Re: [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly

From	Borislav Petkov <bp@alien8.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly
Date	2016-01-23 11:20 +0100
Message-ID	<qU3su-1c2-7@gated-at.bofh.it> (permalink)
References	<qTUIx-3qs-3@gated-at.bofh.it> <qTUIy-3qs-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Jan 22, 2016 at 04:56:05PM -0800, Andy Lutomirski wrote:
> If we have an FPU, there's no need to check CR0 for FPU emulation.
> 
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
>  arch/x86/kernel/traps.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 87f80febf477..183b300f6a8b 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -752,7 +752,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
>  	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
>  
>  #ifdef CONFIG_MATH_EMULATION
> -	if (read_cr0() & X86_CR0_EM) {
> +	if (!cpu_has_fpu && (read_cr0() & X86_CR0_EM)) {

Please use

	boot_cpu_has(X86_FEATURE_FPU)

We want to kill those cpu_has_xxx things.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

Thread

[PATCH 0/5] x86/fpu: eagerfpu fixes, speedups, and default enablement Andy Lutomirski <luto@kernel.org> - 2016-01-23 02:00 +0100
  [PATCH 2/5] x86/fpu: Fix FNSAVE usage in eagerfpu mode Andy Lutomirski <luto@kernel.org> - 2016-01-23 02:00 +0100
  [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly Andy Lutomirski <luto@kernel.org> - 2016-01-23 02:00 +0100
    Re: [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly Borislav Petkov <bp@alien8.de> - 2016-01-23 11:20 +0100
      Re: [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly Andy Lutomirski <luto@amacapital.net> - 2016-01-23 23:20 +0100
        Re: [PATCH 4/5] x86/fpu: Speed up lazy FPU restores slightly Borislav Petkov <bp@alien8.de> - 2016-01-24 00:40 +0100
  [PATCH 5/5] x86/fpu: Default eagerfpu=on on all CPUs Andy Lutomirski <luto@kernel.org> - 2016-01-23 02:00 +0100
    Re: [PATCH 5/5] x86/fpu: Default eagerfpu=on on all CPUs Borislav Petkov <bp@alien8.de> - 2016-01-23 11:30 +0100
  [PATCH 1/5] x86/fpu: Fix math emulation in eager fpu mode Andy Lutomirski <luto@kernel.org> - 2016-01-23 02:00 +0100
    Re: [PATCH 1/5] x86/fpu: Fix math emulation in eager fpu mode Borislav Petkov <bp@alien8.de> - 2016-01-23 11:10 +0100
      Re: [PATCH 1/5] x86/fpu: Fix math emulation in eager fpu mode Andy Lutomirski <luto@amacapital.net> - 2016-01-23 18:50 +0100
        Re: [PATCH 1/5] x86/fpu: Fix math emulation in eager fpu mode Borislav Petkov <bp@alien8.de> - 2016-01-23 19:00 +0100

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