From: Sebastian Lackner <sebastian@fds-team.de>
To: Andy Lutomirski <luto@amacapital.net>,
Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Cc: Anish Bhatt <anish@chelsio.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Chuck Ebbert <cebbert.lkml@gmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 1/2] x86_64,entry: Filter RFLAGS.NT on entry from userspace
Date: Wed, 01 Oct 2014 07:09:19 +0200 [thread overview]
Message-ID: <542B8C7F.70108@fds-team.de> (raw)
In-Reply-To: <0e906bdeba3660c9766248d3d7229e78a423ca5b.1412138935.git.luto@amacapital.net>
> + testl $X86_EFLAGS_NT,EFLAGS(%rsp) /* saved EFLAGS match cpu */
> + jz 1f
> + pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_FIXED)
> + popfq_cfi
> +1:
> +
Do you think it makes sense to change the order here, so that no jump happens if
NT is not set (which happens a bit more often, than the other way round)? Just a
guess though, haven't measured if pipeline effects have such a big influence in this
case. ;)
next prev parent reply other threads:[~2014-10-01 5:09 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-01 4:51 [PATCH v2 0/2] x86_64,entry: Clear NT on entry and speed up switch_to Andy Lutomirski
2014-10-01 4:51 ` [PATCH v2 1/2] x86_64,entry: Filter RFLAGS.NT on entry from userspace Andy Lutomirski
2014-10-01 5:09 ` Sebastian Lackner [this message]
2014-10-01 5:24 ` Andy Lutomirski
2014-10-01 15:19 ` H. Peter Anvin
2014-10-01 14:09 ` Chuck Ebbert
2014-10-01 14:32 ` Chuck Ebbert
2014-10-01 14:46 ` Andy Lutomirski
2014-10-01 14:56 ` Chuck Ebbert
2014-10-01 15:03 ` Andy Lutomirski
2014-10-01 15:22 ` H. Peter Anvin
2014-10-01 15:26 ` H. Peter Anvin
2014-10-01 15:50 ` Andy Lutomirski
2014-10-01 16:04 ` Andy Lutomirski
2014-10-01 16:17 ` H. Peter Anvin
2014-10-01 4:51 ` [PATCH v2 2/2] x86_64: Don't save flags on context switch Andy Lutomirski
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