linux-kernel - [tip:x86/asm] x86/cpu: Do the feature test first in enable_sep

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Date:	Tue, 29 Mar 2016 05:28:04 -0700
From:	tip-bot for Borislav Petkov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	bp@...e.de, mingo@...nel.org, luto@...capital.net, hpa@...or.com,
	luto@...nel.org, torvalds@...ux-foundation.org, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, peterz@...radead.org
Subject: [tip:x86/asm] x86/cpu: Do the feature test first in
 enable_sep_cpu()

Commit-ID:  b3edfda4382ffaef5e5c1cffb25a33b3b9ef4546
Gitweb:     http://git.kernel.org/tip/b3edfda4382ffaef5e5c1cffb25a33b3b9ef4546
Author:     Borislav Petkov <bp@...e.de>
AuthorDate: Wed, 16 Mar 2016 13:19:29 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 29 Mar 2016 12:57:12 +0200

x86/cpu: Do the feature test first in enable_sep_cpu()

... before assigning local vars. Kill out label too and simplify.

No functionality change.

Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Andy Lutomirski <luto@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1458130769-24963-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/common.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 8394b3d..7fea407 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1076,12 +1076,12 @@ void enable_sep_cpu(void)
 	struct tss_struct *tss;
 	int cpu;
 
+	if (!boot_cpu_has(X86_FEATURE_SEP))
+		return;
+
 	cpu = get_cpu();
 	tss = &per_cpu(cpu_tss, cpu);
 
-	if (!boot_cpu_has(X86_FEATURE_SEP))
-		goto out;
-
 	/*
 	 * We cache MSR_IA32_SYSENTER_CS's value in the TSS's ss1 field --
 	 * see the big comment in struct x86_hw_tss's definition.
@@ -1096,7 +1096,6 @@ void enable_sep_cpu(void)
 
 	wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0);
 
-out:
 	put_cpu();
 }
 #endif