From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 41271 invoked by alias); 9 Nov 2018 15:28:48 -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 41252 invoked by uid 89); 9 Nov 2018 15:28:47 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy=H*u:1.3.6, H*UA:1.3.6 X-HELO: smtp.polymtl.ca Received: from smtp.polymtl.ca (HELO smtp.polymtl.ca) (132.207.4.11) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 09 Nov 2018 15:28:46 +0000 Received: from simark.ca (simark.ca [158.69.221.121]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id wA9FSdCj001910 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 9 Nov 2018 10:28:43 -0500 Received: by simark.ca (Postfix, from userid 112) id 154321E519; Fri, 9 Nov 2018 10:28:39 -0500 (EST) Received: from simark.ca (localhost [127.0.0.1]) by simark.ca (Postfix) with ESMTP id 0406A1E0A9; Fri, 9 Nov 2018 10:28:37 -0500 (EST) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 09 Nov 2018 15:28:00 -0000 From: Simon Marchi To: John Baldwin Cc: gdb-patches@sourceware.org Subject: Re: [PATCH v2 2/3] Add an optional "alias" attribute to syscall entries. In-Reply-To: <20181106175431.59832-3-jhb@FreeBSD.org> References: <20181106175431.59832-1-jhb@FreeBSD.org> <20181106175431.59832-3-jhb@FreeBSD.org> Message-ID: <5e2f036844a8cbf04c3947555bee41fc@polymtl.ca> X-Sender: simon.marchi@polymtl.ca User-Agent: Roundcube Webmail/1.3.6 X-IsSubscribed: yes X-SW-Source: 2018-11/txt/msg00146.txt.bz2 On 2018-11-06 12:54, John Baldwin wrote: > When setting a syscall catchpoint by name, catch syscalls whose name > or alias matches the requested string. > > When the ABI of a system call is changed in the FreeBSD kernel, this > is implemented by leaving a compatibility system call using the old > ABI at the existing "slot" and allocating a new system call for the > version using the new ABI. For example, new fields were added to the > 'struct kevent' used by the kevent() system call in FreeBSD 12. The > previous kevent() system call in FreeBSD 12 kernels is now called > freebsd11_kevent() and is still used by older binaries compiled > against the older ABI. The freebsd11_kevent() system call can be > tagged with an "alias" attribute of "kevent" permitting 'catch syscall > kevent' to catch both system calls and providing the expected user > behavior for both old and new binaries. It also provides the expected > behavior if GDB is compiled on an older host (such as a FreeBSD 11 > host). Will we ever need to provide more than one alias to a syscall? Simon