes: 24 additions & 21 deletions arch/arm64/crypto/chacha20-neon-core.S → arch/arm64/crypto/chacha-neon-core.S
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* ChaCha20 256-bit cipher algorithm, RFC7539, arm64 NEON functions
* ChaCha/XChaCha NEON helper functions
*
* Copyright (C) 2016 Linaro, Ltd. <ard.biesheuvel@linaro.org>
*
Expand All @@ -24,17 +24,18 @@
.align 6

/*
* 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 v0-v3. It performs matrix operations on four words in parallel,
* but requires shuffling to rearrange the words after each round.
*
* Clobbers: x3, x10, v4, v12
* The round count is given in w3.
*
* Clobbers: w3, x10, v4, v12
*/
chacha20_permute:
chacha_permute:

mov x3, #10
adr x10, ROT8
ld1 {v12.4s}, [x10]

Expand Down Expand Up @@ -97,16 +98,17 @@ chacha20_permute:
// x3 = shuffle32(x3, MASK(0, 3, 2, 1))
ext v3.16b, v3.16b, v3.16b, #4

subs x3, x3, #1
subs w3, w3, #2
b.ne .Ldoubleround

ret
ENDPROC(chacha20_permute)
ENDPROC(chacha_permute)

ENTRY(chacha20_block_xor_neon)
ENTRY(chacha_block_xor_neon)
// x0: Input state matrix, s
// x1: 1 data block output, o
// x2: 1 data block input, i
// w3: nrounds

stp x29, x30, [sp, #-16]!
mov x29, sp
Expand All @@ -115,7 +117,7 @@ ENTRY(chacha20_block_xor_neon)
ld1 {v0.4s-v3.4s}, [x0]
ld1 {v8.4s-v11.4s}, [x0]

bl chacha20_permute
bl chacha_permute

ld1 {v4.16b-v7.16b}, [x2]

Expand All @@ -139,42 +141,45 @@ ENTRY(chacha20_block_xor_neon)

ldp x29, x30, [sp], #16
ret
ENDPROC(chacha20_block_xor_neon)
ENDPROC(chacha_block_xor_neon)

ENTRY(hchacha20_block_neon)
ENTRY(hchacha_block_neon)
// x0: Input state matrix, s
// x1: output (8 32-bit words)
// w2: nrounds

stp x29, x30, [sp, #-16]!
mov x29, sp

ld1 {v0.4s-v3.4s}, [x0]

bl chacha20_permute
mov w3, w2
bl chacha_permute

st1 {v0.16b}, [x1], #16
st1 {v3.16b}, [x1]

ldp x29, x30, [sp], #16
ret
ENDPROC(hchacha20_block_neon)
ENDPROC(hchacha_block_neon)

.align 6
ENTRY(chacha20_4block_xor_neon)
ENTRY(chacha_4block_xor_neon)
// x0: Input state matrix, s
// x1: 4 data blocks output, o
// x2: 4 data blocks input, i
// w3: 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. For final XORing step we transpose the
// matrix by interleaving 32- and then 64-bit words, which allows us to
// do XOR in NEON registers.
//
adr x3, CTRINC // ... and ROT8
ld1 {v30.4s-v31.4s}, [x3]
adr x9, CTRINC // ... and ROT8
ld1 {v30.4s-v31.4s}, [x9]

// x0..15[0-3] = s0..3[0..3]
mov x4, x0
Expand All @@ -186,8 +191,6 @@ ENTRY(chacha20_4block_xor_neon)
// x12 += counter values 0-3
add v12.4s, v12.4s, v30.4s

mov x3, #10

.Ldoubleround4:
// x0 += x4, x12 = rotl32(x12 ^ x0, 16)
// x1 += x5, x13 = rotl32(x13 ^ x1, 16)
Expand Down Expand Up @@ -361,7 +364,7 @@ ENTRY(chacha20_4block_xor_neon)
sri v7.4s, v18.4s, #25
sri v4.4s, v19.4s, #25

subs x3, x3, #1
subs w3, w3, #2
b.ne .Ldoubleround4

ld4r {v16.4s-v19.4s}, [x0], #16
Expand Down Expand Up @@ -475,7 +478,7 @@ ENTRY(chacha20_4block_xor_neon)
st1 {v28.16b-v31.16b}, [x1]

ret
ENDPROC(chacha20_4block_xor_neon)
ENDPROC(chacha_4block_xor_neon)

CTRINC: .word 0, 1, 2, 3
ROT8: .word 0x02010003, 0x06050407, 0x0a09080b, 0x0e0d0c0f
57 changes: 31 additions & 26 deletions arch/arm64/crypto/chacha20-neon-glue.c → arch/arm64/crypto/chacha-neon-glue.c
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
/*
* ChaCha20 256-bit cipher algorithm, RFC7539, arm64 NEON functions
* ARM NEON accelerated ChaCha and XChaCha stream ciphers,
* including ChaCha20 (RFC7539)
*
* Copyright (C) 2016 - 2017 Linaro, Ltd. <ard.biesheuvel@linaro.org>
*
Expand Down Expand Up @@ -28,18 +29,20 @@
#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);
asmlinkage void chacha_block_xor_neon(u32 *state, u8 *dst, const u8 *src,
int nrounds);
asmlinkage void chacha_4block_xor_neon(u32 *state, u8 *dst, const u8 *src,
int nrounds);
asmlinkage void hchacha_block_neon(const u32 *state, u32 *out, int nrounds);

static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
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) {
kernel_neon_begin();
chacha20_4block_xor_neon(state, dst, src);
chacha_4block_xor_neon(state, dst, src, nrounds);
kernel_neon_end();
bytes -= CHACHA_BLOCK_SIZE * 4;
src += CHACHA_BLOCK_SIZE * 4;
Expand All @@ -52,22 +55,22 @@ static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src,

kernel_neon_begin();
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);
}
kernel_neon_end();
}

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 @@ -83,26 +86,26 @@ static int chacha20_neon_stream_xor(struct skcipher_request *req,
if (nbytes < walk.total)
nbytes = round_down(nbytes, walk.stride);

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);
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 @@ -116,12 +119,13 @@ 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 @@ -139,8 +143,8 @@ 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 @@ -155,27 +159,28 @@ 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_ASIMD))
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

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