linux-kernel - [PATCH] LoongArch: vDSO: vgetrandom-chacha: Make use of the t8 register

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20250221113341.108063-1-xry111@xry111.site>
Date: Fri, 21 Feb 2025 19:32:43 +0800
From: Xi Ruoyao <xry111@...111.site>
To: Huacai Chen <chenhuacai@...nel.org>,
	WANG Xuerui <kernel@...0n.name>,
	"Jason A. Donenfeld" <Jason@...c4.com>
Cc: linux-crypto@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Xi Ruoyao <xry111@...111.site>
Subject: [PATCH] LoongArch: vDSO: vgetrandom-chacha: Make use of the t8 register

So we don't need to reuse a register and rematerialize a constant.  I
couldn't count :(.

Signed-off-by: Xi Ruoyao <xry111@...111.site>
---

Tested with vdso_test_getrandom and vdso_test_chacha.

 arch/loongarch/vdso/vgetrandom-chacha.S | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/arch/loongarch/vdso/vgetrandom-chacha.S b/arch/loongarch/vdso/vgetrandom-chacha.S
index c2733e6c3a8d..c4dd2bab8825 100644
--- a/arch/loongarch/vdso/vgetrandom-chacha.S
+++ b/arch/loongarch/vdso/vgetrandom-chacha.S
@@ -58,9 +58,7 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 #define copy0		t5
 #define copy1		t6
 #define copy2		t7
-
-/* Reuse i as copy3 */
-#define copy3		i
+#define copy3		t8
 
 /* Packs to be used with OP_4REG */
 #define line0		state0, state1, state2, state3
@@ -99,6 +97,7 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	li.w		copy0, 0x61707865
 	li.w		copy1, 0x3320646e
 	li.w		copy2, 0x79622d32
+	li.w		copy3, 0x6b206574
 
 	ld.w		cnt_lo, counter, 0
 	ld.w		cnt_hi, counter, 4
@@ -108,7 +107,7 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	move		state0, copy0
 	move		state1, copy1
 	move		state2, copy2
-	li.w		state3, 0x6b206574
+	move		state3, copy3
 
 	/* state[4,5,..,11] = key */
 	ld.w		state4, key, 0
@@ -167,12 +166,6 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack)
 	addi.w		i, i, -1
 	bnez		i, .Lpermute
 
-	/*
-	 * copy[3] = "expa", materialize it here because copy[3] shares the
-	 * same register with i which just became dead.
-	 */
-	li.w		copy3, 0x6b206574
-
 	/* output[0,1,2,3] = copy[0,1,2,3] + state[0,1,2,3] */
 	OP_4REG	add.w	line0, copy
 	st.w		state0, output, 0
-- 
2.48.1