[PATCH crypto-next v2 3/3] crypto: arm/arm64/mips/poly1305 - remove redundant non-reduction from emit

Jason A. Donenfeld
2019-12-12T09:30:43Z

This appears to be some kind of copy and paste error, and is actually
dead code.

Pre: f = 0 ⇒ (f >> 32) = 0
f = (f >> 32) + le32_to_cpu(digest[0]);
Post: 0 ≤ f < 2³²
put_unaligned_le32(f, dst);

Pre: 0 ≤ f < 2³² ⇒ (f >> 32) = 0
f = (f >> 32) + le32_to_cpu(digest[1]);
Post: 0 ≤ f < 2³²
put_unaligned_le32(f, dst + 4);

Pre: 0 ≤ f < 2³² ⇒ (f >> 32) = 0
f = (f >> 32) + le32_to_cpu(digest[2]);
Post: 0 ≤ f < 2³²
put_unaligned_le32(f, dst + 8);

Pre: 0 ≤ f < 2³² ⇒ (f >> 32) = 0
f = (f >> 32) + le32_to_cpu(digest[3]);
Post: 0 ≤ f < 2³²
put_unaligned_le32(f, dst + 12);

Therefore this sequence is redundant. And Andy's code appears to handle
misalignment acceptably.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm/crypto/poly1305-glue.c | 18 ++----------------
arch/arm64/crypto/poly1305-glue.c | 18 ++----------------
arch/mips/crypto/poly1305-glue.c | 18 ++----------------
3 files changed, 6 insertions(+), 48 deletions(-)

diff --git a/arch/arm/crypto/poly1305-glue.c b/arch/arm/crypto/poly1305-glue.c
index abe3f2d587dc..ceec04ec2f40 100644
--- a/arch/arm/crypto/poly1305-glue.c
+++ b/arch/arm/crypto/poly1305-glue.c
@@ -20,7 +20,7 @@

void poly1305_init_arm(void *state, const u8 *key);
void poly1305_blocks_arm(void *state, const u8 *src, u32 len, u32 hibit);
-void poly1305_emit_arm(void *state, __le32 *digest, const u32 *nonce);
+void poly1305_emit_arm(void *state, u8 *digest, const u32 *nonce);

void __weak poly1305_blocks_neon(void *state, const u8 *src, u32 len, u32 hibit)
{
@@ -179,9 +179,6 @@ EXPORT_SYMBOL(poly1305_update_arch);

void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
{
- __le32 digest[4];
- u64 f = 0;
-
if (unlikely(dctx->buflen)) {
dctx->buf[dctx->buflen++] = 1;
memset(dctx->buf + dctx->buflen, 0,
@@ -189,18 +186,7 @@ void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
poly1305_blocks_arm(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 0);
}

- poly1305_emit_arm(&dctx->h, digest, dctx->s);
-
- /* mac = (h + s) % (2^128) */
- f = (f >> 32) + le32_to_cpu(digest[0]);
- put_unaligned_le32(f, dst);
- f = (f >> 32) + le32_to_cpu(digest[1]);
- put_unaligned_le32(f, dst + 4);
- f = (f >> 32) + le32_to_cpu(digest[2]);
- put_unaligned_le32(f, dst + 8);
- f = (f >> 32) + le32_to_cpu(digest[3]);
- put_unaligned_le32(f, dst + 12);
-
+ poly1305_emit_arm(&dctx->h, dst, dctx->s);
*dctx = (struct poly1305_desc_ctx){};
}
EXPORT_SYMBOL(poly1305_final_arch);
diff --git a/arch/arm64/crypto/poly1305-glue.c b/arch/arm64/crypto/poly1305-glue.c
index 83a2338a8826..e97b092f56b8 100644
--- a/arch/arm64/crypto/poly1305-glue.c
+++ b/arch/arm64/crypto/poly1305-glue.c
@@ -21,7 +21,7 @@
asmlinkage void poly1305_init_arm64(void *state, const u8 *key);
asmlinkage void poly1305_blocks(void *state, const u8 *src, u32 len, u32 hibit);
asmlinkage void poly1305_blocks_neon(void *state, const u8 *src, u32 len, u32 hibit);
-asmlinkage void poly1305_emit(void *state, __le32 *digest, const u32 *nonce);
+asmlinkage void poly1305_emit(void *state, u8 *digest, const u32 *nonce);

static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);

@@ -162,9 +162,6 @@ EXPORT_SYMBOL(poly1305_update_arch);

void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
{
- __le32 digest[4];
- u64 f = 0;
-
if (unlikely(dctx->buflen)) {
dctx->buf[dctx->buflen++] = 1;
memset(dctx->buf + dctx->buflen, 0,
@@ -172,18 +169,7 @@ void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
poly1305_blocks(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 0);
}

- poly1305_emit(&dctx->h, digest, dctx->s);
-
- /* mac = (h + s) % (2^128) */
- f = (f >> 32) + le32_to_cpu(digest[0]);
- put_unaligned_le32(f, dst);
- f = (f >> 32) + le32_to_cpu(digest[1]);
- put_unaligned_le32(f, dst + 4);
- f = (f >> 32) + le32_to_cpu(digest[2]);
- put_unaligned_le32(f, dst + 8);
- f = (f >> 32) + le32_to_cpu(digest[3]);
- put_unaligned_le32(f, dst + 12);
-
+ poly1305_emit(&dctx->h, dst, dctx->s);
*dctx = (struct poly1305_desc_ctx){};
}
EXPORT_SYMBOL(poly1305_final_arch);
diff --git a/arch/mips/crypto/poly1305-glue.c b/arch/mips/crypto/poly1305-glue.c
index b37d29cf5d0a..fc881b46d911 100644
--- a/arch/mips/crypto/poly1305-glue.c
+++ b/arch/mips/crypto/poly1305-glue.c
@@ -15,7 +15,7 @@

asmlinkage void poly1305_init_mips(void *state, const u8 *key);
asmlinkage void poly1305_blocks_mips(void *state, const u8 *src, u32 len, u32 hibit);
-asmlinkage void poly1305_emit_mips(void *state, __le32 *digest, const u32 *nonce);
+asmlinkage void poly1305_emit_mips(void *state, u8 *digest, const u32 *nonce);

void poly1305_init_arch(struct poly1305_desc_ctx *dctx, const u8 *key)
{
@@ -134,9 +134,6 @@ EXPORT_SYMBOL(poly1305_update_arch);

void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
{
- __le32 digest[4];
- u64 f = 0;
-
if (unlikely(dctx->buflen)) {
dctx->buf[dctx->buflen++] = 1;
memset(dctx->buf + dctx->buflen, 0,
@@ -144,18 +141,7 @@ void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
poly1305_blocks_mips(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 0);
}

- poly1305_emit_mips(&dctx->h, digest, dctx->s);
-
- /* mac = (h + s) % (2^128) */
- f = (f >> 32) + le32_to_cpu(digest[0]);
- put_unaligned_le32(f, dst);
- f = (f >> 32) + le32_to_cpu(digest[1]);
- put_unaligned_le32(f, dst + 4);
- f = (f >> 32) + le32_to_cpu(digest[2]);
- put_unaligned_le32(f, dst + 8);
- f = (f >> 32) + le32_to_cpu(digest[3]);
- put_unaligned_le32(f, dst + 12);
-
+ poly1305_emit_mips(&dctx->h, dst, dctx->s);
*dctx = (struct poly1305_desc_ctx){};
}
EXPORT_SYMBOL(poly1305_final_arch);
--
2.24.0