[PATCH 4.19 029/101] crypto: arm64/aes-modes - get rid of literal load of addend vector

From: Greg Kroah-Hartman
Date: Tue Nov 17 2020 - 08:59:35 EST


From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

commit ed6ed11830a9ded520db31a6e2b69b6b0a1eb0e2 upstream.

Replace the literal load of the addend vector with a sequence that
performs each add individually. This sequence is only 2 instructions
longer than the original, and 2% faster on Cortex-A53.

This is an improvement by itself, but also works around a Clang issue,
whose integrated assembler does not implement the GNU ARM asm syntax
completely, and does not support the =literal notation for FP registers
(more info at https://bugs.llvm.org/show_bug.cgi?id=38642)

Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/arm64/crypto/aes-modes.S | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

--- a/arch/arm64/crypto/aes-modes.S
+++ b/arch/arm64/crypto/aes-modes.S
@@ -232,17 +232,19 @@ AES_ENTRY(aes_ctr_encrypt)
bmi .Lctr1x
cmn w6, #4 /* 32 bit overflow? */
bcs .Lctr1x
- ldr q8, =0x30000000200000001 /* addends 1,2,3[,0] */
- dup v7.4s, w6
+ add w7, w6, #1
mov v0.16b, v4.16b
- add v7.4s, v7.4s, v8.4s
+ add w8, w6, #2
mov v1.16b, v4.16b
- rev32 v8.16b, v7.16b
+ add w9, w6, #3
mov v2.16b, v4.16b
+ rev w7, w7
mov v3.16b, v4.16b
- mov v1.s[3], v8.s[0]
- mov v2.s[3], v8.s[1]
- mov v3.s[3], v8.s[2]
+ rev w8, w8
+ mov v1.s[3], w7
+ rev w9, w9
+ mov v2.s[3], w8
+ mov v3.s[3], w9
ld1 {v5.16b-v7.16b}, [x20], #48 /* get 3 input blocks */
bl aes_encrypt_block4x
eor v0.16b, v5.16b, v0.16b