From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 124542 invoked by alias); 24 Nov 2016 21:55:19 -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 124526 invoked by uid 89); 24 Nov 2016 21:55:17 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,RCVD_IN_SORBS_SPAM,SPF_PASS autolearn=no version=3.3.2 spammy= X-HELO: mail-wm0-f65.google.com Received: from mail-wm0-f65.google.com (HELO mail-wm0-f65.google.com) (74.125.82.65) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 24 Nov 2016 21:55:16 +0000 Received: by mail-wm0-f65.google.com with SMTP id g23so6117185wme.1 for ; Thu, 24 Nov 2016 13:55:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=wW8woiweNjyN97NcigFuZmcOnvhWzV7yMP3hqqgoWOQ=; b=a1mUtCu68wbSQcjgFqHqlMUcxJhL4zM59RX2jIiY+zrXhL+Kpt7UBpSi59RWpSAwt5 UeRo4phqLvUMT/gQ1Rb0ATI44WOzaCPxT9bt7aNvRAqh8NZafkf4kcw76NDlr+NTYROy quJ1azV5h2RRg4gLexiIK+uTHu3Bi0VDqvnBUHaC2djsSSUuui/mEOgJs1O/oCLDMHMT aU69g53d1KJ7cPFtw6e4eJj9Sv2MolF/Mmm+jCUZzF9+jgj/qFCY1n98pc8KNul+h8MQ 221EeQDSNTGrXUkWJs7/o7DnamVuAUgFWYT/b1/3b549mjc4KuEwIre5KkxcWY+hOwRo MwTA== X-Gm-Message-State: AKaTC03osSWJkIUTkPILbhdR5bSxOxNSSojrg+KIoXVt5Ofc5VT62/OzbY52NWYMSUZoAw== X-Received: by 10.28.69.217 with SMTP id l86mr4197642wmi.129.1480024514620; Thu, 24 Nov 2016 13:55:14 -0800 (PST) Received: from localhost ([2a02:c7d:8e80:c00:d0e6:26b1:fa3d:de1c]) by smtp.gmail.com with ESMTPSA id ct7sm25628213wjc.2.2016.11.24.13.55.13 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 24 Nov 2016 13:55:13 -0800 (PST) Date: Thu, 24 Nov 2016 21:55:00 -0000 From: Yao Qi To: Antoine Tremblay Cc: Pedro Alves , gdb-patches@sourceware.org Subject: Re: [PATCH 0/9 V3] Use reinsert breakpoint for vCont;s Message-ID: <20161124215510.pbsobdtj6niycjhd@localhost> References: <1467295765-3457-1-git-send-email-yao.qi@linaro.org> <20161121120822.GA28605@E107787-LIN> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20161014 (1.7.1) X-IsSubscribed: yes X-SW-Source: 2016-11/txt/msg00789.txt.bz2 On Mon, Nov 21, 2016 at 10:34:44AM -0500, Antoine Tremblay wrote: > > Thread 1 either sees the original instruction on address A or the > > breakpoint instruction. Unless ptrace read/write 32-bit is not > > atomic, IOW, partial ptrace write result is visible to other > > threads, I don't see why we get SIGILL here. > > I think this is the problem, ptrace read/write doesn't seem to be > atomic, and thread 1 sees some half written memory. (Given that we get > SIGILL/SIGSEGV issues) We need to check in linux-arm-kernel@. > > Did you have any reference suggesting it was atomic ? > No. > While testing it seems to be atomic for 32bit writes but in thumb mode > with a 16 byte write, it is not. I think you meant "16 bit write". Why is that? > > Given the SIGILL/SIGSEG I get maybe that one is 2 writes of 1 byte ? > I'll have to dig in the ptrace code I guess. > It is good to get some a clear answer instead of ambiguous speculation. I think we need to ask in linux-arm-kernel@ -- Yao