From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5499 invoked by alias); 7 Oct 2014 17:49:27 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 5484 invoked by uid 89); 7 Oct 2014 17:49:27 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 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 (AES256-GCM-SHA384 encrypted) ESMTPS; Tue, 07 Oct 2014 17:49:26 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s97HnL54010892 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 7 Oct 2014 13:49:22 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s97HnKe1008443; Tue, 7 Oct 2014 13:49:21 -0400 Message-ID: <543427A0.5040708@redhat.com> Date: Tue, 07 Oct 2014 17:49:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1 MIME-Version: 1.0 To: Eli Zaretskii CC: gdb@sourceware.org Subject: Re: Reporting the STATUS_INVALID_UNWIND_TARGET fatal error References: <831tqtkn9e.fsf@gnu.org> <54341C7B.70700@redhat.com> <83iojvlrkn.fsf@gnu.org> In-Reply-To: <83iojvlrkn.fsf@gnu.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2014-10/txt/msg00019.txt.bz2 On 10/07/2014 06:26 PM, Eli Zaretskii wrote: >> Date: Tue, 07 Oct 2014 18:01:47 +0100 >> From: Pedro Alves >> >> On 09/30/2014 06:54 PM, Eli Zaretskii wrote: >>> In the native MinGW build of GDB, we currently do not interpret >>> STATUS_INVALID_UNWIND_TARGET, neither as a Posix-style signal nor as a >>> Windows exception (under debugexceptions). As result, GDB says >>> something like >>> >>> gdb: unknown target exception 0xc0000029 at 0x7c9502cc >>> >>> Would it make sense to report this as SIGSEGV instead? >> >> Doesn't sound like segmentation fault, but rather the >> runtime detecting some corruption. > > But stack-related trouble, like stack overflows, are reported as > segfaults, right? Only if they really cause a segmentation fault. Reusing the stack of another thread would not, as that stack would be mapped in to the process. > >> Like, e.g., glibc's malloc/free detecting a heap corruption and >> printing about that. > > It's not a case of corruption. Nothing is wrong with the stack per > se. In addition, it's a true exception, not a debugging feature > provided by some library. So I think it's different. > >>> This happens, e.g., when a thread tries to longjmp using stack >>> information recorded by a different thread. What will GDB report in >>> such a case on GNU/Linux or other Posix platforms? >> >> I think nothing. > > Could you or someone else try? > >> In absence of a more specific signal, I think SIGTRAP is the >> best match, for being a "debugger" signal. This has the advantage >> that SIGTRAP is not passed to the program by default, so a plain >> "continue" should suppress the exception, while "signal SIGTRAP" >> will pass it to the program (which I guess will usually terminate >> the application). > > You cannot continue from this exception, not on Windows anyway. Your > program dies. > >> Though overall, I think it'd be better if we added a new >> "target exception" waitkind or some such, and stopped trying >> to masquerade Windows exceptions as Unix signals. > > What would it take to do something like that? I'd try adding a new TARGET_WAITKIND_EXCEPTION, and have windows-nat.c report that, putting the exception number in waitstatus.value.integer. In handle_inferior_event, you'd handle it probably similarly to TARGET_WAITKIND_NO_HISTORY, by reporting the exception and causing a stop. To interpret the exception number, and say, convert it to a printable string, you'd add a new gdbarch hook, that'd be implemented in windows-tdep.c. To make the contents of the whole exception object available to GDB and the user, I'd try adding a new convenience variable, similar to $_siginfo or $_tlb. See windows-tdep.c for the latter. Thanks, Pedro Alves