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

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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
This commit is contained in:
Uros Bizjak
2020-10-29 17:02:58 +01:00
committed by Borislav Petkov
parent 61b39ad9a7
commit ab09b58e4b
1 changed files with 4 additions and 4 deletions
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8
arch/x86/boot/compressed/head_64.S
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@@ -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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