From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29510 invoked by alias); 24 Feb 2011 12:42:58 -0000 Received: (qmail 29501 invoked by uid 22791); 24 Feb 2011 12:42:57 -0000 X-SWARE-Spam-Status: No, hits=-1.2 required=5.0 tests=AWL,BAYES_00,KAM_STOCKGEN,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mail.codesourcery.com (HELO mail.codesourcery.com) (38.113.113.100) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 24 Feb 2011 12:42:53 +0000 Received: (qmail 31522 invoked from network); 24 Feb 2011 12:42:51 -0000 Received: from unknown (HELO scottsdale.localnet) (pedro@127.0.0.2) by mail.codesourcery.com with ESMTPA; 24 Feb 2011 12:42:51 -0000 From: Pedro Alves To: gdb-patches@sourceware.org Subject: Re: [patch] [gdbserver] Do not crash on file load without inferior Date: Thu, 24 Feb 2011 14:26:00 -0000 User-Agent: KMail/1.13.5 (Linux/2.6.35-25-generic; KDE/4.6.0; x86_64; ; ) Cc: Jan Kratochvil References: <20110224114001.GA24673@host1.dyn.jankratochvil.net> In-Reply-To: <20110224114001.GA24673@host1.dyn.jankratochvil.net> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201102241242.49342.pedro@codesourcery.com> X-IsSubscribed: yes 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 X-SW-Source: 2011-02/txt/msg00693.txt.bz2 On Thursday 24 February 2011 11:40:02, Jan Kratochvil wrote: > Hi Pedro, > > I always got: > > (gdb) file .../gdb/testsuite/gdb.server/ext-run > Load new symbol table from ".../gdb/testsuite/gdb.server/ext-run"? (y or n) y > Reading symbols from .../gdb/testsuite/gdb.server/ext-run...done. > gdbserver: Current inferior requested, but current_inferior is NULL > > Remote connection closed > (gdb) > > if one connects to gdbserver --multi before loading the file. One needs to > load the file first to be able to place a breakpoint at *_start or main. > > But I face other bugs so I cannot say much more. > > I do not think this patch can ever have a regression. Thanks. I that revealed a problem on the GDB side instead. E.g., if you have two inferiors loaded, and the not-current inferior is running, but you do "file" on the not-running-yet inferior, you'll see: $ ./gdb ./testsuite/gdb.server/ext-run -ex "tar extended-remote :9999" -ex "set remote exec-file /home/pedro/gdb/baseline/build/gdb/testsuite/gdb.server/ext-run" -ex "start" ... Reading symbols from /home/pedro/gdb/baseline/build/gdb/testsuite/gdb.server/ext-run...done. Setting up the environment for debugging gdb. Remote debugging using :9999 Temporary breakpoint 1 at 0x4004ef: file ../../../src/gdb/testsuite/gdb.server/server.c, line 21. Starting program: /home/pedro/gdb/baseline/build/gdb/testsuite/gdb.server/ext-run Temporary breakpoint 1, main (argc=1, argv=0x7fffffffe068) at ../../../src/gdb/testsuite/gdb.server/server.c:21 21 return 0; (gdb) add-inferior Added inferior 2 (gdb) info inferiors Num Description Executable 2 * 1 process 15952 /home/pedro/gdb/baseline/build/gdb/testsuite/gdb.server/ext-run (gdb) inferior 2 [Switching to inferior 2 [Thread 0.0] ()] (gdb) set debug remote 1 (gdb) file /home/pedro/gdb/baseline/build/gdb/testsuite/gdb.server/ext-run Reading symbols from /home/pedro/gdb/baseline/build/gdb/testsuite/gdb.server/ext-run...done. Sending packet: $Hgp0.0#ad...Packet received: OK ^^^^^^^ Sending packet: $qSymbol::#5b...Packet received: qSymbol:6764625f6167656e745f6764625f74705f686561705f627566666572 Sending packet: $qSymbol::6764625f6167656e745f6764625f74705f686561705f627566666572#1e...Packet received: qSymbol:6764625f6167656e745f6764625f6a756d705f7061645f627566666572 Sending packet: $qSymbol::6764625f6167656e745f6764625f6a756d705f7061645f627566666572#e1...Packet received: qSymbol:6764625f6167656e745f6764625f6a756d705f7061645f6275666665725f656e64 Sending packet: $qSymbol::6764625f6167656e745f6764625f6a756d705f7061645f6275666665725f656e64#ec...Packet received: qSymbol:6764625f6167656e745f636f6c6c656374696e67 But, Hgp0.0 means select _any_ thread in any process, not _no thread at all_. Meaning GDBserver's current_inferior ends up set to a thread of the wrong process, and GDBserver is querying inferior 1's symbols on inferior 2! See on GDBserver: (gdb) p current_inferior->entry.id $3 = {pid = 15952, lwp = 15952, tid = 0} So I think that we shouldn't send qSymbol at all when inferior_ptid is null_ptid or rather with !target_has_execution (which ends up in default_child_has_execution and currently resolves the same)? -- Pedro Alves