linux-kernel - [PATCH v5 26/33] arm64: crypto: Remove unnecessary stackframe

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Message-ID: <20220622154920.95075-27-chenzhongjin@huawei.com>
Date:   Wed, 22 Jun 2022 23:49:13 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
        <linuxppc-dev@...ts.ozlabs.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kbuild@...r.kernel.org>, <live-patching@...r.kernel.org>
CC:     <jpoimboe@...nel.org>, <peterz@...radead.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <masahiroy@...nel.org>, <michal.lkml@...kovi.net>,
        <ndesaulniers@...gle.com>, <mark.rutland@....com>,
        <pasha.tatashin@...een.com>, <broonie@...nel.org>,
        <chenzhongjin@...wei.com>, <rmk+kernel@...linux.org.uk>,
        <madvenka@...ux.microsoft.com>, <christophe.leroy@...roup.eu>
Subject: [PATCH v5 26/33] arm64: crypto: Remove unnecessary stackframe

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 1882c4110026..6e2a96e05c5a 100644
--- a/arch/arm64/crypto/sha512-armv8.pl
+++ b/arch/arm64/crypto/sha512-armv8.pl
@@ -648,8 +648,6 @@ $code.=<<___;
 .align	4
 sha256_block_neon:
 .Lneon_entry:
-	stp	x29, x30, [sp, #-16]!
-	mov	x29, sp
 	sub	sp,sp,#16*4
 
 	adr	$Ktbl,K256
@@ -736,8 +734,7 @@ $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