diff mbox series

[v2] crypto: vmx: Improved AES/XTS performance of 6-way unrolling for ppc.

Message ID 20230830134911.179765-1-dtsen@linux.ibm.com
State Accepted
Commit 6b36dafedd53276a8fb7d7a12ee549560e48b8ee
Headers show
Series [v2] crypto: vmx: Improved AES/XTS performance of 6-way unrolling for ppc. | expand

Commit Message

Danny Tsen Aug. 30, 2023, 1:49 p.m. UTC 
Improve AES/XTS performance of 6-way unrolling for PowerPC up
to 17% with tcrypt.  This is done by using one instruction,
vpermxor, to replace xor and vsldoi.

The same changes were applied to OpenSSL code and a pull request was
submitted.

This patch has been tested with the kernel crypto module tcrypt.ko and
has passed the selftest.  The patch is also tested with
CONFIG_CRYPTO_MANAGER_EXTRA_TESTS enabled.

Signed-off-by: Danny Tsen <dtsen@linux.ibm.com>
---
 drivers/crypto/vmx/aesp8-ppc.pl | 141 +++++++++++++++++++++-----------
 1 file changed, 92 insertions(+), 49 deletions(-)

Comments

Danny Tsen Sept. 15, 2023, 11:23 a.m. UTC | #1 
Thanks Herbert.

-Danny

On 9/15/23 5:41 AM, Herbert Xu wrote:
> On Wed, Aug 30, 2023 at 09:49:11AM -0400, Danny Tsen wrote:
>> Improve AES/XTS performance of 6-way unrolling for PowerPC up
>> to 17% with tcrypt.  This is done by using one instruction,
>> vpermxor, to replace xor and vsldoi.
>>
>> The same changes were applied to OpenSSL code and a pull request was
>> submitted.
>>
>> This patch has been tested with the kernel crypto module tcrypt.ko and
>> has passed the selftest.  The patch is also tested with
>> CONFIG_CRYPTO_MANAGER_EXTRA_TESTS enabled.
>>
>> Signed-off-by: Danny Tsen <dtsen@linux.ibm.com>
>> ---
>>   drivers/crypto/vmx/aesp8-ppc.pl | 141 +++++++++++++++++++++-----------
>>   1 file changed, 92 insertions(+), 49 deletions(-)
> Patch applied.  Thanks.
Michael Ellerman Sept. 15, 2023, 1:29 p.m. UTC | #2 
Danny Tsen <dtsen@linux.ibm.com> writes:
> Improve AES/XTS performance of 6-way unrolling for PowerPC up
> to 17% with tcrypt.  This is done by using one instruction,
> vpermxor, to replace xor and vsldoi.
>
> The same changes were applied to OpenSSL code and a pull request was
> submitted.

https://github.com/openssl/openssl/pull/21812

Still unmerged as of today.

cheers
diff mbox series

Patch

diff --git a/drivers/crypto/vmx/aesp8-ppc.pl b/drivers/crypto/vmx/aesp8-ppc.pl
index 50a0a18f35da..f729589d792e 100644
--- a/drivers/crypto/vmx/aesp8-ppc.pl
+++ b/drivers/crypto/vmx/aesp8-ppc.pl
@@ -132,11 +132,12 @@  rcon:
 .long	0x1b000000, 0x1b000000, 0x1b000000, 0x1b000000	?rev
 .long	0x0d0e0f0c, 0x0d0e0f0c, 0x0d0e0f0c, 0x0d0e0f0c	?rev
 .long	0,0,0,0						?asis
+.long	0x0f102132, 0x43546576, 0x8798a9ba, 0xcbdcedfe
 Lconsts:
 	mflr	r0
 	bcl	20,31,\$+4
 	mflr	$ptr	 #vvvvv "distance between . and rcon
-	addi	$ptr,$ptr,-0x48
+	addi	$ptr,$ptr,-0x58
 	mtlr	r0
 	blr
 	.long	0
@@ -2495,6 +2496,17 @@  _aesp8_xts_encrypt6x:
 	li		$x70,0x70
 	mtspr		256,r0
 
+	xxlor		2, 32+$eighty7, 32+$eighty7
+	vsldoi		$eighty7,$tmp,$eighty7,1        # 0x010101..87
+	xxlor		1, 32+$eighty7, 32+$eighty7
+
+	# Load XOR Lconsts.
+	mr		$x70, r6
+	bl		Lconsts
+	lxvw4x		0, $x40, r6		# load XOR contents
+	mr		r6, $x70
+	li		$x70,0x70
+
 	subi		$rounds,$rounds,3	# -4 in total
 
 	lvx		$rndkey0,$x00,$key1	# load key schedule
@@ -2537,69 +2549,77 @@  Load_xts_enc_key:
 	?vperm		v31,v31,$twk5,$keyperm
 	lvx		v25,$x10,$key_		# pre-load round[2]
 
+	# Switch to use the following codes with 0x010101..87 to generate tweak.
+	#     eighty7 = 0x010101..87
+	# vsrab         tmp, tweak, seven       # next tweak value, right shift 7 bits
+	# vand          tmp, tmp, eighty7       # last byte with carry
+	# vaddubm       tweak, tweak, tweak     # left shift 1 bit (x2)
+	# xxlor         vsx, 0, 0
+	# vpermxor      tweak, tweak, tmp, vsx
+
 	 vperm		$in0,$inout,$inptail,$inpperm
 	 subi		$inp,$inp,31		# undo "caller"
 	vxor		$twk0,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out0,$in0,$twk0
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in1, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in1
 
 	 lvx_u		$in1,$x10,$inp
 	vxor		$twk1,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in1,$in1,$in1,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out1,$in1,$twk1
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in2, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in2
 
 	 lvx_u		$in2,$x20,$inp
 	 andi.		$taillen,$len,15
 	vxor		$twk2,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in2,$in2,$in2,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out2,$in2,$twk2
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in3, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in3
 
 	 lvx_u		$in3,$x30,$inp
 	 sub		$len,$len,$taillen
 	vxor		$twk3,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in3,$in3,$in3,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out3,$in3,$twk3
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in4, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in4
 
 	 lvx_u		$in4,$x40,$inp
 	 subi		$len,$len,0x60
 	vxor		$twk4,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in4,$in4,$in4,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out4,$in4,$twk4
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in5, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in5
 
 	 lvx_u		$in5,$x50,$inp
 	 addi		$inp,$inp,0x60
 	vxor		$twk5,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in5,$in5,$in5,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out5,$in5,$twk5
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in0, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in0
 
 	vxor		v31,v31,$rndkey0
 	mtctr		$rounds
@@ -2625,6 +2645,8 @@  Loop_xts_enc6x:
 	lvx		v25,$x10,$key_		# round[4]
 	bdnz		Loop_xts_enc6x
 
+	xxlor		32+$eighty7, 1, 1	# 0x010101..87
+
 	subic		$len,$len,96		# $len-=96
 	 vxor		$in0,$twk0,v31		# xor with last round key
 	vcipher		$out0,$out0,v24
@@ -2634,7 +2656,6 @@  Loop_xts_enc6x:
 	 vaddubm	$tweak,$tweak,$tweak
 	vcipher		$out2,$out2,v24
 	vcipher		$out3,$out3,v24
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vcipher		$out4,$out4,v24
 	vcipher		$out5,$out5,v24
 
@@ -2642,7 +2663,8 @@  Loop_xts_enc6x:
 	 vand		$tmp,$tmp,$eighty7
 	vcipher		$out0,$out0,v25
 	vcipher		$out1,$out1,v25
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in1, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in1
 	vcipher		$out2,$out2,v25
 	vcipher		$out3,$out3,v25
 	 vxor		$in1,$twk1,v31
@@ -2653,13 +2675,13 @@  Loop_xts_enc6x:
 
 	and		r0,r0,$len
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vcipher		$out0,$out0,v26
 	vcipher		$out1,$out1,v26
 	 vand		$tmp,$tmp,$eighty7
 	vcipher		$out2,$out2,v26
 	vcipher		$out3,$out3,v26
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in2, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in2
 	vcipher		$out4,$out4,v26
 	vcipher		$out5,$out5,v26
 
@@ -2673,7 +2695,6 @@  Loop_xts_enc6x:
 	 vaddubm	$tweak,$tweak,$tweak
 	vcipher		$out0,$out0,v27
 	vcipher		$out1,$out1,v27
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vcipher		$out2,$out2,v27
 	vcipher		$out3,$out3,v27
 	 vand		$tmp,$tmp,$eighty7
@@ -2681,7 +2702,8 @@  Loop_xts_enc6x:
 	vcipher		$out5,$out5,v27
 
 	addi		$key_,$sp,$FRAME+15	# rewind $key_
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in3, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in3
 	vcipher		$out0,$out0,v28
 	vcipher		$out1,$out1,v28
 	 vxor		$in3,$twk3,v31
@@ -2690,7 +2712,6 @@  Loop_xts_enc6x:
 	vcipher		$out2,$out2,v28
 	vcipher		$out3,$out3,v28
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vcipher		$out4,$out4,v28
 	vcipher		$out5,$out5,v28
 	lvx		v24,$x00,$key_		# re-pre-load round[1]
@@ -2698,7 +2719,8 @@  Loop_xts_enc6x:
 
 	vcipher		$out0,$out0,v29
 	vcipher		$out1,$out1,v29
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in4, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in4
 	vcipher		$out2,$out2,v29
 	vcipher		$out3,$out3,v29
 	 vxor		$in4,$twk4,v31
@@ -2708,14 +2730,14 @@  Loop_xts_enc6x:
 	vcipher		$out5,$out5,v29
 	lvx		v25,$x10,$key_		# re-pre-load round[2]
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 
 	vcipher		$out0,$out0,v30
 	vcipher		$out1,$out1,v30
 	 vand		$tmp,$tmp,$eighty7
 	vcipher		$out2,$out2,v30
 	vcipher		$out3,$out3,v30
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in5, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in5
 	vcipher		$out4,$out4,v30
 	vcipher		$out5,$out5,v30
 	 vxor		$in5,$twk5,v31
@@ -2725,7 +2747,6 @@  Loop_xts_enc6x:
 	vcipherlast	$out0,$out0,$in0
 	 lvx_u		$in0,$x00,$inp		# load next input block
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vcipherlast	$out1,$out1,$in1
 	 lvx_u		$in1,$x10,$inp
 	vcipherlast	$out2,$out2,$in2
@@ -2738,7 +2759,10 @@  Loop_xts_enc6x:
 	vcipherlast	$out4,$out4,$in4
 	 le?vperm	$in2,$in2,$in2,$leperm
 	 lvx_u		$in4,$x40,$inp
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		10, 32+$in0, 32+$in0
+	 xxlor		32+$in0, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in0
+	 xxlor		32+$in0, 10, 10
 	vcipherlast	$tmp,$out5,$in5		# last block might be needed
 						# in stealing mode
 	 le?vperm	$in3,$in3,$in3,$leperm
@@ -2771,6 +2795,8 @@  Loop_xts_enc6x:
 	mtctr		$rounds
 	beq		Loop_xts_enc6x		# did $len-=96 borrow?
 
+	xxlor		32+$eighty7, 2, 2	# 0x010101..87
+
 	addic.		$len,$len,0x60
 	beq		Lxts_enc6x_zero
 	cmpwi		$len,0x20
@@ -3147,6 +3173,17 @@  _aesp8_xts_decrypt6x:
 	li		$x70,0x70
 	mtspr		256,r0
 
+	xxlor		2, 32+$eighty7, 32+$eighty7
+	vsldoi		$eighty7,$tmp,$eighty7,1        # 0x010101..87
+	xxlor		1, 32+$eighty7, 32+$eighty7
+
+	# Load XOR Lconsts.
+	mr		$x70, r6
+	bl		Lconsts
+	lxvw4x		0, $x40, r6		# load XOR contents
+	mr		r6, $x70
+	li		$x70,0x70
+
 	subi		$rounds,$rounds,3	# -4 in total
 
 	lvx		$rndkey0,$x00,$key1	# load key schedule
@@ -3194,64 +3231,64 @@  Load_xts_dec_key:
 	vxor		$twk0,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out0,$in0,$twk0
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in1, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in1
 
 	 lvx_u		$in1,$x10,$inp
 	vxor		$twk1,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in1,$in1,$in1,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out1,$in1,$twk1
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in2, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in2
 
 	 lvx_u		$in2,$x20,$inp
 	 andi.		$taillen,$len,15
 	vxor		$twk2,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in2,$in2,$in2,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out2,$in2,$twk2
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in3, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in3
 
 	 lvx_u		$in3,$x30,$inp
 	 sub		$len,$len,$taillen
 	vxor		$twk3,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in3,$in3,$in3,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out3,$in3,$twk3
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in4, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in4
 
 	 lvx_u		$in4,$x40,$inp
 	 subi		$len,$len,0x60
 	vxor		$twk4,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in4,$in4,$in4,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out4,$in4,$twk4
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in5, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in5
 
 	 lvx_u		$in5,$x50,$inp
 	 addi		$inp,$inp,0x60
 	vxor		$twk5,$tweak,$rndkey0
 	vsrab		$tmp,$tweak,$seven	# next tweak value
 	vaddubm		$tweak,$tweak,$tweak
-	vsldoi		$tmp,$tmp,$tmp,15
 	 le?vperm	$in5,$in5,$in5,$leperm
 	vand		$tmp,$tmp,$eighty7
 	 vxor		$out5,$in5,$twk5
-	vxor		$tweak,$tweak,$tmp
+	xxlor		32+$in0, 0, 0
+	vpermxor	$tweak, $tweak, $tmp, $in0
 
 	vxor		v31,v31,$rndkey0
 	mtctr		$rounds
@@ -3277,6 +3314,8 @@  Loop_xts_dec6x:
 	lvx		v25,$x10,$key_		# round[4]
 	bdnz		Loop_xts_dec6x
 
+	xxlor		32+$eighty7, 1, 1	# 0x010101..87
+
 	subic		$len,$len,96		# $len-=96
 	 vxor		$in0,$twk0,v31		# xor with last round key
 	vncipher	$out0,$out0,v24
@@ -3286,7 +3325,6 @@  Loop_xts_dec6x:
 	 vaddubm	$tweak,$tweak,$tweak
 	vncipher	$out2,$out2,v24
 	vncipher	$out3,$out3,v24
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vncipher	$out4,$out4,v24
 	vncipher	$out5,$out5,v24
 
@@ -3294,7 +3332,8 @@  Loop_xts_dec6x:
 	 vand		$tmp,$tmp,$eighty7
 	vncipher	$out0,$out0,v25
 	vncipher	$out1,$out1,v25
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in1, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in1
 	vncipher	$out2,$out2,v25
 	vncipher	$out3,$out3,v25
 	 vxor		$in1,$twk1,v31
@@ -3305,13 +3344,13 @@  Loop_xts_dec6x:
 
 	and		r0,r0,$len
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vncipher	$out0,$out0,v26
 	vncipher	$out1,$out1,v26
 	 vand		$tmp,$tmp,$eighty7
 	vncipher	$out2,$out2,v26
 	vncipher	$out3,$out3,v26
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in2, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in2
 	vncipher	$out4,$out4,v26
 	vncipher	$out5,$out5,v26
 
@@ -3325,7 +3364,6 @@  Loop_xts_dec6x:
 	 vaddubm	$tweak,$tweak,$tweak
 	vncipher	$out0,$out0,v27
 	vncipher	$out1,$out1,v27
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vncipher	$out2,$out2,v27
 	vncipher	$out3,$out3,v27
 	 vand		$tmp,$tmp,$eighty7
@@ -3333,7 +3371,8 @@  Loop_xts_dec6x:
 	vncipher	$out5,$out5,v27
 
 	addi		$key_,$sp,$FRAME+15	# rewind $key_
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in3, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in3
 	vncipher	$out0,$out0,v28
 	vncipher	$out1,$out1,v28
 	 vxor		$in3,$twk3,v31
@@ -3342,7 +3381,6 @@  Loop_xts_dec6x:
 	vncipher	$out2,$out2,v28
 	vncipher	$out3,$out3,v28
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vncipher	$out4,$out4,v28
 	vncipher	$out5,$out5,v28
 	lvx		v24,$x00,$key_		# re-pre-load round[1]
@@ -3350,7 +3388,8 @@  Loop_xts_dec6x:
 
 	vncipher	$out0,$out0,v29
 	vncipher	$out1,$out1,v29
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in4, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in4
 	vncipher	$out2,$out2,v29
 	vncipher	$out3,$out3,v29
 	 vxor		$in4,$twk4,v31
@@ -3360,14 +3399,14 @@  Loop_xts_dec6x:
 	vncipher	$out5,$out5,v29
 	lvx		v25,$x10,$key_		# re-pre-load round[2]
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 
 	vncipher	$out0,$out0,v30
 	vncipher	$out1,$out1,v30
 	 vand		$tmp,$tmp,$eighty7
 	vncipher	$out2,$out2,v30
 	vncipher	$out3,$out3,v30
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		32+$in5, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in5
 	vncipher	$out4,$out4,v30
 	vncipher	$out5,$out5,v30
 	 vxor		$in5,$twk5,v31
@@ -3377,7 +3416,6 @@  Loop_xts_dec6x:
 	vncipherlast	$out0,$out0,$in0
 	 lvx_u		$in0,$x00,$inp		# load next input block
 	 vaddubm	$tweak,$tweak,$tweak
-	 vsldoi		$tmp,$tmp,$tmp,15
 	vncipherlast	$out1,$out1,$in1
 	 lvx_u		$in1,$x10,$inp
 	vncipherlast	$out2,$out2,$in2
@@ -3390,7 +3428,10 @@  Loop_xts_dec6x:
 	vncipherlast	$out4,$out4,$in4
 	 le?vperm	$in2,$in2,$in2,$leperm
 	 lvx_u		$in4,$x40,$inp
-	 vxor		$tweak,$tweak,$tmp
+	 xxlor		10, 32+$in0, 32+$in0
+	 xxlor		32+$in0, 0, 0
+	 vpermxor	$tweak, $tweak, $tmp, $in0
+	 xxlor		32+$in0, 10, 10
 	vncipherlast	$out5,$out5,$in5
 	 le?vperm	$in3,$in3,$in3,$leperm
 	 lvx_u		$in5,$x50,$inp
@@ -3421,6 +3462,8 @@  Loop_xts_dec6x:
 	mtctr		$rounds
 	beq		Loop_xts_dec6x		# did $len-=96 borrow?
 
+	xxlor		32+$eighty7, 2, 2	# 0x010101..87
+
 	addic.		$len,$len,0x60
 	beq		Lxts_dec6x_zero
 	cmpwi		$len,0x20