ARM assembly for AES.

ChangeLog

+2013-03-08  Niels Möller  <nisse@lysator.liu.se>
+
+	* armv7/aes-decrypt-internal.asm: New file, 15% speedup.
+	* armv7/aes-encrypt-internal.asm: New file, 25% speedup.
+	* armv7/aes.m4: New file.
+
 2013-03-07  Niels Möller  <nisse@lysator.liu.se>
 
 	* gmp-glue.c (mpz_limbs_cmp): Don't use PTR and SIZ macros.

armv7/aes-decrypt-internal.asm

+C nettle, low-level cryptographics library
+C 
+C Copyright (C) 2013 Niels Möller
+C  
+C The nettle library is free software; you can redistribute it and/or modify
+C it under the terms of the GNU Lesser General Public License as published by
+C the Free Software Foundation; either version 2.1 of the License, or (at your
+C option) any later version.
+C 
+C The nettle library is distributed in the hope that it will be useful, but
+C WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+C or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+C License for more details.
+C 
+C You should have received a copy of the GNU Lesser General Public License
+C along with the nettle library; see the file COPYING.LIB.  If not, write to
+C the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+C MA 02111-1301, USA.
+
+include_src(<armv7/aes.m4>)
+
+C	Benchmarked at at 785, 914, 1051 cycles/block on cortex A9,
+C	for 128, 192 and 256 bit key sizes. Unclear why it is slower
+C	than _aes_encrypt.
+
+define(<CTX>, <r0>)
+define(<TABLE>, <r1>)
+define(<LENGTH>, <r2>)
+define(<DST>, <r3>)
+define(<SRC>, <r12>)
+
+define(<W0>, <r4>)
+define(<W1>, <r5>)
+define(<W2>, <r6>)
+define(<W3>, <r7>)
+define(<T0>, <r8>)
+define(<KEY>, <r10>)
+define(<ROUND>, <r11>)
+
+define(<X0>, <r2>)	C Overlaps LENGTH, SRC, DST
+define(<X1>, <r3>)
+define(<X2>, <r12>)
+define(<X3>, <r14>)	C lr
+
+
+	.file "aes-decrypt-internal.asm"
+	
+	C _aes_decrypt(struct aes_context *ctx, 
+	C	       const struct aes_table *T,
+	C	       unsigned length, uint8_t *dst,
+	C	       uint8_t *src)
+	.text
+	.align 2
+PROLOGUE(_nettle_aes_decrypt)
+	teq	LENGTH, #0
+	beq	.Lend
+	ldr	SRC, [sp]
+
+	push	{r4,r5,r6,r7,r8,r10,r11,lr}
+.Lblock_loop:
+	mov	KEY, CTX
+	AES_LOAD(SRC,KEY,W0)
+	AES_LOAD(SRC,KEY,W1)
+	AES_LOAD(SRC,KEY,W2)
+	AES_LOAD(SRC,KEY,W3)
+
+	push	{LENGTH, DST, SRC}
+	ldr	ROUND, [CTX, #+AES_NROUNDS]
+	add	TABLE, TABLE, #AES_TABLE0
+
+	b	.Lentry
+	.align 2
+.Lround_loop:
+	C	Transform X -> W
+	AES_DECRYPT_ROUND(X0, X1, X2, X3, W0, W1, W2, W3, KEY)
+	
+.Lentry:
+	subs	ROUND, ROUND,#2
+	C	Transform W -> X
+	AES_DECRYPT_ROUND(W0, W1, W2, W3, X0, X1, X2, X3, KEY)
+
+	bne	.Lround_loop
+
+	sub	TABLE, TABLE, #AES_TABLE0
+	C	Final round
+	AES_FINAL_ROUND(X0, X3, X2, X1, KEY, W0)
+	AES_FINAL_ROUND(X1, X0, X3, X2, KEY, W1)
+	AES_FINAL_ROUND(X2, X1, X0, X3, KEY, W2)
+	AES_FINAL_ROUND(X3, X2, X1, X0, KEY, W3)
+
+	pop	{LENGTH, DST, SRC}
+	
+	AES_STORE(DST,W0)
+	AES_STORE(DST,W1)
+	AES_STORE(DST,W2)
+	AES_STORE(DST,W3)
+
+	subs	LENGTH, LENGTH, #16
+	bhi	.Lblock_loop
+
+	pop	{r4,r5,r6,r7,r8,r10,r11,pc}
+	
+.Lend:
+	bx	lr
+EPILOGUE(_nettle_aes_decrypt)

armv7/aes-encrypt-internal.asm

+C nettle, low-level cryptographics library
+C 
+C Copyright (C) 2013 Niels Möller
+C  
+C The nettle library is free software; you can redistribute it and/or modify
+C it under the terms of the GNU Lesser General Public License as published by
+C the Free Software Foundation; either version 2.1 of the License, or (at your
+C option) any later version.
+C 
+C The nettle library is distributed in the hope that it will be useful, but
+C WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+C or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+C License for more details.
+C 
+C You should have received a copy of the GNU Lesser General Public License
+C along with the nettle library; see the file COPYING.LIB.  If not, write to
+C the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+C MA 02111-1301, USA.
+
+include_src(<armv7/aes.m4>)
+
+C	Benchmarked at at 693, 824, 950 cycles/block on cortex A9,
+C	for 128, 192 and 256 bit key sizes.
+
+C	Possible improvements: More efficient load and store with
+C	aligned accesses. Better scheduling.
+
+define(<CTX>, <r0>)
+define(<TABLE>, <r1>)
+define(<LENGTH>, <r2>)
+define(<DST>, <r3>)
+define(<SRC>, <r12>)
+
+define(<W0>, <r4>)
+define(<W1>, <r5>)
+define(<W2>, <r6>)
+define(<W3>, <r7>)
+define(<T0>, <r8>)
+define(<KEY>, <r10>)
+define(<ROUND>, <r11>)
+
+define(<X0>, <r2>)	C Overlaps LENGTH, SRC, DST
+define(<X1>, <r3>)
+define(<X2>, <r12>)
+define(<X3>, <r14>)	C lr
+
+
+	.file "aes-encrypt-internal.asm"
+	
+	C _aes_encrypt(struct aes_context *ctx, 
+	C	       const struct aes_table *T,
+	C	       unsigned length, uint8_t *dst,
+	C	       uint8_t *src)
+	.text
+	.align 2
+PROLOGUE(_nettle_aes_encrypt)
+	teq	LENGTH, #0
+	beq	.Lend
+	ldr	SRC, [sp]
+
+	push	{r4,r5,r6,r7,r8,r10,r11,lr}
+.Lblock_loop:
+	mov	KEY, CTX
+	AES_LOAD(SRC,KEY,W0)
+	AES_LOAD(SRC,KEY,W1)
+	AES_LOAD(SRC,KEY,W2)
+	AES_LOAD(SRC,KEY,W3)
+
+	push	{LENGTH, DST, SRC}
+	ldr	ROUND, [CTX, #+AES_NROUNDS]
+	add	TABLE, TABLE, #AES_TABLE0
+
+	b	.Lentry
+	.align 2
+.Lround_loop:
+	C	Transform X -> W
+	AES_ENCRYPT_ROUND(X0, X1, X2, X3, W0, W1, W2, W3, KEY)
+	
+.Lentry:
+	subs	ROUND, ROUND,#2
+	C	Transform W -> X
+	AES_ENCRYPT_ROUND(W0, W1, W2, W3, X0, X1, X2, X3, KEY)
+
+	bne	.Lround_loop
+
+	sub	TABLE, TABLE, #AES_TABLE0
+	C	Final round
+	AES_FINAL_ROUND(X0, X1, X2, X3, KEY, W0)
+	AES_FINAL_ROUND(X1, X2, X3, X0, KEY, W1)
+	AES_FINAL_ROUND(X2, X3, X0, X1, KEY, W2)
+	AES_FINAL_ROUND(X3, X0, X1, X2, KEY, W3)
+
+	pop	{LENGTH, DST, SRC}
+	
+	AES_STORE(DST,W0)
+	AES_STORE(DST,W1)
+	AES_STORE(DST,W2)
+	AES_STORE(DST,W3)
+
+	subs	LENGTH, LENGTH, #16
+	bhi	.Lblock_loop
+
+	pop	{r4,r5,r6,r7,r8,r10,r11,pc}
+	
+.Lend:
+	bx	lr
+EPILOGUE(_nettle_aes_encrypt)

armv7/aes.m4

+C Loads one word, and adds it to the subkey. Uses T0
+C AES_LOAD(SRC, KEY, REG)
+define(<AES_LOAD>, <
+	ldrb	$3, [$1], #+1
+	ldrb	T0, [$1], #+1
+	orr	$3, T0, lsl #8
+	ldrb	T0, [$1], #+1
+	orr	$3, T0, lsl #16
+	ldrb	T0, [$1], #+1
+	orr	$3, T0, lsl #24
+	ldr	T0, [$2], #+4
+	eor	$3, T0
+>)
+C Stores one word. Destroys input.
+C AES_STORE(DST, X)
+define(<AES_STORE>, <
+	strb	$2, [$1], #+1
+	ror	$2, $2, #8
+	strb	$2, [$1], #+1
+	ror	$2, $2, #8
+	strb	$2, [$1], #+1
+	ror	$2, $2, #8
+	strb	$2, [$1], #+1
+>)
+
+C 53 instr.
+C It's tempting to use eor with rotation, but that's slower.
+C AES_ENCRYPT_ROUND(x0,x1,x2,x3,w0,w1,w2,w3,key)
+define(<AES_ENCRYPT_ROUND>, <
+	uxtb	T0, $1 
+	ldr	$5, [TABLE, T0, lsl #2]
+	uxtb	T0, $2
+	ldr	$6, [TABLE, T0, lsl #2]
+	uxtb	T0, $3
+	ldr	$7, [TABLE, T0, lsl #2]
+	uxtb	T0, $4
+	ldr	$8, [TABLE, T0, lsl #2]
+
+	uxtb	T0, $2, ror #8
+	add	TABLE, TABLE, #1024
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$5, $5, T0
+	uxtb	T0, $3, ror #8
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$6, $6, T0
+	uxtb	T0, $4, ror #8
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$7, $7, T0
+	uxtb	T0, $1, ror #8
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$8, $8, T0
+
+	uxtb	T0, $3, ror #16
+	add	TABLE, TABLE, #1024
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$5, $5, T0
+	uxtb	T0, $4, ror #16
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$6, $6, T0
+	uxtb	T0, $1, ror #16
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$7, $7, T0
+	uxtb	T0, $2, ror #16
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$8, $8, T0
+
+	uxtb	T0, $4, ror #24
+	add	TABLE, TABLE, #1024
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$5, $5, T0
+	uxtb	T0, $1, ror #24
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$6, $6, T0
+	uxtb	T0, $2, ror #24
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$7, $7, T0
+	uxtb	T0, $3, ror #24
+	ldr	T0, [TABLE, T0, lsl #2]
+
+	ldm	$9!, {$1,$2,$3,$4}
+	eor	$8, $8, T0
+	sub	TABLE, TABLE, #3072
+	eor	$5, $5, $1
+	eor	$6, $6, $2
+	eor	$7, $7, $3
+	eor	$8, $8, $4
+>)
+
+define(<AES_DECRYPT_ROUND>, <
+	uxtb	T0, $1
+	ldr	$5, [TABLE, T0, lsl #2]
+	uxtb	T0, $2
+	ldr	$6, [TABLE, T0, lsl #2]
+	uxtb	T0, $3
+	ldr	$7, [TABLE, T0, lsl #2]
+	uxtb	T0, $4
+	ldr	$8, [TABLE, T0, lsl #2]
+
+	uxtb	T0, $4, ror #8
+	add	TABLE, TABLE, #1024
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$5, $5, T0
+	uxtb	T0, $1, ror #8
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$6, $6, T0
+	uxtb	T0, $2, ror #8
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$7, $7, T0
+	uxtb	T0, $3, ror #8
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$8, $8, T0
+
+	uxtb	T0, $3, ror #16
+	add	TABLE, TABLE, #1024
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$5, $5, T0
+	uxtb	T0, $4, ror #16
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$6, $6, T0
+	uxtb	T0, $1, ror #16
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$7, $7, T0
+	uxtb	T0, $2, ror #16
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$8, $8, T0
+
+	uxtb	T0, $2, ror #24
+	add	TABLE, TABLE, #1024
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$5, $5, T0
+	uxtb	T0, $3, ror #24
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$6, $6, T0
+	uxtb	T0, $4, ror #24
+	ldr	T0, [TABLE, T0, lsl #2]
+	eor	$7, $7, T0
+	uxtb	T0, $1, ror #24
+	ldr	T0, [TABLE, T0, lsl #2]
+
+	ldm	$9!, {$1,$2,$3,$4}
+	eor	$8, $8, T0
+	sub	TABLE, TABLE, #3072
+	eor	$5, $5, $1
+	eor	$6, $6, $2
+	eor	$7, $7, $3
+	eor	$8, $8, $4
+>)
+
+C AES_FINAL_ROUND(a,b,c,d,key,res)
+define(<AES_FINAL_ROUND>, <
+	uxtb	T0, $1
+	ldrb	$6, [TABLE, T0]
+	uxtb	T0, $2, ror #8
+	ldrb	T0, [TABLE, T0]
+	eor	$6, $6, T0, lsl #8
+	uxtb	T0, $3, ror #16
+	ldrb	T0, [TABLE, T0]
+	eor	$6, $6, T0, lsl #16
+	uxtb	T0, $4, ror #24
+	ldrb	T0, [TABLE, T0]
+	eor	$6, $6, T0, lsl #24
+	ldr	T0, [$5], #+4
+	eor	$6, T0
+>)