linux-kernel - [tip: x86/cleanups] x86/boot/compressed/64: Use TEST %reg,%reg instead of CMP $0,%reg

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Date:   Sat, 21 Nov 2020 09:38:07 -0000
From:   "tip-bot2 for Uros Bizjak" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Uros Bizjak <ubizjak@...il.com>, Borislav Petkov <bp@...e.de>,
        Andy Lutomirski <luto@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/cleanups] x86/boot/compressed/64: Use TEST %reg,%reg
 instead of CMP $0,%reg

The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID:     ab09b58e4bdfdbcec425e54ebeaf6e209a96318f
Gitweb:        https://git.kernel.org/tip/ab09b58e4bdfdbcec425e54ebeaf6e209a96318f
Author:        Uros Bizjak <ubizjak@...il.com>
AuthorDate:    Thu, 29 Oct 2020 17:02:58 +01:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Sat, 21 Nov 2020 10:26:25 +01:00

x86/boot/compressed/64: Use TEST %reg,%reg instead of CMP $0,%reg

Use TEST %reg,%reg which sets the zero flag in the same way as CMP
$0,%reg, but the encoding uses one byte less.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Andy Lutomirski <luto@...nel.org>
Link: https://lkml.kernel.org/r/20201029160258.139216-1-ubizjak@gmail.com
---
 arch/x86/boot/compressed/head_64.S | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 017de6c..e94874f 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -241,12 +241,12 @@ SYM_FUNC_START(startup_32)
 	leal	rva(startup_64)(%ebp), %eax
 #ifdef CONFIG_EFI_MIXED
 	movl	rva(efi32_boot_args)(%ebp), %edi
-	cmp	$0, %edi
+	testl	%edi, %edi
 	jz	1f
 	leal	rva(efi64_stub_entry)(%ebp), %eax
 	movl	rva(efi32_boot_args+4)(%ebp), %esi
 	movl	rva(efi32_boot_args+8)(%ebp), %edx	// saved bootparams pointer
-	cmpl	$0, %edx
+	testl	%edx, %edx
 	jnz	1f
 	/*
 	 * efi_pe_entry uses MS calling convention, which requires 32 bytes of
@@ -592,7 +592,7 @@ SYM_CODE_START(trampoline_32bit_src)
 	movl	%eax, %cr0
 
 	/* Check what paging mode we want to be in after the trampoline */
-	cmpl	$0, %edx
+	testl	%edx, %edx
 	jz	1f
 
 	/* We want 5-level paging: don't touch CR3 if it already points to 5-level page tables */
@@ -622,7 +622,7 @@ SYM_CODE_START(trampoline_32bit_src)
 
 	/* Enable PAE and LA57 (if required) paging modes */
 	movl	$X86_CR4_PAE, %eax
-	cmpl	$0, %edx
+	testl	%edx, %edx
 	jz	1f
 	orl	$X86_CR4_LA57, %eax
 1: