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

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

[Borislav Petkov]

From: Borislav Petkov <bp@suse.de>

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

No functionality change.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
 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 249461f95851..63658d23d3dd 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1030,12 +1030,12 @@ 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.
@@ -1050,7 +1050,6 @@ void enable_sep_cpu(void)
 
 	wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0);
 
-out:
 	put_cpu();
 }
 #endif
-- 
2.7.3

Re: [PATCH] x86/cpu: Do the feature test first in enable_sep_cpu()

[Andy Lutomirski]

On Wed, Mar 16, 2016 at 5:19 AM, Borislav Petkov <bp@alien8.de> wrote:
> From: Borislav Petkov <bp@suse.de>
>
> ... before assigning local vars. Kill out label too and simplify.
>
> No functionality change.

Acked-by: Andy Lutomirski <luto@kernel.org>

>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
>  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 249461f95851..63658d23d3dd 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -1030,12 +1030,12 @@ 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.
> @@ -1050,7 +1050,6 @@ void enable_sep_cpu(void)
>
>         wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0);
>
> -out:
>         put_cpu();
>  }
>  #endif
> --
> 2.7.3
>



-- 
Andy Lutomirski
AMA Capital Management, LLC

[tip:x86/asm] x86/cpu: Do the feature test first in enable_sep_cpu()

[tip-bot for Borislav Petkov]

Commit-ID:  b3edfda4382ffaef5e5c1cffb25a33b3b9ef4546
Gitweb:     http://git.kernel.org/tip/b3edfda4382ffaef5e5c1cffb25a33b3b9ef4546
Author:     Borislav Petkov <bp@suse.de>
AuthorDate: Wed, 16 Mar 2016 13:19:29 +0100
Committer:  Ingo Molnar <mingo@kernel.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@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1458130769-24963-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.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