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x86/head_64: Use TESTB instead of TESTL in secondary_startup_64_no_verify()

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There is no need to use TESTL when checking the least-significant bit
with a TEST instruction. Use TESTB, which is three bytes shorter:

   f6 05 00 00 00 00 01    testb  $0x1,0x0(%rip)

vs:

   f7 05 00 00 00 00 01    testl  $0x1,0x0(%rip)
   00 00 00

for the same effect.

No functional changes intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231109201032.4439-1-ubizjak@gmail.com
This commit is contained in:
Uros Bizjak 2023-11-09 21:09:56 +01:00 committed by Borislav Petkov (AMD)
parent 7a0a6d55ed
commit 7d28365a06
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/head_64.S
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@ -182,7 +182,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
/* Enable PAE mode, PSE, PGE and LA57 */
orl $(X86_CR4_PAE | X86_CR4_PSE | X86_CR4_PGE), %ecx
#ifdef CONFIG_X86_5LEVEL
testl $1, __pgtable_l5_enabled(%rip)
testb $1, __pgtable_l5_enabled(%rip)
jz 1f
orl $X86_CR4_LA57, %ecx
1: