From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 112020 invoked by alias); 21 Nov 2017 16:53:18 -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 112008 invoked by uid 89); 21 Nov 2017 16:53:17 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.7 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,KB_WAM_FROM_NAME_SINGLEWORD,SPF_HELO_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy= 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; Tue, 21 Nov 2017 16:53:16 +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 159D33680B; Tue, 21 Nov 2017 16:53:15 +0000 (UTC) Received: from localhost (unused-10-15-17-193.yyz.redhat.com [10.15.17.193]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E1F0B5C552; Tue, 21 Nov 2017 16:53:14 +0000 (UTC) From: Sergio Durigan Junior To: Pedro Alves Cc: gdb-patches@sourceware.org, Joel Brobecker Subject: Re: [PATCH 2/2] Don't lose language determined from the "main" name (fix gdb.ada/minsyms.exp) References: <1511280661-14725-1-git-send-email-palves@redhat.com> <1511280661-14725-3-git-send-email-palves@redhat.com> <87a7zfob1w.fsf@redhat.com> <687c9d8c-25e5-63e0-c506-dfb1ce79f2f9@redhat.com> Date: Tue, 21 Nov 2017 16:53:00 -0000 In-Reply-To: <687c9d8c-25e5-63e0-c506-dfb1ce79f2f9@redhat.com> (Pedro Alves's message of "Tue, 21 Nov 2017 16:42:26 +0000") Message-ID: <87wp2jmv45.fsf@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-IsSubscribed: yes X-SW-Source: 2017-11/txt/msg00446.txt.bz2 On Tuesday, November 21 2017, Pedro Alves wrote: > On 11/21/2017 04:23 PM, Sergio Durigan Junior wrote: >> On Tuesday, November 21 2017, Pedro Alves wrote: >> >>> gdb.ada/minsyms.exp fails like this here: >>> >>> FAIL: gdb.ada/minsyms.exp: print integer(some_minsym) >>> FAIL: gdb.ada/minsyms.exp: print /x integer(&some_minsym) >>> >>> The problem is that if you have debug info for glibc, GDB switches the >>> current language to C before it reaches the program's entry point, and >>> then Ada's cast syntax doesn't work when the current language is C: >>> >>> print integer(some_minsym) >>> A syntax error in expression, near `some_minsym)'. >>> (gdb) FAIL: gdb.ada/minsyms.exp: print integer(some_minsym) >>> >>> I first thought of doing "set language ada" in the testcase, but >>> looking deeper, I realized that before running to main, GDB knows the >>> program is Ada, determined by reading __gnat_ada_main_program_name, >>> via set_initial_language->main_language->find_main_name-> >>> ada_main_name, and loses that when it is handling a shared library >>> event. That looks like a bug to me. >>> >>> gdb/testsuite/ChangeLog: >>> 2017-11-21 Pedro Alves >>> >>> * solib-svr4.c: Save/restore language around evaluating a probe >>> argument. >>> --- >>> gdb/solib-svr4.c | 15 +++++++++++++++ >>> 1 file changed, 15 insertions(+) >>> >>> diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c >>> index 5ec606d..e6f818a 100644 >>> --- a/gdb/solib-svr4.c >>> +++ b/gdb/solib-svr4.c >>> @@ -1936,6 +1936,21 @@ svr4_handle_solib_event (void) >>> usm_chain = make_cleanup (resume_section_map_updates_cleanup, >>> current_program_space); >>> >>> + /* Make sure evaluating probe arguments doesn't cause us to switch >>> + the user's current language to the runtime's language. >>> + Evaluating probe arguments relies on reading registers off the >>> + selected frame. When we're handling a shared library event, this >>> + is going to be the first time we fetch the selected frame (as >>> + opposed to the current frame), and if there's debug info for the >>> + loader (e.g., glibc), this switches to its language (usually C). >>> + Usually that ends up masked because we will usually next stop in >>> + the main program (e.g., user did "start"), and switch to the >>> + right language again then, if the program has debug info. >>> + However, if the program does not have debug info, then GDB won't >>> + switch, and we'd lose the language that was determined earlier by >>> + sniffing the program's main name. */ >>> + scoped_restore_current_language save_language; >>> + >>> TRY >>> { >>> val = evaluate_probe_argument (pa->probe, 1, frame); >> >> Hey, thanks for the patch. >> >> Since this is guaranteed to be an stap probe, WDYT about moving this >> scoped_restore_current_language to >> stap-probe.c:stap_evaluate_probe_argument? This way we won't be bit by >> this problem in other parts that also evaluate arguments of probes. >> >> Arguably, this should be set for every probe type IMHO, but it's fine if >> we just do it for stap probes for now. > > That sounds like a good idea. But we could do it in > evaluate_probe_argument then, which handles all probe types? Yes, I was going to suggest that, but I thought about my C++-ification patch, as you imagined. > [In your probe C++ification, that translates to evaluate_probe_argument > becoming a non-virtual method of probe, which then calls into a > protected virtual method that is overridden by the actual probe > implementation (see e.g., the do_xxx methods of class ui_out).] Great, I will do that in my local tree. Thanks, -- Sergio GPG key ID: 237A 54B1 0287 28BF 00EF 31F4 D0EB 7628 65FC 5E36 Please send encrypted e-mail if possible http://sergiodj.net/