From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id McAHHXCniV8zZQAAWB0awg (envelope-from ) for ; Fri, 16 Oct 2020 10:00:16 -0400 Received: by simark.ca (Postfix, from userid 112) id 69C2B1EF6F; Fri, 16 Oct 2020 10:00:16 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id A25231E58E for ; Fri, 16 Oct 2020 10:00:14 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id B00E03857817; Fri, 16 Oct 2020 14:00:13 +0000 (GMT) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by sourceware.org (Postfix) with ESMTPS id 50FE23857817 for ; Fri, 16 Oct 2020 14:00:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 50FE23857817 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tdevries@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 6624AB1DA; Fri, 16 Oct 2020 14:00:09 +0000 (UTC) Date: Fri, 16 Oct 2020 16:00:07 +0200 From: Tom de Vries To: gdb-patches@sourceware.org Subject: [PATCH][gdb/symtab] Handle setting line bp without debug line info Message-ID: <20201016140006.GA22271@delia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tom Tromey Errors-To: gdb-patches-bounces@sourceware.org Sender: "Gdb-patches" Hi, When setting a breakpoint on a line in an executable without debug line info, we run into an abort. The problem occurs when calling set_default_source_symtab_and_line, which calls select_source_symtab (0), which is where we try to find the line number for main: ... /* Make the default place to list be the function `main' if one exists. */ block_symbol bsym = lookup_symbol (main_name (), 0, VAR_DOMAIN, 0); if (bsym.symbol != nullptr && SYMBOL_CLASS (bsym.symbol) == LOC_BLOCK) { symtab_and_line sal = find_function_start_sal (bsym.symbol, true); loc->set (sal.symtab, std::max (sal.line - (lines_to_list - 1), 1)); return; } ... However, due to the missing debug line info, find_function_start_sal returns a sal with sal.symtab == 0: ... (gdb) p /x sal $2 = {pspace = 0x1a4a7f0, symtab = 0x0, symbol = 0x1d9e480, section = 0x1d5b398, msymbol = 0x0, line = 0x0, pc = 0x4004ab, end = 0x0, explicit_pc = 0x0, explicit_line = 0x0, is_stmt = 0x0, prob = 0x0, objfile = 0x0} ... which eventually causes an segfault in create_sals_line_offset because self->default_symtab->filename is accessed while self->default_symtab == NULL. Fix this by handling sal.symtab == NULL in select_source_symtab. Tested on x86_64-linux. Any comments? Thanks, - Tom [gdb/symtab] Handle setting line bp without debug line info gdb/ChangeLog: 2020-10-16 Tom de Vries PR symtab/26317 * source.c (select_source_symtab): Handling sal.symtab == NULL for symbol main. gdb/testsuite/ChangeLog: 2020-10-16 Tom de Vries PR symtab/26317 * gdb.dwarf2/dw2-main-no-line-number.exp: New file. --- gdb/source.c | 7 ++- .../gdb.dwarf2/dw2-main-no-line-number.exp | 68 ++++++++++++++++++++++ 2 files changed, 74 insertions(+), 1 deletion(-) diff --git a/gdb/source.c b/gdb/source.c index a73a31f644..779efa40d9 100644 --- a/gdb/source.c +++ b/gdb/source.c @@ -306,7 +306,12 @@ select_source_symtab (struct symtab *s) if (bsym.symbol != nullptr && SYMBOL_CLASS (bsym.symbol) == LOC_BLOCK) { symtab_and_line sal = find_function_start_sal (bsym.symbol, true); - loc->set (sal.symtab, std::max (sal.line - (lines_to_list - 1), 1)); + if (sal.symtab == NULL) + /* We couldn't find the location of `main', possibly due to missing + line number info, fall back to line 1 in the corresponding file. */ + loc->set (symbol_symtab (bsym.symbol), 1); + else + loc->set (sal.symtab, std::max (sal.line - (lines_to_list - 1), 1)); return; } diff --git a/gdb/testsuite/gdb.dwarf2/dw2-main-no-line-number.exp b/gdb/testsuite/gdb.dwarf2/dw2-main-no-line-number.exp new file mode 100644 index 0000000000..aad7ab1c1b --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-main-no-line-number.exp @@ -0,0 +1,68 @@ +# Copyright 2020 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +# Setup a main without line number info, and verify that attempting to +# set a breakpoint on a line number doesn't crash gdb. + +load_lib dwarf.exp + +set testname [file rootname [file tail [info script]]] + +# This test can only be run on targets which support DWARF-2 and use gas. +if {![dwarf2_support]} { + verbose "Skipping $testname test." + return 0 +} + +# The .c files use __attribute__. +if [get_compiler_info] { + return -1 +} +if !$gcc_compiled { + verbose "Skipping $testname test." + return 0 +} + +standard_testfile main.c main-dw.S + +set asm_file [standard_output_file $srcfile2] +Dwarf::assemble $asm_file { + declare_labels Llines + global srcdir subdir srcfile + + cu {} { + compile_unit { + {language @DW_LANG_C} + {name $srcfile} + } { + subprogram { + {external 1 flag} + {MACRO_AT_func {main}} + } + } + } +} + +if { [prepare_for_testing "failed to prepare" ${testfile} \ + [list $srcfile $asm_file] {nodebug}] } { + return -1 +} + +if ![runto_main] { + return -1 +} + +set breakpoint_at_missing_lineno_set [gdb_breakpoint "1" no-message] +gdb_assert { !$breakpoint_at_missing_lineno_set }