linux-kernel - Re: [PATCH 3/3] x86, cpu: Enable/disable SMEP

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: <m2k4dwj24x.fsf@firstfloor.org>
Date:	Wed, 11 May 2011 15:36:30 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	"Fenghua Yu" <fenghua.yu@...el.com>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"H Peter Anvin" <hpa@...or.com>,
	"Asit K Mallick" <asit.k.mallick@...el.com>,
	"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] x86, cpu: Enable/disable SMEP

"Fenghua Yu" <fenghua.yu@...el.com> writes:
  
> +static int disable_smep;

If you add a __initdata here the whole thing will completely disappear
after boot.

> @@ -867,6 +886,8 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
>  	/* Init Machine Check Exception if available. */
>  	mcheck_cpu_init(c);
>  
> +	setup_smep(c);

My feeling is you're setting this too late. In theory there could be
early overflows. Better use a early_param and set it as early
as possible, directly after the cpuid flags are set up in early
initialization.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only
--
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/