The register %rdx is written, but never read till the end of the encryption
routine. Therefore let's delete the useless instruction.
Signed-off-by: Johannes Goetzfried <[email protected]>
---
arch/x86/crypto/twofish-avx-x86_64-asm_64.S | 1 -
1 files changed, 0 insertions(+), 1 deletions(-)
diff --git a/arch/x86/crypto/twofish-avx-x86_64-asm_64.S b/arch/x86/crypto/twofish-avx-x86_64-asm_64.S
index fc31b89..35f4557 100644
--- a/arch/x86/crypto/twofish-avx-x86_64-asm_64.S
+++ b/arch/x86/crypto/twofish-avx-x86_64-asm_64.S
@@ -243,7 +243,6 @@ __twofish_enc_blk_8way:
popq %rbx;
leaq (4*4*4)(%rsi), %rax;
- leaq (4*4*4)(%rax), %rdx;
testb %cl, %cl;
jnz __enc_xor8;
--
1.7.2.5
On Thu, 05 Jul 2012, Johannes Goetzfried wrote:
> The register %rdx is written, but never read till the end of the encryption
> routine. Therefore let's delete the useless instruction.
Is it useless, or is it there to harden against some side-channel
attack?
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
On Thu, Jul 05, 2012 at 08:46:12PM -0300, Henrique de Moraes Holschuh wrote:
> Is it useless, or is it there to harden against some side-channel
> attack?
When writing this implementation, I first had a different approach with more
data getting read in and I just forgot to delete this instruction in the end.
The instruction didn't have any purpose regarding side-channel attacks. In the
decryption routine the instruction has been correctly deleted in the same
place.
On Thu, Jul 05, 2012 at 08:43:58PM +0200, Johannes Goetzfried wrote:
> The register %rdx is written, but never read till the end of the encryption
> routine. Therefore let's delete the useless instruction.
>
> Signed-off-by: Johannes Goetzfried <[email protected]>
Patch applied. Thanks!
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt