linux-kernel - Re: [PATCH 1/2] x86/mce: Only restart instruction after machine check recovery if it is safe

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 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 14 May 2012 19:17:02 +0200
From:	Borislav Petkov <bp@...64.org>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	Borislav Petkov <bp@...64.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Chen Gong <gong.chen@...ux.intel.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Subject: Re: [PATCH 1/2] x86/mce: Only restart instruction after machine
 check recovery if it is safe

On Mon, May 14, 2012 at 04:16:05PM +0000, Luck, Tony wrote:
> >> +	int			restartable;
> >
> > Is it me or does this look like a flag, or a bitfield? Instead of
> > wasting a whole integer for a single bit of information.
> 
> I could make it "int flags;" and "#define MCE_INFO_RESTARTABLE 1"
> to make it clear that we have lots more bits available for special
> cases?

I was wondering about that but don't have any other flags/use cases.
Well, we can always change it later if needed.

> > It will probably end up the same size though due to compiler padding
> > since this struct is currently 4 + 2*8 byte without the ->restartable
> > thing.
> 
> Yup - we can't save any memory (unless we introduce more complexity to
> the code ... low PAGE_SHIFT bits of the "paddr" field are simply thrown
> away ... so we could allocate a bit there ... but I don't think that
> the resulting ugliness is worth the memory savings).

Agreed, that would be too ugly for no reason :-)

-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/