linux-kernel - [RFC PATCH v4 26/37] arm64: crypto: Remove unnecessary stackframe

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Message-ID: <20220429094355.122389-27-chenzhongjin@huawei.com>
Date:   Fri, 29 Apr 2022 17:43:44 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-arch@...r.kernel.org>
CC:     <jthierry@...hat.com>, <catalin.marinas@....com>,
        <will@...nel.org>, <masahiroy@...nel.org>, <jpoimboe@...hat.com>,
        <peterz@...radead.org>, <ycote@...hat.com>,
        <herbert@...dor.apana.org.au>, <mark.rutland@....com>,
        <davem@...emloft.net>, <ardb@...nel.org>, <maz@...nel.org>,
        <tglx@...utronix.de>, <luc.vanoostenryck@...il.com>,
        <chenzhongjin@...wei.com>
Subject: [RFC PATCH v4 26/37] arm64: crypto: Remove unnecessary stackframe

From: Julien Thierry <jthierry@...hat.com>

The way sha256_block_neon restore the stackframe confuses objtool.
But it turns out this function is a leaf function and does not use
FP nor LR as scratch register.

Do not create a stackframe in this function as it is not necessary.

Signed-off-by: Julien Thierry <jthierry@...hat.com>
Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
---
 arch/arm64/crypto/sha512-armv8.pl | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arm64/crypto/sha512-armv8.pl b/arch/arm64/crypto/sha512-armv8.pl
index 35ec9ae99fe1..dca0f22df07f 100644
--- a/arch/arm64/crypto/sha512-armv8.pl
+++ b/arch/arm64/crypto/sha512-armv8.pl
@@ -644,8 +644,6 @@ $code.=<<___;
 .align	4
 sha256_block_neon:
 .Lneon_entry:
-	stp	x29, x30, [sp, #-16]!
-	mov	x29, sp
 	sub	sp,sp,#16*4
 
 	adr	$Ktbl,.LK256
@@ -732,8 +730,7 @@ $code.=<<___;
 	 mov	$Xfer,sp
 	b.ne	.L_00_48
 
-	ldr	x29,[x29]
-	add	sp,sp,#16*4+16
+	add	sp,sp,#16*4
 	ret
 .size	sha256_block_neon,.-sha256_block_neon
 ___
-- 
2.17.1