From: Uros Bizjak Date: Thu, 9 Nov 2023 20:09:56 +0000 (+0100) Subject: x86/head_64: Use TESTB instead of TESTL in secondary_startup_64_no_verify() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7d28365a06af74cee015a448d32ab6e98cd05cfb;p=linux.git x86/head_64: Use TESTB instead of TESTL in secondary_startup_64_no_verify() 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 Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20231109201032.4439-1-ubizjak@gmail.com --- diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 086a2c3aaaa04..1f79d809305d0 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -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: