linux-kernel - Re: [RFC][PATCH 0/3] x86/nmi: Print all cpu stacks from NMI safely

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: <alpine.LNX.2.00.1406200137310.15014@pobox.suse.cz>
Date:	Fri, 20 Jun 2014 01:38:59 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Steven Rostedt <rostedt@...dmis.org>
cc:	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...e.cz>, Jan Kara <jack@...e.cz>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Dave Anderson <anderson@...hat.com>,
	Petr Mladek <pmladek@...e.cz>
Subject: Re: [RFC][PATCH 0/3] x86/nmi: Print all cpu stacks from NMI safely

On Thu, 19 Jun 2014, Steven Rostedt wrote:

> > I don't think there is a need for a global stop_machine()-like 
> > synchronization here. The printing CPU will be sending IPI to the CPU N+1 
> > only after it has finished printing CPU N stacktrace.
> 
> So you plan on sending an IPI to a CPU then wait for it to acknowledge
> that it is spinning, and then print out the data and then tell the CPU
> it can stop spinning?

Yes, that was exactly my idea. You have to be synchronized with the CPU 
receiving the NMI anyway in case you'd like to get its pt_regs and dump 
those as part of the dump.

-- 
Jiri Kosina
SUSE Labs
--
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/