linux-kernel - RE: [PATCH 1/3] mce: Add a msg string to the MCE tracepoint

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]

Date:	Wed, 29 Feb 2012 17:11:08 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Borislav Petkov <bp@...64.org>,
	Mauro Carvalho Chehab <mchehab@...hat.com>
CC:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Ingo Molnar <mingo@...e.hu>,
	EDAC devel <linux-edac@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/3] mce: Add a msg string to the MCE tracepoint

>> - on Nehalem, the MCE status register encodes not only the error message; it
>>   also encodes the DIMM that generated the  error. So, it is possible to 
>>   completely decode the error on userspace, using only the MCE registers.
>
> Well, depending on what Tony wants to do there, either decode the error
> in the kernel and pass it on with the 'msg' arg or do the whole decoding
> in userspace.

For best results - we should decode right away in the kernel. Decoding later
requires that we carry a lot of additional information about the system
configuration at the time of the error.  Consider the case of a hard error
(either fatal or recoverable). If the system reboots, then the DIMM
with the error should fail self test - and thus be mapped out of the system.
If the error analyzer doesn't realize that this has happened, it will be
very confused. Even if it does notice - the Sandy bridge decoder won't be
able to check that the right DIMM was mapped out (since the configuration
registers it reads to map addresses to DIMMS will now be set for the new
configuration, with different mappings).

-Tony
--
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/