From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH v5 07/12] x86: remove the syscall_64 fast-path Date: Sun, 28 Jan 2018 10:29:14 +0100 Message-ID: <20180128092914.dabnzq7arv4bebhn@gmail.com> References: <151703971300.26578.1185595719337719486.stgit@dwillia2-desk3.amr.corp.intel.com> <151703975137.26578.11230688940391207602.stgit@dwillia2-desk3.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <151703975137.26578.11230688940391207602.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Dan Williams Cc: tglx@linutronix.de, linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, gregkh@linuxfoundation.org, x86@kernel.org, Ingo Molnar , Andy Lutomirski , "H. Peter Anvin" , torvalds@linux-foundation.org, alan@linux.intel.com, linux-kernel@vger.kernel.org List-Id: linux-arch.vger.kernel.org * Dan Williams wrote: > Quoting Linus: > > "Honestly, I'd rather get rid of the fast-path entirely. Compared to > all the PTI mess, it's not even noticeable. > > And if we ever get CPU's that have this all fixed, we can re-visit > introducing the fastpath. But this is all very messy and it doesn't > seem worth it right now. > > If we get rid of the fastpath, we can lay out the slow path slightly > better, and get rid of some of those jump-overs. And we'd get rid of > the ptregs hooks entirely. > > So we can try to make the "slow" path better while at it, but I > really don't think it matters much now in the post-PTI era. Sadly." Please fix the title to have the proper prefix and to reference the function that is actually modified by the patch, i.e. something like: s/ x86: remove the syscall_64 fast-path / x86/entry/64: Remove the entry_SYSCALL_64() fast-path With the title fixed: Reviewed-by: Ingo Molnar Thanks, Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f65.google.com ([74.125.82.65]:35454 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751212AbeA1J3S (ORCPT ); Sun, 28 Jan 2018 04:29:18 -0500 Date: Sun, 28 Jan 2018 10:29:14 +0100 From: Ingo Molnar Subject: Re: [PATCH v5 07/12] x86: remove the syscall_64 fast-path Message-ID: <20180128092914.dabnzq7arv4bebhn@gmail.com> References: <151703971300.26578.1185595719337719486.stgit@dwillia2-desk3.amr.corp.intel.com> <151703975137.26578.11230688940391207602.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <151703975137.26578.11230688940391207602.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dan Williams Cc: tglx@linutronix.de, linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, gregkh@linuxfoundation.org, x86@kernel.org, Ingo Molnar , Andy Lutomirski , "H. Peter Anvin" , torvalds@linux-foundation.org, alan@linux.intel.com, linux-kernel@vger.kernel.org Message-ID: <20180128092914.02sbfSuF806rvIhsvTPHfUldMDozGR_d8FInWn3UQxI@z> * Dan Williams wrote: > Quoting Linus: > > "Honestly, I'd rather get rid of the fast-path entirely. Compared to > all the PTI mess, it's not even noticeable. > > And if we ever get CPU's that have this all fixed, we can re-visit > introducing the fastpath. But this is all very messy and it doesn't > seem worth it right now. > > If we get rid of the fastpath, we can lay out the slow path slightly > better, and get rid of some of those jump-overs. And we'd get rid of > the ptregs hooks entirely. > > So we can try to make the "slow" path better while at it, but I > really don't think it matters much now in the post-PTI era. Sadly." Please fix the title to have the proper prefix and to reference the function that is actually modified by the patch, i.e. something like: s/ x86: remove the syscall_64 fast-path / x86/entry/64: Remove the entry_SYSCALL_64() fast-path With the title fixed: Reviewed-by: Ingo Molnar Thanks, Ingo