[PATCH] [gdb/symtab] Error out for .debug_types section in dwz file
Tom de Vries
tdevries@suse.de
Tue Sep 12 08:43:26 GMT 2023
There are two methods to factor out type information in a dwarf4 executable:
- use -fdebug-info-types to generate type units in a .debug_types section, and
- use dwz to create partial units.
The dwz method has an extra benefit: it also allows to factor out information
between executables into a newly created .dwz file, pointed to by a
.gnu_debugaltlink section.
There is nothing prohibiting a .gnu_debugaltlink file to contain a
.debug_types section.
It's just not generated by dwz or any other tool atm, and consequently gdb has
no support for it. Enhancement PR symtab/30838 is open about the lack of
support.
Make the current situation explicit by emitting a dwarf error:
...
(gdb) file struct-with-sig-2^M
Reading symbols from struct-with-sig-2...^M
Dwarf Error: .debug_types section not supported in dwz file^M
...
and add an assert in write_gdbindex:
...
+ /* See enhancement PR symtab/30838. */
+ gdb_assert (!(per_cu->is_dwz && per_cu->is_debug_types));
...
to clarify why we can use:
...
data_buf &cu_list = (per_cu->is_debug_types
? types_cu_list
: per_cu->is_dwz ? dwz_cu_list : objfile_cu_list);
...
The test-case is a modified copy from gdb.dwarf2/struct-with-sig.exp, so it
keeps the copyright years range.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30838
---
gdb/dwarf2/dwz.c | 5 +
gdb/dwarf2/dwz.h | 1 +
gdb/dwarf2/index-write.c | 3 +
gdb/dwarf2/read.c | 6 +
.../gdb.dwarf2/struct-with-sig-2.exp | 128 ++++++++++++++++++
5 files changed, 143 insertions(+)
create mode 100644 gdb/testsuite/gdb.dwarf2/struct-with-sig-2.exp
diff --git a/gdb/dwarf2/dwz.c b/gdb/dwarf2/dwz.c
index 447c942da6a..bd2bcb91d83 100644
--- a/gdb/dwarf2/dwz.c
+++ b/gdb/dwarf2/dwz.c
@@ -91,6 +91,11 @@ locate_dwz_sections (bfd *abfd, asection *sectp, dwz_file *dwz_file)
dwz_file->debug_names.s.section = sectp;
dwz_file->debug_names.size = bfd_section_size (sectp);
}
+ else if (dwarf2_elf_names.types.matches (sectp->name))
+ {
+ dwz_file->types.s.section = sectp;
+ dwz_file->types.size = bfd_section_size (sectp);
+ }
}
/* Attempt to find a .dwz file (whose full path is represented by
diff --git a/gdb/dwarf2/dwz.h b/gdb/dwarf2/dwz.h
index 232b4dbce01..5f61b5e1216 100644
--- a/gdb/dwarf2/dwz.h
+++ b/gdb/dwarf2/dwz.h
@@ -48,6 +48,7 @@ struct dwz_file
struct dwarf2_section_info macro {};
struct dwarf2_section_info gdb_index {};
struct dwarf2_section_info debug_names {};
+ struct dwarf2_section_info types {};
/* The dwz's BFD. */
gdb_bfd_ref_ptr dwz_bfd;
diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c
index 11f254e263a..7e2f77e3642 100644
--- a/gdb/dwarf2/index-write.c
+++ b/gdb/dwarf2/index-write.c
@@ -1211,6 +1211,9 @@ write_gdbindex (dwarf2_per_bfd *per_bfd, cooked_index *table,
const auto insertpair = cu_index_htab.emplace (per_cu, counter);
gdb_assert (insertpair.second);
+ /* See enhancement PR symtab/30838. */
+ gdb_assert (!(per_cu->is_dwz && per_cu->is_debug_types));
+
/* The all_units list contains CUs read from the objfile as well as
from the eventual dwz file. We need to place the entry in the
corresponding index. */
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 98bedbc5d49..cd4005fb7b2 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -5314,6 +5314,12 @@ create_all_units (dwarf2_per_objfile *per_objfile)
dwz->line.read (objfile);
read_comp_units_from_section (per_objfile, &dwz->info, &dwz->abbrev, 1,
types_htab, rcuh_kind::COMPILE);
+
+ if (!dwz->types.empty ())
+ {
+ /* See enhancement PR symtab/30838. */
+ error (_("Dwarf Error: .debug_types section not supported in dwz file"));
+ }
}
per_objfile->per_bfd->signatured_types = std::move (types_htab);
diff --git a/gdb/testsuite/gdb.dwarf2/struct-with-sig-2.exp b/gdb/testsuite/gdb.dwarf2/struct-with-sig-2.exp
new file mode 100644
index 00000000000..f6877fc6a17
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/struct-with-sig-2.exp
@@ -0,0 +1,128 @@
+# Copyright 2020-2023 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 <http://www.gnu.org/licenses/>.
+
+# Variant of struct-with-sig.exp where TUs are in .gnu_debugaltlink file.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+require dwarf2_support
+
+standard_testfile main-foo.c .S .S
+
+set build_id [string repeat ff 20]
+
+# Make some DWARF for the dwz file.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+ build_id $::build_id
+
+ tu {} 0x0000000000000001 the_type_i {
+ type_unit {} {
+ declare_labels int_type
+
+ the_type_i: structure_type {
+ {name s}
+ {byte_size 4 sdata}
+ } {
+ member {
+ {name i}
+ {type :$int_type}
+ }
+ }
+ int_type: base_type {
+ {name int}
+ {encoding @DW_ATE_signed}
+ {byte_size 4 sdata}
+ }
+ }
+ }
+
+ tu {} 0x0000000000000002 the_type_j {
+ type_unit {} {
+ declare_labels int_type
+
+ the_type_j: structure_type {
+ {name s}
+ {byte_size 4 sdata}
+ } {
+ member {
+ {name j}
+ {type :$int_type}
+ }
+ }
+ int_type: base_type {
+ {name int}
+ {encoding @DW_ATE_signed}
+ {byte_size 4 sdata}
+ }
+ }
+ }
+}
+
+# We're using an object instead of executable here to keep cc-with-tweaks.sh
+# from modifying it. It also means we can set the build-id, rather than
+# having to extract it.
+if { [gdb_compile $asm_file $binfile.dwz object {nodebug}] != "" } {
+ return -1
+}
+
+set host_dwz_file [gdb_remote_download host $binfile.dwz]
+
+# Make some DWARF for the executable.
+set asm_file [standard_output_file $srcfile3]
+Dwarf::assemble $asm_file {
+ gnu_debugaltlink $::host_dwz_file $::build_id
+
+ cu {} {
+ compile_unit {
+ {DW_AT_language @DW_LANG_C}
+ {DW_AT_name main.c}
+ } {
+ structure_type {
+ {name s}
+ {signature 0x0000000000000001 ref_sig8}
+ {declaration 1 flag}
+ }
+ DW_TAG_subprogram {
+ {MACRO_AT_func {main}}
+ }
+ }
+ }
+
+ cu {} {
+ compile_unit {
+ {DW_AT_language @DW_LANG_C}
+ {DW_AT_name foo.c}
+ } {
+ structure_type {
+ {name s}
+ {signature 0x0000000000000002 ref_sig8}
+ {declaration 1 flag}
+ }
+ DW_TAG_subprogram {
+ {MACRO_AT_func {foo}}
+ }
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+ [list $srcfile $asm_file] {nodebug}] } {
+ return -1
+}
+
+set re "Dwarf Error: .debug_types section not supported in dwz file"
+gdb_assert { [regexp $re $gdb_file_cmd_msg] } "Dwarf Error message"
base-commit: 318d3bda5cad124bd11eebb0349d0f183ba625b1
--
2.35.3
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