From 6d263fe46e00afd8af3d609c1afd71d05eaf745e Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Thu, 13 Jan 2022 09:48:18 -0700 Subject: [PATCH] Avoid bad breakpoints with --gc-sections We found a case where --gc-sections can cause gdb to set an invalid breakpoint. In the included test case, gdb will set a breakpoint with two locations, one of which is 0x0. The code in lnp_state_machine::check_line_address is intended to filter out this sort of problem, but in this case, the entire CU is empty, causing unrelocated_lowpc==0x0 -- which circumvents the check. It seems to me that if a CU is empty like this, then it is ok to simply ignore the line table, as there won't be any locations anyway. --- gdb/dwarf2/read.c | 9 +++- gdb/testsuite/gdb.ada/inline-section-gc.exp | 41 +++++++++++++++++++ .../gdb.ada/inline-section-gc/callee.adb | 23 +++++++++++ .../gdb.ada/inline-section-gc/callee.ads | 17 ++++++++ .../gdb.ada/inline-section-gc/caller.adb | 21 ++++++++++ 5 files changed, 109 insertions(+), 2 deletions(-) create mode 100644 gdb/testsuite/gdb.ada/inline-section-gc.exp create mode 100644 gdb/testsuite/gdb.ada/inline-section-gc/callee.adb create mode 100644 gdb/testsuite/gdb.ada/inline-section-gc/callee.ads create mode 100644 gdb/testsuite/gdb.ada/inline-section-gc/caller.adb diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 3fe6c3ab90c..f7cb95b40cb 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -10630,8 +10630,13 @@ read_file_scope (struct die_info *die, struct dwarf2_cu *cu) /* Decode line number information if present. We do this before processing child DIEs, so that the line header table is available - for DW_AT_decl_file. */ - handle_DW_AT_stmt_list (die, cu, fnd, lowpc); + for DW_AT_decl_file. The PC check is here because, if LOWPC and + HIGHPC are both 0x0, then there won't be any interesting code in + the CU, but a check later on (in + lnp_state_machine::check_line_address) will fail to properly + exclude an entry that was removed via --gc-sections. */ + if (lowpc != highpc) + handle_DW_AT_stmt_list (die, cu, fnd, lowpc); /* Process all dies in compilation unit. */ if (die->child != NULL) diff --git a/gdb/testsuite/gdb.ada/inline-section-gc.exp b/gdb/testsuite/gdb.ada/inline-section-gc.exp new file mode 100644 index 00000000000..1f6ef667a87 --- /dev/null +++ b/gdb/testsuite/gdb.ada/inline-section-gc.exp @@ -0,0 +1,41 @@ +# Copyright 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 . + +load_lib "ada.exp" + +if { [skip_ada_tests] } { return -1 } + +standard_ada_testfile caller + +set options { + debug + optimize=-O2 + additional_flags=-ffunction-sections + additional_flags=-largs + additional_flags=-Wl,--gc-sections + additional_flags=-margs + additional_flags=-gnatn +} +if {[gdb_compile_ada "${srcfile}" "${binfile}" executable $options] != ""} { + return -1 +} + +clean_restart ${testfile} + +set bp_location [gdb_get_line_number "BREAK" ${testdir}/callee.adb] +# The bug here was that gdb would set a breakpoint with two locations, +# one of them at 0x0. +gdb_test "break callee.adb:$bp_location" \ + "Breakpoint $decimal at $hex: file .*callee.adb, line $bp_location." diff --git a/gdb/testsuite/gdb.ada/inline-section-gc/callee.adb b/gdb/testsuite/gdb.ada/inline-section-gc/callee.adb new file mode 100644 index 00000000000..9ece3cdc20a --- /dev/null +++ b/gdb/testsuite/gdb.ada/inline-section-gc/callee.adb @@ -0,0 +1,23 @@ +-- Copyright 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 . + +with System; + +procedure Callee is + Data : Integer; + for Data'Address use System'To_Address (16#4000_0000#); +begin + Data := 0; -- BREAK +end Callee; diff --git a/gdb/testsuite/gdb.ada/inline-section-gc/callee.ads b/gdb/testsuite/gdb.ada/inline-section-gc/callee.ads new file mode 100644 index 00000000000..e13168d5fb5 --- /dev/null +++ b/gdb/testsuite/gdb.ada/inline-section-gc/callee.ads @@ -0,0 +1,17 @@ +-- Copyright 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 . + +procedure Callee; +pragma Inline (Callee); diff --git a/gdb/testsuite/gdb.ada/inline-section-gc/caller.adb b/gdb/testsuite/gdb.ada/inline-section-gc/caller.adb new file mode 100644 index 00000000000..170227258c4 --- /dev/null +++ b/gdb/testsuite/gdb.ada/inline-section-gc/caller.adb @@ -0,0 +1,21 @@ +-- Copyright 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 . + +with Callee; + +procedure Caller is +begin + Callee; +end Caller; -- 2.30.2