linux-kernel - [PATCH 2/6] x86/cpu: Remove "nosep"

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Date:   Fri, 12 Nov 2021 11:32:42 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/6] x86/cpu: Remove "nosep"

From: Borislav Petkov <bp@...e.de>

That chicken bit was added by

  4f88651125e2 ("[PATCH] i386: allow disabling X86_FEATURE_SEP at boot")

but measuring int80 vsyscall performance on 32-bit doesn't matter
anymore.

If still needed, one can boot with

  clearcpuid=sep

to disable that feature for testing.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 Documentation/admin-guide/kernel-parameters.txt | 2 --
 arch/x86/kernel/cpu/common.c                    | 7 -------
 2 files changed, 9 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index dadb09d30212..13e6f0100970 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3563,8 +3563,6 @@
 
 	nosbagart	[IA-64]
 
-	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
-
 	nosgx		[X86-64,SGX] Disables Intel SGX kernel support.
 
 	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 0d1cf5c65b0c..b4598659d4a8 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -220,13 +220,6 @@ static int __init cachesize_setup(char *str)
 }
 __setup("cachesize=", cachesize_setup);
 
-static int __init x86_sep_setup(char *s)
-{
-	setup_clear_cpu_cap(X86_FEATURE_SEP);
-	return 1;
-}
-__setup("nosep", x86_sep_setup);
-
 /* Standard macro to see if a specific flag is changeable */
 static inline int flag_is_changeable_p(u32 flag)
 {
-- 
2.29.2