From: Oleg Nesterov Subject: Re: [PATCH] x86: make DR*_RESERVED unsigned long Date: Thu, 25 Apr 2013 16:48:18 +0200 Message-ID: <20130425144818.GA25921@redhat.com> References: <20130424072630.GB1780@gmail.com> <20130424170702.GA1867@redhat.com> <5178282D.9030902@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ingo Molnar , Linus Torvalds , Cyrill Gorcunov , Peter Zijlstra , Thomas Gleixner , David Miller , "Theodore Ts'o" , Linux Kernel Mailing List , the arch/x86 maintainers , Network Development , "linux-ext4@vger.kernel.org" , Fr??d??ric Weisbecker To: "H. Peter Anvin" Return-path: Content-Disposition: inline In-Reply-To: <5178282D.9030902@zytor.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On 04/24, H. Peter Anvin wrote: > > On 04/24/2013 10:07 AM, Oleg Nesterov wrote: > > DR6_RESERVED and DR_CONTROL_RESERVED are used to clear the set > > bits in the "unsigned long" data, make them long to ensure that > > "&~" doesn't clear the upper bits. > > > > do_debug() and ptrace_write_dr7() which use DR*_RESERVED look > > safe, but probably it makes sense to cleanup anyway. > > > > Reported-by: Linus Torvalds > > Signed-off-by: Oleg Nesterov > > Can you please put in the description if this is a manifest or > non-manifest bug and, if manifest, what the issues are? It greatly > affects what we otherwise have to do to address the bug. Sorry if it was not clear, I tried to explain in the changelog that this is only cleanup. Yes, dr6 should have all zeroes in 32-64 so the usage of DR6_RESERVED is safe. > Also, the -UL suffix is usually capitalized in our codebase. OK, iiuc otherwise you agree with this change. I'll send v2. Oleg.