From: "H. Peter Anvin" <hpa@zytor.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@xenotime.net>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: On the correctness of dbe3ed1c078c193be34326728d494c5c4bc115e2
Date: Sun, 01 Sep 2013 09:00:42 -0700 [thread overview]
Message-ID: <522364AA.9050506@zytor.com> (raw)
In-Reply-To: <CA+55aFwUKyJwphC7EFCgQKGLfZq1yrjx+4CrMhJeVmxFr8QNdg@mail.gmail.com>
On 09/01/2013 08:58 AM, Linus Torvalds wrote:
> On Sun, Sep 1, 2013 at 5:20 AM, H. Peter Anvin <hpa@zytor.com> wrote:
>>
>> This has the end result that we treat a user space instruction which
>> touches a privileged data structure that then page faults (e.g. a
>> segment load which causes #PF on the GDT) as a user-space fault.
>>
>> This seems very wrong to me, since such a #PF would indicate a serious
>> error in the kernel.
>
> Not necessarily. Don't we basically do exactly that for the F00F bug
> workaround, for example?
>
We do, but only after matching on an exact address (is_f00f_bug()).
Note also that is_f00f_bug() isn't conditional on PF_USER.
-hpa
next prev parent reply other threads:[~2013-09-01 16:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-01 12:20 On the correctness of dbe3ed1c078c193be34326728d494c5c4bc115e2 H. Peter Anvin
2013-09-01 15:58 ` Linus Torvalds
2013-09-01 16:00 ` H. Peter Anvin [this message]
2013-09-01 16:12 ` Linus Torvalds
2013-09-01 16:13 ` H. Peter Anvin
2013-09-01 16:10 ` H. Peter Anvin
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