From: Borislav Petkov <bp@alien8.de>
To: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH 02/10] x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test
Date: Mon, 29 Feb 2016 23:37:22 +0100 [thread overview]
Message-ID: <20160229223722.GI3724@pd.tnic> (raw)
In-Reply-To: <CAMzpN2iXOvUSVXpaFpT0056B-N0zqQg0i1hQFSyWf-kAToAsFQ@mail.gmail.com>
On Mon, Feb 29, 2016 at 05:33:16PM -0500, Brian Gerst wrote:
> SYSENTER doesn't save EFLAGS so we have to fudge it by pushing the
> kernel's flags. Most user programs never set AC, so by adding it to
> the test for flags to clear we can avoid the CLAC or POPF in the
> common case that it is already clear.
Yeah, Andy just explained it to me on IRC. Thanks guys.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
next prev parent reply other threads:[~2016-02-29 22:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 5:28 [PATCH 00/10] x86: Various SYSENTER/SYSEXIT/#DB fixes and cleanups Andy Lutomirski
2016-02-29 5:28 ` [PATCH 01/10] selftests/x86: In syscall_nt, test NT|TF as well Andy Lutomirski
2016-03-02 12:59 ` Borislav Petkov
2016-03-02 14:01 ` One Thousand Gnomes
2016-03-02 14:28 ` Borislav Petkov
2016-03-02 19:03 ` Andy Lutomirski
2016-03-02 19:30 ` Borislav Petkov
2016-02-29 5:28 ` [PATCH 02/10] x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test Andy Lutomirski
2016-02-29 20:39 ` Borislav Petkov
2016-02-29 20:45 ` Andy Lutomirski
2016-02-29 22:09 ` Borislav Petkov
2016-02-29 22:33 ` Brian Gerst
2016-02-29 22:37 ` Borislav Petkov [this message]
2016-02-29 5:28 ` [PATCH 03/10] x86/entry/32: Filter NT and speed up AC filtering in SYSENTER Andy Lutomirski
2016-03-02 13:24 ` Borislav Petkov
2016-02-29 5:28 ` [PATCH 04/10] x86/entry/32: Restore FLAGS on SYSEXIT Andy Lutomirski
2016-02-29 5:28 ` [PATCH 05/10] x86/traps: Clear TIF_BLOCKSTEP on all debug exceptions Andy Lutomirski
2016-02-29 5:28 ` [PATCH 06/10] x86/traps: Clear DR6 early in do_debug and improve the comment Andy Lutomirski
2016-02-29 5:28 ` [PATCH 07/10] x86/entry: Vastly simplify SYSENTER TF handling Andy Lutomirski
2016-02-29 5:28 ` [PATCH 08/10] x86/entry: Only allocate space for SYSENTER_stack if needed Andy Lutomirski
2016-02-29 5:28 ` [PATCH 09/10] x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup Andy Lutomirski
2016-02-29 5:28 ` [PATCH 10/10] x86/entry/32: Add and check a stack canary for the SYSENTER stack Andy Lutomirski
2016-02-29 18:55 ` [PATCH 00/10] x86: Various SYSENTER/SYSEXIT/#DB fixes and cleanups Andy Lutomirski
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