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 23:11:48 +0100 [thread overview]
Message-ID: <20160321221148.GF5083@two.firstfloor.org> (raw)
In-Reply-To: <CALCETrW5RZrh1YCxT2_cnQAHndoiN+J_15iHBKM6BH6WN4UeXg@mail.gmail.com>
> So a patchset to enable these asinine new instructions needs to take
> this into account, and the ABI issue needs to be addressed, even if
What's the ABI issue?
AFAIK we're perfectly consistent.
> the answer is that the proposed code is fine.
>
> (Also, the existing code is fscked up. Guess what xor %eax, %eax; mov
> %ax, %gs does to the base on AMD? The existing code is *wrong*, and I
> don't want to see it get wronger.)
I have no idea, but changing it is definitely not in scope for my patches.
>
> And no, I don't really care about programs detecting context switches.
> I do, however, care about allowing non-determinism in things that
> ought to behave deterministically. Writing a nonzero value to %gs and
> then doing WRGSBASE is something that user code will be able to do
> whether we like it or not, some shitty threading library is likely to
> do this just to spite us, the the kernel needs to do *something* when
> this happens.
They will quickly notice it if there is a problem, so I don't think
we need to worry about that.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2016-03-21 22:11 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 [this message]
2016-03-21 22:27 ` Andy Lutomirski
2016-03-21 22:41 ` Andi Kleen
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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