From b58a68fe5709ed205c3ac54065f1783ce58d9a01 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Tue, 9 Jul 2019 19:26:15 +0100 Subject: [PATCH] Fix "info break" + "catch catch" + -static-{libstdc++,libgcc} If you debug current GDB, set a "catch catch/throw/rethrow" catchpoint, and then do "info breakpoints", the top GDB hits an internal error: (top-gdb) catch catch Catchpoint 1 (catch) (top-gdb) info breakpoints Num Type Disp Enb Address What 1 breakpoint keep y src/gdb/breakpoint.c:6040: internal-error: void print_one_breakpoint_location(breakpoint*, bp_location*, int, bp_location**, int): Assertion `b->loc == NULL || b->loc->next == NULL' failed. A problem internal to GDB has been detected, further debugging may prove unreliable. Quit this debugging session? (y or n) The assertion in question is asserting that a breakpoint with a print_one method only has one location, and it fails because this catchpoint ends up with two locations. Internally, "catch catch" sets a breakpoint at __cxa_begin_catch. If we do that manually, we see the locations: (top-gdb) b -qualified __cxa_begin_catch Breakpoint 2 at 0xb122b0 (2 locations) (top-gdb) info breakpoints Num Type Disp Enb Address What 2 breakpoint keep y 2.1 y 0x0000000000b122b0 <__cxa_begin_catch> 2.2 y 0x00007ffff2f4ddb0 in __cxxabiv1::__cxa_begin_catch(void*) at ../../../../libstdc++-v3/libsupc++/eh_catch.cc:41 Note that I had used -qualified. It seems strange that we get a location for a namespaced symbol, but that happens because the minimal symbol for that address is indeed called __cxa_begin_catch. The real issue is that gdb is linked with -static-libgcc/-static-libstdc++. And then, it _also_ ends up with shared libstc++ loaded: (top-gdb) info sharedlibrary stdc++ From To Syms Read Shared Object Library 0x00007ffff2f4b380 0x00007ffff2ffc018 Yes /lib64/libstdc++.so.6 Location 2.2 is set within libstdc++.so.6's range: (top-gdb) p 0x00007ffff2f4b380 <= 0x00007ffff2f4ddb0 && 0x00007ffff2f4ddb0 < 0x00007ffff2ffc018 $1 = true So due to -static-lib*, we end up with _two_ copies of the __cxa_begin_catch code: (top-gdb) disassemble 0x0000000000b122b0 Dump of assembler code for function __cxa_begin_catch: 0x0000000000b122b0 <+0>: push %rbx 0x0000000000b122b1 <+1>: mov %rdi,%rbx 0x0000000000b122b4 <+4>: callq 0xb11a80 <__cxa_get_globals> 0x0000000000b122b9 <+9>: movabs $0xb8b1aabcbcd4d500,%rdx ... (top-gdb) disassemble 0x00007ffff2f4ddb0 Dump of assembler code for function __cxxabiv1::__cxa_begin_catch(void*): 0x00007ffff2f4ddb0 <+0>: push %rbx 0x00007ffff2f4ddb1 <+1>: mov %rdi,%rbx 0x00007ffff2f4ddb4 <+4>: callq 0x7ffff2f4a090 <__cxa_get_globals@plt> 0x00007ffff2f4ddb9 <+9>: movabs $0xb8b1aabcbcd4d500,%rdx ... I think we end up with libstdc++.so.6 loaded because libsource-highlight.so depends on it. Irrespective of whether it's a good idea to use -static-libgcc/-static-libstdc++, GDB should not crash. Since there are two copies of the code, it seems right to have more than one location. So the fix is just to remove the assertion. A testcase is included, which mimics the scenerio described above, with binary linked with -static-lib{stdc++,gcc} and a shared library that is linked normally, along with other combinations for good measure. gdb/ChangeLog: 2019-07-09 Pedro Alves PR c++/15468 * breakpoint.c (print_one_breakpoint_location): Remove single-location assert. gdb/testsuite/ChangeLog: 2019-07-09 Pedro Alves PR c++/15468 * gdb.cp/except-multi-location-lib.cc: New. * gdb.cp/except-multi-location-main.cc: New. * gdb.cp/except-multi-location.exp: New. --- gdb/ChangeLog | 6 ++ gdb/breakpoint.c | 8 +- gdb/testsuite/ChangeLog | 7 ++ .../gdb.cp/except-multi-location-lib.cc | 25 ++++++ .../gdb.cp/except-multi-location-main.cc | 36 ++++++++ .../gdb.cp/except-multi-location.exp | 87 +++++++++++++++++++ 6 files changed, 162 insertions(+), 7 deletions(-) create mode 100644 gdb/testsuite/gdb.cp/except-multi-location-lib.cc create mode 100644 gdb/testsuite/gdb.cp/except-multi-location-main.cc create mode 100644 gdb/testsuite/gdb.cp/except-multi-location.exp diff --git a/gdb/ChangeLog b/gdb/ChangeLog index b1200e9a87b..de2b02ca42b 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2019-07-09 Pedro Alves + + PR c++/15468 + * breakpoint.c (print_one_breakpoint_location): Remove + single-location assert. + 2019-07-09 Tom Tromey * contrib/ari/gdb_ari.sh: Change common to gdbsupport. diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index 00fd76220e2..db46741fd1d 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -6033,13 +6033,7 @@ print_one_breakpoint_location (struct breakpoint *b, /* 5 and 6 */ if (b->ops != NULL && b->ops->print_one != NULL) - { - /* Although the print_one can possibly print all locations, - calling it here is not likely to get any nice result. So, - make sure there's just one location. */ - gdb_assert (b->loc == NULL || b->loc->next == NULL); - b->ops->print_one (b, last_loc); - } + b->ops->print_one (b, last_loc); else switch (b->type) { diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 3df5e587eb0..46a16470446 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,10 @@ +2019-07-09 Pedro Alves + + PR c++/15468 + * gdb.cp/except-multi-location-lib.cc: New. + * gdb.cp/except-multi-location-main.cc: New. + * gdb.cp/except-multi-location.exp: New. + 2019-07-09 Sergio Durigan Junior * gdb.base/printcmds.exp (test_printf_convenience_var): Set diff --git a/gdb/testsuite/gdb.cp/except-multi-location-lib.cc b/gdb/testsuite/gdb.cp/except-multi-location-lib.cc new file mode 100644 index 00000000000..8767d756b33 --- /dev/null +++ b/gdb/testsuite/gdb.cp/except-multi-location-lib.cc @@ -0,0 +1,25 @@ +/* Copyright 2019 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 +trycatch_lib () +{ + try + { + throw 1; + } + catch (...) + { + } +} diff --git a/gdb/testsuite/gdb.cp/except-multi-location-main.cc b/gdb/testsuite/gdb.cp/except-multi-location-main.cc new file mode 100644 index 00000000000..161897a22ee --- /dev/null +++ b/gdb/testsuite/gdb.cp/except-multi-location-main.cc @@ -0,0 +1,36 @@ +/* Copyright 2019 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 trycatch_lib (); + +void +trycatch_main () +{ + try + { + throw 1; + } + catch (...) + { + } +} + +int +main () +{ + trycatch_lib (); + trycatch_main (); + + return 0; +} diff --git a/gdb/testsuite/gdb.cp/except-multi-location.exp b/gdb/testsuite/gdb.cp/except-multi-location.exp new file mode 100644 index 00000000000..60d6d0b9351 --- /dev/null +++ b/gdb/testsuite/gdb.cp/except-multi-location.exp @@ -0,0 +1,87 @@ +# Copyright 2019 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 . + +# Regression test for a GDB internal error that would trigger if a +# "catch catch" catchpoint ended up with multiple locations. This +# testcase exercises that scenario by building the binary with +# -static-libgcc/-static-libstdc++ and a shared library that depends +# on the libstc++.so DSO (which is how GDB was built and revealed the +# bug), and vice versa. + +if {[skip_shlib_tests]} { + return 0 +} + +# STATIC_BIN indicates whether to build the main binary with +# -static-libgcc/-static-libstdc++. STATIC_LIB is the same, but for +# the shared library. +proc test_multi_libstdcpp {static_bin static_lib} { + global srcdir subdir + global decimal hex + + # Library file. + set libname "except-multi-location-lib" + set srcfile_lib ${srcdir}/${subdir}/${libname}.cc + set binfile_lib [standard_output_file ${libname}-$static_bin-$static_lib.so] + set lib_flags {debug c++} + if {$static_lib} { + lappend lib_flags additional_flags=-static-libgcc additional_flags=-static-libstdc++ + } + + # Binary file. + set testfile "except-multi-location-main" + set srcfile ${srcdir}/${subdir}/${testfile}.cc + set binfile [standard_output_file ${testfile}-$static_bin-$static_lib] + set bin_flags [list debug c++ shlib=${binfile_lib}] + if {$static_bin} { + lappend bin_flags additional_flags=-static-libgcc additional_flags=-static-libstdc++ + } + + if { [gdb_compile_shlib ${srcfile_lib} ${binfile_lib} $lib_flags] != "" + || [gdb_compile ${srcfile} ${binfile} executable $bin_flags] != "" } { + untested "failed to compile" + return -1 + } + + clean_restart + + gdb_load ${binfile} + gdb_load_shlib $binfile_lib + + if ![runto_main] { + fail "can't run to main" + return 0 + } + + gdb_test "catch catch" "Catchpoint \[0-9\]+ \\(catch\\)" \ + "catch catch" + gdb_test "catch throw" "Catchpoint \[0-9\]+ \\(throw\\)" \ + "catch throw" + gdb_test "catch rethrow" "Catchpoint \[0-9\]+ \\(rethrow\\)" \ + "catch rethrow" + + set ws "\[ \t\]*" + gdb_test "info breakpoints" \ + [multi_line \ + "${decimal}${ws}breakpoint${ws}keep${ws}y${ws}${hex}${ws}exception catch" \ + "${decimal}${ws}breakpoint${ws}keep${ws}y${ws}${hex}${ws}exception throw" \ + "${decimal}${ws}breakpoint${ws}keep${ws}y${ws}${hex}${ws}exception rethrow"] +} + +# Try different static/not-static combinations. +foreach_with_prefix static_lib {"0" "1"} { + foreach_with_prefix static_bin {"0" "1"} { + test_multi_libstdcpp $static_lib $static_bin + } +} -- 2.30.2