s390/vdso: Get rid of permutation constants

The three byte masks for VECTOR PERMUTE are not needed, since the
instruction VECTOR SHIFT LEFT DOUBLE BY BYTE can be used to implement
the required "rotate left" easily.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/vdso64/vgetrandom-chacha.S

 /* SPDX-License-Identifier: GPL-2.0 */
 
+#include <linux/stringify.h>
 #include <linux/linkage.h>
 #include <asm/alternative.h>
 #include <asm/fpu-insn.h>
@@ -12,9 +13,6 @@
 #define COPY1	%v5
 #define COPY2	%v6
 #define COPY3	%v7
-#define PERM4	%v16
-#define PERM8	%v17
-#define PERM12	%v18
 #define BEPERM	%v19
 #define TMP0	%v20
 #define TMP1	%v21
@@ -23,12 +21,9 @@
 
 	.section .rodata
 
-	.balign 128
+	.balign 32
 .Lconstants:
 	.long	0x61707865,0x3320646e,0x79622d32,0x6b206574 # endian-neutral
-	.long	0x04050607,0x08090a0b,0x0c0d0e0f,0x00010203 # rotl  4 bytes
-	.long	0x08090a0b,0x0c0d0e0f,0x00010203,0x04050607 # rotl  8 bytes
-	.long	0x0c0d0e0f,0x00010203,0x04050607,0x08090a0b # rotl 12 bytes
 	.long	0x03020100,0x07060504,0x0b0a0908,0x0f0e0d0c # byte swap
 
 	.text
@@ -48,8 +43,8 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	/* COPY0 = "expand 32-byte k" */
 	VL	COPY0,0,,%r1
 
-	/* PERM4-PERM12,BEPERM = byte selectors for VPERM */
-	VLM	PERM4,BEPERM,16,%r1
+	/* BEPERM = byte selectors for VPERM */
+	ALTERNATIVE __stringify(VL BEPERM,16,,%r1), "brcl 0,0", ALT_FACILITY(148)
 
 	/* COPY1,COPY2 = key */
 	VLM	COPY1,COPY2,0,%r3
@@ -89,11 +84,11 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	VERLLF	STATE1,STATE1,7
 
 	/* STATE1[0,1,2,3] = STATE1[1,2,3,0] */
-	VPERM	STATE1,STATE1,STATE1,PERM4
+	VSLDB	STATE1,STATE1,STATE1,4
 	/* STATE2[0,1,2,3] = STATE2[2,3,0,1] */
-	VPERM	STATE2,STATE2,STATE2,PERM8
+	VSLDB	STATE2,STATE2,STATE2,8
 	/* STATE3[0,1,2,3] = STATE3[3,0,1,2] */
-	VPERM	STATE3,STATE3,STATE3,PERM12
+	VSLDB	STATE3,STATE3,STATE3,12
 
 	/* STATE0 += STATE1, STATE3 = rotl32(STATE3 ^ STATE0, 16) */
 	VAF	STATE0,STATE0,STATE1
@@ -116,11 +111,11 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	VERLLF	STATE1,STATE1,7
 
 	/* STATE1[0,1,2,3] = STATE1[3,0,1,2] */
-	VPERM	STATE1,STATE1,STATE1,PERM12
+	VSLDB	STATE1,STATE1,STATE1,12
 	/* STATE2[0,1,2,3] = STATE2[2,3,0,1] */
-	VPERM	STATE2,STATE2,STATE2,PERM8
+	VSLDB	STATE2,STATE2,STATE2,8
 	/* STATE3[0,1,2,3] = STATE3[1,2,3,0] */
-	VPERM	STATE3,STATE3,STATE3,PERM4
+	VSLDB	STATE3,STATE3,STATE3,4
 	brctg	%r0,.Ldoubleround
 
 	/* OUTPUT0 = STATE0 + STATE0 */