linux-kernel - Re: [PATCH], issue EOI to APIC prior to calling crash_kexec in die

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: <p73ir0z2xtm.fsf@bingen.suse.de>
Date:	Fri, 08 Feb 2008 17:54:29 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Ingo Molnar <public-mingo-X9Un+BFzKDI@...h.gmane.org>
Cc:	Neil Horman 
	<public-nhorman-2XuSBdqkA4R54TAoqtyWWQ@...h.gmane.org>,
	public-kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@...h.gmane.org,
	public-linux-kernel-u79uwXL29TY76Z2rM5mHXA@...h.gmane.org,
	public-mingo-H+wXaHxf7aLQT0dZR+AlfA@...h.gmane.org,
	"Eric W. Biederman" 
	<public-ebiederm-aS9lmoZGLiVWk0Htik3J/w@...h.gmane.org>,
	"H. Peter Anvin" <public-hpa-YMNOUZJC4hwAvxtiuMwx3w@...h.gmane.org>,
	public-tglx-hfZtesqFncYOwBW4kG4KsQ@...h.gmane.org,
	Vivek Goyal <public-vgoyal-H+wXaHxf7aLQT0dZR+AlfA@...h.gmane.org>
Subject: Re: [PATCH], issue EOI to APIC prior to calling crash_kexec in die_nmi path



Ingo Molnar <mingo-X9Un+BFzKDI@...lic.gmane.org> writes:
>
> try a dummy iret, something like:
>
>   asm volatile ("pushf; push $1f; iret; 1: \n");
>
> to get the CPU out of its 'nested NMI' state. (totally untested)

Just if you do this while running on the NMI stack (and I think
you do if you insert it at the same place as Neil's original patch)
and another NMI happens for some reason you will be dead
because your stack will corrupt.

If you really want nested NMIs you would need to fix up the NMI
stacks first by pointing them below your own stack.

-Andi

--
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/