From: "H. Peter Anvin" <hpa@zytor.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Andy Lutomirski <luto@amacapital.net>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/7] x86: Add support for rd/wr fs/gs base
Date: Thu, 01 May 2014 15:45:27 -0700 [thread overview]
Message-ID: <5362CE87.7010908@zytor.com> (raw)
In-Reply-To: <20140501221836.GI19657@tassilo.jf.intel.com>
On 05/01/2014 03:18 PM, Andi Kleen wrote:
>> I haven't looked through the flows (I'm at LCE so I have limited screen
>> bandwidth) to see how that would be handled in this case, but in the
>> general paranoid case it comes down to the fact that in this particular
>> subcase we don't necessarily know exactly how many SWAPGS are between us
>> and userspace after we IRET.
>
> There is none as far as I know. Certainly wasn't any when the code
> was originally written.
>
This applies for an asynchronous entry from kernel space. Obviously in
the case where we actually come directly from user space (the stack
frame CS.RPL == 3) then that doesn't apply.
-hpa
next prev parent reply other threads:[~2014-05-01 22:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-28 22:12 Add support for RD/WR FS/GSBASE Andi Kleen
2014-04-28 22:12 ` [PATCH 1/7] percpu: Add a DEFINE_PER_CPU_2PAGE_ALIGNED Andi Kleen
2014-05-02 15:18 ` Tejun Heo
2014-04-28 22:12 ` [PATCH 2/7] x86: Naturally align the debug IST stack Andi Kleen
2014-04-28 22:12 ` [PATCH 3/7] x86: Add C intrinsics for new rd/wr fs/gs base instructions Andi Kleen
2014-04-29 14:10 ` Konrad Rzeszutek Wilk
2014-04-28 22:12 ` [PATCH 4/7] x86: Add support for rd/wr fs/gs base Andi Kleen
2014-04-29 18:19 ` Andy Lutomirski
2014-04-29 23:39 ` Andi Kleen
2014-04-30 4:52 ` H. Peter Anvin
2014-04-30 4:57 ` H. Peter Anvin
2014-04-30 23:44 ` Andy Lutomirski
2014-04-30 23:47 ` Andy Lutomirski
2014-05-01 21:15 ` Andi Kleen
2014-05-01 21:39 ` Andy Lutomirski
2014-05-01 21:51 ` Andi Kleen
2014-05-01 21:53 ` Andy Lutomirski
2014-05-01 21:58 ` H. Peter Anvin
2014-05-01 22:06 ` Andy Lutomirski
2014-05-01 22:18 ` Andi Kleen
2014-05-01 22:45 ` H. Peter Anvin [this message]
2014-04-28 22:12 ` [PATCH 5/7] x86: Make old K8 swapgs workaround conditional Andi Kleen
2014-04-30 4:57 ` H. Peter Anvin
2014-04-28 22:12 ` [PATCH 6/7] x86: Enumerate kernel FSGS capability in AT_HWCAP2 Andi Kleen
2014-04-28 22:12 ` [PATCH 7/7] x86: Add documentation for rd/wr fs/gs base Andi Kleen
2014-04-29 2:23 ` Randy Dunlap
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