linux-kernel - Re: [PATCH] x86-64, espfix: consider IRQs are off when initializing

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] [day] [month] [year] [list]

Date:	Thu, 17 Jul 2014 09:16:11 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Sasha Levin <sasha.levin@...cle.com>
CC:	tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86-64, espfix: consider IRQs are off when initializing

On 07/17/2014 08:58 AM, Sasha Levin wrote:
> 
> This is the result of getting an error message for allocating with GFP_KERNEL
> saying that we can't do that with IRQs off.
> 
> My assumption after that was that we're not going to be sleeping at all, which
> is why spinlock/GFP_ATOMIC would be correct here.
> 

So we have a problem, but the proposed solution is wrong.  This is
messy... we need this code to be successfully executed before we can
safely schedule *user space* on that processor, but there is no
requirement that we execute it before we enable *interrupts* on that
processor, so maybe there is a way we can fulfill those requirements.

The alternative would be to fail to enable the processor or going into a
spin loop, but either of those would been rather toxic to me.

	-hpa

--
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/