lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 4 Mar 2019 11:15:12 -0800
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        x86 <x86@...nel.org>, kvm@...r.kernel.org
Subject: Re: [PATCH v4 04/17] x86/split_lock: Align x86_capability to
 unsigned long to avoid split locked access

On Mon, Mar 04, 2019 at 10:52:19AM -0800, Dave Hansen wrote:
> On 3/1/19 6:44 PM, Fenghua Yu wrote:
> > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> > index 33051436c864..eb8ae701ef65 100644
> > --- a/arch/x86/include/asm/processor.h
> > +++ b/arch/x86/include/asm/processor.h
> > @@ -93,7 +93,9 @@ struct cpuinfo_x86 {
> >  	__u32			extended_cpuid_level;
> >  	/* Maximum supported CPUID level, -1=no CPUID: */
> >  	int			cpuid_level;
> > -	__u32			x86_capability[NCAPINTS + NBUGINTS];
> > +	/* Unsigned long alignment to avoid split lock in atomic bitmap ops */
> > +	__u32			x86_capability[NCAPINTS + NBUGINTS]
> > +				__aligned(sizeof(unsigned long));
> 
> I think this also warrants a comment in the changelog about the
> alignment of 'struct cpuinfo_x86'.

How about add "Depending on the starting address where GCC generates
for data of struct cpuinfo_x86, x86_capability[] may or may not align to
unsigned long...."?

Thanks.

-Fenghua

Powered by blists - more mailing lists