From b9f3fbc9f3453bcb24fece0c46acf581d13d3f64 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Fri, 6 Aug 2021 16:44:17 +0200 Subject: [PATCH] [gdb/symtab] Fix zero address complaint for shlib In PR28004 the following warning / Internal error is reported: ... $ gdb -q -batch \ -iex "set sysroot $(pwd -P)/repro" \ ./repro/gdb \ ./repro/core \ -ex bt ... Program terminated with signal SIGABRT, Aborted. #0 0x00007ff8fe8e5d22 in raise () from repro/usr/lib/libc.so.6 [Current thread is 1 (LWP 1762498)] #1 0x00007ff8fe8cf862 in abort () from repro/usr/lib/libc.so.6 warning: (Internal error: pc 0x7ff8feb2c21d in read in psymtab, \ but not in symtab.) warning: (Internal error: pc 0x7ff8feb2c218 in read in psymtab, \ but not in symtab.) ... #2 0x00007ff8feb2c21e in __gnu_debug::_Error_formatter::_M_error() const \ [clone .cold] (warning: (Internal error: pc 0x7ff8feb2c21d in read in \ psymtab, but not in symtab.) ) from repro/usr/lib/libstdc++.so.6 ... The warning is about the following: - in find_pc_sect_compunit_symtab we try to find the address (0x7ff8feb2c218 / 0x7ff8feb2c21d) in the symtabs. - that fails, so we try again in the partial symtabs. - we find a matching partial symtab - however, the partial symtab has a full symtab, so we should have found a matching symtab in the first step. The addresses are: ... (gdb) info sym 0x7ff8feb2c218 __gnu_debug::_Error_formatter::_M_error() const [clone .cold] in \ section .text of repro/usr/lib/libstdc++.so.6 (gdb) info sym 0x7ff8feb2c21d __gnu_debug::_Error_formatter::_M_error() const [clone .cold] + 5 in \ section .text of repro/usr/lib/libstdc++.so.6 ... which correspond to unrelocated addresses 0x9c218 and 0x9c21d: ... $ nm -C repro/usr/lib/libstdc++.so.6.0.29 | grep 000000000009c218 000000000009c218 t __gnu_debug::_Error_formatter::_M_error() const \ [clone .cold] ... which belong to function __gnu_debug::_Error_formatter::_M_error() in /build/gcc/src/gcc/libstdc++-v3/src/c++11/debug.cc. The partial symtab that is found for the addresses is instead the one for /build/gcc/src/gcc/libstdc++-v3/src/c++98/bitmap_allocator.cc, which is incorrect. This happens as follows. The bitmap_allocator.cc CU has DW_AT_ranges at .debug_rnglist offset 0x4b50: ... 00004b50 0000000000000000 0000000000000056 00004b5a 00000000000a4790 00000000000a479c 00004b64 00000000000a47a0 00000000000a47ac ... When reading the first range 0x0..0x56, it doesn't trigger the "start address of zero" complaint here: ... /* A not-uncommon case of bad debug info. Don't pollute the addrmap with bad data. */ if (range_beginning + baseaddr == 0 && !per_objfile->per_bfd->has_section_at_zero) { complaint (_(".debug_rnglists entry has start address of zero" " [in module %s]"), objfile_name (objfile)); continue; } ... because baseaddr != 0, which seems incorrect given that when loading the shared library individually in gdb (and consequently baseaddr == 0), we do see the complaint. Consequently, we run into this case in dwarf2_get_pc_bounds: ... if (low == 0 && !per_objfile->per_bfd->has_section_at_zero) return PC_BOUNDS_INVALID; ... which then results in this code in process_psymtab_comp_unit_reader being called with cu_bounds_kind == PC_BOUNDS_INVALID, which sets the set_addrmap argument to 1: ... scan_partial_symbols (first_die, &lowpc, &highpc, cu_bounds_kind <= PC_BOUNDS_INVALID, cu); ... and consequently, the CU addrmap gets build using address info from the functions. During that process, addrmap_set_empty is called with a range that includes 0x9c218 and 0x9c21d: ... (gdb) p /x start $7 = 0x9989c (gdb) p /x end_inclusive $8 = 0xb200d ... but it's called for a function at DIE 0x54153 with DW_AT_ranges at 0x40ae: ... 000040ae 00000000000b1ee0 00000000000b200e 000040b9 000000000009989c 00000000000998c4 000040c3 ... and neither range includes 0x9c218 and 0x9c21d. This is caused by this code in partial_die_info::read: ... if (dwarf2_ranges_read (ranges_offset, &lowpc, &highpc, cu, nullptr, tag)) has_pc_info = 1; ... which pretends that the function is located at addresses 0x9989c..0xb200d, which is indeed not the case. This patch fixes the first problem encountered: fix the "start address of zero" complaint warning by removing the baseaddr part from the condition. Same for dwarf2_ranges_process. The effect is that: - the complaint is triggered, and - the warning / Internal error is no longer triggered. This does not fix the observed problem in partial_die_info::read, which is filed as PR28200. Tested on x86_64-linux. Co-Authored-By: Simon Marchi gdb/ChangeLog: 2021-07-29 Simon Marchi Tom de Vries PR symtab/28004 * gdb/dwarf2/read.c (dwarf2_rnglists_process, dwarf2_ranges_process): Fix zero address complaint. * gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c: New test. * gdb/testsuite/gdb.dwarf2/dw2-zero-range.c: New test. * gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp: New file. --- gdb/dwarf2/read.c | 10 +- .../gdb.dwarf2/dw2-zero-range-shlib.c | 21 ++ gdb/testsuite/gdb.dwarf2/dw2-zero-range.c | 24 +++ gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp | 185 ++++++++++++++++++ 4 files changed, 232 insertions(+), 8 deletions(-) create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-zero-range.c create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index acabee3315f..bac02b5a1bd 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -13631,7 +13631,6 @@ dwarf2_rnglists_process (unsigned offset, struct dwarf2_cu *cu, /* Base address selection entry. */ gdb::optional base; const gdb_byte *buffer; - CORE_ADDR baseaddr; bool overflow = false; ULONGEST addr_index; struct dwarf2_section_info *rnglists_section; @@ -13648,8 +13647,6 @@ dwarf2_rnglists_process (unsigned offset, struct dwarf2_cu *cu, } buffer = rnglists_section->buffer + offset; - baseaddr = objfile->text_section_offset (); - while (1) { /* Initialize it due to a false compiler warning. */ @@ -13791,7 +13788,7 @@ dwarf2_rnglists_process (unsigned offset, struct dwarf2_cu *cu, /* A not-uncommon case of bad debug info. Don't pollute the addrmap with bad data. */ - if (range_beginning + baseaddr == 0 + if (range_beginning == 0 && !per_objfile->per_bfd->has_section_at_zero) { complaint (_(".debug_rnglists entry has start address of zero" @@ -13833,7 +13830,6 @@ dwarf2_ranges_process (unsigned offset, struct dwarf2_cu *cu, dwarf_tag tag, gdb::optional base; unsigned int dummy; const gdb_byte *buffer; - CORE_ADDR baseaddr; if (cu_header->version >= 5) return dwarf2_rnglists_process (offset, cu, tag, callback); @@ -13849,8 +13845,6 @@ dwarf2_ranges_process (unsigned offset, struct dwarf2_cu *cu, dwarf_tag tag, } buffer = per_objfile->per_bfd->ranges.buffer + offset; - baseaddr = objfile->text_section_offset (); - while (1) { CORE_ADDR range_beginning, range_end; @@ -13901,7 +13895,7 @@ dwarf2_ranges_process (unsigned offset, struct dwarf2_cu *cu, dwarf_tag tag, /* A not-uncommon case of bad debug info. Don't pollute the addrmap with bad data. */ - if (range_beginning + baseaddr == 0 + if (range_beginning == 0 && !per_objfile->per_bfd->has_section_at_zero) { complaint (_(".debug_ranges entry has start address of zero" diff --git a/gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c b/gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c new file mode 100644 index 00000000000..1ddc8d6677b --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c @@ -0,0 +1,21 @@ +/* + Copyright 2021 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 . */ + +void +foo (void) +{ + asm ("foo_label: .globl foo_label"); +} diff --git a/gdb/testsuite/gdb.dwarf2/dw2-zero-range.c b/gdb/testsuite/gdb.dwarf2/dw2-zero-range.c new file mode 100644 index 00000000000..894a04df786 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-zero-range.c @@ -0,0 +1,24 @@ +/* + Copyright 2021 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 . */ + +extern void foo (void); + +int +main (void) +{ + asm ("main_label: .globl main_label"); + foo (); +} diff --git a/gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp b/gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp new file mode 100644 index 00000000000..4f2ac0fe77c --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp @@ -0,0 +1,185 @@ +# Copyright 2021 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 . + +# Check that the ".debug_ranges entry has start address of zero" complaint +# is triggered for a loaded shared lib. + +load_lib dwarf.exp + +# This test can only be run on targets which support DWARF-2 and use gas. +if {![dwarf2_support]} { + verbose "Skipping $gdb_test_file_name." + return 0 +} + +if {[skip_shlib_tests]} { + return 0 +} + +standard_testfile .c -shlib.c -dw.S + +# Test with both a .debug_ranges section (DWARF 4) and a .debug_rnglists +# section (DWARF 5). + +foreach_with_prefix ranges_sect {ranges rnglists} { + set asm_file [standard_output_file ${ranges_sect}-$srcfile3] + + if { $ranges_sect == "ranges" } { + Dwarf::assemble $asm_file { + global srcdir subdir srcfile2 + declare_labels ranges_label + + cu {} { + compile_unit { + {language @DW_LANG_C} + {name $srcfile2} + {ranges ${ranges_label} DW_FORM_sec_offset} + } { + subprogram { + {external 1 flag} + {name foo} + } + } + } + + ranges {is_64 [is_64_target]} { + ranges_label: sequence { + base 0 + range 0 1 + } + } + } + } elseif { $ranges_sect == "rnglists" } { + Dwarf::assemble $asm_file { + global srcdir subdir srcfile2 + declare_labels rnglists_label + + cu { + version 5 + } { + compile_unit { + {language @DW_LANG_C} + {name $srcfile2} + {ranges ${rnglists_label} DW_FORM_sec_offset} + } { + subprogram { + {external 1 flag} + {name foo} + } + } + } + + rnglists { + table { + rnglists_label: list_ { + start_end 0 1 + } + } + } + } + } else { + error "invalid ranges section kind" + } + + set lib1 [standard_output_file shr1.sl] + set lib_opts "nodebug" + + set sources [list ${srcdir}/${subdir}/$srcfile2 $asm_file] + if { [gdb_compile_shlib $sources ${lib1} $lib_opts] != "" } { + untested "failed to compile" + return -1 + } + + set exec_opts [list debug shlib=${lib1}] + set sources ${srcdir}/${subdir}/${srcfile} + if { [gdb_compile $sources ${binfile} executable \ + $exec_opts] != ""} { + untested "failed to compile" + return -1 + } + + clean_restart $binfile + + set readnow_p [readnow] + + # Don't load the symbols for $lib1 during runto_main. + # Instead, we do this afterwards using "sharedlibrary $lib1". + gdb_test_no_output "set auto-solib-add off" + + if { ![runto_main] } { + fail "cannot run to main." + return -1 + } + + set complaint_re ".debug_${ranges_sect} entry has start address of zero" + set re \ + "During symbol reading: $complaint_re \\\[in module \[^\r\n\]*\\\]" + + # Test for presence of complaint, with lib1 relocated. + with_complaints 1 { + set test "Zero address complaint - relocated - psymtab" + set have_complaint 0 + gdb_test_multiple "sharedlibrary $lib1" $test { + -re -wrap $re { + set have_complaint 1 + } + -re -wrap "" { + } + } + + if { $have_complaint } { + pass $test + } else { + set index [have_index $lib1] + if { $index == "gdb_index" } { + kfail symtab/28159 $test + } else { + fail $test + } + } + } + + if { ! $readnow_p } { + with_complaints 1 { + gdb_test "maint expand-symtabs $srcfile2" $re \ + "Zero address complaint - relocated - symtab" + } + } + + clean_restart + # Test for presence of complaint, with lib1 unrelocated. + with_complaints 1 { + gdb_load $lib1 + set test "Zero address complaint - unrelocated - psymtab" + set have_complaint [regexp $re.* $gdb_file_cmd_msg] + if { $have_complaint } { + pass $test + } else { + set index [have_index $lib1] + if { $index == "gdb_index" } { + kfail symtab/28159 $test + } else { + fail $test + } + } + } + + if { ! $readnow_p } { + with_complaints 1 { + gdb_test "maint expand-symtabs $srcfile2" $re \ + "Zero address complaint - unrelocated - symtab" + } + } +} -- 2.30.2