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

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 017de6cc87dc6e5125f2d1ce236572ac56df1159..e94874f4bbc1d2e563ba76fd74145a8e137b2fc7 100644 (file)
--- 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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