From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 86920 invoked by alias); 21 Nov 2017 16:42:33 -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 86911 invoked by uid 89); 21 Nov 2017 16:42:32 -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=Hx-languages-length:3447, Hey 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 16:42:31 +0000 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id EF5A8C04AC4F; Tue, 21 Nov 2017 16:42:29 +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 D1BBB61F30; Tue, 21 Nov 2017 16:42:26 +0000 (UTC) Subject: Re: [PATCH 2/2] Don't lose language determined from the "main" name (fix gdb.ada/minsyms.exp) To: Sergio Durigan Junior References: <1511280661-14725-1-git-send-email-palves@redhat.com> <1511280661-14725-3-git-send-email-palves@redhat.com> <87a7zfob1w.fsf@redhat.com> Cc: gdb-patches@sourceware.org, Joel Brobecker From: Pedro Alves Message-ID: <687c9d8c-25e5-63e0-c506-dfb1ce79f2f9@redhat.com> Date: Tue, 21 Nov 2017 16:42:00 -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: <87a7zfob1w.fsf@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2017-11/txt/msg00443.txt.bz2 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? [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).] Thanks, Pedro Alves