linux-kernel - Re: [crash, bisected] Re: [PATCH 3/4] x86

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: <486912C4.8070705@sgi.com>
Date:	Mon, 30 Jun 2008 10:07:16 -0700
From:	Mike Travis <travis@....com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Christoph Lameter <clameter@....com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu
 area

Eric W. Biederman wrote:
> Mike Travis <travis@....com> writes:
...
>> Can we generate a new symbol which would account for LOAD_OFFSET?
> 
> Ouch.  Absolute symbols indeed.  On the 32bit kernel that may play havoc
> with the relocatable kernel, although we have had similar absolute logic
> for the last year. With __per_cpu_start and __per_cpu_end so it may
> not be a problem.
> 
> To initialize the percpu data you do want to talk to the virtual address
> at __per_coup_load.  But it is absolute Ugh.  
> 
> It might be worth saying something like.
> .data.percpu.start : AT(.data.percpu.dummy - LOAD_OFFSET) {
> 	DATA(0)                   
> 	. = ALIGN(align);
>         __per_cpu_load = . ;                   
> }
> To make __per_cpu_load a relative symbol. ld has a bad habit of taking
> symbols out of empty sections and making them absolute.  Which is why
> I added the DATA(0).
> 
> Still I don't think that would be the 64bit problem.
> 
> Eric

FYI, I did try this out and it caused the bootloader to scramble the
loaded data.  The first corruption I found was the .x86cpuvendor.init
section contained all zeroes.

Mike
--
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/