primary Rust gdb development branch/repo? #39

m4b · 2017-12-03T03:29:10Z

There are a dizzying array of branches in gdb, and I'm also unfamiliar with its open source development process.

But basically:

when I'm running my gdb from my distro, say GNU gdb (GDB) 8.0.1, what branch was eventually used in its compilation, was it just whatever is in the 8.0.1 tag (if there is one?) and which upstream git repo would that be in?
Where would you say the major gdb development for rust features is taking place? Specifically I want to add things and also investigate some unusual behavior, and it looks like there's a lot of activity, but again the number of branches makes it hard.

If a lot of the features are taking place here,I'd propose collecting a list of the hot branches, or at least some fairly decent representative of what has a chance of going into the next tagged release of upstream gdb, as well as perhaps having future branches prefix rust_ or something to easily disambiguate them.

Again, not sure if this is even the right place to bring this up...!

The text was updated successfully, but these errors were encountered:

tromey · 2017-12-03T16:50:52Z

when I'm running my gdb from my distro, say GNU gdb (GDB) 8.0.1, what branch was eventually used in its compilation, was it just whatever is in the 8.0.1 tag (if there is one?) and which upstream git repo would that be in?

Distros generally take something from the main gdb repository -- either a release or sometimes a branch (it's complicated but Fedora at least is sometimes a bit newer). For upstream look here: https://sourceware.org/gdb/current/; git repo is git://sourceware.org/git/binutils-gdb.git. gdb release branches tend to have names like "gdb-8.0-branch".

If you're doing development on gdb, just check out master from that repository.

Where would you say the major gdb development for rust features is taking place?

Upstream. gdb is primarily mailing-list based, so you would want to follow the "gdb-patches" mailing list. There's also the file gdb/CONTRIBUTE in the source tree that might be reasonably accurate :)

gdb's bugzilla has some known Rust issues. See the list; but there are a couple I know of that I still haven't filed. When a Rust bug is fixed, I just close it and set the target milestone to the next release; so you can search closed ones to see what might be fixed in the next release.

If a lot of the features are taking place here

This is really just my personal repository where I stash things and sometimes develop features (but there's other stuff I never push...). A few gdb folks have these.

I should probably go through and close all the issues here, those were from when I was working on the initial rust support -- but that's all landed upstream now.

Again, not sure if this is even the right place to bring this up...!

Not technically but it doesn't matter :)

We should definitely coordinate our efforts. You have to jump through hoops to get a new bugzilla account nowadays (spam...), but that would be a good way to go. I'm working full-time on Rust debugging right now, but most of my time is taken up working on the lldb plugin.

m4b · 2017-12-13T05:47:00Z

Hey thanks so much for this response! I've run into a couple issues while investigating stuff related to the debugging issues i opened on rust repo; i'm starting to realize some of the issues also appear to be exacerbated by the gdb rust language support not working properly in some cases. I'll ping you with an example in a rustc PR in a little bit if you don't mind!

When running the test gdb.dwarf2/dw2-bad-parameter-type.exp under valgrind, I see the following issue reported (on x86-64 Fedora): (gdb) ptype f ==5203== Invalid read of size 1 ==5203== at 0x6931FE: process_die_scope::~process_die_scope() (dwarf2read.c:10642) ==5203== by 0x66818F: process_die(die_info*, dwarf2_cu*) (dwarf2read.c:10664) ==5203== by 0x66A01F: read_file_scope(die_info*, dwarf2_cu*) (dwarf2read.c:11650) ==5203== by 0x667F2D: process_die(die_info*, dwarf2_cu*) (dwarf2read.c:10672) ==5203== by 0x6677B6: process_full_comp_unit(dwarf2_per_cu_data*, language) (dwarf2read.c:10445) ==5203== by 0x66657A: process_queue(dwarf2_per_objfile*) (dwarf2read.c:9945) ==5203== by 0x6559B4: dw2_do_instantiate_symtab(dwarf2_per_cu_data*) (dwarf2read.c:3163) ==5203== by 0x66683D: psymtab_to_symtab_1(partial_symtab*) (dwarf2read.c:10034) ==5203== by 0x66622A: dwarf2_read_symtab(partial_symtab*, objfile*) (dwarf2read.c:9811) ==5203== by 0x787984: psymtab_to_symtab(objfile*, partial_symtab*) (psymtab.c:792) ==5203== by 0x786E3E: psym_lookup_symbol(objfile*, int, char const*, domain_enum_tag) (psymtab.c:522) ==5203== by 0x804BD0: lookup_symbol_via_quick_fns(objfile*, int, char const*, domain_enum_tag) (symtab.c:2383) ==5203== Address 0x147ed063 is 291 bytes inside a block of size 4,064 free'd ==5203== at 0x4C2CD5A: free (vg_replace_malloc.c:530) ==5203== by 0x444415: void xfree<void>(void*) (common-utils.h:60) ==5203== by 0x9DA8C2: call_freefun (obstack.c:103) ==5203== by 0x9DAD35: _obstack_free (obstack.c:280) ==5203== by 0x44464C: auto_obstack::~auto_obstack() (gdb_obstack.h:73) ==5203== by 0x68AFB0: dwarf2_cu::~dwarf2_cu() (dwarf2read.c:25080) ==5203== by 0x68B204: free_one_cached_comp_unit(dwarf2_per_cu_data*) (dwarf2read.c:25174) ==5203== by 0x66668C: dwarf2_release_queue(void*) (dwarf2read.c:9982) ==5203== by 0x563A4C: do_my_cleanups(cleanup**, cleanup*) (cleanups.c:154) ==5203== by 0x563AA7: do_cleanups(cleanup*) (cleanups.c:176) ==5203== by 0x5646CE: throw_exception_cxx(gdb_exception) (common-exceptions.c:289) ==5203== by 0x5647B7: throw_exception(gdb_exception) (common-exceptions.c:317) ==5203== Block was alloc'd at ==5203== at 0x4C2BBAD: malloc (vg_replace_malloc.c:299) ==5203== by 0x564BE8: xmalloc (common-utils.c:44) ==5203== by 0x9DA872: call_chunkfun (obstack.c:94) ==5203== by 0x9DA935: _obstack_begin_worker (obstack.c:141) ==5203== by 0x9DAA3C: _obstack_begin (obstack.c:164) ==5203== by 0x4445E0: auto_obstack::auto_obstack() (gdb_obstack.h:70) ==5203== by 0x68AE07: dwarf2_cu::dwarf2_cu(dwarf2_per_cu_data*) (dwarf2read.c:25073) ==5203== by 0x661A8A: init_cutu_and_read_dies(dwarf2_per_cu_data*, abbrev_table*, int, int, void (*)(die_reader_specs const*, unsigned char const*, die_info*, int, void*), void*) (dwarf2read.c:7869) ==5203== by 0x666A29: load_full_comp_unit(dwarf2_per_cu_data*, language) (dwarf2read.c:10108) ==5203== by 0x655847: load_cu(dwarf2_per_cu_data*) (dwarf2read.c:3120) ==5203== by 0x655928: dw2_do_instantiate_symtab(dwarf2_per_cu_data*) (dwarf2read.c:3148) ==5203== by 0x66683D: psymtab_to_symtab_1(partial_symtab*) (dwarf2read.c:10034) There's actually a series of three issues reported, but it turns out they're all related, so we can consider on the first one. The invalid read is triggered from a destructor which is being invoked as part of a stack unwind after throwing an error. At the time the error is thrown, the stack looks like this: #0 0x00000000009f4ecd in __cxa_throw () #1 0x0000000000564761 in throw_exception_cxx (exception=...) at ../../src/gdb/common/common-exceptions.c:303 #2 0x00000000005647b8 in throw_exception (exception=...) at ../../src/gdb/common/common-exceptions.c:317 #3 0x00000000005648ff in throw_it(return_reason, errors, const char *, typedef __va_list_tag __va_list_tag *) (reason=RETURN_ERROR, error=GENERIC_ERROR, fmt=0xb33020 "Dwarf Error: Cannot find DIE at 0x%x referenced from DIE at 0x%x [in module %s]", ap=0x7fff387f2d68) at ../../src/gdb/common/common-exceptions.c:373 #4 0x0000000000564929 in throw_verror (error=GENERIC_ERROR, fmt=0xb33020 "Dwarf Error: Cannot find DIE at 0x%x referenced from DIE at 0x%x [in module %s]", ap=0x7fff387f2d68) at ../../src/gdb/common/common-exceptions.c:379 #5 0x0000000000867be4 in verror (string=0xb33020 "Dwarf Error: Cannot find DIE at 0x%x referenced from DIE at 0x%x [in module %s]", args=0x7fff387f2d68) at ../../src/gdb/utils.c:251 #6 0x000000000056879d in error (fmt=0xb33020 "Dwarf Error: Cannot find DIE at 0x%x referenced from DIE at 0x%x [in module %s]") at ../../src/gdb/common/errors.c:43 #7 0x0000000000686875 in follow_die_ref (src_die=0x30bc8a0, attr=0x30bc8c8, ref_cu=0x7fff387f2ed0) at ../../src/gdb/dwarf2read.c:22969 #8 0x00000000006844cd in lookup_die_type (die=0x30bc8a0, attr=0x30bc8c8, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:21976 #9 0x0000000000683f27 in die_type (die=0x30bc8a0, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:21832 #10 0x0000000000679b39 in read_subroutine_type (die=0x30bc830, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:17343 #11 0x00000000006845fb in read_type_die_1 (die=0x30bc830, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:22035 #12 0x0000000000684576 in read_type_die (die=0x30bc830, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:22010 #13 0x000000000067003f in read_func_scope (die=0x30bc830, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:13822 #14 0x0000000000667f5e in process_die (die=0x30bc830, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:10679 #15 0x000000000066a020 in read_file_scope (die=0x30bc720, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:11650 #16 0x0000000000667f2e in process_die (die=0x30bc720, cu=0x30bc5d0) at ../../src/gdb/dwarf2read.c:10672 #17 0x00000000006677b7 in process_full_comp_unit (per_cu=0x3089b80, pretend_language=language_minimal) at ../../src/gdb/dwarf2read.c:10445 #18 0x000000000066657b in process_queue (dwarf2_per_objfile=0x30897d0) at ../../src/gdb/dwarf2read.c:9945 #19 0x00000000006559b5 in dw2_do_instantiate_symtab (per_cu=0x3089b80) at ../../src/gdb/dwarf2read.c:3163 #20 0x000000000066683e in psymtab_to_symtab_1 (pst=0x3089bd0) at ../../src/gdb/dwarf2read.c:10034 #21 0x000000000066622b in dwarf2_read_symtab (self=0x3089bd0, objfile=0x3073f40) at ../../src/gdb/dwarf2read.c:9811 #22 0x0000000000787985 in psymtab_to_symtab (objfile=0x3073f40, pst=0x3089bd0) at ../../src/gdb/psymtab.c:792 #23 0x0000000000786e3f in psym_lookup_symbol (objfile=0x3073f40, block_index=1, name=0x30b2e30 "f", domain=VAR_DOMAIN) at ../../src/gdb/psymtab.c:522 #24 0x0000000000804bd1 in lookup_symbol_via_quick_fns (objfile=0x3073f40, block_index=1, name=0x30b2e30 "f", domain=VAR_DOMAIN) at ../../src/gdb/symtab.c:2383 #25 0x0000000000804fe4 in lookup_symbol_in_objfile (objfile=0x3073f40, block_index=1, name=0x30b2e30 "f", domain=VAR_DOMAIN) at ../../src/gdb/symtab.c:2558 #26 0x0000000000805125 in lookup_static_symbol (name=0x30b2e30 "f", domain=VAR_DOMAIN) at ../../src/gdb/symtab.c:2595 #27 0x0000000000804357 in lookup_symbol_aux (name=0x30b2e30 "f", match_type=symbol_name_match_type::FULL, block=0x0, domain=VAR_DOMAIN, language=language_c, is_a_field_of_this=0x0) at ../../src/gdb/symtab.c:2105 #28 0x0000000000803ad9 in lookup_symbol_in_language (name=0x30b2e30 "f", block=0x0, domain=VAR_DOMAIN, lang=language_c, is_a_field_of_this=0x0) at ../../src/gdb/symtab.c:1887 #29 0x0000000000803b53 in lookup_symbol (name=0x30b2e30 "f", block=0x0, domain=VAR_DOMAIN, is_a_field_of_this=0x0) at ../../src/gdb/symtab.c:1899 #30 0x000000000053b246 in classify_name (par_state=0x7fff387f6090, block=0x0, is_quoted_name=false, is_after_structop=false) at ../../src/gdb/c-exp.y:2879 #31 0x000000000053b7e9 in c_yylex () at ../../src/gdb/c-exp.y:3083 #32 0x000000000053414a in c_yyparse () at c-exp.c:1903 #33 0x000000000053c2e7 in c_parse (par_state=0x7fff387f6090) at ../../src/gdb/c-exp.y:3255 #34 0x0000000000774a02 in parse_exp_in_context_1 (stringptr=0x7fff387f61c0, pc=0, block=0x0, comma=0, void_context_p=0, out_subexp=0x0) at ../../src/gdb/parse.c:1213 #35 0x000000000077476a in parse_exp_in_context (stringptr=0x7fff387f61c0, pc=0, block=0x0, comma=0, void_context_p=0, out_subexp=0x0) at ../../src/gdb/parse.c:1115 #36 0x0000000000774714 in parse_exp_1 (stringptr=0x7fff387f61c0, pc=0, block=0x0, comma=0) at ../../src/gdb/parse.c:1106 #37 0x0000000000774c53 in parse_expression (string=0x27ff996 "f") at ../../src/gdb/parse.c:1253 #38 0x0000000000861dc4 in whatis_exp (exp=0x27ff996 "f", show=1) at ../../src/gdb/typeprint.c:472 #39 0x00000000008620d8 in ptype_command (type_name=0x27ff996 "f", from_tty=1) at ../../src/gdb/typeprint.c:561 #40 0x000000000047430b in do_const_cfunc (c=0x3012010, args=0x27ff996 "f", from_tty=1) at ../../src/gdb/cli/cli-decode.c:106 #41 0x000000000047715e in cmd_func (cmd=0x3012010, args=0x27ff996 "f", from_tty=1) at ../../src/gdb/cli/cli-decode.c:1886 #42 0x00000000008431bb in execute_command (p=0x27ff996 "f", from_tty=1) at ../../src/gdb/top.c:630 #43 0x00000000006bf946 in command_handler (command=0x27ff990 "ptype f") at ../../src/gdb/event-top.c:583 #44 0x00000000006bfd12 in command_line_handler (rl=0x30bb3a0 "\240\305\v\003") at ../../src/gdb/event-top.c:774 The problem is that in `process_die` (frames 14 and 16) we create a `process_die_scope` object, that takes a copy of the `struct dwarf2_cu *` passed into the frame. The destructor of the `process_die_scope` dereferences the stored pointer. This wouldn't be an issue, except... ... in dw2_do_instantiate_symtab (frame 19) a clean up was registered that clears the dwarf2_queue in case of an error. Part of this clean up involves deleting the `struct dwarf2_cu`s referenced from the queue.. The problem then, is that cleanups are processed at the site of the throw, while, class destructors are invoked as we unwind their frame. The result is that we process the frame 19 cleanup (and delete the struct dwarf2_cu) before we process the destructors in frames 14 and 16. When we do get back to frames 14 and 16 the objects being references have already been deleted. The solution is to remove the cleanup from dw2_do_instantiate_symtab, and instead use a destructor to release the dwarf2_queue instead. With this patch in place, the valgrind errors are now resolved. gdb/ChangeLog: * dwarf2read.c (dwarf2_release_queue): Delete function, move body into... (class dwarf2_queue_guard): ...the destructor of this new class. (dw2_do_instantiate_symtab): Create instance of the new class dwarf2_queue_guard, remove cleanup.

tromey · 2018-05-14T17:25:45Z

Finally closing this. Feel free to ask questions here; but as noted before main development is upstream.

… when attaching / handling a fork child When trying to attach to a pthread process on a Linux system with glibc 2.33, we get: $ ./gdb -q -nx --data-directory=data-directory -p 1472010 Attaching to process 1472010 [New LWP 1472013] [New LWP 1472014] [New LWP 1472015] Error while reading shared library symbols for /usr/lib/libpthread.so.0: Cannot find user-level thread for LWP 1472015: generic error 0x00007ffff6d3637f in poll () from /usr/lib/libc.so.6 (gdb) When attaching to a process (or handling a fork child, an operation very similar to attaching), GDB reads the shared library list from the process. For each shared library (if "set auto-solib-add" is on), it reads its symbols and calls the "new_objfile" observable. The libthread-db code monitors this observable, and if it sees an objfile named somewhat like "libpthread.so" go by, it tries to load libthread_db.so in the GDB process itself. libthread_db knows how to navigate libpthread's data structures to get information about the existing threads. To locate these data structures, libthread_db calls ps_pglobal_lookup (implemented in proc-service.c), passing in a symbol name and expecting an address in return. Before glibc 2.33, libthread_db always asked for symbols found in libpthread. There was no ordering problem: since we were always trying to load libthread_db in reaction to processing libpthread (and reading in its symbols) and libthread_db only asked symbols from libpthread, the requested symbols could always be found. Starting with glibc 2.33, libthread_db now asks for a symbol name that can be found in /lib/ld-linux-x86-64.so.2 (_rtld_global). And the ordering in which GDB reads the shared libraries from the inferior when attaching is unfortunate, in that libpthread is processed before ld-linux. So when loading libthread_db in reaction to processing libpthread, and libthread_db requests the symbol that is from ld-linux, GDB is not yet able to supply it. That problematic symbol lookup happens in the thread_from_lwp function, when we call td_ta_map_lwp2thr_p, and an exception is thrown at this point: #0 0x00007ffff6681012 in __cxxabiv1::__cxa_throw (obj=0x60e000006100, tinfo=0x555560033b50 <typeinfo for gdb_exception_error>, dest=0x55555d9404bc <gdb_exception_error::~gdb_exception_error()>) at /build/gcc/src/gcc/libstdc++-v3/libsupc++/eh_throw.cc:78 #1 0x000055555e5d3734 in throw_it(return_reason, errors, const char *, typedef __va_list_tag __va_list_tag *) (reason=RETURN_ERROR, error=GENERIC_ERROR, fmt=0x55555f0c5360 "Cannot find user-level thread for LWP %ld: %s", ap=0x7fffffffaae0) at /home/simark/src/binutils-gdb/gdbsupport/common-exceptions.cc:200 #2 0x000055555e5d37d4 in throw_verror (error=GENERIC_ERROR, fmt=0x55555f0c5360 "Cannot find user-level thread for LWP %ld: %s", ap=0x7fffffffaae0) at /home/simark/src/binutils-gdb/gdbsupport/common-exceptions.cc:208 #3 0x000055555e0b0ed2 in verror (string=0x55555f0c5360 "Cannot find user-level thread for LWP %ld: %s", args=0x7fffffffaae0) at /home/simark/src/binutils-gdb/gdb/utils.c:171 #4 0x000055555e5e898a in error (fmt=0x55555f0c5360 "Cannot find user-level thread for LWP %ld: %s") at /home/simark/src/binutils-gdb/gdbsupport/errors.cc:43 #5 0x000055555d06b4bc in thread_from_lwp (stopped=0x617000035d80, ptid=...) at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:418 #6 0x000055555d07040d in try_thread_db_load_1 (info=0x60c000011140) at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:912 #7 0x000055555d071103 in try_thread_db_load (library=0x55555f0c62a0 "libthread_db.so.1", check_auto_load_safe=false) at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1014 #8 0x000055555d072168 in try_thread_db_load_from_sdir () at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1091 #9 0x000055555d072d1c in thread_db_load_search () at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1146 #10 0x000055555d07365c in thread_db_load () at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1203 #11 0x000055555d07373e in check_for_thread_db () at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1246 #12 0x000055555d0738ab in thread_db_new_objfile (objfile=0x61300000c0c0) at /home/simark/src/binutils-gdb/gdb/linux-thread-db.c:1275 #13 0x000055555bd10740 in std::__invoke_impl<void, void (*&)(objfile*), objfile*> (__f=@0x616000068d88: 0x55555d073745 <thread_db_new_objfile(objfile*)>) at /usr/include/c++/10.2.0/bits/invoke.h:60 #14 0x000055555bd02096 in std::__invoke_r<void, void (*&)(objfile*), objfile*> (__fn=@0x616000068d88: 0x55555d073745 <thread_db_new_objfile(objfile*)>) at /usr/include/c++/10.2.0/bits/invoke.h:153 #15 0x000055555bce0392 in std::_Function_handler<void (objfile*), void (*)(objfile*)>::_M_invoke(std::_Any_data const&, objfile*&&) (__functor=..., __args#0=@0x7fffffffb4a0: 0x61300000c0c0) at /usr/include/c++/10.2.0/bits/std_function.h:291 #16 0x000055555d3595c0 in std::function<void (objfile*)>::operator()(objfile*) const (this=0x616000068d88, __args#0=0x61300000c0c0) at /usr/include/c++/10.2.0/bits/std_function.h:622 #17 0x000055555d356b7f in gdb::observers::observable<objfile*>::notify (this=0x555566727020 <gdb::observers::new_objfile>, args#0=0x61300000c0c0) at /home/simark/src/binutils-gdb/gdb/../gdbsupport/observable.h:106 #18 0x000055555da3f228 in symbol_file_add_with_addrs (abfd=0x61200001ccc0, name=0x6190000d9090 "/usr/lib/libpthread.so.0", add_flags=..., addrs=0x7fffffffbc10, flags=..., parent=0x0) at /home/simark/src/binutils-gdb/gdb/symfile.c:1131 #19 0x000055555da3f763 in symbol_file_add_from_bfd (abfd=0x61200001ccc0, name=0x6190000d9090 "/usr/lib/libpthread.so.0", add_flags=<error reading variable: Cannot access memory at address 0xffffffffffffffb0>, addrs=0x7fffffffbc10, flags=<error reading variable: Cannot access memory at address 0xffffffffffffffc0>, parent=0x0) at /home/simark/src/binutils-gdb/gdb/symfile.c:1167 #20 0x000055555d95f9fa in solib_read_symbols (so=0x6190000d8e80, flags=...) at /home/simark/src/binutils-gdb/gdb/solib.c:681 #21 0x000055555d96233d in solib_add (pattern=0x0, from_tty=0, readsyms=1) at /home/simark/src/binutils-gdb/gdb/solib.c:987 #22 0x000055555d93646e in enable_break (info=0x608000008f20, from_tty=0) at /home/simark/src/binutils-gdb/gdb/solib-svr4.c:2238 #23 0x000055555d93cfc0 in svr4_solib_create_inferior_hook (from_tty=0) at /home/simark/src/binutils-gdb/gdb/solib-svr4.c:3049 #24 0x000055555d96610d in solib_create_inferior_hook (from_tty=0) at /home/simark/src/binutils-gdb/gdb/solib.c:1195 #25 0x000055555cdee318 in post_create_inferior (from_tty=0) at /home/simark/src/binutils-gdb/gdb/infcmd.c:318 #26 0x000055555ce00e6e in setup_inferior (from_tty=0) at /home/simark/src/binutils-gdb/gdb/infcmd.c:2439 #27 0x000055555ce59c34 in handle_one (event=...) at /home/simark/src/binutils-gdb/gdb/infrun.c:4887 #28 0x000055555ce5cd00 in stop_all_threads () at /home/simark/src/binutils-gdb/gdb/infrun.c:5064 #29 0x000055555ce7f0da in stop_waiting (ecs=0x7fffffffd170) at /home/simark/src/binutils-gdb/gdb/infrun.c:8006 #30 0x000055555ce67f5c in handle_signal_stop (ecs=0x7fffffffd170) at /home/simark/src/binutils-gdb/gdb/infrun.c:6062 #31 0x000055555ce63653 in handle_inferior_event (ecs=0x7fffffffd170) at /home/simark/src/binutils-gdb/gdb/infrun.c:5727 #32 0x000055555ce4f297 in fetch_inferior_event () at /home/simark/src/binutils-gdb/gdb/infrun.c:4105 #33 0x000055555cdbe3bf in inferior_event_handler (event_type=INF_REG_EVENT) at /home/simark/src/binutils-gdb/gdb/inf-loop.c:42 #34 0x000055555d018047 in handle_target_event (error=0, client_data=0x0) at /home/simark/src/binutils-gdb/gdb/linux-nat.c:4060 #35 0x000055555e5ea77e in handle_file_event (file_ptr=0x60600008b1c0, ready_mask=1) at /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:575 #36 0x000055555e5eb09c in gdb_wait_for_event (block=0) at /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:701 #37 0x000055555e5e8d19 in gdb_do_one_event () at /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:212 #38 0x000055555dd6e0d4 in wait_sync_command_done () at /home/simark/src/binutils-gdb/gdb/top.c:528 #39 0x000055555dd6e372 in maybe_wait_sync_command_done (was_sync=0) at /home/simark/src/binutils-gdb/gdb/top.c:545 #40 0x000055555d0ec7c8 in catch_command_errors (command=0x55555ce01bb8 <attach_command(char const*, int)>, arg=0x7fffffffe28d "1472010", from_tty=1, do_bp_actions=false) at /home/simark/src/binutils-gdb/gdb/main.c:452 #41 0x000055555d0f03ad in captured_main_1 (context=0x7fffffffdd10) at /home/simark/src/binutils-gdb/gdb/main.c:1149 #42 0x000055555d0f1239 in captured_main (data=0x7fffffffdd10) at /home/simark/src/binutils-gdb/gdb/main.c:1232 #43 0x000055555d0f1315 in gdb_main (args=0x7fffffffdd10) at /home/simark/src/binutils-gdb/gdb/main.c:1257 #44 0x000055555bb70cf9 in main (argc=7, argv=0x7fffffffde88) at /home/simark/src/binutils-gdb/gdb/gdb.c:32 The exception is caught here: #0 __cxxabiv1::__cxa_begin_catch (exc_obj_in=0x60e0000060e0) at /build/gcc/src/gcc/libstdc++-v3/libsupc++/eh_catch.cc:84 #1 0x000055555d95fded in solib_read_symbols (so=0x6190000d8e80, flags=...) at /home/simark/src/binutils-gdb/gdb/solib.c:689 #2 0x000055555d96233d in solib_add (pattern=0x0, from_tty=0, readsyms=1) at /home/simark/src/binutils-gdb/gdb/solib.c:987 #3 0x000055555d93646e in enable_break (info=0x608000008f20, from_tty=0) at /home/simark/src/binutils-gdb/gdb/solib-svr4.c:2238 #4 0x000055555d93cfc0 in svr4_solib_create_inferior_hook (from_tty=0) at /home/simark/src/binutils-gdb/gdb/solib-svr4.c:3049 #5 0x000055555d96610d in solib_create_inferior_hook (from_tty=0) at /home/simark/src/binutils-gdb/gdb/solib.c:1195 #6 0x000055555cdee318 in post_create_inferior (from_tty=0) at /home/simark/src/binutils-gdb/gdb/infcmd.c:318 #7 0x000055555ce00e6e in setup_inferior (from_tty=0) at /home/simark/src/binutils-gdb/gdb/infcmd.c:2439 #8 0x000055555ce59c34 in handle_one (event=...) at /home/simark/src/binutils-gdb/gdb/infrun.c:4887 #9 0x000055555ce5cd00 in stop_all_threads () at /home/simark/src/binutils-gdb/gdb/infrun.c:5064 #10 0x000055555ce7f0da in stop_waiting (ecs=0x7fffffffd170) at /home/simark/src/binutils-gdb/gdb/infrun.c:8006 #11 0x000055555ce67f5c in handle_signal_stop (ecs=0x7fffffffd170) at /home/simark/src/binutils-gdb/gdb/infrun.c:6062 #12 0x000055555ce63653 in handle_inferior_event (ecs=0x7fffffffd170) at /home/simark/src/binutils-gdb/gdb/infrun.c:5727 #13 0x000055555ce4f297 in fetch_inferior_event () at /home/simark/src/binutils-gdb/gdb/infrun.c:4105 #14 0x000055555cdbe3bf in inferior_event_handler (event_type=INF_REG_EVENT) at /home/simark/src/binutils-gdb/gdb/inf-loop.c:42 #15 0x000055555d018047 in handle_target_event (error=0, client_data=0x0) at /home/simark/src/binutils-gdb/gdb/linux-nat.c:4060 #16 0x000055555e5ea77e in handle_file_event (file_ptr=0x60600008b1c0, ready_mask=1) at /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:575 #17 0x000055555e5eb09c in gdb_wait_for_event (block=0) at /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:701 #18 0x000055555e5e8d19 in gdb_do_one_event () at /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:212 #19 0x000055555dd6e0d4 in wait_sync_command_done () at /home/simark/src/binutils-gdb/gdb/top.c:528 #20 0x000055555dd6e372 in maybe_wait_sync_command_done (was_sync=0) at /home/simark/src/binutils-gdb/gdb/top.c:545 #21 0x000055555d0ec7c8 in catch_command_errors (command=0x55555ce01bb8 <attach_command(char const*, int)>, arg=0x7fffffffe28d "1472010", from_tty=1, do_bp_actions=false) at /home/simark/src/binutils-gdb/gdb/main.c:452 #22 0x000055555d0f03ad in captured_main_1 (context=0x7fffffffdd10) at /home/simark/src/binutils-gdb/gdb/main.c:1149 #23 0x000055555d0f1239 in captured_main (data=0x7fffffffdd10) at /home/simark/src/binutils-gdb/gdb/main.c:1232 #24 0x000055555d0f1315 in gdb_main (args=0x7fffffffdd10) at /home/simark/src/binutils-gdb/gdb/main.c:1257 #25 0x000055555bb70cf9 in main (argc=7, argv=0x7fffffffde88) at /home/simark/src/binutils-gdb/gdb/gdb.c:32 Catching the exception at this point means that the thread_db_info object for this inferior will be left in place, despite the failure to load libthread_db. This means that there won't be further attempts at loading libthread_db, because thread_db_load will think that libthread_db is already loaded for this inferior and will always exit early. To fix this, add a try/catch around calling try_thread_db_load_1 in try_thread_db_load, such that if some exception is thrown while trying to load libthread_db, we reset / delete the thread_db_info for that inferior. That alone makes attach work fine again, because check_for_thread_db is called again in the thread_db_inferior_created observer (that happens after we learned about all shared libraries and their symbols), and libthread_db is successfully loaded then. When attaching, I think that the inferior_created observer is a good place to try to load libthread_db: it is called once everything has stabilized, when we learned about all shared libraries. The only problem then is that when we first try (and fail) to load libthread_db, in reaction to learning about libpthread, we show this warning: warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available. This is misleading, because we do succeed in loading it later. So when attaching, I think we shouldn't try to load libthread_db in reaction to the new_objfile events, we should wait until we have learned about all shared libraries (using the inferior_created observable). To do so, add an `in_initial_library_scan` flag to struct inferior. This flag is used to postpone loading libthread_db if we are attaching or handling a fork child. When debugging remotely with GDBserver, the same problem happens, except that the qSymbol mechanism (allowing the remote side to ask GDB for symbols values) is involved. The fix there is the same idea, we make GDB wait until all shared libraries and their symbols are known before sending out a qSymbol packet. This way, we never present the remote side a state where libpthread.so's symbols are known but ld-linux's symbols aren't. gdb/ChangeLog: * inferior.h (class inferior) <in_initial_library_scan>: New. * infcmd.c (post_create_inferior): Set in_initial_library_scan. * infrun.c (follow_fork_inferior): Likewise. * linux-thread-db.c (try_thread_db_load): Catch exception thrown by try_thread_db_load_1 (thread_db_load): Return early if in_initial_library_scan is set. * remote.c (remote_new_objfile): Return early if in_initial_library_scan is set. Change-Id: I7a279836cfbb2b362b4fde11b196b4aab82f5efb

When loading a mach-o (macOS) executable and trying to set a breakpoint, a GDB built with ASan or -D_GLIBCXX_DEBUG will crash with an out-of-bound vector access. This can be reproduced on Linux using the repro files in bug 28017 [1]: $ ./gdb -nx --data-directory=data-directory -q repro/test -ex "b main" -batch /usr/include/c++/11.1.0/debug/vector:445: In function: std::__debug::vector<_Tp, _Allocator>::const_reference std::__debug::vector<_Tp, _Allocator>::operator[](std::__debug::vector<_Tp, _Allocator>::size_type) const [with _Tp = long unsigned int; _Allocator = std::allocator<long unsigned int>; std::__debug::vector<_Tp, _Allocator>::const_reference = const long unsigned int&; std::__debug::vector<_Tp, _Allocator>::size_type = long unsigned int] Error: attempt to subscript container with out-of-bounds index 13, but container only holds 13 elements. Objects involved in the operation: sequence "this" @ 0x0x61300000a590 { type = std::__debug::vector<unsigned long, std::allocator<unsigned long> >; } The out-of-bound access happens here: #0 0x00007ffff6405d22 in raise () from /usr/lib/libc.so.6 #1 0x00007ffff63ef862 in abort () from /usr/lib/libc.so.6 #2 0x00007ffff664e21e in __gnu_debug::_Error_formatter::_M_error() const [clone .cold] from /usr/lib/libstdc++.so.6 #3 0x000055555699e5ff in std::__debug::vector<unsigned long, std::allocator<unsigned long> >::operator[] (this=0x61300000a590, __n=13) at /usr/include/c++/11.1.0/debug/vector:445 #4 0x0000555556a58c17 in objfile::section_offset (this=0x61300000a4c0, section=0x55555bbe4ac0 <_bfd_std_section>) at /home/simark/src/binutils-gdb/gdb/objfiles.h:644 #5 0x0000555556a58cac in obj_section::offset (this=0x62100016d2a8) at /home/simark/src/binutils-gdb/gdb/objfiles.h:838 #6 0x0000555556a58cfa in obj_section::addr (this=0x62100016d2a8) at /home/simark/src/binutils-gdb/gdb/objfiles.h:850 #7 0x000055555779f5f7 in sort_cmp (sect1=0x62100016d2a8, sect2=0x62100016d170) at /home/simark/src/binutils-gdb/gdb/objfiles.c:902 #8 0x00005555577aae35 in __gnu_cxx::__ops::_Iter_comp_iter<bool (*)(obj_section const*, obj_section const*)>::operator()<obj_section**, obj_section**> (this=0x7fffffffa9e0, __it1=0x60c000015970, __it2=0x60c000015940) at /usr/include/c++/11.1.0/bits/predefined_ops.h:158 #9 0x00005555577aa2b8 in std::__insertion_sort<obj_section**, __gnu_cxx::__ops::_Iter_comp_iter<bool (*)(obj_section const*, obj_section const*)> > (__first=0x60c000015940, __last=0x60c0000159c0, __comp=...) at /usr/include/c++/11.1.0/bits/stl_algo.h:1826 #10 0x00005555577a8e26 in std::__final_insertion_sort<obj_section**, __gnu_cxx::__ops::_Iter_comp_iter<bool (*)(obj_section const*, obj_section const*)> > (__first=0x60c000015940, __last=0x60c0000159c0, __comp=...) at /usr/include/c++/11.1.0/bits/stl_algo.h:1871 #11 0x00005555577a723c in std::__sort<obj_section**, __gnu_cxx::__ops::_Iter_comp_iter<bool (*)(obj_section const*, obj_section const*)> > (__first=0x60c000015940, __last=0x60c0000159c0, __comp=...) at /usr/include/c++/11.1.0/bits/stl_algo.h:1957 #12 0x00005555577a50f4 in std::sort<obj_section**, bool (*)(obj_section const*, obj_section const*)> (__first=0x60c000015940, __last=0x60c0000159c0, __comp=0x55555779f4e7 <sort_cmp(obj_section const*, obj_section const*)>) at /usr/include/c++/11.1.0/bits/stl_algo.h:4875 #13 0x00005555577a147e in update_section_map (pspace=0x61200001d2c0, pmap=0x6030000d40b0, pmap_size=0x6030000d40b8) at /home/simark/src/binutils-gdb/gdb/objfiles.c:1165 #14 0x00005555577a19a0 in find_pc_section (pc=0x100003fa0) at /home/simark/src/binutils-gdb/gdb/objfiles.c:1212 #15 0x00005555576dd39e in lookup_minimal_symbol_by_pc_section (pc_in=0x100003fa0, section=0x0, prefer=lookup_msym_prefer::TEXT, previous=0x0) at /home/simark/src/binutils-gdb/gdb/minsyms.c:750 #16 0x00005555576de552 in lookup_minimal_symbol_by_pc (pc=0x100003fa0) at /home/simark/src/binutils-gdb/gdb/minsyms.c:986 #17 0x0000555557d44b54 in find_pc_sect_line (pc=0x100003fa0, section=0x62100016d170, notcurrent=0) at /home/simark/src/binutils-gdb/gdb/symtab.c:3163 #18 0x0000555557d489fa in find_function_start_sal_1 (func_addr=0x100003fa0, section=0x62100016d170, funfirstline=true) at /home/simark/src/binutils-gdb/gdb/symtab.c:3650 #19 0x0000555557d49015 in find_function_start_sal (sym=0x621000191670, funfirstline=true) at /home/simark/src/binutils-gdb/gdb/symtab.c:3706 #20 0x0000555557485283 in symbol_to_sal (result=0x7fffffffbb30, funfirstline=1, sym=0x621000191670) at /home/simark/src/binutils-gdb/gdb/linespec.c:4460 #21 0x00005555574728c2 in convert_linespec_to_sals (state=0x7fffffffc390, ls=0x7fffffffc3e0) at /home/simark/src/binutils-gdb/gdb/linespec.c:2335 #22 0x0000555557475a8e in parse_linespec (parser=0x7fffffffc360, arg=0x60200007a550 "main", match_type=symbol_name_match_type::WILD) at /home/simark/src/binutils-gdb/gdb/linespec.c:2716 #23 0x0000555557479027 in event_location_to_sals (parser=0x7fffffffc360, location=0x606000097be0) at /home/simark/src/binutils-gdb/gdb/linespec.c:3173 #24 0x00005555574798f7 in decode_line_full (location=0x606000097be0, flags=1, search_pspace=0x0, default_symtab=0x0, default_line=0, canonical=0x7fffffffcca0, select_mode=0x0, filter=0x0) at /home/simark/src/binutils-gdb/gdb/linespec.c:3253 #25 0x0000555556b4949f in parse_breakpoint_sals (location=0x606000097be0, canonical=0x7fffffffcca0) at /home/simark/src/binutils-gdb/gdb/breakpoint.c:9134 #26 0x0000555556b6ce95 in create_sals_from_location_default (location=0x606000097be0, canonical=0x7fffffffcca0, type_wanted=bp_breakpoint) at /home/simark/src/binutils-gdb/gdb/breakpoint.c:13819 #27 0x0000555556b645a6 in bkpt_create_sals_from_location (location=0x606000097be0, canonical=0x7fffffffcca0, type_wanted=bp_breakpoint) at /home/simark/src/binutils-gdb/gdb/breakpoint.c:12631 #28 0x0000555556b4badf in create_breakpoint (gdbarch=0x621000152d10, location=0x606000097be0, cond_string=0x0, thread=0, extra_string=0x0, force_condition=false, parse_extra=1, tempflag=0, type_wanted=bp_breakpoint, ignore_count=0, pending_break_support=AUTO_BOOLEAN_AUTO, ops=0x55555bd728a0 <bkpt_breakpoint_ops>, from_tty=0, enabled=1, internal=0, flags=0) at /home/simark/src/binutils-gdb/gdb/breakpoint.c:9410 #29 0x0000555556b4d3b1 in break_command_1 (arg=0x7fffffffe291 "", flag=0, from_tty=0) at /home/simark/src/binutils-gdb/gdb/breakpoint.c:9590 #30 0x0000555556b4dc1b in break_command (arg=0x7fffffffe28d "main", from_tty=0) at /home/simark/src/binutils-gdb/gdb/breakpoint.c:9660 #31 0x0000555556d24ca9 in do_const_cfunc (c=0x61100003a240, args=0x7fffffffe28d "main", from_tty=0) at /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:102 #32 0x0000555556d2fcd3 in cmd_func (cmd=0x61100003a240, args=0x7fffffffe28d "main", from_tty=0) at /home/simark/src/binutils-gdb/gdb/cli/cli-decode.c:2160 #33 0x0000555557e84e93 in execute_command (p=0x7fffffffe290 "n", from_tty=0) at /home/simark/src/binutils-gdb/gdb/top.c:674 #34 0x00005555575a9933 in catch_command_errors (command=0x555557e84043 <execute_command(char const*, int)>, arg=0x7fffffffe28b "b main", from_tty=0, do_bp_actions=true) at /home/simark/src/binutils-gdb/gdb/main.c:523 #35 0x00005555575a9fdb in execute_cmdargs (cmdarg_vec=0x7fffffffd910, file_type=CMDARG_FILE, cmd_type=CMDARG_COMMAND, ret=0x7fffffffd5b0) at /home/simark/src/binutils-gdb/gdb/main.c:618 #36 0x00005555575ad48a in captured_main_1 (context=0x7fffffffdd00) at /home/simark/src/binutils-gdb/gdb/main.c:1322 #37 0x00005555575ada9c in captured_main (data=0x7fffffffdd00) at /home/simark/src/binutils-gdb/gdb/main.c:1343 #38 0x00005555575adb31 in gdb_main (args=0x7fffffffdd00) at /home/simark/src/binutils-gdb/gdb/main.c:1368 #39 0x000055555681e179 in main (argc=8, argv=0x7fffffffde78) at /home/simark/src/binutils-gdb/gdb/gdb.c:32 The section being dealt with at that moment is the special *COM* section: (top-gdb) p section.name $1 = 0x55555a1bbe60 "*COM*" (top-gdb) p section $2 = (bfd_section *) 0x55555bbe4ac0 <_bfd_std_section> I'm not too sure what this section is for, but this is one of four special BFD sections that GDB puts after the regular sections in the objfile::sections and objfile::section_offsets lists. You can check gdb_bfd_section_index to see how they are handled. gdb_bfd_count_sections returns "+ 4" to account for those sections. The problem is that macho_symfile_offsets uses bfd_count_sections instead of gdb_bfd_count_sections when allocating the objfile::section_offsets vector. The vector will therefore contain, say, 13 elements instead of 17. When trying to access the section offset of the *COM* section, the first after the regular sections, we access section_offsets[13], which is out of bounds. Fix that by using gdb_bfd_count_sections instead of bfd_count_sections. I'm fairly confident that this is correct, as this is what default_symfile_offsets does. With this patch, the command shown above terminates normally: $ ./gdb -nx --data-directory=data-directory -q repro/test -ex "b main" -batch Breakpoint 1 at 0x100003fad: file test.c, line 2. [1] https://sourceware.org/bugzilla/show_bug.cgi?id=28017 gdb/ChangeLog: PR gdb/28017 * machoread.c (macho_symfile_offsets): Use gdb_bfd_count_sections to allocate objfile::section_offsets. Change-Id: Ic3a56f46f7232e9f24581f8255fc1ab981935450

As documented in bug 28086, test gdb.btrace/enable-new-thread.exp started failing with commit 0618ae4 ("gdb: optimize all_matching_threads_iterator"): (gdb) record btrace^M (gdb) PASS: gdb.btrace/enable-new-thread.exp: record btrace break 24^M Breakpoint 2 at 0x555555555175: file /home/smarchi/src/binutils-gdb/gdb/testsuite/gdb.btrace/enable-new-thread.c, line 24.^M (gdb) continue^M Continuing.^M /home/smarchi/src/binutils-gdb/gdb/inferior.c:303: internal-error: inferior* find_inferior_pid(process_stratum_target*, int): Assertion `pid != 0' failed.^M A problem internal to GDB has been detected,^M further debugging may prove unreliable.^M Quit this debugging session? (y or n) FAIL: gdb.btrace/enable-new-thread.exp: continue to breakpoint: cont to bp.1 (GDB internal error) Note that I only see the failure if GDB is compiled without libipt support. This is because GDB then makes use BTS instead of PT, so exercises different code paths. I think that the commit above just exposed an existing problem. The stack trace of the internal error is: #8 0x0000561cb81e404e in internal_error (file=0x561cb83aa2f8 "/home/smarchi/src/binutils-gdb/gdb/inferior.c", line=303, fmt=0x561cb83aa099 "%s: Assertion `%s' failed.") at /home/smarchi/src/binutils-gdb/gdbsupport/errors.cc:55 #9 0x0000561cb7b5c031 in find_inferior_pid (targ=0x561cb8aafb60 <the_amd64_linux_nat_target>, pid=0) at /home/smarchi/src/binutils-gdb/gdb/inferior.c:303 #10 0x0000561cb7b5c102 in find_inferior_ptid (targ=0x561cb8aafb60 <the_amd64_linux_nat_target>, ptid=...) at /home/smarchi/src/binutils-gdb/gdb/inferior.c:317 #11 0x0000561cb7f1d1c3 in find_thread_ptid (targ=0x561cb8aafb60 <the_amd64_linux_nat_target>, ptid=...) at /home/smarchi/src/binutils-gdb/gdb/thread.c:487 #12 0x0000561cb7f1b921 in all_matching_threads_iterator::all_matching_threads_iterator (this=0x7ffc4ee34678, filter_target=0x561cb8aafb60 <the_amd64_linux_nat_target>, filter_ptid=...) at /home/smarchi/src/binutils-gdb/gdb/thread-iter.c:125 #13 0x0000561cb77bc462 in filtered_iterator<all_matching_threads_iterator, non_exited_thread_filter>::filtered_iterator<process_stratum_target* const&, ptid_t const&> (this=0x7ffc4ee34670) at /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/filtered-iterator.h:42 #14 0x0000561cb77b97cb in all_non_exited_threads_range::begin (this=0x7ffc4ee34650) at /home/smarchi/src/binutils-gdb/gdb/thread-iter.h:243 #15 0x0000561cb7d8ba30 in record_btrace_target::record_is_replaying (this=0x561cb8aa6250 <record_btrace_ops>, ptid=...) at /home/smarchi/src/binutils-gdb/gdb/record-btrace.c:1411 #16 0x0000561cb7d8bb83 in record_btrace_target::xfer_partial (this=0x561cb8aa6250 <record_btrace_ops>, object=TARGET_OBJECT_MEMORY, annex=0x0, readbuf=0x7ffc4ee34c58 "\260g\343N\374\177", writebuf=0x0, offset=140737352774277, len=1, xfered_len=0x7ffc4ee34ad8) at /home/smarchi/src/binutils-gdb/gdb/record-btrace.c:1437 #17 0x0000561cb7ef73a9 in raw_memory_xfer_partial (ops=0x561cb8aa6250 <record_btrace_ops>, readbuf=0x7ffc4ee34c58 "\260g\343N\374\177", writebuf=0x0, memaddr=140737352774277, len=1, xfered_len=0x7ffc4ee34ad8) at /home/smarchi/src/binutils-gdb/gdb/target.c:1504 #18 0x0000561cb7ef77da in memory_xfer_partial_1 (ops=0x561cb8aa6250 <record_btrace_ops>, object=TARGET_OBJECT_CODE_MEMORY, readbuf=0x7ffc4ee34c58 "\260g\343N\374\177", writebuf=0x0, memaddr=140737352774277, len=1, xfered_len=0x7ffc4ee34ad8) at /home/smarchi/src/binutils-gdb/gdb/target.c:1635 #19 0x0000561cb7ef78b5 in memory_xfer_partial (ops=0x561cb8aa6250 <record_btrace_ops>, object=TARGET_OBJECT_CODE_MEMORY, readbuf=0x7ffc4ee34c58 "\260g\343N\374\177", writebuf=0x0, memaddr=140737352774277, len=1, xfered_len=0x7ffc4ee34ad8) at /home/smarchi/src/binutils-gdb/gdb/target.c:1664 #20 0x0000561cb7ef7ba4 in target_xfer_partial (ops=0x561cb8aa6250 <record_btrace_ops>, object=TARGET_OBJECT_CODE_MEMORY, annex=0x0, readbuf=0x7ffc4ee34c58 "\260g\343N\374\177", writebuf=0x0, offset=140737352774277, len=1, xfered_len=0x7ffc4ee34ad8) at /home/smarchi/src/binutils-gdb/gdb/target.c:1721 #21 0x0000561cb7ef8503 in target_read_partial (ops=0x561cb8aa6250 <record_btrace_ops>, object=TARGET_OBJECT_CODE_MEMORY, annex=0x0, buf=0x7ffc4ee34c58 "\260g\343N\374\177", offset=140737352774277, len=1, xfered_len=0x7ffc4ee34ad8) at /home/smarchi/src/binutils-gdb/gdb/target.c:1974 #22 0x0000561cb7ef861f in target_read (ops=0x561cb8aa6250 <record_btrace_ops>, object=TARGET_OBJECT_CODE_MEMORY, annex=0x0, buf=0x7ffc4ee34c58 "\260g\343N\374\177", offset=140737352774277, len=1) at /home/smarchi/src/binutils-gdb/gdb/target.c:2014 #23 0x0000561cb7ef809f in target_read_code (memaddr=140737352774277, myaddr=0x7ffc4ee34c58 "\260g\343N\374\177", len=1) at /home/smarchi/src/binutils-gdb/gdb/target.c:1869 #24 0x0000561cb7937f4d in gdb_disassembler::dis_asm_read_memory (memaddr=140737352774277, myaddr=0x7ffc4ee34c58 "\260g\343N\374\177", len=1, info=0x7ffc4ee34e88) at /home/smarchi/src/binutils-gdb/gdb/disasm.c:139 #25 0x0000561cb80ab66d in fetch_data (info=0x7ffc4ee34e88, addr=0x7ffc4ee34c59 "g\343N\374\177") at /home/smarchi/src/binutils-gdb/opcodes/i386-dis.c:194 #26 0x0000561cb80ab7e2 in ckprefix () at /home/smarchi/src/binutils-gdb/opcodes/i386-dis.c:8628 #27 0x0000561cb80adbd8 in print_insn (pc=140737352774277, info=0x7ffc4ee34e88) at /home/smarchi/src/binutils-gdb/opcodes/i386-dis.c:9587 #28 0x0000561cb80abe4f in print_insn_i386 (pc=140737352774277, info=0x7ffc4ee34e88) at /home/smarchi/src/binutils-gdb/opcodes/i386-dis.c:8894 #29 0x0000561cb7744a19 in default_print_insn (memaddr=140737352774277, info=0x7ffc4ee34e88) at /home/smarchi/src/binutils-gdb/gdb/arch-utils.c:1029 #30 0x0000561cb7b33067 in i386_print_insn (pc=140737352774277, info=0x7ffc4ee34e88) at /home/smarchi/src/binutils-gdb/gdb/i386-tdep.c:4013 #31 0x0000561cb7acd8f4 in gdbarch_print_insn (gdbarch=0x561cbae2fb60, vma=140737352774277, info=0x7ffc4ee34e88) at /home/smarchi/src/binutils-gdb/gdb/gdbarch.c:3478 #32 0x0000561cb793a32d in gdb_disassembler::print_insn (this=0x7ffc4ee34e80, memaddr=140737352774277, branch_delay_insns=0x0) at /home/smarchi/src/binutils-gdb/gdb/disasm.c:795 #33 0x0000561cb793a5b0 in gdb_print_insn (gdbarch=0x561cbae2fb60, memaddr=140737352774277, stream=0x561cb8ac99f8 <null_stream>, branch_delay_insns=0x0) at /home/smarchi/src/binutils-gdb/gdb/disasm.c:850 #34 0x0000561cb793a631 in gdb_insn_length (gdbarch=0x561cbae2fb60, addr=140737352774277) at /home/smarchi/src/binutils-gdb/gdb/disasm.c:859 #35 0x0000561cb77f53f4 in btrace_compute_ftrace_bts (tp=0x561cbba11210, btrace=0x7ffc4ee35188, gaps=...) at /home/smarchi/src/binutils-gdb/gdb/btrace.c:1107 #36 0x0000561cb77f55f5 in btrace_compute_ftrace_1 (tp=0x561cbba11210, btrace=0x7ffc4ee35180, cpu=0x0, gaps=...) at /home/smarchi/src/binutils-gdb/gdb/btrace.c:1527 #37 0x0000561cb77f5705 in btrace_compute_ftrace (tp=0x561cbba11210, btrace=0x7ffc4ee35180, cpu=0x0) at /home/smarchi/src/binutils-gdb/gdb/btrace.c:1560 #38 0x0000561cb77f583b in btrace_add_pc (tp=0x561cbba11210) at /home/smarchi/src/binutils-gdb/gdb/btrace.c:1589 #39 0x0000561cb77f5a86 in btrace_enable (tp=0x561cbba11210, conf=0x561cb8ac6878 <record_btrace_conf>) at /home/smarchi/src/binutils-gdb/gdb/btrace.c:1629 #40 0x0000561cb7d88d26 in record_btrace_enable_warn (tp=0x561cbba11210) at /home/smarchi/src/binutils-gdb/gdb/record-btrace.c:294 #41 0x0000561cb7c603dc in std::__invoke_impl<void, void (*&)(thread_info*), thread_info*> (__f=@0x561cbb6c4878: 0x561cb7d88cdc <record_btrace_enable_warn(thread_info*)>) at /usr/include/c++/10/bits/invoke.h:60 #42 0x0000561cb7c5e5a6 in std::__invoke_r<void, void (*&)(thread_info*), thread_info*> (__fn=@0x561cbb6c4878: 0x561cb7d88cdc <record_btrace_enable_warn(thread_info*)>) at /usr/include/c++/10/bits/invoke.h:153 #43 0x0000561cb7c5dc92 in std::_Function_handler<void (thread_info*), void (*)(thread_info*)>::_M_invoke(std::_Any_data const&, thread_info*&&) (__functor=..., __args#0=@0x7ffc4ee35310: 0x561cbba11210) at /usr/include/c++/10/bits/std_function.h:291 #44 0x0000561cb7f2600f in std::function<void (thread_info*)>::operator()(thread_info*) const (this=0x561cbb6c4878, __args#0=0x561cbba11210) at /usr/include/c++/10/bits/std_function.h:622 #45 0x0000561cb7f23dc8 in gdb::observers::observable<thread_info*>::notify (this=0x561cb8ac5aa0 <gdb::observers::new_thread>, args#0=0x561cbba11210) at /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/observable.h:150 #46 0x0000561cb7f1c436 in add_thread_silent (targ=0x561cb8aafb60 <the_amd64_linux_nat_target>, ptid=...) at /home/smarchi/src/binutils-gdb/gdb/thread.c:263 #47 0x0000561cb7f1c479 in add_thread_with_info (targ=0x561cb8aafb60 <the_amd64_linux_nat_target>, ptid=..., priv=0x561cbb3f7ab0) at /home/smarchi/src/binutils-gdb/gdb/thread.c:272 #48 0x0000561cb7bfa1d0 in record_thread (info=0x561cbb0413a0, tp=0x0, ptid=..., th_p=0x7ffc4ee35610, ti_p=0x7ffc4ee35620) at /home/smarchi/src/binutils-gdb/gdb/linux-thread-db.c:1380 #49 0x0000561cb7bf7a2a in thread_from_lwp (stopped=0x561cba81db20, ptid=...) at /home/smarchi/src/binutils-gdb/gdb/linux-thread-db.c:429 #50 0x0000561cb7bf7ac5 in thread_db_notice_clone (parent=..., child=...) at /home/smarchi/src/binutils-gdb/gdb/linux-thread-db.c:447 #51 0x0000561cb7bdc9a2 in linux_handle_extended_wait (lp=0x561cbae25720, status=4991) at /home/smarchi/src/binutils-gdb/gdb/linux-nat.c:1981 #52 0x0000561cb7bdf0f3 in linux_nat_filter_event (lwpid=435403, status=198015) at /home/smarchi/src/binutils-gdb/gdb/linux-nat.c:2920 #53 0x0000561cb7bdfed6 in linux_nat_wait_1 (ptid=..., ourstatus=0x7ffc4ee36398, target_options=...) at /home/smarchi/src/binutils-gdb/gdb/linux-nat.c:3202 #54 0x0000561cb7be0b68 in linux_nat_target::wait (this=0x561cb8aafb60 <the_amd64_linux_nat_target>, ptid=..., ourstatus=0x7ffc4ee36398, target_options=...) at /home/smarchi/src/binutils-gdb/gdb/linux-nat.c:3440 #55 0x0000561cb7bfa2fc in thread_db_target::wait (this=0x561cb8a9acd0 <the_thread_db_target>, ptid=..., ourstatus=0x7ffc4ee36398, options=...) at /home/smarchi/src/binutils-gdb/gdb/linux-thread-db.c:1412 #56 0x0000561cb7d8e356 in record_btrace_target::wait (this=0x561cb8aa6250 <record_btrace_ops>, ptid=..., status=0x7ffc4ee36398, options=...) at /home/smarchi/src/binutils-gdb/gdb/record-btrace.c:2547 #57 0x0000561cb7ef996d in target_wait (ptid=..., status=0x7ffc4ee36398, options=...) at /home/smarchi/src/binutils-gdb/gdb/target.c:2608 #58 0x0000561cb7b6d297 in do_target_wait_1 (inf=0x561cba6d8780, ptid=..., status=0x7ffc4ee36398, options=...) at /home/smarchi/src/binutils-gdb/gdb/infrun.c:3640 #59 0x0000561cb7b6d43e in operator() (__closure=0x7ffc4ee36190, inf=0x561cba6d8780) at /home/smarchi/src/binutils-gdb/gdb/infrun.c:3701 #60 0x0000561cb7b6d7b2 in do_target_wait (ecs=0x7ffc4ee36370, options=...) at /home/smarchi/src/binutils-gdb/gdb/infrun.c:3720 #61 0x0000561cb7b6e67d in fetch_inferior_event () at /home/smarchi/src/binutils-gdb/gdb/infrun.c:4069 #62 0x0000561cb7b4659b in inferior_event_handler (event_type=INF_REG_EVENT) at /home/smarchi/src/binutils-gdb/gdb/inf-loop.c:41 #63 0x0000561cb7be25f7 in handle_target_event (error=0, client_data=0x0) at /home/smarchi/src/binutils-gdb/gdb/linux-nat.c:4227 #64 0x0000561cb81e4ee2 in handle_file_event (file_ptr=0x561cbae24e10, ready_mask=1) at /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:575 #65 0x0000561cb81e5490 in gdb_wait_for_event (block=0) at /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:701 #66 0x0000561cb81e41be in gdb_do_one_event () at /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:212 #67 0x0000561cb7c18096 in start_event_loop () at /home/smarchi/src/binutils-gdb/gdb/main.c:421 #68 0x0000561cb7c181e0 in captured_command_loop () at /home/smarchi/src/binutils-gdb/gdb/main.c:481 #69 0x0000561cb7c19d7e in captured_main (data=0x7ffc4ee366a0) at /home/smarchi/src/binutils-gdb/gdb/main.c:1353 #70 0x0000561cb7c19df0 in gdb_main (args=0x7ffc4ee366a0) at /home/smarchi/src/binutils-gdb/gdb/main.c:1368 #71 0x0000561cb7693186 in main (argc=11, argv=0x7ffc4ee367b8) at /home/smarchi/src/binutils-gdb/gdb/gdb.c:32 At frame 45, the new_thread observable is fired. At this moment, the new thread isn't the current thread, inferior_ptid is null_ptid. I think this is ok: the new_thread observable doesn't give any guarantee on the global context when observers are invoked. Frame 35, btrace_compute_ftrace_bts, calls gdb_insn_length. gdb_insn_length doesn't have a thread_info or other parameter what could indicate where to read memory from, it implicitly uses the global context (inferior_ptid). So we reach the all_non_exited_threads_range in record_btrace_target::record_is_replaying with a null inferior_ptid. The previous implemention of all_non_exited_threads_range didn't care, but the new one does. The problem of calling gdb_insn_length and ultimately trying to read memory with a null inferior_ptid already existed, but the commit mentioned above made it visible. Something between frames 40 (record_btrace_enable_warn) and 35 (btrace_compute_ftrace_bts) needs to be switching the global context to make TP the current thread. Since btrace_compute_ftrace_bts takes the thread_info to work with as a parameter, that typically means that it doesn't require its caller to also set the global current context (current thread) when calling. If it needs to call other functions that do require the global current thread to be set, then it needs to temporarily change the current thread while calling these other functions. Therefore, switch and restore the current thread in btrace_compute_ftrace_bts. By inspection, it looks like btrace_compute_ftrace_pt may also call functions sensitive to the global context: it installs the btrace_pt_readmem_callback callback in the PT instruction decoder. When this function gets called, inferior_ptid must be set appropriately. Add a switch and restore in there too. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28086 Change-Id: I407fbfe41aab990068bd102491aa3709b0a034b3

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 <memory> int main() { std::unique_ptr<int> 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<int>") 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

Commit 7a8de0c ("Remove ALL_BREAKPOINTS_SAFE") introduced a use-after-free in the breakpoints iterations (see below for full ASan report). This makes gdb.base/stale-infcall.exp fail when GDB is build with ASan. check_longjmp_breakpoint_for_call_dummy iterates on all breakpoints, possibly deleting the current breakpoint as well as related breakpoints. The problem arises when a breakpoint in the B->related_breakpoint chain is also B->next. In that case, deleting that related breakpoint frees the breakpoint that all_breakpoints_safe has saved. The old code worked around that by manually changing B_TMP, which was the next breakpoint saved by the "safe iterator": while (b->related_breakpoint != b) { if (b_tmp == b->related_breakpoint) b_tmp = b->related_breakpoint->next; delete_breakpoint (b->related_breakpoint); } (Note that this seemed to assume that b->related_breakpoint->next was the same as b->next->next, not sure this is guaranteed.) The new code kept the B_TMP variable, but it's not useful in that context. We can't go change the next breakpoint as saved by the safe iterator, like we did before. I suggest fixing that by saving the breakpoints to delete in a map and deleting them all at the end. Here's the full ASan report: (gdb) PASS: gdb.base/stale-infcall.exp: continue to breakpoint: break-run1 print infcall () ================================================================= ==47472==ERROR: AddressSanitizer: heap-use-after-free on address 0x611000034980 at pc 0x563f7012c7bc bp 0x7ffdf3804d70 sp 0x7ffdf3804d60 READ of size 8 at 0x611000034980 thread T0 #0 0x563f7012c7bb in next_iterator<breakpoint>::operator++() /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/next-iterator.h:66 #1 0x563f702ce8c0 in basic_safe_iterator<next_iterator<breakpoint> >::operator++() /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/safe-iterator.h:84 #2 0x563f7021522a in check_longjmp_breakpoint_for_call_dummy(thread_info*) /home/smarchi/src/binutils-gdb/gdb/breakpoint.c:7611 #3 0x563f714567b1 in process_event_stop_test /home/smarchi/src/binutils-gdb/gdb/infrun.c:6881 #4 0x563f71454e07 in handle_signal_stop /home/smarchi/src/binutils-gdb/gdb/infrun.c:6769 #5 0x563f7144b680 in handle_inferior_event /home/smarchi/src/binutils-gdb/gdb/infrun.c:6023 #6 0x563f71436165 in fetch_inferior_event() /home/smarchi/src/binutils-gdb/gdb/infrun.c:4387 #7 0x563f7136ff51 in inferior_event_handler(inferior_event_type) /home/smarchi/src/binutils-gdb/gdb/inf-loop.c:42 #8 0x563f7168038d in handle_target_event /home/smarchi/src/binutils-gdb/gdb/linux-nat.c:4219 #9 0x563f72fccb6d in handle_file_event /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:573 #10 0x563f72fcd503 in gdb_wait_for_event /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:694 #11 0x563f72fcaf2b in gdb_do_one_event(int) /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:217 #12 0x563f7262b9bb in wait_sync_command_done() /home/smarchi/src/binutils-gdb/gdb/top.c:426 #13 0x563f7137a7c3 in run_inferior_call /home/smarchi/src/binutils-gdb/gdb/infcall.c:650 #14 0x563f71381295 in call_function_by_hand_dummy(value*, type*, gdb::array_view<value*>, void (*)(void*, int), void*) /home/smarchi/src/binutils-gdb/gdb/infcall.c:1332 #15 0x563f7137c0e2 in call_function_by_hand(value*, type*, gdb::array_view<value*>) /home/smarchi/src/binutils-gdb/gdb/infcall.c:780 #16 0x563f70fe5960 in evaluate_subexp_do_call(expression*, noside, value*, gdb::array_view<value*>, char const*, type*) /home/smarchi/src/binutils-gdb/gdb/eval.c:649 #17 0x563f70fe6617 in expr::operation::evaluate_funcall(type*, expression*, noside, char const*, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/eval.c:677 #18 0x563f6fd19668 in expr::operation::evaluate_funcall(type*, expression*, noside, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/expression.h:136 #19 0x563f70fe6bba in expr::var_value_operation::evaluate_funcall(type*, expression*, noside, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/eval.c:689 #20 0x563f704b71dc in expr::funcall_operation::evaluate(type*, expression*, noside) /home/smarchi/src/binutils-gdb/gdb/expop.h:2219 #21 0x563f70fe0f02 in expression::evaluate(type*, noside) /home/smarchi/src/binutils-gdb/gdb/eval.c:110 #22 0x563f71b1373e in process_print_command_args /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1319 #23 0x563f71b1391b in print_command_1 /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1332 #24 0x563f71b147ec in print_command /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1465 #25 0x563f706029b8 in do_simple_func /home/smarchi/src/binutils-gdb/gdb/cli/cli-decode.c:95 #26 0x563f7061972a in cmd_func(cmd_list_element*, char const*, int) /home/smarchi/src/binutils-gdb/gdb/cli/cli-decode.c:2735 #27 0x563f7262d0ef in execute_command(char const*, int) /home/smarchi/src/binutils-gdb/gdb/top.c:572 #28 0x563f7100ed9c in command_handler(char const*) /home/smarchi/src/binutils-gdb/gdb/event-top.c:543 #29 0x563f7101014b in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) /home/smarchi/src/binutils-gdb/gdb/event-top.c:779 #30 0x563f72777942 in tui_command_line_handler /home/smarchi/src/binutils-gdb/gdb/tui/tui-interp.c:104 #31 0x563f7100d059 in gdb_rl_callback_handler /home/smarchi/src/binutils-gdb/gdb/event-top.c:250 #32 0x7f5a80418246 in rl_callback_read_char (/usr/lib/libreadline.so.8+0x3b246) (BuildId: 092e91fc4361b0ef94561e3ae03a75f69398acbb) #33 0x563f7100ca06 in gdb_rl_callback_read_char_wrapper_noexcept /home/smarchi/src/binutils-gdb/gdb/event-top.c:192 #34 0x563f7100cc5e in gdb_rl_callback_read_char_wrapper /home/smarchi/src/binutils-gdb/gdb/event-top.c:225 #35 0x563f728c70db in stdin_event_handler /home/smarchi/src/binutils-gdb/gdb/ui.c:155 #36 0x563f72fccb6d in handle_file_event /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:573 #37 0x563f72fcd503 in gdb_wait_for_event /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:694 #38 0x563f72fcb15c in gdb_do_one_event(int) /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:264 #39 0x563f7177ec1c in start_event_loop /home/smarchi/src/binutils-gdb/gdb/main.c:412 #40 0x563f7177f12e in captured_command_loop /home/smarchi/src/binutils-gdb/gdb/main.c:476 #41 0x563f717846e4 in captured_main /home/smarchi/src/binutils-gdb/gdb/main.c:1320 #42 0x563f71784821 in gdb_main(captured_main_args*) /home/smarchi/src/binutils-gdb/gdb/main.c:1339 #43 0x563f6fcedfbd in main /home/smarchi/src/binutils-gdb/gdb/gdb.c:32 #44 0x7f5a7e43984f (/usr/lib/libc.so.6+0x2384f) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e) #45 0x7f5a7e439909 in __libc_start_main (/usr/lib/libc.so.6+0x23909) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e) #46 0x563f6fcedd84 in _start (/home/smarchi/build/binutils-gdb/gdb/gdb+0xafb0d84) (BuildId: 50bd32e6e9d5e84543e9897b8faca34858ca3995) 0x611000034980 is located 0 bytes inside of 208-byte region [0x611000034980,0x611000034a50) freed by thread T0 here: #0 0x7f5a7fce312a in operator delete(void*, unsigned long) /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_new_delete.cpp:164 #1 0x563f702bd1fa in momentary_breakpoint::~momentary_breakpoint() /home/smarchi/src/binutils-gdb/gdb/breakpoint.c:304 #2 0x563f702771c5 in delete_breakpoint(breakpoint*) /home/smarchi/src/binutils-gdb/gdb/breakpoint.c:12404 #3 0x563f702150a7 in check_longjmp_breakpoint_for_call_dummy(thread_info*) /home/smarchi/src/binutils-gdb/gdb/breakpoint.c:7673 #4 0x563f714567b1 in process_event_stop_test /home/smarchi/src/binutils-gdb/gdb/infrun.c:6881 #5 0x563f71454e07 in handle_signal_stop /home/smarchi/src/binutils-gdb/gdb/infrun.c:6769 #6 0x563f7144b680 in handle_inferior_event /home/smarchi/src/binutils-gdb/gdb/infrun.c:6023 #7 0x563f71436165 in fetch_inferior_event() /home/smarchi/src/binutils-gdb/gdb/infrun.c:4387 #8 0x563f7136ff51 in inferior_event_handler(inferior_event_type) /home/smarchi/src/binutils-gdb/gdb/inf-loop.c:42 #9 0x563f7168038d in handle_target_event /home/smarchi/src/binutils-gdb/gdb/linux-nat.c:4219 #10 0x563f72fccb6d in handle_file_event /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:573 #11 0x563f72fcd503 in gdb_wait_for_event /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:694 #12 0x563f72fcaf2b in gdb_do_one_event(int) /home/smarchi/src/binutils-gdb/gdbsupport/event-loop.cc:217 #13 0x563f7262b9bb in wait_sync_command_done() /home/smarchi/src/binutils-gdb/gdb/top.c:426 #14 0x563f7137a7c3 in run_inferior_call /home/smarchi/src/binutils-gdb/gdb/infcall.c:650 #15 0x563f71381295 in call_function_by_hand_dummy(value*, type*, gdb::array_view<value*>, void (*)(void*, int), void*) /home/smarchi/src/binutils-gdb/gdb/infcall.c:1332 #16 0x563f7137c0e2 in call_function_by_hand(value*, type*, gdb::array_view<value*>) /home/smarchi/src/binutils-gdb/gdb/infcall.c:780 #17 0x563f70fe5960 in evaluate_subexp_do_call(expression*, noside, value*, gdb::array_view<value*>, char const*, type*) /home/smarchi/src/binutils-gdb/gdb/eval.c:649 #18 0x563f70fe6617 in expr::operation::evaluate_funcall(type*, expression*, noside, char const*, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/eval.c:677 #19 0x563f6fd19668 in expr::operation::evaluate_funcall(type*, expression*, noside, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/expression.h:136 #20 0x563f70fe6bba in expr::var_value_operation::evaluate_funcall(type*, expression*, noside, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/eval.c:689 #21 0x563f704b71dc in expr::funcall_operation::evaluate(type*, expression*, noside) /home/smarchi/src/binutils-gdb/gdb/expop.h:2219 #22 0x563f70fe0f02 in expression::evaluate(type*, noside) /home/smarchi/src/binutils-gdb/gdb/eval.c:110 #23 0x563f71b1373e in process_print_command_args /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1319 #24 0x563f71b1391b in print_command_1 /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1332 #25 0x563f71b147ec in print_command /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1465 #26 0x563f706029b8 in do_simple_func /home/smarchi/src/binutils-gdb/gdb/cli/cli-decode.c:95 #27 0x563f7061972a in cmd_func(cmd_list_element*, char const*, int) /home/smarchi/src/binutils-gdb/gdb/cli/cli-decode.c:2735 #28 0x563f7262d0ef in execute_command(char const*, int) /home/smarchi/src/binutils-gdb/gdb/top.c:572 #29 0x563f7100ed9c in command_handler(char const*) /home/smarchi/src/binutils-gdb/gdb/event-top.c:543 previously allocated by thread T0 here: #0 0x7f5a7fce2012 in operator new(unsigned long) /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_new_delete.cpp:95 #1 0x563f7029a9a3 in new_momentary_breakpoint<program_space*&, frame_id&, int&> /home/smarchi/src/binutils-gdb/gdb/breakpoint.c:8129 #2 0x563f702212f6 in momentary_breakpoint_from_master /home/smarchi/src/binutils-gdb/gdb/breakpoint.c:8169 #3 0x563f70212db1 in set_longjmp_breakpoint_for_call_dummy() /home/smarchi/src/binutils-gdb/gdb/breakpoint.c:7582 #4 0x563f713804db in call_function_by_hand_dummy(value*, type*, gdb::array_view<value*>, void (*)(void*, int), void*) /home/smarchi/src/binutils-gdb/gdb/infcall.c:1260 #5 0x563f7137c0e2 in call_function_by_hand(value*, type*, gdb::array_view<value*>) /home/smarchi/src/binutils-gdb/gdb/infcall.c:780 #6 0x563f70fe5960 in evaluate_subexp_do_call(expression*, noside, value*, gdb::array_view<value*>, char const*, type*) /home/smarchi/src/binutils-gdb/gdb/eval.c:649 #7 0x563f70fe6617 in expr::operation::evaluate_funcall(type*, expression*, noside, char const*, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/eval.c:677 #8 0x563f6fd19668 in expr::operation::evaluate_funcall(type*, expression*, noside, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/expression.h:136 #9 0x563f70fe6bba in expr::var_value_operation::evaluate_funcall(type*, expression*, noside, std::__debug::vector<std::unique_ptr<expr::operation, std::default_delete<expr::operation> >, std::allocator<std::unique_ptr<expr::operation, std::default_delete<expr::operation> > > > const&) /home/smarchi/src/binutils-gdb/gdb/eval.c:689 #10 0x563f704b71dc in expr::funcall_operation::evaluate(type*, expression*, noside) /home/smarchi/src/binutils-gdb/gdb/expop.h:2219 #11 0x563f70fe0f02 in expression::evaluate(type*, noside) /home/smarchi/src/binutils-gdb/gdb/eval.c:110 #12 0x563f71b1373e in process_print_command_args /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1319 #13 0x563f71b1391b in print_command_1 /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1332 #14 0x563f71b147ec in print_command /home/smarchi/src/binutils-gdb/gdb/printcmd.c:1465 #15 0x563f706029b8 in do_simple_func /home/smarchi/src/binutils-gdb/gdb/cli/cli-decode.c:95 #16 0x563f7061972a in cmd_func(cmd_list_element*, char const*, int) /home/smarchi/src/binutils-gdb/gdb/cli/cli-decode.c:2735 #17 0x563f7262d0ef in execute_command(char const*, int) /home/smarchi/src/binutils-gdb/gdb/top.c:572 #18 0x563f7100ed9c in command_handler(char const*) /home/smarchi/src/binutils-gdb/gdb/event-top.c:543 #19 0x563f7101014b in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) /home/smarchi/src/binutils-gdb/gdb/event-top.c:779 #20 0x563f72777942 in tui_command_line_handler /home/smarchi/src/binutils-gdb/gdb/tui/tui-interp.c:104 #21 0x563f7100d059 in gdb_rl_callback_handler /home/smarchi/src/binutils-gdb/gdb/event-top.c:250 #22 0x7f5a80418246 in rl_callback_read_char (/usr/lib/libreadline.so.8+0x3b246) (BuildId: 092e91fc4361b0ef94561e3ae03a75f69398acbb) Change-Id: Id00c17ab677f847fbf4efdf0f4038373668d3d88 Approved-By: Tom Tromey <[email protected]>

With gdb build with -fsanitize=thread and test-case gdb.base/index-cache.exp I run into: ... (gdb) file build/gdb/testsuite/outputs/gdb.base/index-cache/index-cache Reading symbols from build/gdb/testsuite/outputs/gdb.base/index-cache/index-cache... ================== WARNING: ThreadSanitizer: data race (pid=24296) Write of size 1 at 0x7b200000420d by main thread: #0 queue_comp_unit gdb/dwarf2/read.c:5564 (gdb+0x8939ce) #1 dw2_do_instantiate_symtab gdb/dwarf2/read.c:1754 (gdb+0x885b96) #2 dw2_instantiate_symtab gdb/dwarf2/read.c:1792 (gdb+0x885d86) #3 dw2_expand_symtabs_matching_one(dwarf2_per_cu_data*, dwarf2_per_objfile*, gdb::function_view<bool (char const*, bool)>, gdb::function_view<bool (compunit_symtab*)>) gdb/dwarf2/read.c:3042 (gdb+0x88ac77) #4 cooked_index_functions::expand_symtabs_matching(objfile*, gdb::function_view<bool (char const*, bool)>, lookup_name_info const*, gdb::function_view<bool (char const*)>, gdb::function_view<bool (compunit_symtab*)>, enum_flags<block_search_flag_values>, domain_enum, search_domain) gdb/dwarf2/read.c:16915 (gdb+0x8c1c8a) #5 objfile::lookup_symbol(block_enum, char const*, domain_enum) gdb/symfile-debug.c:288 (gdb+0xf389a1) #6 lookup_symbol_via_quick_fns gdb/symtab.c:2385 (gdb+0xf66403) #7 lookup_symbol_in_objfile gdb/symtab.c:2516 (gdb+0xf66a67) #8 operator() gdb/symtab.c:2562 (gdb+0xf66bbe) #9 operator() gdb/../gdbsupport/function-view.h:305 (gdb+0xf76ffd) #10 _FUN gdb/../gdbsupport/function-view.h:299 (gdb+0xf77054) #11 gdb::function_view<bool (objfile*)>::operator()(objfile*) const gdb/../gdbsupport/function-view.h:289 (gdb+0xc3f5e3) #12 svr4_iterate_over_objfiles_in_search_order gdb/solib-svr4.c:3455 (gdb+0xeca793) #13 gdbarch_iterate_over_objfiles_in_search_order(gdbarch*, gdb::function_view<bool (objfile*)>, objfile*) gdb/gdbarch.c:5041 (gdb+0x537cad) #14 lookup_global_or_static_symbol gdb/symtab.c:2559 (gdb+0xf66e47) #15 lookup_global_symbol(char const*, block const*, domain_enum) gdb/symtab.c:2615 (gdb+0xf670cc) #16 language_defn::lookup_symbol_nonlocal(char const*, block const*, domain_enum) const gdb/symtab.c:2447 (gdb+0xf666ba) #17 lookup_symbol_aux gdb/symtab.c:2123 (gdb+0xf655ff) #18 lookup_symbol_in_language(char const*, block const*, domain_enum, language, field_of_this_result*) gdb/symtab.c:1931 (gdb+0xf646f7) #19 set_initial_language() gdb/symfile.c:1708 (gdb+0xf429c0) #20 symbol_file_add_main_1 gdb/symfile.c:1212 (gdb+0xf40f54) #21 symbol_file_command(char const*, int) gdb/symfile.c:1681 (gdb+0xf428fb) #22 file_command gdb/exec.c:554 (gdb+0x94f875) #23 do_simple_func gdb/cli/cli-decode.c:95 (gdb+0x6d9528) #24 cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735 (gdb+0x6e0f69) #25 execute_command(char const*, int) gdb/top.c:575 (gdb+0xff3166) #26 command_handler(char const*) gdb/event-top.c:552 (gdb+0x94af08) #27 command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:788 (gdb+0x94b5c5) #28 tui_command_line_handler gdb/tui/tui-interp.c:104 (gdb+0x10348c6) #29 gdb_rl_callback_handler gdb/event-top.c:259 (gdb+0x94a4ad) #30 rl_callback_read_char readline/readline/callback.c:290 (gdb+0x11bdf87) #31 gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195 (gdb+0x94a2ac) #32 gdb_rl_callback_read_char_wrapper gdb/event-top.c:234 (gdb+0x94a36d) #33 stdin_event_handler gdb/ui.c:155 (gdb+0x1074b6a) #34 handle_file_event gdbsupport/event-loop.cc:573 (gdb+0x1d9502c) #35 gdb_wait_for_event gdbsupport/event-loop.cc:694 (gdb+0x1d95764) #36 gdb_do_one_event(int) gdbsupport/event-loop.cc:264 (gdb+0x1d93b50) #37 start_event_loop gdb/main.c:412 (gdb+0xb5a49e) #38 captured_command_loop gdb/main.c:476 (gdb+0xb5a68d) #39 captured_main gdb/main.c:1320 (gdb+0xb5c80d) #40 gdb_main(captured_main_args*) gdb/main.c:1339 (gdb+0xb5c8bc) #41 main gdb/gdb.c:32 (gdb+0x416776) Previous read of size 1 at 0x7b200000420d by thread T12: #0 write_gdbindex gdb/dwarf2/index-write.c:1229 (gdb+0x8310c8) #1 write_dwarf_index(dwarf2_per_bfd*, char const*, char const*, char const*, dw_index_kind) gdb/dwarf2/index-write.c:1484 (gdb+0x83232f) #2 index_cache::store(dwarf2_per_bfd*, index_cache_store_context*) gdb/dwarf2/index-cache.c:177 (gdb+0x82d62b) #3 cooked_index::maybe_write_index(dwarf2_per_bfd*) gdb/dwarf2/cooked-index.c:640 (gdb+0x7f1bf7) #4 operator() gdb/dwarf2/cooked-index.c:470 (gdb+0x7f0f40) #5 _M_invoke /usr/include/c++/7/bits/std_function.h:316 (gdb+0x7f2909) #6 std::function<void ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x700952) #7 void std::__invoke_impl<void, std::function<void ()>&>(std::__invoke_other, std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:60 (gdb+0x7381a0) #8 std::__invoke_result<std::function<void ()>&>::type std::__invoke<std::function<void ()>&>(std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x737e91) #9 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()#1}::operator()() const /usr/include/c++/7/future:1421 (gdb+0x737b59) #10 std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()#1}, void>::operator()() const /usr/include/c++/7/future:1362 (gdb+0x738660) #11 std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()#1}, void> >::_M_invoke(std::_Any_data const&) /usr/include/c++/7/bits/std_function.h:302 (gdb+0x73825c) #12 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x733623) #13 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*) /usr/include/c++/7/future:561 (gdb+0x732bdf) #14 void std::__invoke_impl<void, void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::__invoke_memfun_deref, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x734c4f) #15 std::__invoke_result<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>::type std::__invoke<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x733bc5) #16 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()#1}::operator()() const /usr/include/c++/7/mutex:672 (gdb+0x73300d) #17 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()#2}::operator()() const /usr/include/c++/7/mutex:677 (gdb+0x7330b2) #18 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()#2}::_FUN() /usr/include/c++/7/mutex:677 (gdb+0x7330f2) #19 pthread_once <null> (libtsan.so.0+0x4457c) #20 __gthread_once /usr/include/c++/7/x86_64-suse-linux/bits/gthr-default.h:699 (gdb+0x72f5dd) #21 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/mutex:684 (gdb+0x733224) #22 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool) /usr/include/c++/7/future:401 (gdb+0x732852) #23 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run() /usr/include/c++/7/future:1423 (gdb+0x737bef) #24 std::packaged_task<void ()>::operator()() /usr/include/c++/7/future:1556 (gdb+0x1dac6da) #25 gdb::thread_pool::thread_function() gdbsupport/thread-pool.cc:242 (gdb+0x1dabffc) #26 void std::__invoke_impl<void, void (gdb::thread_pool::*)(), gdb::thread_pool*>(std::__invoke_memfun_deref, void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x1dad0ab) #27 std::__invoke_result<void (gdb::thread_pool::*)(), gdb::thread_pool*>::type std::__invoke<void (gdb::thread_pool::*)(), gdb::thread_pool*>(void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x1dac4dc) #28 decltype (__invoke((_S_declval<0ul>)(), (_S_declval<1ul>)())) std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::_M_invoke<0ul, 1ul>(std::_Index_tuple<0ul, 1ul>) /usr/include/c++/7/thread:234 (gdb+0x1daf80e) #29 std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::operator()() /usr/include/c++/7/thread:243 (gdb+0x1daf799) #30 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> > >::_M_run() /usr/include/c++/7/thread:186 (gdb+0x1daf74e) #31 <null> <null> (libstdc++.so.6+0xdcac2) ... SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:5564 in queue_comp_unit ... The race happens when issuing the "file $exec" command. The race is between: - a worker thread writing the index cache, and in the process reading dwarf2_per_cu_data::is_debug_type, and - the main thread expanding the CU containing main, and in the process setting dwarf2_per_cu_data::queued. The two bitfields dwarf2_per_cu_data::queue and dwarf2_per_cu_data::is_debug_type share the same bitfield container. Fix this by making dwarf2_per_cu_data::queued a packed<bool, 1>. Tested on x86_64-linux. Approved-By: Tom Tromey <[email protected]> PR symtab/30392 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30392

…s_debug_type} With gdb build with -fsanitize=thread and test-case gdb.base/index-cache.exp and target board debug-types, I run into: ... (gdb) file build/gdb/testsuite/outputs/gdb.base/index-cache/index-cache Reading symbols from build/gdb/testsuite/outputs/gdb.base/index-cache/index-cache... ================== WARNING: ThreadSanitizer: data race (pid=9654) Write of size 1 at 0x7b200000420d by main thread: #0 dwarf2_per_cu_data::get_header() const gdb/dwarf2/read.c:21513 (gdb+0x8d1eee) #1 dwarf2_per_cu_data::addr_size() const gdb/dwarf2/read.c:21524 (gdb+0x8d1f4e) #2 dwarf2_cu::addr_type() const gdb/dwarf2/cu.c:112 (gdb+0x806327) #3 set_die_type gdb/dwarf2/read.c:21932 (gdb+0x8d3870) #4 read_base_type gdb/dwarf2/read.c:15448 (gdb+0x8bcacb) #5 read_type_die_1 gdb/dwarf2/read.c:19832 (gdb+0x8cc0a5) #6 read_type_die gdb/dwarf2/read.c:19767 (gdb+0x8cbe6d) #7 lookup_die_type gdb/dwarf2/read.c:19739 (gdb+0x8cbdc7) #8 die_type gdb/dwarf2/read.c:19593 (gdb+0x8cb68a) #9 read_subroutine_type gdb/dwarf2/read.c:14648 (gdb+0x8b998e) #10 read_type_die_1 gdb/dwarf2/read.c:19792 (gdb+0x8cbf2f) #11 read_type_die gdb/dwarf2/read.c:19767 (gdb+0x8cbe6d) #12 read_func_scope gdb/dwarf2/read.c:10154 (gdb+0x8a4f36) #13 process_die gdb/dwarf2/read.c:6667 (gdb+0x898daa) #14 read_file_scope gdb/dwarf2/read.c:7682 (gdb+0x89bad8) #15 process_die gdb/dwarf2/read.c:6654 (gdb+0x898ced) #16 process_full_comp_unit gdb/dwarf2/read.c:6418 (gdb+0x8981de) #17 process_queue gdb/dwarf2/read.c:5690 (gdb+0x894433) #18 dw2_do_instantiate_symtab gdb/dwarf2/read.c:1770 (gdb+0x88623a) #19 dw2_instantiate_symtab gdb/dwarf2/read.c:1792 (gdb+0x886300) #20 dw2_expand_symtabs_matching_one(dwarf2_per_cu_data*, dwarf2_per_objfile*, gdb::function_view<bool (char const*, bool)>, gdb::function_view<bool (compunit_symtab*)>) gdb/dwarf2/read.c:3042 (gdb+0x88b1f1) #21 cooked_index_functions::expand_symtabs_matching(objfile*, gdb::function_view<bool (char const*, bool)>, lookup_name_info const*, gdb::function_view<bool (char const*)>, gdb::function_view<bool (compunit_symtab*)>, enum_flags<block_search_flag_values>, domain_enum, search_domain) gdb/dwarf2/read.c:16917 (gdb+0x8c228e) #22 objfile::lookup_symbol(block_enum, char const*, domain_enum) gdb/symfile-debug.c:288 (gdb+0xf39055) #23 lookup_symbol_via_quick_fns gdb/symtab.c:2385 (gdb+0xf66ab7) #24 lookup_symbol_in_objfile gdb/symtab.c:2516 (gdb+0xf6711b) #25 operator() gdb/symtab.c:2562 (gdb+0xf67272) #26 operator() gdb/../gdbsupport/function-view.h:305 (gdb+0xf776b1) #27 _FUN gdb/../gdbsupport/function-view.h:299 (gdb+0xf77708) #28 gdb::function_view<bool (objfile*)>::operator()(objfile*) const gdb/../gdbsupport/function-view.h:289 (gdb+0xc3fc97) #29 svr4_iterate_over_objfiles_in_search_order gdb/solib-svr4.c:3455 (gdb+0xecae47) #30 gdbarch_iterate_over_objfiles_in_search_order(gdbarch*, gdb::function_view<bool (objfile*)>, objfile*) gdb/gdbarch.c:5041 (gdb+0x537cad) #31 lookup_global_or_static_symbol gdb/symtab.c:2559 (gdb+0xf674fb) #32 lookup_global_symbol(char const*, block const*, domain_enum) gdb/symtab.c:2615 (gdb+0xf67780) #33 language_defn::lookup_symbol_nonlocal(char const*, block const*, domain_enum) const gdb/symtab.c:2447 (gdb+0xf66d6e) #34 lookup_symbol_aux gdb/symtab.c:2123 (gdb+0xf65cb3) #35 lookup_symbol_in_language(char const*, block const*, domain_enum, language, field_of_this_result*) gdb/symtab.c:1931 (gdb+0xf64dab) #36 set_initial_language() gdb/symfile.c:1708 (gdb+0xf43074) #37 symbol_file_add_main_1 gdb/symfile.c:1212 (gdb+0xf41608) #38 symbol_file_command(char const*, int) gdb/symfile.c:1681 (gdb+0xf42faf) #39 file_command gdb/exec.c:554 (gdb+0x94ff29) #40 do_simple_func gdb/cli/cli-decode.c:95 (gdb+0x6d9528) #41 cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735 (gdb+0x6e0f69) #42 execute_command(char const*, int) gdb/top.c:575 (gdb+0xff379c) #43 command_handler(char const*) gdb/event-top.c:552 (gdb+0x94b5bc) #44 command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:788 (gdb+0x94bc79) #45 tui_command_line_handler gdb/tui/tui-interp.c:104 (gdb+0x1034efc) #46 gdb_rl_callback_handler gdb/event-top.c:259 (gdb+0x94ab61) #47 rl_callback_read_char readline/readline/callback.c:290 (gdb+0x11be4ef) #48 gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195 (gdb+0x94a960) #49 gdb_rl_callback_read_char_wrapper gdb/event-top.c:234 (gdb+0x94aa21) #50 stdin_event_handler gdb/ui.c:155 (gdb+0x10751a0) #51 handle_file_event gdbsupport/event-loop.cc:573 (gdb+0x1d95bac) #52 gdb_wait_for_event gdbsupport/event-loop.cc:694 (gdb+0x1d962e4) #53 gdb_do_one_event(int) gdbsupport/event-loop.cc:264 (gdb+0x1d946d0) #54 start_event_loop gdb/main.c:412 (gdb+0xb5ab52) #55 captured_command_loop gdb/main.c:476 (gdb+0xb5ad41) #56 captured_main gdb/main.c:1320 (gdb+0xb5cec1) #57 gdb_main(captured_main_args*) gdb/main.c:1339 (gdb+0xb5cf70) #58 main gdb/gdb.c:32 (gdb+0x416776) Previous read of size 1 at 0x7b200000420d by thread T11: #0 write_gdbindex gdb/dwarf2/index-write.c:1229 (gdb+0x831630) #1 write_dwarf_index(dwarf2_per_bfd*, char const*, char const*, char const*, dw_index_kind) gdb/dwarf2/index-write.c:1484 (gdb+0x832897) #2 index_cache::store(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/index-cache.c:173 (gdb+0x82db8d) #3 cooked_index::maybe_write_index(dwarf2_per_bfd*, index_cache_store_context const&) gdb/dwarf2/cooked-index.c:645 (gdb+0x7f1d49) #4 operator() gdb/dwarf2/cooked-index.c:474 (gdb+0x7f0f31) #5 _M_invoke /usr/include/c++/7/bits/std_function.h:316 (gdb+0x7f2a13) #6 std::function<void ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x700952) #7 void std::__invoke_impl<void, std::function<void ()>&>(std::__invoke_other, std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:60 (gdb+0x7381a0) #8 std::__invoke_result<std::function<void ()>&>::type std::__invoke<std::function<void ()>&>(std::function<void ()>&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x737e91) #9 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()#1}::operator()() const /usr/include/c++/7/future:1421 (gdb+0x737b59) #10 std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()#1}, void>::operator()() const /usr/include/c++/7/future:1362 (gdb+0x738660) #11 std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run()::{lambda()#1}, void> >::_M_invoke(std::_Any_data const&) /usr/include/c++/7/bits/std_function.h:302 (gdb+0x73825c) #12 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const /usr/include/c++/7/bits/std_function.h:706 (gdb+0x733623) #13 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*) /usr/include/c++/7/future:561 (gdb+0x732bdf) #14 void std::__invoke_impl<void, void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::__invoke_memfun_deref, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x734c4f) #15 std::__invoke_result<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>::type std::__invoke<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x733bc5) #16 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()#1}::operator()() const /usr/include/c++/7/mutex:672 (gdb+0x73300d) #17 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()#2}::operator()() const /usr/include/c++/7/mutex:677 (gdb+0x7330b2) #18 std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&)::{lambda()#2}::_FUN() /usr/include/c++/7/mutex:677 (gdb+0x7330f2) #19 pthread_once <null> (libtsan.so.0+0x4457c) #20 __gthread_once /usr/include/c++/7/x86_64-suse-linux/bits/gthr-default.h:699 (gdb+0x72f5dd) #21 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*>(std::once_flag&, void (std::__future_base::_State_baseV2::*&&)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*), std::__future_base::_State_baseV2*&&, std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*&&, bool*&&) /usr/include/c++/7/mutex:684 (gdb+0x733224) #22 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool) /usr/include/c++/7/future:401 (gdb+0x732852) #23 std::__future_base::_Task_state<std::function<void ()>, std::allocator<int>, void ()>::_M_run() /usr/include/c++/7/future:1423 (gdb+0x737bef) #24 std::packaged_task<void ()>::operator()() /usr/include/c++/7/future:1556 (gdb+0x1dad25a) #25 gdb::thread_pool::thread_function() gdbsupport/thread-pool.cc:242 (gdb+0x1dacb7c) #26 void std::__invoke_impl<void, void (gdb::thread_pool::*)(), gdb::thread_pool*>(std::__invoke_memfun_deref, void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:73 (gdb+0x1dadc2b) #27 std::__invoke_result<void (gdb::thread_pool::*)(), gdb::thread_pool*>::type std::__invoke<void (gdb::thread_pool::*)(), gdb::thread_pool*>(void (gdb::thread_pool::*&&)(), gdb::thread_pool*&&) /usr/include/c++/7/bits/invoke.h:95 (gdb+0x1dad05c) #28 decltype (__invoke((_S_declval<0ul>)(), (_S_declval<1ul>)())) std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::_M_invoke<0ul, 1ul>(std::_Index_tuple<0ul, 1ul>) /usr/include/c++/7/thread:234 (gdb+0x1db038e) #29 std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> >::operator()() /usr/include/c++/7/thread:243 (gdb+0x1db0319) #30 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (gdb::thread_pool::*)(), gdb::thread_pool*> > >::_M_run() /usr/include/c++/7/thread:186 (gdb+0x1db02ce) #31 <null> <null> (libstdc++.so.6+0xdcac2) ... SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:21513 in dwarf2_per_cu_data::get_header() const ... The race happens when issuing the "file $exec" command. The race is between: - a worker thread writing the index cache, and in the process reading dwarf2_per_cu_data::is_debug_type, and - the main thread writing to dwarf2_per_cu_data::m_header_read_in. The two bitfields dwarf2_per_cu_data::m_header_read_in and dwarf2_per_cu_data::is_debug_type share the same bitfield container. Fix this by making dwarf2_per_cu_data::m_header_read_in a packed<bool, 1>. Tested on x86_64-linux. Approved-By: Tom Tromey <[email protected]> PR symtab/30392 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30392

When building gdb with -O0 -fsanitize=address, and running test-case gdb.ada/uninitialized_vars.exp, I run into: ... (gdb) info locals a = 0 z = (a => 1, b => false, c => 2.0) ================================================================= ==66372==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000097f58 at pc 0xffff52c0da1c bp 0xffffc90a1d40 sp 0xffffc90a1d80 READ of size 4 at 0x602000097f58 thread T0 #0 0xffff52c0da18 in memmove (/lib64/libasan.so.8+0x6da18) #1 0xbcab24 in unsigned char* std::__copy_move_backward<false, true, std::random_access_iterator_tag>::__copy_move_b<unsigned char const, unsigned char>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:748 #2 0xbc9bf4 in unsigned char* std::__copy_move_backward_a2<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:769 #3 0xbc898c in unsigned char* std::__copy_move_backward_a1<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:778 #4 0xbc715c in unsigned char* std::__copy_move_backward_a<false, unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:807 #5 0xbc4e6c in unsigned char* std::copy_backward<unsigned char const*, unsigned char*>(unsigned char const*, unsigned char const*, unsigned char*) /usr/include/c++/13/bits/stl_algobase.h:867 #6 0xbc2934 in void gdb::copy<unsigned char const, unsigned char>(gdb::array_view<unsigned char const>, gdb::array_view<unsigned char>) gdb/../gdbsupport/array-view.h:223 #7 0x20e0100 in value::contents_copy_raw(value*, long, long, long) gdb/value.c:1239 #8 0x20e9830 in value::primitive_field(long, int, type*) gdb/value.c:3078 #9 0x20e98f8 in value_field(value*, int) gdb/value.c:3095 #10 0xcafd64 in print_field_values gdb/ada-valprint.c:658 #11 0xcb0fa0 in ada_val_print_struct_union gdb/ada-valprint.c:857 #12 0xcb1bb4 in ada_value_print_inner(value*, ui_file*, int, value_print_options const*) gdb/ada-valprint.c:1042 #13 0xc66e04 in ada_language::value_print_inner(value*, ui_file*, int, value_print_options const*) const (/home/vries/gdb/build/gdb/gdb+0xc66e04) #14 0x20ca1e8 in common_val_print(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1092 #15 0x20caabc in common_val_print_checked(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1184 #16 0x196c524 in print_variable_and_value(char const*, symbol*, frame_info_ptr, ui_file*, int) gdb/printcmd.c:2355 #17 0x1d99ca0 in print_variable_and_value_data::operator()(char const*, symbol*) gdb/stack.c:2308 #18 0x1dabca0 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::operator()(gdb::fv_detail::erased_callable, char const*, symbol*) const gdb/../gdbsupport/function-view.h:305 #19 0x1dabd14 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::_FUN(gdb::fv_detail::erased_callable, char const*, symbol*) gdb/../gdbsupport/function-view.h:299 #20 0x1dab34c in gdb::function_view<void (char const*, symbol*)>::operator()(char const*, symbol*) const gdb/../gdbsupport/function-view.h:289 #21 0x1d9963c in iterate_over_block_locals gdb/stack.c:2240 #22 0x1d99790 in iterate_over_block_local_vars(block const*, gdb::function_view<void (char const*, symbol*)>) gdb/stack.c:2259 #23 0x1d9a598 in print_frame_local_vars gdb/stack.c:2380 #24 0x1d9afac in info_locals_command(char const*, int) gdb/stack.c:2458 #25 0xfd7b30 in do_simple_func gdb/cli/cli-decode.c:95 #26 0xfe5a2c in cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735 #27 0x1f03790 in execute_command(char const*, int) gdb/top.c:575 #28 0x1384080 in command_handler(char const*) gdb/event-top.c:566 #29 0x1384e2c in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:802 #30 0x1f731e4 in tui_command_line_handler gdb/tui/tui-interp.c:104 #31 0x1382a58 in gdb_rl_callback_handler gdb/event-top.c:259 #32 0x21dbb80 in rl_callback_read_char readline/readline/callback.c:290 #33 0x1382510 in gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195 #34 0x138277c in gdb_rl_callback_read_char_wrapper gdb/event-top.c:234 #35 0x1fe9b40 in stdin_event_handler gdb/ui.c:155 #36 0x35ff1bc in handle_file_event gdbsupport/event-loop.cc:573 #37 0x35ff9d8 in gdb_wait_for_event gdbsupport/event-loop.cc:694 #38 0x35fd284 in gdb_do_one_event(int) gdbsupport/event-loop.cc:264 #39 0x1768080 in start_event_loop gdb/main.c:408 #40 0x17684c4 in captured_command_loop gdb/main.c:472 #41 0x176cfc8 in captured_main gdb/main.c:1342 #42 0x176d088 in gdb_main(captured_main_args*) gdb/main.c:1361 #43 0xb73edc in main gdb/gdb.c:39 #44 0xffff519b09d8 in __libc_start_call_main (/lib64/libc.so.6+0x309d8) #45 0xffff519b0aac in __libc_start_main@@GLIBC_2.34 (/lib64/libc.so.6+0x30aac) #46 0xb73c2c in _start (/home/vries/gdb/build/gdb/gdb+0xb73c2c) 0x602000097f58 is located 0 bytes after 8-byte region [0x602000097f50,0x602000097f58) allocated by thread T0 here: #0 0xffff52c65218 in calloc (/lib64/libasan.so.8+0xc5218) #1 0xcbc278 in xcalloc gdb/alloc.c:97 #2 0x35f21e8 in xzalloc(unsigned long) gdbsupport/common-utils.cc:29 #3 0x20de270 in value::allocate_contents(bool) gdb/value.c:937 #4 0x20edc08 in value::fetch_lazy() gdb/value.c:4033 #5 0x20dadc0 in value::entirely_covered_by_range_vector(std::vector<range, std::allocator<range> > const&) gdb/value.c:229 #6 0xcb2298 in value::entirely_optimized_out() gdb/value.h:560 #7 0x20ca6fc in value_check_printable gdb/valprint.c:1133 #8 0x20caa8c in common_val_print_checked(value*, ui_file*, int, value_print_options const*, language_defn const*) gdb/valprint.c:1182 #9 0x196c524 in print_variable_and_value(char const*, symbol*, frame_info_ptr, ui_file*, int) gdb/printcmd.c:2355 #10 0x1d99ca0 in print_variable_and_value_data::operator()(char const*, symbol*) gdb/stack.c:2308 #11 0x1dabca0 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::operator()(gdb::fv_detail::erased_callable, char const*, symbol*) const gdb/../gdbsupport/function-view.h:305 #12 0x1dabd14 in gdb::function_view<void (char const*, symbol*)>::bind<print_variable_and_value_data>(print_variable_and_value_data&)::{lambda(gdb::fv_detail::erased_callable, char const*, symbol*)#1}::_FUN(gdb::fv_detail::erased_callable, char const*, symbol*) gdb/../gdbsupport/function-view.h:299 #13 0x1dab34c in gdb::function_view<void (char const*, symbol*)>::operator()(char const*, symbol*) const gdb/../gdbsupport/function-view.h:289 #14 0x1d9963c in iterate_over_block_locals gdb/stack.c:2240 #15 0x1d99790 in iterate_over_block_local_vars(block const*, gdb::function_view<void (char const*, symbol*)>) gdb/stack.c:2259 #16 0x1d9a598 in print_frame_local_vars gdb/stack.c:2380 #17 0x1d9afac in info_locals_command(char const*, int) gdb/stack.c:2458 #18 0xfd7b30 in do_simple_func gdb/cli/cli-decode.c:95 #19 0xfe5a2c in cmd_func(cmd_list_element*, char const*, int) gdb/cli/cli-decode.c:2735 #20 0x1f03790 in execute_command(char const*, int) gdb/top.c:575 #21 0x1384080 in command_handler(char const*) gdb/event-top.c:566 #22 0x1384e2c in command_line_handler(std::unique_ptr<char, gdb::xfree_deleter<char> >&&) gdb/event-top.c:802 #23 0x1f731e4 in tui_command_line_handler gdb/tui/tui-interp.c:104 #24 0x1382a58 in gdb_rl_callback_handler gdb/event-top.c:259 #25 0x21dbb80 in rl_callback_read_char readline/readline/callback.c:290 #26 0x1382510 in gdb_rl_callback_read_char_wrapper_noexcept gdb/event-top.c:195 #27 0x138277c in gdb_rl_callback_read_char_wrapper gdb/event-top.c:234 #28 0x1fe9b40 in stdin_event_handler gdb/ui.c:155 #29 0x35ff1bc in handle_file_event gdbsupport/event-loop.cc:573 SUMMARY: AddressSanitizer: heap-buffer-overflow (/lib64/libasan.so.8+0x6da18) in memmove ... The error happens when trying to print either variable y or y2: ... type Variable_Record (A : Boolean := True) is record case A is when True => B : Integer; when False => C : Float; D : Integer; end case; end record; Y : Variable_Record := (A => True, B => 1); Y2 : Variable_Record := (A => False, C => 1.0, D => 2); ... when the variables are uninitialized. The error happens only when printing the entire variable: ... (gdb) p y.a $2 = 216 (gdb) p y.b There is no member named b. (gdb) p y.c $3 = 9.18340949e-41 (gdb) p y.d $4 = 1 (gdb) p y <AddressSanitizer: heap-buffer-overflow> ... The error happens as follows: - field a functions as discriminant, choosing either the b, or c+d variant. - when y.a happens to be set to 216, as above, gdb interprets this as the variable having the c+d variant (which is why trying to print y.b fails). - when printing y, gdb allocates a value, copies the bytes into it from the target, and then prints the value. - gdb allocates the value using the type size, which is 8. It's 8 because that's what the DW_AT_byte_size indicates. Note that for valid values of a, it gives correct results: if a is 0 (c+d variant), size is 12, if a is 1 (b variant), size is 8. - gdb tries to print field d, which is at an 8 byte offset, and that results in a out-of-bounds access for the allocated 8-byte value. Fix this by handling this case in value::contents_copy_raw, such that we have: ... (gdb) p y $1 = (a => 24, c => 9.18340949e-41, d => <error reading variable: access outside bounds of object>) ... An alternative (additional) fix could be this: in compute_variant_fields_inner gdb reads the discriminant y.a to decide which variant is active. It would be nice to detect that the value (y.a == 24) is not a valid Boolean, and give up on choosing a variant altoghether. However, the situation regarding the internal type CODE_TYPE_BOOL is currently ambiguous (see PR31282) and it's not possible to reliably decide what valid values are. The test-case source file gdb.ada/uninitialized-variable-record/parse.adb is a reduced version of gdb.ada/uninitialized_vars/parse.adb, so it copies the copyright years. Note that the test-case needs gcc-12 or newer, it's unsupported for older gcc versions. [ So, it would be nice to rewrite it into a dwarf assembly test-case. ] The test-case loops over all languages. This is inherited from an earlier attempt to fix this, which had language-specific fixes (in print_field_values, cp_print_value_fields, pascal_object_print_value_fields and f_language::value_print_inner). I've left this in, but I suppose it's not strictly necessary anymore. Tested on x86_64-linux. PR exp/31258 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31258

From the Python API, we can execute GDB commands via gdb.execute. If the command gives an exception, however, we need to recover the GDB prompt and enable stdin, because the exception does not reach top-level GDB or normal_stop. This was done in commit commit 1ba1ac8 Author: Andrew Burgess <[email protected]> Date: Tue Nov 19 11:17:20 2019 +0000 gdb: Enable stdin on exception in execute_gdb_command with the following code: catch (const gdb_exception &except) { /* If an exception occurred then we won't hit normal_stop (), or have an exception reach the top level of the event loop, which are the two usual places in which stdin would be re-enabled. So, before we convert the exception and continue back in Python, we should re-enable stdin here. */ async_enable_stdin (); GDB_PY_HANDLE_EXCEPTION (except); } In this patch, we explain what happens when we run a GDB command in the context of a synchronous command, e.g. via Python observer notifications. As an example, suppose we have the following objfile event listener, specified in a file named file.py: ~~~ import gdb class MyListener: def __init__(self): gdb.events.new_objfile.connect(self.handle_new_objfile_event) self.processed_objfile = False def handle_new_objfile_event(self, event): if self.processed_objfile: return print("loading " + event.new_objfile.filename) self.processed_objfile = True gdb.execute('add-inferior -no-connection') gdb.execute('inferior 2') gdb.execute('target remote | gdbserver - /tmp/a.out') gdb.execute('inferior 1') the_listener = MyListener() ~~~ Using this Python file, we see the behavior below: $ gdb -q -ex "source file.py" -ex "run" --args a.out Reading symbols from a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 [New inferior 2] Added inferior 2 [Switching to inferior 2 [<null>] (<noexec>)] stdin/stdout redirected Process /tmp/a.out created; pid = 3075406 Remote debugging using stdio Reading /tmp/a.out from remote target... ... [Switching to inferior 1 [process 3075400] (/tmp/a.out)] [Switching to thread 1.1 (process 3075400)] #0 0x00007ffff7fe3290 in ?? () from /lib64/ld-linux-x86-64.so.2 (gdb) [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [Inferior 1 (process 3075400) exited normally] Note how the GDB prompt comes in-between the debugger output. We have this obscure behavior, because the executed command, "target remote", triggers an invocation of `normal_stop` that enables stdin. After that, however, the Python notification context completes and GDB continues with its normal flow of executing the 'run' command. This can be seen in the call stack below: (top-gdb) bt #0 async_enable_stdin () at src/gdb/event-top.c:523 #1 0x00005555561c3acd in normal_stop () at src/gdb/infrun.c:9432 #2 0x00005555561b328e in start_remote (from_tty=0) at src/gdb/infrun.c:3801 #3 0x0000555556441224 in remote_target::start_remote_1 (this=0x5555587882e0, from_tty=0, extended_p=0) at src/gdb/remote.c:5225 #4 0x000055555644166c in remote_target::start_remote (this=0x5555587882e0, from_tty=0, extended_p=0) at src/gdb/remote.c:5316 #5 0x00005555564430cf in remote_target::open_1 (name=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0, extended_p=0) at src/gdb/remote.c:6175 #6 0x0000555556441707 in remote_target::open (name=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0) at src/gdb/remote.c:5338 #7 0x00005555565ea63f in open_target (args=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0, command=0x555558589280) at src/gdb/target.c:824 #8 0x0000555555f0d89a in cmd_func (cmd=0x555558589280, args=0x55555878525e "| gdbserver - /tmp/a.out", from_tty=0) at src/gdb/cli/cli-decode.c:2735 #9 0x000055555661fb42 in execute_command (p=0x55555878529e "t", from_tty=0) at src/gdb/top.c:575 #10 0x0000555555f1a506 in execute_control_command_1 (cmd=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:529 #11 0x0000555555f1abea in execute_control_command (cmd=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:701 #12 0x0000555555f19fc7 in execute_control_commands (cmdlines=0x555558756f00, from_tty=0) at src/gdb/cli/cli-script.c:411 #13 0x0000555556400d91 in execute_gdb_command (self=0x7ffff43b5d00, args=0x7ffff440ab60, kw=0x0) at src/gdb/python/python.c:700 #14 0x00007ffff7a96023 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #15 0x00007ffff7a4dadc in _PyObject_MakeTpCall () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #16 0x00007ffff79e9a1c in _PyEval_EvalFrameDefault () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #17 0x00007ffff7b303af in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #18 0x00007ffff7a50358 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #19 0x00007ffff7a4f3f4 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #20 0x00007ffff7a4f883 in PyObject_CallFunctionObjArgs () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #21 0x00005555563a9758 in evpy_emit_event (event=0x7ffff42b5430, registry=0x7ffff42b4690) at src/gdb/python/py-event.c:104 #22 0x00005555563cb874 in emit_new_objfile_event (objfile=0x555558761700) at src/gdb/python/py-newobjfileevent.c:52 #23 0x00005555563b53bc in python_new_objfile (objfile=0x555558761700) at src/gdb/python/py-inferior.c:195 #24 0x0000555555d6dff0 in std::__invoke_impl<void, void (*&)(objfile*), objfile*> (__f=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:61 #25 0x0000555555d6be18 in std::__invoke_r<void, void (*&)(objfile*), objfile*> (__fn=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:111 #26 0x0000555555d69661 in std::_Function_handler<void (objfile*), void (*)(objfile*)>::_M_invoke(std::_Any_data const&, objfile*&&) (__functor=..., __args#0=@0x7fffffffd080: 0x555558761700) at /usr/include/c++/11/bits/std_function.h:290 #27 0x0000555556314caf in std::function<void (objfile*)>::operator()(objfile*) const (this=0x5555585b5860, __args#0=0x555558761700) at /usr/include/c++/11/bits/std_function.h:590 #28 0x000055555631444e in gdb::observers::observable<objfile*>::notify (this=0x55555836eea0 <gdb::observers::new_objfile>, args#0=0x555558761700) at src/gdb/../gdbsupport/observable.h:166 #29 0x0000555556599b3f in symbol_file_add_with_addrs (abfd=..., name=0x55555875d310 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1125 #30 0x0000555556599ca4 in symbol_file_add_from_bfd (abfd=..., name=0x55555875d310 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1160 #31 0x0000555556546371 in solib_read_symbols (so=..., flags=...) at src/gdb/solib.c:692 #32 0x0000555556546f0f in solib_add (pattern=0x0, from_tty=0, readsyms=1) at src/gdb/solib.c:1015 #33 0x0000555556539891 in enable_break (info=0x55555874e180, from_tty=0) at src/gdb/solib-svr4.c:2416 #34 0x000055555653b305 in svr4_solib_create_inferior_hook (from_tty=0) at src/gdb/solib-svr4.c:3058 #35 0x0000555556547cee in solib_create_inferior_hook (from_tty=0) at src/gdb/solib.c:1217 #36 0x0000555556196f6a in post_create_inferior (from_tty=0) at src/gdb/infcmd.c:275 #37 0x0000555556197670 in run_command_1 (args=0x0, from_tty=1, run_how=RUN_NORMAL) at src/gdb/infcmd.c:486 #38 0x000055555619783f in run_command (args=0x0, from_tty=1) at src/gdb/infcmd.c:512 #39 0x0000555555f0798d in do_simple_func (args=0x0, from_tty=1, c=0x555558567510) at src/gdb/cli/cli-decode.c:95 #40 0x0000555555f0d89a in cmd_func (cmd=0x555558567510, args=0x0, from_tty=1) at src/gdb/cli/cli-decode.c:2735 #41 0x000055555661fb42 in execute_command (p=0x7fffffffe2c4 "", from_tty=1) at src/gdb/top.c:575 #42 0x000055555626303b in catch_command_errors (command=0x55555661f4ab <execute_command(char const*, int)>, arg=0x7fffffffe2c1 "run", from_tty=1, do_bp_actions=true) at src/gdb/main.c:513 #43 0x000055555626328a in execute_cmdargs (cmdarg_vec=0x7fffffffdaf0, file_type=CMDARG_FILE, cmd_type=CMDARG_COMMAND, ret=0x7fffffffda3c) at src/gdb/main.c:612 #44 0x0000555556264849 in captured_main_1 (context=0x7fffffffdd40) at src/gdb/main.c:1293 #45 0x0000555556264a7f in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1314 #46 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343 #47 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39 (top-gdb) The use of the "target remote" command here is just an example. In principle, we would reproduce the problem with any command that triggers an invocation of `normal_stop`. To omit enabling the stdin in `normal_stop`, we would have to check the context we are in. Since we cannot do that, we add a new field to `struct ui` to track whether the prompt was already blocked, and set the tracker flag in the Python context before executing a GDB command. After applying this patch, the output becomes ... Reading symbols from a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 [New inferior 2] Added inferior 2 [Switching to inferior 2 [<null>] (<noexec>)] stdin/stdout redirected Process /tmp/a.out created; pid = 3032261 Remote debugging using stdio Reading /tmp/a.out from remote target... ... [Switching to inferior 1 [process 3032255] (/tmp/a.out)] [Switching to thread 1.1 (process 3032255)] #0 0x00007ffff7fe3290 in ?? () from /lib64/ld-linux-x86-64.so.2 [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". [Inferior 1 (process 3032255) exited normally] (gdb) Let's now consider a secondary scenario, where the command executed from the Python raises an error. As an example, suppose we have the Python file below: def handle_new_objfile_event(self, event): ... print("loading " + event.new_objfile.filename) self.processed_objfile = True gdb.execute('print a') The executed command, "print a", gives an error because "a" is not defined. Without this patch, we see the behavior below, where the prompt is again placed incorrectly: ... Reading symbols from /tmp/a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 Python Exception <class 'gdb.error'>: No symbol "a" in current context. (gdb) [Inferior 1 (process 3980401) exited normally] This time, `async_enable_stdin` is called from the 'catch' block in `execute_gdb_command`: (top-gdb) bt #0 async_enable_stdin () at src/gdb/event-top.c:523 #1 0x0000555556400f0a in execute_gdb_command (self=0x7ffff43b5d00, args=0x7ffff440ab60, kw=0x0) at src/gdb/python/python.c:713 #2 0x00007ffff7a96023 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #3 0x00007ffff7a4dadc in _PyObject_MakeTpCall () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #4 0x00007ffff79e9a1c in _PyEval_EvalFrameDefault () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #5 0x00007ffff7b303af in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #6 0x00007ffff7a50358 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #7 0x00007ffff7a4f3f4 in ?? () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #8 0x00007ffff7a4f883 in PyObject_CallFunctionObjArgs () from /lib/x86_64-linux-gnu/libpython3.10.so.1.0 #9 0x00005555563a9758 in evpy_emit_event (event=0x7ffff42b5430, registry=0x7ffff42b4690) at src/gdb/python/py-event.c:104 #10 0x00005555563cb874 in emit_new_objfile_event (objfile=0x555558761410) at src/gdb/python/py-newobjfileevent.c:52 #11 0x00005555563b53bc in python_new_objfile (objfile=0x555558761410) at src/gdb/python/py-inferior.c:195 #12 0x0000555555d6dff0 in std::__invoke_impl<void, void (*&)(objfile*), objfile*> (__f=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:61 #13 0x0000555555d6be18 in std::__invoke_r<void, void (*&)(objfile*), objfile*> (__fn=@0x5555585b5860: 0x5555563b5360 <python_new_objfile(objfile*)>) at /usr/include/c++/11/bits/invoke.h:111 #14 0x0000555555d69661 in std::_Function_handler<void (objfile*), void (*)(objfile*)>::_M_invoke(std::_Any_data const&, objfile*&&) (__functor=..., __args#0=@0x7fffffffd080: 0x555558761410) at /usr/include/c++/11/bits/std_function.h:290 #15 0x0000555556314caf in std::function<void (objfile*)>::operator()(objfile*) const (this=0x5555585b5860, __args#0=0x555558761410) at /usr/include/c++/11/bits/std_function.h:590 #16 0x000055555631444e in gdb::observers::observable<objfile*>::notify (this=0x55555836eea0 <gdb::observers::new_objfile>, args#0=0x555558761410) at src/gdb/../gdbsupport/observable.h:166 #17 0x0000555556599b3f in symbol_file_add_with_addrs (abfd=..., name=0x55555875d020 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1125 #18 0x0000555556599ca4 in symbol_file_add_from_bfd (abfd=..., name=0x55555875d020 "/lib64/ld-linux-x86-64.so.2", add_flags=..., addrs=0x7fffffffd2f0, flags=..., parent=0x0) at src/gdb/symfile.c:1160 #19 0x0000555556546371 in solib_read_symbols (so=..., flags=...) at src/gdb/solib.c:692 #20 0x0000555556546f0f in solib_add (pattern=0x0, from_tty=0, readsyms=1) at src/gdb/solib.c:1015 #21 0x0000555556539891 in enable_break (info=0x55555874a670, from_tty=0) at src/gdb/solib-svr4.c:2416 #22 0x000055555653b305 in svr4_solib_create_inferior_hook (from_tty=0) at src/gdb/solib-svr4.c:3058 #23 0x0000555556547cee in solib_create_inferior_hook (from_tty=0) at src/gdb/solib.c:1217 #24 0x0000555556196f6a in post_create_inferior (from_tty=0) at src/gdb/infcmd.c:275 #25 0x0000555556197670 in run_command_1 (args=0x0, from_tty=1, run_how=RUN_NORMAL) at src/gdb/infcmd.c:486 #26 0x000055555619783f in run_command (args=0x0, from_tty=1) at src/gdb/infcmd.c:512 #27 0x0000555555f0798d in do_simple_func (args=0x0, from_tty=1, c=0x555558567510) at src/gdb/cli/cli-decode.c:95 #28 0x0000555555f0d89a in cmd_func (cmd=0x555558567510, args=0x0, from_tty=1) at src/gdb/cli/cli-decode.c:2735 #29 0x000055555661fb42 in execute_command (p=0x7fffffffe2c4 "", from_tty=1) at src/gdb/top.c:575 #30 0x000055555626303b in catch_command_errors (command=0x55555661f4ab <execute_command(char const*, int)>, arg=0x7fffffffe2c1 "run", from_tty=1, do_bp_actions=true) at src/gdb/main.c:513 #31 0x000055555626328a in execute_cmdargs (cmdarg_vec=0x7fffffffdaf0, file_type=CMDARG_FILE, cmd_type=CMDARG_COMMAND, ret=0x7fffffffda3c) at src/gdb/main.c:612 #32 0x0000555556264849 in captured_main_1 (context=0x7fffffffdd40) at src/gdb/main.c:1293 #33 0x0000555556264a7f in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1314 #34 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343 #35 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39 (top-gdb) Again, after we enable stdin, GDB continues with its normal flow of the 'run' command and receives the inferior's exit event, where it would have enabled stdin, if we had not done it prematurely. (top-gdb) bt #0 async_enable_stdin () at src/gdb/event-top.c:523 #1 0x00005555561c3acd in normal_stop () at src/gdb/infrun.c:9432 #2 0x00005555561b5bf1 in fetch_inferior_event () at src/gdb/infrun.c:4700 #3 0x000055555618d6a7 in inferior_event_handler (event_type=INF_REG_EVENT) at src/gdb/inf-loop.c:42 #4 0x000055555620ecdb in handle_target_event (error=0, client_data=0x0) at src/gdb/linux-nat.c:4316 #5 0x0000555556f33035 in handle_file_event (file_ptr=0x5555587024e0, ready_mask=1) at src/gdbsupport/event-loop.cc:573 #6 0x0000555556f3362f in gdb_wait_for_event (block=0) at src/gdbsupport/event-loop.cc:694 #7 0x0000555556f322cd in gdb_do_one_event (mstimeout=-1) at src/gdbsupport/event-loop.cc:217 #8 0x0000555556262df8 in start_event_loop () at src/gdb/main.c:407 #9 0x0000555556262f85 in captured_command_loop () at src/gdb/main.c:471 #10 0x0000555556264a84 in captured_main (data=0x7fffffffdd40) at src/gdb/main.c:1324 #11 0x0000555556264b2e in gdb_main (args=0x7fffffffdd40) at src/gdb/main.c:1343 #12 0x0000555555ceccab in main (argc=9, argv=0x7fffffffde78) at src/gdb/gdb.c:39 (top-gdb) The solution implemented by this patch addresses the problem. After applying the patch, the output becomes $ gdb -q -ex "source file.py" -ex "run" --args a.out Reading symbols from /tmp/a.out... Starting program: /tmp/a.out loading /lib64/ld-linux-x86-64.so.2 Python Exception <class 'gdb.error'>: No symbol "a" in current context. [Inferior 1 (process 3984511) exited normally] (gdb) Regression-tested on X86_64 Linux using the default board file (i.e. unix). Co-Authored-By: Oguzhan Karakaya <[email protected]> Reviewed-By: Guinevere Larsen <[email protected]> Approved-By: Tom Tromey <[email protected]>

When running test-case gdb.server/connect-with-no-symbol-file.exp on aarch64-linux (specifically, an opensuse leap 15.5 container on a fedora asahi 39 system), I run into: ... (gdb) detach^M Detaching from program: target:connect-with-no-symbol-file, process 185104^M Ending remote debugging.^M terminate called after throwing an instance of 'gdb_exception_error'^M ... The detailed backtrace of the corefile is: ... (gdb) bt #0 0x0000ffff75504f54 in raise () from /lib64/libpthread.so.0 #1 0x00000000007a86b4 in handle_fatal_signal (sig=6) at gdb/event-top.c:926 #2 <signal handler called> #3 0x0000ffff74b977b4 in raise () from /lib64/libc.so.6 #4 0x0000ffff74b98c18 in abort () from /lib64/libc.so.6 #5 0x0000ffff74ea26f4 in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib64/libstdc++.so.6 #6 0x0000ffff74ea011c in ?? () from /usr/lib64/libstdc++.so.6 #7 0x0000ffff74ea0180 in std::terminate() () from /usr/lib64/libstdc++.so.6 #8 0x0000ffff74ea0464 in __cxa_throw () from /usr/lib64/libstdc++.so.6 #9 0x0000000001548870 in throw_it (reason=RETURN_ERROR, error=TARGET_CLOSE_ERROR, fmt=0x16c7810 "Remote connection closed", ap=...) at gdbsupport/common-exceptions.cc:203 #10 0x0000000001548920 in throw_verror (error=TARGET_CLOSE_ERROR, fmt=0x16c7810 "Remote connection closed", ap=...) at gdbsupport/common-exceptions.cc:211 #11 0x0000000001548a00 in throw_error (error=TARGET_CLOSE_ERROR, fmt=0x16c7810 "Remote connection closed") at gdbsupport/common-exceptions.cc:226 #12 0x0000000000ac8f2c in remote_target::readchar (this=0x233d3d90, timeout=2) at gdb/remote.c:9856 #13 0x0000000000ac9f04 in remote_target::getpkt (this=0x233d3d90, buf=0x233d40a8, forever=false, is_notif=0x0) at gdb/remote.c:10326 #14 0x0000000000acf3d0 in remote_target::remote_hostio_send_command (this=0x233d3d90, command_bytes=13, which_packet=17, remote_errno=0xfffff1a3cf38, attachment=0xfffff1a3ce88, attachment_len=0xfffff1a3ce90) at gdb/remote.c:12567 #15 0x0000000000ad03bc in remote_target::fileio_fstat (this=0x233d3d90, fd=3, st=0xfffff1a3d020, remote_errno=0xfffff1a3cf38) at gdb/remote.c:12979 #16 0x0000000000c39878 in target_fileio_fstat (fd=0, sb=0xfffff1a3d020, target_errno=0xfffff1a3cf38) at gdb/target.c:3315 #17 0x00000000007eee5c in target_fileio_stream::stat (this=0x233d4400, abfd=0x2323fc40, sb=0xfffff1a3d020) at gdb/gdb_bfd.c:467 #18 0x00000000007f012c in <lambda(bfd*, void*, stat*)>::operator()(bfd *, void *, stat *) const (__closure=0x0, abfd=0x2323fc40, stream=0x233d4400, sb=0xfffff1a3d020) at gdb/gdb_bfd.c:955 #19 0x00000000007f015c in <lambda(bfd*, void*, stat*)>::_FUN(bfd *, void *, stat *) () at gdb/gdb_bfd.c:956 #20 0x0000000000f9b838 in opncls_bstat (abfd=0x2323fc40, sb=0xfffff1a3d020) at bfd/opncls.c:665 #21 0x0000000000f90adc in bfd_stat (abfd=0x2323fc40, statbuf=0xfffff1a3d020) at bfd/bfdio.c:431 #22 0x000000000065fe20 in reopen_exec_file () at gdb/corefile.c:52 #23 0x0000000000c3a3e8 in generic_mourn_inferior () at gdb/target.c:3642 #24 0x0000000000abf3f0 in remote_unpush_target (target=0x233d3d90) at gdb/remote.c:6067 #25 0x0000000000aca8b0 in remote_target::mourn_inferior (this=0x233d3d90) at gdb/remote.c:10587 #26 0x0000000000c387cc in target_mourn_inferior ( ptid=<error reading variable: Cannot access memory at address 0x2d310>) at gdb/target.c:2738 #27 0x0000000000abfff0 in remote_target::remote_detach_1 (this=0x233d3d90, inf=0x22fce540, from_tty=1) at gdb/remote.c:6421 #28 0x0000000000ac0094 in remote_target::detach (this=0x233d3d90, inf=0x22fce540, from_tty=1) at gdb/remote.c:6436 #29 0x0000000000c37c3c in target_detach (inf=0x22fce540, from_tty=1) at gdb/target.c:2526 #30 0x0000000000860424 in detach_command (args=0x0, from_tty=1) at gdb/infcmd.c:2817 #31 0x000000000060b594 in do_simple_func (args=0x0, from_tty=1, c=0x231431a0) at gdb/cli/cli-decode.c:94 #32 0x00000000006108c8 in cmd_func (cmd=0x231431a0, args=0x0, from_tty=1) at gdb/cli/cli-decode.c:2741 #33 0x0000000000c65a94 in execute_command (p=0x232e52f6 "", from_tty=1) at gdb/top.c:570 #34 0x00000000007a7d2c in command_handler (command=0x232e52f0 "") at gdb/event-top.c:566 #35 0x00000000007a8290 in command_line_handler (rl=...) at gdb/event-top.c:802 #36 0x0000000000c9092c in tui_command_line_handler (rl=...) at gdb/tui/tui-interp.c:103 #37 0x00000000007a750c in gdb_rl_callback_handler (rl=0x23385330 "detach") at gdb/event-top.c:258 #38 0x0000000000d910f4 in rl_callback_read_char () at readline/readline/callback.c:290 #39 0x00000000007a7338 in gdb_rl_callback_read_char_wrapper_noexcept () at gdb/event-top.c:194 #40 0x00000000007a73f0 in gdb_rl_callback_read_char_wrapper (client_data=0x22fbf640) at gdb/event-top.c:233 #41 0x0000000000cbee1c in stdin_event_handler (error=0, client_data=0x22fbf640) at gdb/ui.c:154 #42 0x000000000154ed60 in handle_file_event (file_ptr=0x232be730, ready_mask=1) at gdbsupport/event-loop.cc:572 #43 0x000000000154f21c in gdb_wait_for_event (block=1) at gdbsupport/event-loop.cc:693 #44 0x000000000154dec4 in gdb_do_one_event (mstimeout=-1) at gdbsupport/event-loop.cc:263 #45 0x0000000000910f98 in start_event_loop () at gdb/main.c:400 #46 0x0000000000911130 in captured_command_loop () at gdb/main.c:464 #47 0x0000000000912b5c in captured_main (data=0xfffff1a3db58) at gdb/main.c:1338 #48 0x0000000000912bf4 in gdb_main (args=0xfffff1a3db58) at gdb/main.c:1357 #49 0x00000000004170f4 in main (argc=10, argv=0xfffff1a3dcc8) at gdb/gdb.c:38 (gdb) ... The abort happens because a c++ exception escapes to c code, specifically opncls_bstat in bfd/opncls.c. Compiling with -fexceptions works around this. Fix this by catching the exception just before it escapes, in stat_trampoline and likewise in few similar spot. Add a new template catch_exceptions to do so in a consistent way. Tested on aarch64-linux. Approved-by: Pedro Alves <[email protected]> PR remote/31577 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31577

tromey closed this as completed May 14, 2018

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primary Rust gdb development branch/repo? #39

primary Rust gdb development branch/repo? #39

m4b commented Dec 3, 2017

tromey commented Dec 3, 2017

m4b commented Dec 13, 2017

tromey commented May 14, 2018

primary Rust gdb development branch/repo? #39

primary Rust gdb development branch/repo? #39

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m4b commented Dec 3, 2017

tromey commented Dec 3, 2017

m4b commented Dec 13, 2017

tromey commented May 14, 2018