linux-kernel - Re: [PATCH 2/3] x86/mce: Pack boolean MCE flags into a structure

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <5048473F.9070704@linux.vnet.ibm.com>
Date:	Thu, 06 Sep 2012 12:18:31 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	Tony Luck <tony.luck@...el.com>, bp@...64.org
CC:	andi@...stfloor.org, gong.chen@...ux.intel.com, ananth@...ibm.com,
	x86@...nel.org, linux-kernel@...r.kernel.org, mingo@...hat.com,
	hpa@...or.com, tglx@...utronix.de, gregkh@...e.de,
	linux-edac@...r.kernel.org
Subject: Re: [PATCH 2/3] x86/mce: Pack boolean MCE flags into a structure

On 09/06/2012 12:26 AM, Tony Luck wrote:
> On Wed, Sep 5, 2012 at 3:22 AM, Naveen N. Rao
> <naveen.n.rao@...ux.vnet.ibm.com> wrote:
>> Many MCE flags are boolean in nature, but are declared as integers
>> currently. We can pack these into a bitfield to save some space.
>
> Before this patch:
> size arch/x86/kernel/cpu/mcheck/mce.o
>     text	   data	    bss	    dec	    hex	filename
>    18946	   4930	    776	  24652	   604c	arch/x86/kernel/cpu/mcheck/mce.o
>
> After:
> size arch/x86/kernel/cpu/mcheck/mce.o
>     text	   data	    bss	    dec	    hex	filename
>    19335	   4890	    776	  25001	   61a9	arch/x86/kernel/cpu/mcheck/mce.o
>
> So we do indeed see "data" reduced by 40 bytes. But
> "text" is up by 389.  This seems to be because you have
> another change, not described in the commit log, buried
> in part 2 to add get_dont_log_ce(), set_dont_log_ce() etc.
>
> Compiler version: gcc version 4.4.6 20120305 (Red Hat 4.4.6-4) (GCC)
>
> I know I'm contradicting the feedback you got from Borislav here, but
> is this code churn really worth it to save 40 bytes? I don't think so.

Hmm.. I think I agree. I don't see a good way to get rid of the 
individual getters and setters without adding some more code churn. I 
guess using boolean would be better. Boris?


Thanks,
Naveen

--
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/