From: Dave Hansen <dave.hansen@linux.intel.com>
To: "H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@amacapital.net>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Minor PKRU bug?
Date: Tue, 12 Jul 2016 15:59:32 -0700 [thread overview]
Message-ID: <57857654.1000309@linux.intel.com> (raw)
In-Reply-To: <bdb6c72a-9119-968f-9d85-c0db59835db7@zytor.com>
On 07/12/2016 03:55 PM, H. Peter Anvin wrote:
> On 07/12/16 08:32, Dave Hansen wrote:
>> On 07/09/2016 02:27 PM, Andy Lutomirski wrote:
>>> is_prefetch in arch/x86/mm/fault.c can be called on a user address
>>> that's not readable due to PKRU. This could break it. You might need
>>> to add a get_user_exec or similar.
>>
>> Thanks for the heads-up. I think I'll just need a version that does
>> something along the lines of stac/clac, but with PKRU.
>>
>> I think I can do it with an "_exec" variant of probe_kernel_address(),
>> but it's a bit messy.
>
> Can this particular codepath even be executed on a PKRU-equipped
> machine? I thought it was a bug fix for a specific AMD CPU line.
Yeah, I think we hit it unconditionally in the naughty paths of the page
fault handler. I don't see any CPU model detection in the call path. I
think we just assume that everybody has prefetch bugs.
next prev parent reply other threads:[~2016-07-12 23:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-09 21:27 Minor PKRU bug? Andy Lutomirski
2016-07-12 15:32 ` Dave Hansen
2016-07-12 22:55 ` H. Peter Anvin
2016-07-12 22:59 ` Dave Hansen [this message]
2016-07-12 22:59 ` Andy Lutomirski
2016-07-21 21:35 ` Dave Hansen
2016-07-21 21:45 ` Andy Lutomirski
2016-07-21 21:48 ` H. Peter Anvin
2016-07-21 22:26 ` Dave Hansen
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