linux-kernel - Re: [PATCH] trim memory not covered by WB MTRRs

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: <200706271006.16956.jesse.barnes@intel.com>
Date:	Wed, 27 Jun 2007 10:06:16 -0700
From:	Jesse Barnes <jesse.barnes@...el.com>
To:	Pim Zandbergen <P.Zandbergen@...roscoop.nl>
Cc:	Mauro Giachero <mauro.giachero@...il.com>,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	Andi Kleen <andi@...stfloor.org>,
	Justin Piszcz <jpiszcz@...idpixels.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Yinghai Lu <yhlu.kernel@...il.com>
Subject: Re: [PATCH] trim memory not covered by WB MTRRs

On Wednesday, June 27, 2007 10:02:35 Pim Zandbergen wrote:
> Jesse Barnes wrote:
> > It looks like end_pfn might be ~0UL now... can you print that out
> > in your configuration?
>
> Er, do you need the value of end_pfn ?
> Here's what I changed:
>
> if ((highest_addr >> PAGE_SHIFT) != end_pfn) {
>          printk(KERN_WARNING "***************\n");
>          printk(KERN_WARNING "**** WARNING: likely BIOS bug\n");
>          printk(KERN_WARNING "**** MTRRs don't cover all of "
>                 "memory, trimmed %lu pages\n", end_pfn -
>                 (highest_addr >> PAGE_SHIFT));
>          printk(KERN_WARNING "**** end_pfn before = %lu\n", end_pfn);
>          end_pfn = highest_addr >> PAGE_SHIFT;
>          printk(KERN_WARNING "**** end_pfn after = %lu\n", end_pfn);
>          printk(KERN_WARNING "***************\n");
> }
>
> Here's the result:
> ***************
> **** WARNING: likely BIOS bug
> **** MTRRs don't cover all of memory, trimmed 18446744073709486080
> pages **** end_pfn before = 2293760
> **** end_pfn after = 2359296
> ***************
>
> Hope that's what you needed.

Yeah, that's what I needed.  end_pfn looks ok, but I guess my test is a 
little too precise.  It should be if ((highest_addr >> PAGE_SHIFT) < 
end_pfn) rather than !=.  That should keep it from trying to extend 
your memory with bogus math.  I thought that the two values should 
always match, but I guess slightly different memory configurations 
might break that assumption.

Thanks,
Jesse
-
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/