linux-kernel - Re: [PATCH] selftests/x86: Disable ldt_gdt

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Message-ID: <568ECF61.4040007@osg.samsung.com>
Date:	Thu, 7 Jan 2016 13:49:37 -0700
From:	Shuah Khan <shuahkh@....samsung.com>
To:	Andy Lutomirski <luto@...nel.org>, x86@...nel.org
Cc:	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now

On 01/06/2016 12:51 PM, Andy Lutomirski wrote:
> ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its
> tests.  On 32-bit builds, this works fine, but on 64-bit builds, it
> only works if the kernel has proper SS sigcontext handling for
> 64-bit user programs.
> 
> Since the SS fixes are currently reverted, restrict the test case to
> 32 bits for now.
> 
> In principle, I could change the test to use a different segment
> register, but it would be messy: CS can't point to the LDT for
> 64-bit code, and the other registers don't result in immediate
> faults because they aren't reloaded on kernel -> user transitions.
> 
> When we fix sigcontext (in 4.6?), we can revert this.
> 
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> --

Andy,

This patch didn't apply to linux-kselftest next.
It probably has to go through x86.

thanks,
-- Shuah

-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@....samsung.com | (970) 217-8978