From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.polymtl.ca (smtp.polymtl.ca [132.207.4.11]) by sourceware.org (Postfix) with ESMTPS id 71E31385DC31 for ; Thu, 27 Jan 2022 17:45:42 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 71E31385DC31 Received: from simark.ca (simark.ca [158.69.221.121]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id 20RHjblF001938 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 27 Jan 2022 12:45:41 -0500 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp.polymtl.ca 20RHjblF001938 Received: from [10.0.0.11] (192-222-157-6.qc.cable.ebox.net [192.222.157.6]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id BDF1D1ECEB for ; Thu, 27 Jan 2022 12:45:36 -0500 (EST) Message-ID: <50cd832a-984b-7e5c-ba4f-7891f98afbdf@polymtl.ca> Date: Thu, 27 Jan 2022 12:45:36 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: [PATCH v4] gdb: work around negative DW_AT_data_member_location GCC 11 bug Content-Language: en-US To: Simon Marchi via Gdb-patches References: <20220127171520.2138171-1-simon.marchi@polymtl.ca> From: Simon Marchi In-Reply-To: <20220127171520.2138171-1-simon.marchi@polymtl.ca> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Poly-FromMTA: (simark.ca [158.69.221.121]) at Thu, 27 Jan 2022 17:45:37 +0000 X-Spam-Status: No, score=-3039.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_PASS, SPF_PASS, TXREP, WEIRD_PORT autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org 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: , X-List-Received-Date: Thu, 27 Jan 2022 17:45:45 -0000 On 2022-01-27 12:15, Simon Marchi wrote: > New in v3: > > - change the test source code from an array of chars to an int, to > match what is described in the DWARF Actually, the original version here might have been a simple way to make the test work even if the target has ints that are not 4 bytes. So I'll revert this bit to the original version, but add a comment. Latest version (v4) is below. Simon >From db15f7b4dc3e0f9e4e3f050dbf1715b526892ee3 Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Wed, 26 Jan 2022 14:55:47 -0500 Subject: [PATCH v4] gdb: work around negative DW_AT_data_member_location GCC 11 bug New in v4: - revert the change to the test made in v3 New in v3: - change the test source code from an array of chars to an int, to match what is described in the DWARF - update copyright years - formatting fixes New in v2: - formatting fixes in the .exp file - add producer (GCC 11) check, update test file accordingly to contain a producer string - issue complaint when applying the fixup g++ 11.1.0 has a bug where it will emit a negative DW_AT_data_member_location in some cases: $ cat test.cpp #include int main() { std::unique_ptr ptr; } $ g++ -g test.cpp $ llvm-dwarfdump -F a.out ... 0x00000964: DW_TAG_member DW_AT_name [DW_FORM_strp] ("_M_head_impl") DW_AT_decl_file [DW_FORM_data1] ("/usr/include/c++/11.1.0/tuple") DW_AT_decl_line [DW_FORM_data1] (125) DW_AT_decl_column [DW_FORM_data1] (0x27) DW_AT_type [DW_FORM_ref4] (0x0000067a "default_delete") DW_AT_data_member_location [DW_FORM_sdata] (-1) ... This leads to a GDB crash (when built with ASan, otherwise probably garbage results), since it tries to read just before (to the left, in ASan speak) of the value's buffer: ==888645==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000c52af at pc 0x7f711b239f4b bp 0x7fff356bd470 sp 0x7fff356bcc18 READ of size 1 at 0x6020000c52af thread T0 #0 0x7f711b239f4a in __interceptor_memcpy /build/gcc/src/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827 #1 0x555c4977efa1 in value_contents_copy_raw /home/simark/src/binutils-gdb/gdb/value.c:1347 #2 0x555c497909cd in value_primitive_field(value*, long, int, type*) /home/simark/src/binutils-gdb/gdb/value.c:3126 #3 0x555c478f2eaa in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:333 #4 0x555c478f63b2 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:513 #5 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #6 0x555c478f63b2 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:513 #7 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #8 0x555c478f63b2 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:513 #9 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #10 0x555c4760d45f in c_value_print_struct /home/simark/src/binutils-gdb/gdb/c-valprint.c:383 #11 0x555c4760df4c in c_value_print_inner(value*, ui_file*, int, value_print_options const*) /home/simark/src/binutils-gdb/gdb/c-valprint.c:438 #12 0x555c483ff9a7 in language_defn::value_print_inner(value*, ui_file*, int, value_print_options const*) const /home/simark/src/binutils-gdb/gdb/language.c:632 #13 0x555c49758b68 in do_val_print /home/simark/src/binutils-gdb/gdb/valprint.c:1048 #14 0x555c49759b17 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) /home/simark/src/binutils-gdb/gdb/valprint.c:1151 #15 0x555c478f2fcb in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:335 #16 0x555c478f63b2 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:513 #17 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #18 0x555c4760d45f in c_value_print_struct /home/simark/src/binutils-gdb/gdb/c-valprint.c:383 #19 0x555c4760df4c in c_value_print_inner(value*, ui_file*, int, value_print_options const*) /home/simark/src/binutils-gdb/gdb/c-valprint.c:438 #20 0x555c483ff9a7 in language_defn::value_print_inner(value*, ui_file*, int, value_print_options const*) const /home/simark/src/binutils-gdb/gdb/language.c:632 #21 0x555c49758b68 in do_val_print /home/simark/src/binutils-gdb/gdb/valprint.c:1048 #22 0x555c49759b17 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) /home/simark/src/binutils-gdb/gdb/valprint.c:1151 #23 0x555c478f2fcb in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:335 #24 0x555c4760d45f in c_value_print_struct /home/simark/src/binutils-gdb/gdb/c-valprint.c:383 #25 0x555c4760df4c in c_value_print_inner(value*, ui_file*, int, value_print_options const*) /home/simark/src/binutils-gdb/gdb/c-valprint.c:438 #26 0x555c483ff9a7 in language_defn::value_print_inner(value*, ui_file*, int, value_print_options const*) const /home/simark/src/binutils-gdb/gdb/language.c:632 #27 0x555c49758b68 in do_val_print /home/simark/src/binutils-gdb/gdb/valprint.c:1048 #28 0x555c49759b17 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) /home/simark/src/binutils-gdb/gdb/valprint.c:1151 #29 0x555c4760f04c in c_value_print(value*, ui_file*, value_print_options const*) /home/simark/src/binutils-gdb/gdb/c-valprint.c:587 #30 0x555c483ff954 in language_defn::value_print(value*, ui_file*, value_print_options const*) const /home/simark/src/binutils-gdb/gdb/language.c:614 #31 0x555c49759f61 in value_print(value*, ui_file*, value_print_options const*) /home/simark/src/binutils-gdb/gdb/valprint.c:1189 #32 0x555c48950f70 in print_formatted /home/simark/src/binutils-gdb/gdb/printcmd.c:337 #33 0x555c48958eda in print_value(value*, value_print_options const&) /home/simark/src/binutils-gdb/gdb/printcmd.c:1258 #34 0x555c48959891 in print_command_1 /home/simark/src/binutils-gdb/gdb/printcmd.c:1367 #35 0x555c4895a3df in print_command /home/simark/src/binutils-gdb/gdb/printcmd.c:1458 #36 0x555c4767f974 in do_simple_func /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:97 #37 0x555c47692e25 in cmd_func(cmd_list_element*, char const*, int) /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:2475 #38 0x555c4936107e in execute_command(char const*, int) /home/simark/src/binutils-gdb/gdb/top.c:670 #39 0x555c485f1bff in catch_command_errors /home/simark/src/binutils-gdb/gdb/main.c:523 #40 0x555c485f249c in execute_cmdargs /home/simark/src/binutils-gdb/gdb/main.c:618 #41 0x555c485f6677 in captured_main_1 /home/simark/src/binutils-gdb/gdb/main.c:1317 #42 0x555c485f6c83 in captured_main /home/simark/src/binutils-gdb/gdb/main.c:1338 #43 0x555c485f6d65 in gdb_main(captured_main_args*) /home/simark/src/binutils-gdb/gdb/main.c:1363 #44 0x555c46e41ba8 in main /home/simark/src/binutils-gdb/gdb/gdb.c:32 #45 0x7f71198bcb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24) #46 0x555c46e4197d in _start (/home/simark/build/binutils-gdb-one-target/gdb/gdb+0x77f197d) 0x6020000c52af is located 1 bytes to the left of 8-byte region [0x6020000c52b0,0x6020000c52b8) allocated by thread T0 here: #0 0x7f711b2b7459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154 #1 0x555c470acdc9 in xcalloc /home/simark/src/binutils-gdb/gdb/alloc.c:100 #2 0x555c49b775cd in xzalloc(unsigned long) /home/simark/src/binutils-gdb/gdbsupport/common-utils.cc:29 #3 0x555c4977bdeb in allocate_value_contents /home/simark/src/binutils-gdb/gdb/value.c:1029 #4 0x555c4977be25 in allocate_value(type*) /home/simark/src/binutils-gdb/gdb/value.c:1040 #5 0x555c4979030d in value_primitive_field(value*, long, int, type*) /home/simark/src/binutils-gdb/gdb/value.c:3092 #6 0x555c478f6280 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:501 #7 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #8 0x555c478f63b2 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:513 #9 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #10 0x555c478f63b2 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:513 #11 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #12 0x555c4760d45f in c_value_print_struct /home/simark/src/binutils-gdb/gdb/c-valprint.c:383 #13 0x555c4760df4c in c_value_print_inner(value*, ui_file*, int, value_print_options const*) /home/simark/src/binutils-gdb/gdb/c-valprint.c:438 #14 0x555c483ff9a7 in language_defn::value_print_inner(value*, ui_file*, int, value_print_options const*) const /home/simark/src/binutils-gdb/gdb/language.c:632 #15 0x555c49758b68 in do_val_print /home/simark/src/binutils-gdb/gdb/valprint.c:1048 #16 0x555c49759b17 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) /home/simark/src/binutils-gdb/gdb/valprint.c:1151 #17 0x555c478f2fcb in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:335 #18 0x555c478f63b2 in cp_print_value /home/simark/src/binutils-gdb/gdb/cp-valprint.c:513 #19 0x555c478f02ca in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:161 #20 0x555c4760d45f in c_value_print_struct /home/simark/src/binutils-gdb/gdb/c-valprint.c:383 #21 0x555c4760df4c in c_value_print_inner(value*, ui_file*, int, value_print_options const*) /home/simark/src/binutils-gdb/gdb/c-valprint.c:438 #22 0x555c483ff9a7 in language_defn::value_print_inner(value*, ui_file*, int, value_print_options const*) const /home/simark/src/binutils-gdb/gdb/language.c:632 #23 0x555c49758b68 in do_val_print /home/simark/src/binutils-gdb/gdb/valprint.c:1048 #24 0x555c49759b17 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) /home/simark/src/binutils-gdb/gdb/valprint.c:1151 #25 0x555c478f2fcb in cp_print_value_fields(value*, ui_file*, int, value_print_options const*, type**, int) /home/simark/src/binutils-gdb/gdb/cp-valprint.c:335 #26 0x555c4760d45f in c_value_print_struct /home/simark/src/binutils-gdb/gdb/c-valprint.c:383 #27 0x555c4760df4c in c_value_print_inner(value*, ui_file*, int, value_print_options const*) /home/simark/src/binutils-gdb/gdb/c-valprint.c:438 #28 0x555c483ff9a7 in language_defn::value_print_inner(value*, ui_file*, int, value_print_options const*) const /home/simark/src/binutils-gdb/gdb/language.c:632 #29 0x555c49758b68 in do_val_print /home/simark/src/binutils-gdb/gdb/valprint.c:1048 Since there are some binaries with this in the wild, I think it would be useful for GDB to work around this. I did the obvious simple thing, if the DW_AT_data_member_location's value is -1, replace it with 0. I added a producer check to only apply this fixup for GCC 11. The idea is that if some other compiler ever uses a DW_AT_data_member_location value of -1 by mistake, we don't know (before analyzing the bug at least) if they did mean 0 or some other value. So I wouldn't want to apply the fixup in that case. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28063 Change-Id: Ieef3459b0b9bbce8bdad838ba83b4b64e7269d42 --- gdb/dwarf2/cu.c | 1 + gdb/dwarf2/cu.h | 1 + gdb/dwarf2/read.c | 14 ++++ .../negative-data-member-location.c | 31 ++++++++ .../negative-data-member-location.exp | 77 +++++++++++++++++++ 5 files changed, 124 insertions(+) create mode 100644 gdb/testsuite/gdb.dwarf2/negative-data-member-location.c create mode 100644 gdb/testsuite/gdb.dwarf2/negative-data-member-location.exp diff --git a/gdb/dwarf2/cu.c b/gdb/dwarf2/cu.c index 019165f6e6c5..b1fd688188a7 100644 --- a/gdb/dwarf2/cu.c +++ b/gdb/dwarf2/cu.c @@ -32,6 +32,7 @@ dwarf2_cu::dwarf2_cu (dwarf2_per_cu_data *per_cu, checked_producer (false), producer_is_gxx_lt_4_6 (false), producer_is_gcc_lt_4_3 (false), + producer_is_gcc_11 (false), producer_is_icc (false), producer_is_icc_lt_14 (false), producer_is_codewarrior (false), diff --git a/gdb/dwarf2/cu.h b/gdb/dwarf2/cu.h index 078479a56988..bce0a3de63a4 100644 --- a/gdb/dwarf2/cu.h +++ b/gdb/dwarf2/cu.h @@ -253,6 +253,7 @@ struct dwarf2_cu bool checked_producer : 1; bool producer_is_gxx_lt_4_6 : 1; bool producer_is_gcc_lt_4_3 : 1; + bool producer_is_gcc_11 : 1; bool producer_is_icc : 1; bool producer_is_icc_lt_14 : 1; bool producer_is_codewarrior : 1; diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index f7cb95b40cba..1a749eac334f 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -14320,6 +14320,7 @@ check_producer (struct dwarf2_cu *cu) { cu->producer_is_gxx_lt_4_6 = major < 4 || (major == 4 && minor < 6); cu->producer_is_gcc_lt_4_3 = major < 4 || (major == 4 && minor < 3); + cu->producer_is_gcc_11 = major == 11; } else if (producer_is_icc (cu->producer, &major, &minor)) { @@ -14464,6 +14465,19 @@ handle_member_location (struct die_info *die, struct dwarf2_cu *cu, if (attr->form_is_constant ()) { LONGEST offset = attr->constant_value (0); + + /* Work around this GCC 11 bug, where it would erroneously use -1 + data member locations, instead of 0: + + Negative DW_AT_data_member_location + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101378 + */ + if (offset == -1 && cu->producer_is_gcc_11) + { + complaint (_("DW_AT_data_member_location value of -1, assuming 0")); + offset = 0; + } + field->set_loc_bitpos (offset * bits_per_byte); } else if (attr->form_is_section_offset ()) diff --git a/gdb/testsuite/gdb.dwarf2/negative-data-member-location.c b/gdb/testsuite/gdb.dwarf2/negative-data-member-location.c new file mode 100644 index 000000000000..6d8e8df01e9d --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/negative-data-member-location.c @@ -0,0 +1,31 @@ +/* Copyright (C) 2021-2022 Free Software Foundation, Inc. + + This file is part of GDB. + + 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 . */ + +struct the_struct +{ + /* Define the field as an array of char instead of an int to support targets + that have sizeof(int) != 4. */ + char x[4]; +}; + +struct the_struct s = { { 0x11, 0x22, 0x22, 0x11 } }; + +int +main (void) +{ + return 0; +} diff --git a/gdb/testsuite/gdb.dwarf2/negative-data-member-location.exp b/gdb/testsuite/gdb.dwarf2/negative-data-member-location.exp new file mode 100644 index 000000000000..57030d77134b --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/negative-data-member-location.exp @@ -0,0 +1,77 @@ +# Copyright 2021-2022 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 . + +# Test our workaround for a GCC 11 bug, where it sometimes puts a -1 value for +# DW_AT_data_member_location: +# +# Negative DW_AT_data_member_location +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101378 + +load_lib dwarf.exp + +# This test can only be run on targets which support DWARF-2 and use gas. +if { ![dwarf2_support] } { + return 0 +} + +standard_testfile .c -dw.S + +set asm_file [standard_output_file ${srcfile2}] + +Dwarf::assemble ${asm_file} { + cu {} { + DW_TAG_compile_unit { + {DW_AT_language @DW_LANG_C99} + {DW_AT_producer "GNU C++17 11.1.0 -mtune=generic -march=x86-64 -g3 -O0"} + {name ${::srcfile}} + } { + declare_labels int_label struct_label + + int_label: DW_TAG_base_type { + {DW_AT_byte_size 4 DW_FORM_udata} + {DW_AT_encoding @DW_ATE_signed} + {DW_AT_name "int"} + } + + struct_label: DW_TAG_structure_type { + {DW_AT_name "the_struct"} + {DW_AT_byte_size 4 DW_FORM_udata} + } { + DW_TAG_member { + {DW_AT_name "field"} + {DW_AT_type :$int_label} + {DW_AT_data_member_location -1 DW_FORM_sdata} + } + } + + DW_TAG_variable { + {DW_AT_name "s"} + {DW_AT_type :$struct_label} + {DW_AT_location {DW_OP_addr [gdb_target_symbol "s"]} SPECIAL_expr} + } + } + } +} + +if { [prepare_for_testing "failed to prepare" ${testfile} [list $srcfile $asm_file] {nodebug}] } { + return +} + +if { ![runto_main] } { + return +} + +gdb_test "print /x s" " = {field = 0x11222211}" +gdb_test "print /x s.field" " = 0x11222211" base-commit: 0d8cbc5f2fcbcb9eb207f12507fdfe04f3d3ae14 -- 2.34.1