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Message-ID: <20240828170350.3422587-1-Jason@zx2c4.com>
Date: Wed, 28 Aug 2024 19:03:50 +0200
From: "Jason A. Donenfeld" <Jason@...c4.com>
To: linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org,
christophe.leroy@...roup.eu
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH] random: vDSO: assume key is 32-bit aligned on x86_64
The prototype of this function ensures a u32* type for the key, and all
uses of it are using state->key, which is a u32 array. When userspace
slices up a memory region into an array of states, it does so using a
state size that also ensures the alignment. So it's safe to assume that
the key is always 32-bit aligned. That in turn means it's possible to
use movaps instead of movups for loading the key.
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
arch/x86/entry/vdso/vgetrandom-chacha.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/vdso/vgetrandom-chacha.S b/arch/x86/entry/vdso/vgetrandom-chacha.S
index bcba5639b8ee..07ae91dcdbda 100644
--- a/arch/x86/entry/vdso/vgetrandom-chacha.S
+++ b/arch/x86/entry/vdso/vgetrandom-chacha.S
@@ -43,8 +43,8 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
/* copy0 = "expand 32-byte k" */
movaps CONSTANTS(%rip),copy0
/* copy1,copy2 = key */
- movups 0x00(key),copy1
- movups 0x10(key),copy2
+ movaps 0x00(key),copy1
+ movaps 0x10(key),copy2
/* copy3 = counter || zero nonce */
movq 0x00(counter),copy3
/* one = 1 || 0 */
--
2.46.0
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