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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@gmail.com>
AuthorDate: Thu, 29 Oct 2020 17:02:58 +01:00
Committer: Borislav Petkov <bp@suse.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@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.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
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