crypto: x86/aegis128 - take advantage of block-aligned len

Update a caller of aegis128_aesni_ad() to round down the length to a
block boundary.  After that, aegis128_aesni_ad(), aegis128_aesni_enc(),
and aegis128_aesni_dec() are only passed whole blocks.  Update the
assembly code to take advantage of that, which eliminates some unneeded
instructions.  For aegis128_aesni_enc() and aegis128_aesni_dec(), the
length is also always nonzero, so stop checking for zero length.

Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Author: ebiggers

arch/x86/crypto/aegis128-aesni-asm.S

@@ -190,15 +190,17 @@ SYM_FUNC_END(aegis128_aesni_init)
 /*
  * void aegis128_aesni_ad(struct aegis_state *state, const u8 *data,
  *			  unsigned int len);
+ *
+ * len must be a multiple of 16.
  */
 SYM_FUNC_START(aegis128_aesni_ad)
 	.set STATEP, %rdi
 	.set SRC, %rsi
 	.set LEN, %edx
 	FRAME_BEGIN
 
-	cmp $0x10, LEN
-	jb .Lad_out
+	test LEN, LEN
+	jz .Lad_out
 
 	/* load the state: */
 	movdqu 0x00(STATEP), STATE0
@@ -213,36 +215,31 @@ SYM_FUNC_START(aegis128_aesni_ad)
 	aegis128_update
 	pxor MSG, STATE4
 	sub $0x10, LEN
-	cmp $0x10, LEN
-	jl .Lad_out_1
+	jz .Lad_out_1
 
 	movdqu 0x10(SRC), MSG
 	aegis128_update
 	pxor MSG, STATE3
 	sub $0x10, LEN
-	cmp $0x10, LEN
-	jl .Lad_out_2
+	jz .Lad_out_2
 
 	movdqu 0x20(SRC), MSG
 	aegis128_update
 	pxor MSG, STATE2
 	sub $0x10, LEN
-	cmp $0x10, LEN
-	jl .Lad_out_3
+	jz .Lad_out_3
 
 	movdqu 0x30(SRC), MSG
 	aegis128_update
 	pxor MSG, STATE1
 	sub $0x10, LEN
-	cmp $0x10, LEN
-	jl .Lad_out_4
+	jz .Lad_out_4
 
 	movdqu 0x40(SRC), MSG
 	aegis128_update
 	pxor MSG, STATE0
 	sub $0x10, LEN
-	cmp $0x10, LEN
-	jl .Lad_out_0
+	jz .Lad_out_0
 
 	add $0x50, SRC
 	jmp .Lad_loop
@@ -312,13 +309,14 @@ SYM_FUNC_END(aegis128_aesni_ad)
 	pxor MSG, \s4
 
 	sub $0x10, LEN
-	cmp $0x10, LEN
-	jl .Lenc_out_\i
+	jz .Lenc_out_\i
 .endm
 
 /*
  * void aegis128_aesni_enc(struct aegis_state *state, const u8 *src, u8 *dst,
  *			   unsigned int len);
+ *
+ * len must be nonzero and a multiple of 16.
  */
 SYM_FUNC_START(aegis128_aesni_enc)
 	.set STATEP, %rdi
@@ -327,9 +325,6 @@ SYM_FUNC_START(aegis128_aesni_enc)
 	.set LEN, %ecx
 	FRAME_BEGIN
 
-	cmp $0x10, LEN
-	jb .Lenc_out
-
 	/* load the state: */
 	movdqu 0x00(STATEP), STATE0
 	movdqu 0x10(STATEP), STATE1
@@ -459,13 +454,14 @@ SYM_FUNC_END(aegis128_aesni_enc_tail)
 	pxor MSG, \s4
 
 	sub $0x10, LEN
-	cmp $0x10, LEN
-	jl .Ldec_out_\i
+	jz .Ldec_out_\i
 .endm
 
 /*
  * void aegis128_aesni_dec(struct aegis_state *state, const u8 *src, u8 *dst,
  *			   unsigned int len);
+ *
+ * len must be nonzero and a multiple of 16.
  */
 SYM_FUNC_START(aegis128_aesni_dec)
 	.set STATEP, %rdi
@@ -474,9 +470,6 @@ SYM_FUNC_START(aegis128_aesni_dec)
 	.set LEN, %ecx
 	FRAME_BEGIN
 
-	cmp $0x10, LEN
-	jb .Ldec_out
-
 	/* load the state: */
 	movdqu 0x00(STATEP), STATE0
 	movdqu 0x10(STATEP), STATE1

arch/x86/crypto/aegis128-aesni-glue.c

@@ -87,8 +87,8 @@ static void crypto_aegis128_aesni_process_ad(
 				src += fill;
 			}
 
-			aegis128_aesni_ad(state, src, left);
-
+			aegis128_aesni_ad(state, src,
+					  left & ~(AEGIS128_BLOCK_SIZE - 1));
 			src += left & ~(AEGIS128_BLOCK_SIZE - 1);
 			left &= AEGIS128_BLOCK_SIZE - 1;
 		}