linux-kernel - Re: [tip:x86/smep] x86, cpu: Enable/disable Supervisor Mode Execution Protection

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Message-ID: <20110521104310.GC26447@elte.hu>
Date:	Sat, 21 May 2011 12:43:10 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	fenghua.yu@...el.com, tglx@...utronix.de, hpa@...ux.intel.com,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/smep] x86, cpu: Enable/disable Supervisor Mode
 Execution Protection


* Yinghai Lu <yinghai@...nel.org> wrote:

> > +static __init void setup_smep(struct cpuinfo_x86 *c)
> > +{
> > +	if (cpu_has(c, X86_FEATURE_SMEP)) {
> > +		if (unlikely(disable_smep)) {
> > +			setup_clear_cpu_cap(X86_FEATURE_SMEP);
> > +			clear_in_cr4(X86_CR4_SMEP);
> > +		} else
> > +			set_in_cr4(X86_CR4_SMEP);
> > +	}
> > +}
> 
> should be __cpuinit for this function.
> 
> otherwise got:
> 
> WARNING: arch/x86/built-in.o(.cpuinit.text+0x1b10): Section mismatch in reference from the function identify_cpu() to the function .init.text:setup_smep()
> The function __cpuinit identify_cpu() references
> a function __init setup_smep().
> If setup_smep is only used by identify_cpu then
> annotate setup_smep with a matching annotation.

Yeah, indeed, and it might in fact crash with certain .config's. Mind sending a 
tested patch?

Thanks,

	Ingo
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