From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23978 invoked by alias); 9 Nov 2017 22:25:56 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 23968 invoked by uid 89); 9 Nov 2017 22:25:55 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.9 required=5.0 tests=BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=no version=3.3.2 spammy=agent X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 09 Nov 2017 22:25:54 +0000 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1B9125F7B8; Thu, 9 Nov 2017 22:25:53 +0000 (UTC) Received: from [127.0.0.1] (ovpn04.gateway.prod.ext.ams2.redhat.com [10.39.146.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id 720405C883; Thu, 9 Nov 2017 22:25:52 +0000 (UTC) Subject: Re: [PATCH 3/3] [AArch64] Remove tag from address for watchpoint To: Yao Qi References: <1509006590-9401-1-git-send-email-yao.qi@linaro.org> <1509006590-9401-4-git-send-email-yao.qi@linaro.org> <2fe62186-f1db-cf5c-f0e2-c18e35089dd9@redhat.com> <20171109210950.GD318@1170ee0b50d5> Cc: gdb-patches@sourceware.org From: Pedro Alves Message-ID: Date: Thu, 09 Nov 2017 22:25:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20171109210950.GD318@1170ee0b50d5> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2017-11/txt/msg00214.txt.bz2 On 11/09/2017 09:09 PM, Yao Qi wrote: > On 17-11-09 20:30:42, Pedro Alves wrote: >> And then at places where we need to save or compare memory addresses, >> like in the watchpoint location addresses case we strip out / ignore >> non-significant bits. >> >> And the next question is: if you're adding a gdbarch hook such as >> this one (either significant_addr_bit or addr_tag_remove) >> why not use it for all the cases handled by the different patches in >> this series, instead of using different solutions for each case? >> I.e., for memory access, saving breakpoint and watchpoint >> location addresses, the dcache, and any other future case we run >> into, like e.g., maybe agent expressions. > > I thought about this, using this new added gdbarch method everywhere. > The reason I didn't do that is due to breakpoint location address > comparison (I think I can use the new gdbarch method for the rest, > watchpoint location and dcache). > > As I wrote in patch #2, > >> When program hits a breakpoint, the stopped pc reported by Linux kernle is >> the address *without* tag, so it is better the address recorded in >> breakpoint location is the one without tag too, so we can still match >> breakpoint location address and stopped pc reported by Linux kernel, by >> simple compare. I did try the different approach, that is keep the tag in >> the address saved in the breakpoint location, but I need to change many >> places of "loc->address == pc", so I give up on this way. > > I remember code pattern "loc->address == pc" exists many places in > breakpoint.c. I can give a try again. Since target-reported addresses always have the non-significant bits zeroed, you'd only need to use the new gdbarch hook in breakpoint.c:adjust_breakpoint_address ? Seems like that's already used for watchpoints too, even. Thanks, Pedro Alves