linux-kernel - Re: [PATCH v2] x86/entry/32: Remove duplicate initialization of tss.ss1

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Message-ID: <20150823112652.GA3655@gmail.com>
Date:	Sun, 23 Aug 2015 13:26:52 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	X86 ML <x86@...nel.org>, linux-kernel@...r.kernel.org,
	Brian Gerst <brgerst@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>, Willy Tarreau <w@....eu>,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2] x86/entry/32: Remove duplicate initialization of
 tss.ss1


* Andy Lutomirski <luto@...nel.org> wrote:

> It's statically initialized, so we don't need to dynamically
> initialize it too.
> 
> Reported-by: Brian Gerst <brgerst@...il.com>
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
> 
> Changes since v1: Delete the code :)
> 
> arch/x86/kernel/cpu/common.c | 8 --------
>  1 file changed, 8 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index e2ed2513a51e..e08eee98a5f8 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -1005,14 +1005,6 @@ void enable_sep_cpu(void)
>  	if (IS_ENABLED(CONFIG_X86_32) && !boot_cpu_has(X86_FEATURE_SEP))
>  		goto out;
>  
> -#ifdef CONFIG_X86_32
> -	/*
> -	 * 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.
> -	 */
> -	tss->x86_tss.ss1 = __KERNEL_CS;
> -#endif
> -
>  	wrmsrl_safe(MSR_IA32_SYSENTER_CS, __KERNEL_CS);
>  	wrmsrl_safe(MSR_IA32_SYSENTER_ESP,
>  		    (unsigned long)tss +

So this code changed substantially in tip:x86/asm - do we still need this patch?

Thanks,

	Ingo
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