Bug 246537
| Summary: | lib.libexecinfo.backtrace_test.backtrace_fmt_basic starts failing on amd64 after r360915 | ||
|---|---|---|---|
| Product: | Base System | Reporter: | Li-Wen Hsu <lwhsu> |
| Component: | tests | Assignee: | freebsd-testing (Nobody) <testing> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | CC: | cem, dchagin, dim, emaste, kan, kib |
| Priority: | --- | Keywords: | regression |
| Version: | CURRENT | ||
| Hardware: | amd64 | ||
| OS: | Any | ||
|
Description
Li-Wen Hsu
2020-05-18 12:13:18 UTC
A commit references this bug: Author: lwhsu Date: Mon May 18 12:36:29 UTC 2020 New revision: 361210 URL: https://svnweb.freebsd.org/changeset/base/361210 Log: Temporarily disable failing case in CI of amd64: - lib.libexecinfo.backtrace_test.backtrace_fmt_basic PR: 246537 Sponsored by: The FreeBSD Foundation Changes: head/contrib/netbsd-tests/lib/libexecinfo/t_backtrace.c After more testing, it starts failing on amd64 after https://svnweb.freebsd.org/changeset/base/360915 i386 is not affected. I suspect r360915 is just wrong and should be reverted. We're missing the frame below /above atf_tc_run (probably "_start" and "main"). $ nm crt1.o: .. 0000000000000000 T _start If we had one more frame (_start or main), the test would be: 18 >= 12 + 2 + 4 (pass). (Our backtrace / libexecinfo (llvm-libunwind) relies on asynchronous unwind tables and does not know about frame pointers. Sure, maybe it should! That would be nice.) (In reply to Conrad Meyer from comment #3) This was done to fix bug 246322. As explained there, it is to work around a BFD ld assertion or bug. I'm fine with reverting, as long as we either fix BFD ld, or ban the use of it. :) (In reply to Dimitry Andric from comment #6) > work around a BFD ld assertion or bug. For more explanation see base r209294. It still hits the assertion with binutils master as of last week. We switched to both ld.lld and llvm-libunwind in CURRENT, so maybe leave it be in stable/ and just revert in CURRENT? > places the special CIE into the .eh_frame indicating the end of section,
> that is located before generated unwind table. New ld has assertion that
> verifies that closing CIE is indeed the last CIE,
Would it be possible to (?)fix LLVM to not mark the CIE as end of section? I guess I'm unclear on if ld.bfd's assertion is reasonable or what. Why doesn't this happen for other objects built with async unwind tables?
(In reply to Conrad Meyer from comment #9) Maybe, but I'm not sure that is the right way to go. In base r209294 the problem in BFD ld was first spotted, and at that time it was likely triggered by newer versions of gcc. But kan@ may know a bit more about this. E.g. with the information I have now, I think this is a BFD ld bug/misfeature, and it should be fixed there. Any idea why this trips for crt1.o but not any other .o? (In reply to Conrad Meyer from comment #11) You mean the ld.bfd assertion? Maybe it is because crt1.o is linked using -r from crt1_c.o and crt1_s.o? (In reply to Dimitry Andric from comment #12) Yep, the ld.bfd assertion. Trips exactly what ? crt1.o is specially added to the linker command line to create the final binary. It mist go first among all object files supplied to the linker. (In reply to Konstantin Belousov from comment #14) Trips bug 246322: > /usr/bin/ld: error in /usr/lib/crt1.o(.eh_frame); no .eh_frame_hdr table will be created. I would like to fix this for 13.0. I think we can just revert the change that broke this now, some discussion over in another bug: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=246322#c14 (In reply to Conrad Meyer from comment #16) So if reverting, does gcc+binutils toolchain work still ? If yes, then there should be no reason to not revert. Might be an exp run for amd64+i386 is due. Yeah, in the other bug we are unable to reproduce the original issue with current binutils (comments #15 and 16). And the original reporter has not responded for ~4 months. A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=c969310c992a12459ed4025c1cd8b22f29c763b5 commit c969310c992a12459ed4025c1cd8b22f29c763b5 Author: Dmitry Chagin <dchagin@FreeBSD.org> AuthorDate: 2023-06-29 16:34:39 +0000 Commit: Dmitry Chagin <dchagin@FreeBSD.org> CommitDate: 2023-06-29 16:34:39 +0000 csu: Implement _start using as to satisfy unwinders on x86_64 The right unwinding stop indicator should be CFI-undefined PC. https://dwarfstd.org/doc/Dwarf3.pdf - page 118: If a Return Address register is defined in the virtual unwind table, and its rule is undefined (for example, by DW_CFA_undefined), then there is no return address and no call address, and the virtual unwind of stack activations is complete. This requires the crt code be built with unwind tables, for that remove -fno-asynchronous-unwind-tables to enable unwind tables generation. PR: 241562, 246322, 246537 Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D40780 lib/csu/Makefile.inc | 20 +++++----- lib/csu/amd64/Makefile | 3 ++ lib/csu/amd64/crt1_c.c | 22 ----------- lib/csu/amd64/crt1_s.S (new) | 88 ++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 102 insertions(+), 31 deletions(-) A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=a18b956b73cee784e5c422d20fd0e4dabebd7eee commit a18b956b73cee784e5c422d20fd0e4dabebd7eee Author: Dmitry Chagin <dchagin@FreeBSD.org> AuthorDate: 2023-06-29 16:53:07 +0000 Commit: Dmitry Chagin <dchagin@FreeBSD.org> CommitDate: 2023-06-29 16:53:07 +0000 libexecinfo: Enable backtrace_test.backtrace_fmt_basic on amd64 again Due to unwind tables generation enabled after c969310c for csu. PR: 241562, 246322, 246537 Reviewed by: kib, ngie Differential Revision: https://reviews.freebsd.org/D40758 contrib/netbsd-tests/lib/libexecinfo/t_backtrace.c | 5 ----- 1 file changed, 5 deletions(-) |