Add two versions of a new function build_id_equal which can be used to
compare build-ids, then make use of these functions in GDB. It seems
better to have a specific function for the task of comparing build-ids
rather than having a length check followed by a memcmp call.
There should be no user visible changes after this commit.
Approved-By: Tom Tromey <tom@tromey.com>
This commit is the result of the following actions:
- Running gdb/copyright.py to update all of the copyright headers to
include 2024,
- Manually updating a few files the copyright.py script told me to
update, these files had copyright headers embedded within the
file,
- Regenerating gdbsupport/Makefile.in to refresh it's copyright
date,
- Using grep to find other files that still mentioned 2023. If
these files were updated last year from 2022 to 2023 then I've
updated them this year to 2024.
I'm sure I've probably missed some dates. Feel free to fix them up as
you spot them.
After the commit:
commit 6647f05df0
Date: Tue Jan 24 18:13:38 2023 +0100
gdb: defer warnings when loading separate debug files
It was pointed out[1] that the warnings being deferred and then later
emitted lacked styling. The warnings lacked styling before the above
commit, but it was suggested that the filenames in these warnings
should be styled, and this commit does this.
There were a couple of previous attempts[2][3][4] to solve this
problem, but these all tried to extend the mechanism introduced in the
above commit, the deferred warnings were placed directly into a
std::vector, but now we tried to, when appropriate, style these
warnings. The review feedback that this approach looked too complex.
So instead, this revision adds a new helper class 'deferred_warnings'
which can be used to collect a set of deferred warnings, and then emit
these deferred warnings later, if needed. This helper class hides the
complexity, so at the point the deferred warning is created no extra
logic is required.
The deferred_warnings class will style the deferred warnings only if
gdb_stderr supports styling. GDB's warnings are sent to gdb_stderr,
so this should ensure we only style when expected.
There was also review feedback[5] that all of the warnings should be
bundled into a single string_file, this has not been done. I feel
pretty strongly that separate warnings should be emitted using
separate "warning" calls. If we do end up with multiple warnings in
this case they aren't really related, one will be about looking up
debug via .gnu_debuglink, while the other will be about build-id based
lookup. So I'd really rather keep the warnings separate.
[1] https://inbox.sourceware.org/gdb-patches/87edr9pcku.fsf@tromey.com/
[2] https://inbox.sourceware.org/gdb-patches/20230216195604.2685177-1-ahajkova@redhat.com/
[3] https://inbox.sourceware.org/gdb-patches/20230217123547.2737612-1-ahajkova@redhat.com/
[4] https://inbox.sourceware.org/gdb-patches/20230320145638.1202335-1-ahajkova@redhat.com/
[5] https://inbox.sourceware.org/gdb-patches/87o7nh1g8h.fsf@tromey.com/
Co-Authored-By: Alexandra Hájková <ahajkova@redhat.com>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Currently, when GDB loads debug information from a separate debug
file, there are a couple of warnings that could be produced if things
go wrong.
In find_separate_debug_file_by_buildid (build-id.c) GDB can give a
warning if the separate debug file doesn't include any actual debug
information, and in separate_debug_file_exists (symfile.c) we can warn
if the CRC checksum in the separate debug file doesn't match the
checksum in the original executable.
The problem here is that, when looking up debug information, GDB will
try several different approaches, lookup by build-id, lookup by
debug-link, and then a lookup from debuginfod. GDB can potentially
give a warning from an earlier attempt, and then succeed with a later
attempt. In the cases I have run into this is primarily a warning
about some out of date debug information on my machine, but then GDB
finds the correct information using debuginfod. This can be confusing
to a user, they will see warnings from GDB when really everything is
working just fine.
For example:
warning: the debug information found in "/usr/lib/debug//lib64/ld-2.32.so.debug" \
does not match "/lib64/ld-linux-x86-64.so.2" (CRC mismatch).
This diagnostic was printed on Fedora 33 even when the correct
debuginfo was downloaded.
In this patch I propose that we defer any warnings related to looking
up debug information from a separate debug file. If any of the
approaches are successful then GDB will not print any of the warnings.
As far as the user is concerned, everything "just worked". Only if
GDB completely fails to find any suitable debug information will the
warnings be printed.
The crc_mismatch test compiles two executables: crc_mismatch and
crc_mismatch-2 and then strips them of debuginfo creating separate
debug files. The test then replaces crc_mismatch-2.debug with
crc_mismatch.debug to trigger "CRC mismatch" warning. A local
debuginfod server is setup to supply the correct debug file, now when
GDB looks up the debug info no warning is given.
The build-id-no-debug-warning.exp is similar to the previous test. It
triggers the "separate debug info file has no debug info" warning by
replacing the build-id based .debug file with the stripped binary and
then loading it to GDB. It then also sets up local debuginfod server
with the correct debug file to download to make sure no warnings are
emitted.
This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
This patch uses new BFD support for detecting build-ids in core
files.
After this patch, it is possible to run gdb with only the
core file, and gdb will automatically load the executable and
debug info [example from tests]:
$ gdb -nx -q
(gdb) core-file corefile-buildid.core
[New LWP 29471]
Reading symbols from gdb.base/corefile-buildid/debugdir-exec/.build-id/36/fe5722c5a7ca3ac746a84e223c6a2a69193a24...
Core was generated by `outputs/gdb.base/coref'.
Program terminated with signal SIGABRT, Aborted.
(gdb)
This work is based on functionality available in Fedora originally
written by Jan Kratochvil.
Regression tested on buildbot.
gdb/ChangeLog:
2019-12-07 Keith Seitz <keiths@redhat.com>
* build-id.c (build_id_bfd_get): Permit bfd_core, too.
(build_id_to_debug_bfd): Make static, rewriting to use
build_id_to_bfd_suffix.
(build_id_to_bfd_suffix): Copy of build_id_to_debug_bfd,
adding `suffix' parameter. Append SUFFIX to file names
when searching for matching files.
(build_id_to_debug_bfd): Use build_id_to_bfd_suffix.
(build_id_to_exec_bfd): Likewise.
* build-id.h (build_id_to_debug_bfd): Clarify that function
searches for BFD of debug info file.
(build_id_to_exec_bfd): Declare.
* corelow.c: Include build-id.h.
(locate_exec_from_corefile_build_id): New function.
(core_target_open): If no executable BFD is found,
search for a core file BFD using build-id.
gdb/testsuite/ChangeLog:
2019-12-07 Keith Seitz <keiths@redhat.com>
* gdb.base/corefile-buildid-shlib-shr.c: New file.
* gdb.base/corefile-buildid-shlib.c: New file.
* gdb.base/corefile-buildid.c: New file.
* gdb.base/corefile-buildid.exp: New file.
Change-Id: I15e9e8e58f10c68b5cae55e2eba58df1e8aef529
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
New in v3:
- Remove things related to the dwarf-5 format.
- Fix compilation on mingw (scoped_mmap.c).
GDB can generate indexes for DWARF debug information, which, when
integrated in the original binary, can speed up loading object files.
This can be done using the gdb-add-index script or directly by the
linker itself. However, not many people know about this. And even
among those who do, because it requires additional steps, I don't know a
lot of people who actually go through that trouble.
To help make using the DWARF index more transparent, this patch
introduces a DWARF index cache. When enabled, loading an index-less
binary in GDB will automatically save an index file in ~/.cache/gdb.
When loading that same object file again, the index file will be looked
up and used to load the DWARF index. You therefore get the benefit of
the DWARF index without having to do additional manual steps or
modifying your build system. When an index section is already present
in the file, GDB will prefer that one over looking up the cache.
When doing my edit-compile-debug cycle, I often debug multiple times the
same build, so the cache helps reducing the load time of the debug
sessions after the first one.
- The saved index file is exactly the same as the output of the "save
gdb-index" command. It is therefore the exact same content that would
be found in the .gdb_index or .debug_names section. We just leave it
as a standalone file instead of merging it in the binary.
- The cache is just a directory with files named after the object
file's build-id. It is not possible to save/load the index for an
object file without build-id in the cache.
- The cache uses the gdb index format. The problem with the dwarf-5
format is that we can generate an addendum to the .debug_str section
that you're supposed to integrate to the original binary. This
complicates a little bit loading the data from the cached index files,
so I would leave this for later.
- The size taken up by ~/.cache/gdb is not limited. I was thinking we
could add configurable limit (like ccache does), but that would come
after. Also, maybe a command to flush the cache.
- The cache is disabled by default. I think once it's been out there
and tested for a while, it could be turned on by default, so that
everybody can enjoy it.
- The code was made to follow the XDG specification: if the
XDG_CACHE_HOME environment variable, it is used, otherwise it falls
back to ~/.cache/gdb. It is possible to change it using "set
index-cache directory". On other OSes than GNU/Linux, ~/.cache may
not be the best place to put such data. On macOS it should probably
default to ~/Library/Caches/... On Windows, %LocalAppData%/... I
don't intend to do this part, but further patches are welcome.
- I think that we need to be careful that multiple instances of GDB
don't interfere with each other (not far fetched at all if you run GDB
in some automated script) and the cache is always coherent (either the
file is not found, or it is found and entirely valid). Writing the
file directly to its final location seems like a recipe for failure.
One GDB could read a file in the index while it is being written by
another GDB. To mitigate this, I made write_psymtabs_to_index write
to temporary files and rename them once it's done. Two GDB instances
writing the index for the same file should not step on each other's
toes (the last file to be renamed will stay). A GDB looking up a file
will only see a complete file or no file. Also, if GDB crashes while
generating the index file, it will leave a work-in-progress file, but
it won't be picked up by other instances looking up in the cache.
gdb/ChangeLog:
* common/pathstuff.h (get_standard_cache_dir): New.
* common/pathstuff.c (get_standard_cache_dir): New.
* build-id.h (build_id_to_string): New.
* dwarf-index-common.h (INDEX4_SUFFIX, INDEX5_SUFFIX,
DEBUG_STR_SUFFIX): Move to here.
* dwarf-index-write.c (INDEX4_SUFFIX, INDEX5_SUFFIX,
DEBUG_STR_SUFFIX): Move from there.
(write_psymtabs_to_index): Make non-static, add basename
parameter. Write to temporary files, rename when done.
(save_gdb_index_command): Adjust call to
write_psymtabs_to_index.
* dwarf2read.h (dwarf2_per_objfile) <index_cache_res>: New
field.
* dwarf2read.c (dwz_file) <index_cache_res>: New field.
(get_gdb_index_contents_from_cache): New.
(get_gdb_index_contents_from_cache_dwz): New.
(dwarf2_initialize_objfile): Read index from cache.
(dwarf2_build_psymtabs): Save to index.
* dwarf-index-cache.h: New file.
* dwarf-index-cache.c: New file.
* dwarf-index-write.h: New file.
gdb/testsuite/ChangeLog:
* boards/index-cache-gdb.exp: New file.
* gdb.dwarf2/index-cache.exp: New file.
* gdb.dwarf2/index-cache.c: New file.
* gdb.base/maint.exp: Check if we are using the index cache.
This patch makes the find_separate_debug_file* functions return
std::string, which allows to get rid of some manual memory management
and one cleanup.
gdb/ChangeLog:
* build-id.c (find_separate_debug_file_by_buildid): Return
std::string.
* build-id.h (find_separate_debug_file_by_buildid): Return
std::string.
* coffread.c (coff_symfile_read): Adjust to std::string.
* elfread.c (elf_symfile_read): Adjust to std::string.
* symfile.c (separate_debug_file_exists): Change parameter to
std::string.
(find_separate_debug_file): Return std::string.
(find_separate_debug_file_by_debuglink): Return std::string.
* symfile.h (find_separate_debug_file_by_debuglink): Return
std::string.
This introduces a new specialization of gdb::ref_ptr that can be used
to manage BFD reference counts. Then it changes most places in gdb to
use this new class, rather than explicit reference-counting or
cleanups. This patch removes make_cleanup_bfd_unref.
If you look you will see a couple of spots using "release" where a use
of gdb_bfd_ref_ptr would be cleaner. These will be fixed in the next
patch.
I think this patch fixes some latent bugs. For example, it seems to
me that previously objfpy_add_separate_debug_file leaked a BFD.
I'm not 100% certain that the macho_symfile_read_all_oso change is
correct. The existing code here is hard for me to follow. One goal
of this sort of automated reference counting, though, is to make it
more difficult to make logic errors; so hopefully the code is clear
now.
2017-01-10 Tom Tromey <tom@tromey.com>
* windows-tdep.c (windows_xfer_shared_library): Update.
* windows-nat.c (windows_make_so): Update.
* utils.h (make_cleanup_bfd_unref): Remove.
* utils.c (do_bfd_close_cleanup, make_cleanup_bfd_unref): Remove.
* symfile.h (symfile_bfd_open)
(find_separate_debug_file_in_section): Return gdb_bfd_ref_ptr.
* symfile.c (read_symbols, symbol_file_add)
(separate_debug_file_exists): Update.
(symfile_bfd_open): Return gdb_bfd_ref_ptr.
(generic_load, reread_symbols): Update.
* symfile-mem.c (symbol_file_add_from_memory): Update.
* spu-linux-nat.c (spu_bfd_open): Return gdb_bfd_ref_ptr.
(spu_symbol_file_add_from_memory): Update.
* solist.h (struct target_so_ops) <bfd_open>: Return
gdb_bfd_ref_ptr.
(solib_bfd_fopen, solib_bfd_open): Return gdb_bfd_ref_ptr.
* solib.c (solib_bfd_fopen, solib_bfd_open): Return
gdb_bfd_ref_ptr.
(solib_map_sections, reload_shared_libraries_1): Update.
* solib-svr4.c (enable_break): Update.
* solib-spu.c (spu_bfd_fopen): Return gdb_bfd_ref_ptr.
* solib-frv.c (enable_break2): Update.
* solib-dsbt.c (enable_break): Update.
* solib-darwin.c (gdb_bfd_mach_o_fat_extract): Return
gdb_bfd_ref_ptr.
(darwin_solib_get_all_image_info_addr_at_init): Update.
(darwin_bfd_open): Return gdb_bfd_ref_ptr.
* solib-aix.c (solib_aix_bfd_open): Return gdb_bfd_ref_ptr.
* record-full.c (record_full_save): Update.
* python/py-objfile.c (objfpy_add_separate_debug_file): Update.
* procfs.c (insert_dbx_link_bpt_in_file): Update.
* minidebug.c (find_separate_debug_file_in_section): Return
gdb_bfd_ref_ptr.
* machoread.c (macho_add_oso_symfile): Change abfd to
gdb_bfd_ref_ptr.
(macho_symfile_read_all_oso): Update.
(macho_check_dsym): Return gdb_bfd_ref_ptr.
(macho_symfile_read): Update.
* jit.c (bfd_open_from_target_memory): Return gdb_bfd_ref_ptr.
(jit_bfd_try_read_symtab): Update.
* gdb_bfd.h (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
(gdb_bfd_openw, gdb_bfd_openr_iovec)
(gdb_bfd_openr_next_archived_file, gdb_bfd_fdopenr): Return
gdb_bfd_ref_ptr.
(gdb_bfd_ref_policy): New struct.
(gdb_bfd_ref_ptr): New typedef.
* gdb_bfd.c (gdb_bfd_open, gdb_bfd_fopen, gdb_bfd_openr)
(gdb_bfd_openw, gdb_bfd_openr_iovec)
(gdb_bfd_openr_next_archived_file, gdb_bfd_fdopenr): Return
gdb_bfd_ref_ptr.
* gcore.h (create_gcore_bfd): Return gdb_bfd_ref_ptr.
* gcore.c (create_gcore_bfd): Return gdb_bfd_ref_ptr.
(gcore_command): Update.
* exec.c (exec_file_attach): Update.
* elfread.c (elf_symfile_read): Update.
* dwarf2read.c (dwarf2_get_dwz_file): Update.
(try_open_dwop_file, open_dwo_file): Return gdb_bfd_ref_ptr.
(open_and_init_dwo_file): Update.
(open_dwp_file): Return gdb_bfd_ref_ptr.
(open_and_init_dwp_file): Update.
* corelow.c (core_open): Update.
* compile/compile-object-load.c (compile_object_load): Update.
* common/gdb_ref_ptr.h (ref_ptr::operator->): New operator.
* coffread.c (coff_symfile_read): Update.
* cli/cli-dump.c (bfd_openr_or_error, bfd_openw_or_error): Return
gdb_bfd_ref_ptr. Rename.
(dump_bfd_file, restore_command): Update.
* build-id.h (build_id_to_debug_bfd): Return gdb_bfd_ref_ptr.
* build-id.c (build_id_to_debug_bfd): Return gdb_bfd_ref_ptr.
(find_separate_debug_file_by_buildid): Update.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This promotes BFD's struct elf_build_id to the generic struct bfd_build_id,
populated when an ELF or PE BFD is read.
gdb is updated to use that, and to use the build-id to find symbols for PE files
also.
There is currently no generic way to extract the build-id from an object file,
perhaps an option to objdump to do this might make sense?
On x86_64-pc-cygwin, gdb's sepdebug.exp changes:
-# of unsupported tests 1
+# of expected passes 90
I don't seem to get consistent testsuite runs on i686-linux-gnu, but there
don't appear to be any regressions.
bfd/ChangeLog:
2015-06-10 Jon Turney <jon.turney@dronecode.org.uk>
* elf-bfd.h : Remove struct elf_build_id.
* bfd.c : Add struct bfd_build_id.
* bfd-in2.h: Regenerate.
* elf.c (elfobj_grok_gnu_build_id): Update to use bfd_build_id.
* libpei.h: Add protoype and macros for
bfd_XXi_slurp_codeview_record.
* peXXigen.c (_bfd_XXi_slurp_codeview_record): Make public
* peicode.h (pe_bfd_read_buildid): Add.
(pe_bfd_object_p): Use pe_bfd_read_buildid().
gdb/ChangeLog:
2015-06-10 Jon Turney <jon.turney@dronecode.org.uk>
* build-id.c: Don't include elf-bfd.h.
(build_id_bfd_get): Use bfd_build_id.
(build_id_verify): Ditto.
* build-id.h: Ditto.
(find_separate_debug_file_by_buildid): Ditto.
* python/py-objfile.c: Don't include elf-bfd.h.
(objfpy_get_build_id) Use bfd_build_id.
(objfpy_build_id_matches, objfpy_lookup_objfile_by_build_id): Ditto.
* coffread.c: Include build-id.h.
(coff_symfile_read): Try find_separate_debug_file_by_buildid.
gdb/doc/ChangeLog:
2015-06-10 Jon Turney <jon.turney@dronecode.org.uk>
* gdb.texinfo (Separate Debug Files): Document that PE is also
supported.
gdb/testsuite/ChangeLog:
2015-06-10 Jon Turney <jon.turney@dronecode.org.uk>
* gdb.base/sepdebug.exp: Add EXEEXT where needed.
* lib/gdb.exp (get_build_id): Teach how to extract build-id from a
PE file.
* lib/future.exp (gdb_find_objdump): Add gdb_find_objdump.
Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>
This patch fixes gdb PR symtab/15597.
The bug is that the .gnu_debugaltlink section includes the build-id of
the alt file, but gdb does not use it.
This patch fixes the problem by changing gdb to do what it ought to
always have done: verify the build id of the file found using the
filename in .gnu_debugaltlink; and if that does not match, try to find
the correct debug file using the build-id and debug-file-directory.
This patch touches BFD. Previously, gdb had its own code for parsing
.gnu_debugaltlink; I changed it to use the BFD functions after those
were introduced. However, the BFD functions are incorrect -- they
assume that .gnu_debugaltlink is formatted like .gnu_debuglink.
However, it it is not. Instead, it consists of a file name followed
by the build-id -- no alignment, and the build-id is not a CRC.
Fixing this properly is a bit of a pain. But, because
separate_alt_debug_file_exists just has a FIXME for the build-id case,
I did not fix it properly. Instead I introduced a hack. This leaves
BFD working just as well as it did before my patch.
I'm willing to do something better here but I could use some guidance
as to what. It seems that the build-id code in BFD is largely punted
on.
FWIW gdb is the only user of bfd_get_alt_debug_link_info outside of
BFD itself.
I moved the build-id logic out of elfread.c and into a new file.
This seemed cleanest to me.
Writing a test case was a bit of a pain. I added a couple new
features to the DWARF assembler to handle this.
Built and regtested on x86-64 Fedora 18.
* bfd-in2.h: Rebuild.
* opncls.c (bfd_get_alt_debug_link_info): Add buildid_len
parameter. Change type of buildid_out. Update.
(get_alt_debug_link_info_shim): New function.
(bfd_follow_gnu_debuglink): Use it.
* Makefile.in (SFILES): Add build-id.c.
(HFILES_NO_SRCDIR): Add build-id.h.
* build-id.c: New file, largely from elfread.c. Modified
most functions.
* build-id.h: New file.
* dwarf2read.c (dwarf2_get_dwz_file): Update for change to
bfd_get_alt_debug_link_info. Verify dwz file's build-id.
Search for dwz file using build-id.
* elfread.c (build_id_bfd_get, build_id_verify)
(build_id_to_debug_filename, find_separate_debug_file): Remove.
* gdb.dwarf2/dwzbuildid.exp: New file.
* lib/dwarf.exp (Dwarf::_section): Add "flags" and "type"
parameters.
(Dwarf::_defer_output): Change "section" parameter to
"section_spec"; update.
(Dwarf::gnu_debugaltlink, Dwarf::_note, Dwarf::build_id): New
procs.
