From: Andi Kleen <andi@firstfloor.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andi Kleen <andi@firstfloor.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Updated version of RD/WR FS/GS BASE patchkit
Date: Mon, 21 Mar 2016 23:41:52 +0100 [thread overview]
Message-ID: <20160321224152.GH5083@two.firstfloor.org> (raw)
In-Reply-To: <CALCETrVrZyg98YiNOtMpx2m2pcjZm6TuqQDPPuohu8+puke5xw@mail.gmail.com>
> Imagine that some brilliant lightweight threading library does:
>
> - set GS to nonzero (by whatever means -- arch_prctl(ARCH_SET_GS,
> whatever) on a pre-IVB host followed by migration, some modify_ldt
> garbage, simple bloody-mindedness, whatever);
Migration is only possible when the CPUID flags match.
> - WRGSBASE
> - Use GS for a bit
>
> This will work most of the time until it gets unlucky with preemption.
As soon as a kernel thread or something else schedules the value
will be lost.
> And yes, runtime library authors really do mess up in amazing ways.
>
> It's an issue. It needs conscious design.
Ok. So your only objection is the order of the context switch
updates?
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2016-03-21 22:41 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-21 16:16 Updated version of RD/WR FS/GS BASE patchkit Andi Kleen
2016-03-21 16:16 ` [PATCH 1/9] x86: Add intrinsics/macros for new rd/wr fs/gs base instructions Andi Kleen
2016-03-21 18:14 ` Andy Lutomirski
2016-03-21 16:16 ` [PATCH 2/9] x86: Add support for rd/wr fs/gs base Andi Kleen
2016-03-21 18:13 ` Andy Lutomirski
2016-03-21 19:05 ` Andi Kleen
2016-03-21 19:22 ` Andy Lutomirski
2016-03-21 22:05 ` Andi Kleen
2016-03-21 22:08 ` Andy Lutomirski
2016-03-21 22:15 ` Andi Kleen
2016-03-22 8:36 ` Thomas Gleixner
2016-03-22 14:40 ` Brian Gerst
2016-04-15 0:06 ` Andy Lutomirski
2016-03-21 16:16 ` [PATCH 3/9] x86: Make old K8 swapgs workaround conditional Andi Kleen
2016-03-21 16:16 ` [PATCH 4/9] x86: Enumerate kernel FSGS capability in AT_HWCAP2 Andi Kleen
2016-03-21 18:49 ` Brian Gerst
2016-03-21 18:54 ` Andi Kleen
2016-03-21 19:32 ` Brian Gerst
2016-03-21 19:43 ` Andi Kleen
2016-03-21 22:10 ` Andy Lutomirski
2016-03-21 16:16 ` [PATCH 5/9] x86: Add documentation for rd/wr fs/gs base Andi Kleen
2016-03-23 19:14 ` Valdis.Kletnieks
2016-03-21 16:16 ` [PATCH 6/9] x86: Use rd/wr fs/gs base in arch_prctl Andi Kleen
2016-03-21 18:17 ` Andy Lutomirski
2016-03-21 16:16 ` [PATCH 7/9] x86: Add self test code for fsgsbase Andi Kleen
2016-03-21 16:16 ` [PATCH 8/9] x86: Support arbitrary fs/gs base in getregs Andi Kleen
2016-03-21 16:16 ` [PATCH 9/9] x86: Save FS/GS base in core dump Andi Kleen
2016-03-21 18:39 ` Updated version of RD/WR FS/GS BASE patchkit Andy Lutomirski
2016-03-21 19:03 ` Andi Kleen
2016-03-21 19:23 ` Andy Lutomirski
2016-03-21 19:40 ` Andi Kleen
2016-03-21 22:05 ` Andy Lutomirski
2016-03-21 22:11 ` Andi Kleen
2016-03-21 22:27 ` Andy Lutomirski
2016-03-21 22:41 ` Andi Kleen [this message]
2016-03-21 22:47 ` Andy Lutomirski
2016-03-21 22:52 ` Andi Kleen
2016-03-21 22:57 ` Andy Lutomirski
2016-03-21 23:02 ` Andi Kleen
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