From: Eric Biggers <ebiggers@kernel.org>
To: linux-crypto@vger.kernel.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Martin Willi <martin@strongswan.org>,
Antonio Quartulli <antonio@mandelbit.com>,
Eric Biggers <ebiggers@kernel.org>
Subject: [PATCH] lib/crypto: x86/chacha: Remove vzeroupper at beginning of functions
Date: Tue, 3 Nov 2026 21:38:30 -0800 [thread overview]
Message-ID: <20261104053830.82604-1-ebiggers@kernel.org> (raw)
There's no point in executing vzeroupper at the beginning of the AVX2
and AVX-512 optimized functions. Remove it, leaving the vzeroupper at
the end (where it is needed) only.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
lib/crypto/x86/chacha-avx2-x86_64.S | 5 -----
lib/crypto/x86/chacha-avx512-x86_64.S | 6 ------
2 files changed, 11 deletions(-)
diff --git a/lib/crypto/x86/chacha-avx2-x86_64.S b/lib/crypto/x86/chacha-avx2-x86_64.S
index f3d8fc018249..0b0cf92a022c 100644
--- a/lib/crypto/x86/chacha-avx2-x86_64.S
+++ b/lib/crypto/x86/chacha-avx2-x86_64.S
@@ -46,8 +46,6 @@ SYM_FUNC_START(chacha_2block_xor_avx2)
# on four words in each matrix in parallel, but requires shuffling to
# rearrange the words after each round.
- vzeroupper
-
# x0..3[0-2] = s0..3
vbroadcasti128 0x00(%rdi),%ymm0
vbroadcasti128 0x10(%rdi),%ymm1
@@ -240,8 +238,6 @@ SYM_FUNC_START(chacha_4block_xor_avx2)
# required word shuffling has a rather high latency, we can do the
# arithmetic on two matrix-pairs without much slowdown.
- vzeroupper
-
# x0..3[0-4] = s0..3
vbroadcasti128 0x00(%rdi),%ymm0
vbroadcasti128 0x10(%rdi),%ymm1
@@ -548,7 +544,6 @@ SYM_FUNC_START(chacha_8block_xor_avx2)
# rotation is done with the slightly better performing byte shuffling,
# 7/12-bit word rotation uses traditional shift+OR.
- vzeroupper
# 4 * 32 byte stack, 32-byte aligned
lea 8(%rsp),%r10
and $~31, %rsp
diff --git a/lib/crypto/x86/chacha-avx512-x86_64.S b/lib/crypto/x86/chacha-avx512-x86_64.S
index 422479631d5b..ffdfe005cba6 100644
--- a/lib/crypto/x86/chacha-avx512-x86_64.S
+++ b/lib/crypto/x86/chacha-avx512-x86_64.S
@@ -55,8 +55,6 @@ SYM_FUNC_START(chacha_2block_xor_avx512vl)
# on four words in each matrix in parallel, but requires shuffling to
# rearrange the words after each round.
- vzeroupper
-
# x0..3[0-2] = s0..3
vbroadcasti128 0x00(%rdi),%ymm0
vbroadcasti128 0x10(%rdi),%ymm1
@@ -220,8 +218,6 @@ SYM_FUNC_START(chacha_4block_xor_avx512vl)
# required word shuffling has a rather high latency, we can do the
# arithmetic on two matrix-pairs without much slowdown.
- vzeroupper
-
# x0..3[0-4] = s0..3
vbroadcasti128 0x00(%rdi),%ymm0
vbroadcasti128 0x10(%rdi),%ymm1
@@ -489,8 +485,6 @@ SYM_FUNC_END(chacha_4block_xor_avx512vl)
# VL=32 encrypts eight blocks in 256-bit ymm registers.
# VL=64 encrypts sixteen blocks in 512-bit zmm registers.
- vzeroupper
-
# x0..15[0-VL/4] = s[0..15]
vpbroadcastd 0x00(%rdi),V0
vpbroadcastd 0x04(%rdi),V1
base-commit: 9fbbbaefd5f95551da18426c200cf41e1b4255a1
prerequisite-patch-id: 890b33260038bff2e3adfe7867af5919666677fc
--
2.56.0
reply other threads:[~2026-11-04 5:38 UTC|newest]
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