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8b39ec7074
If gcc is configured on aarch64-linux against new binutils, such as
2.46, it doesn't emit into assembly markings like
.section .note.gnu.property,"a"
.align 3
.word 4
.word 16
.word 5
.string "GNU"
.word 0xc0000000
.word 4
.word 0x7
.align 3
but instead emits
.aeabi_subsection aeabi_feature_and_bits, optional, ULEB128
.aeabi_attribute Tag_Feature_BTI, 1
.aeabi_attribute Tag_Feature_PAC, 1
.aeabi_attribute Tag_Feature_GCS, 1
The former goes into .note.gnu.propery section, the latter goes into
.ARM.attributes section.
Now, when linking without LTO or with LTO but without -g, all behaves
for the linked binaries the same, say for test.c
int main () {}
$ gcc -g -mbranch-protection=standard test.c -o test; readelf -j .note.gnu.property test
Displaying notes found in: .note.gnu.property
Owner Data size Description
GNU 0x00000010 NT_GNU_PROPERTY_TYPE_0
Properties: AArch64 feature: BTI, PAC, GCS
$ gcc -flto -mbranch-protection=standard test.c -o test; readelf -j .note.gnu.property test
Displaying notes found in: .note.gnu.property
Owner Data size Description
GNU 0x00000010 NT_GNU_PROPERTY_TYPE_0
Properties: AArch64 feature: BTI, PAC, GCS
$ gcc -flto -g -mbranch-protection=standard test.c -o test; readelf -j .note.gnu.property test
readelf: Warning: Section '.note.gnu.property' was not dumped because it does not exist
The problem is that the *.debug.temp.o object files created by lto-wrapper
don't have these markings. The function copies over .note.GNU-stack section
(so that it doesn't similarly on most arches break PT_GNU_STACK segment
flags), and .note.gnu.property (which used to hold this stuff e.g. on
aarch64 or x86, added in PR93966). But it doesn't copy the new
.ARM.attributes section.
The following patch fixes it by copying that section too. The function
unfortunately only works on names, doesn't know if it is copying ELF or some
other format (PE, Mach-O) or if it is copying ELF, whether it is EM_AARCH64
or some other arch. The following patch just copies the section always,
I think it is very unlikely people would use .ARM.attributes section for
some random unrelated stuff. If we'd want to limit it to just EM_AARCH64,
guess it would need to be done in
libiberty/simple-object-elf.c (simple_object_elf_copy_lto_debug_sections)
instead as an exception for the (*pfn) callback results (and there it could
e.g. verify SHT_AARCH64_ATTRIBUTES type but even there dunno if it has
access to the Ehdr stuff).
No testcase from me, dunno if e.g. the linker can flag the lack of those
during linking with some option rather than using readelf after link and
what kind of effective targets we'd need for such a test.
2026-03-05 Jakub Jelinek <jakub@redhat.com>
PR target/124365
* simple-object.c (handle_lto_debug_sections): Also copy over
.ARM.attributes section.
This directory contains the -liberty library of free software.
It is a collection of subroutines used by various GNU programs.
Current members include:
getopt -- get options from command line
obstack -- stacks of arbitrarily-sized objects
strerror -- error message strings corresponding to errno
strtol -- string-to-long conversion
strtoul -- string-to-unsigned-long conversion
We expect many of the GNU subroutines that are floating around to
eventually arrive here.
The library must be configured from the top source directory. Don't
try to run configure in this directory. Follow the configuration
instructions in ../README.
Please report bugs to https://gcc.gnu.org/bugzilla/ and send fixes to
"gcc-patches@gcc.gnu.org". Thank you.
ADDING A NEW FILE
=================
There are two sets of files: Those that are "required" will be
included in the library for all configurations, while those
that are "optional" will be included in the library only if "needed."
To add a new required file, edit Makefile.in to add the source file
name to CFILES and the object file to REQUIRED_OFILES.
To add a new optional file, it must provide a single function, and the
name of the function must be the same as the name of the file.
* Add the source file name to CFILES in Makefile.in and the object
file to CONFIGURED_OFILES.
* Add the function to name to the funcs shell variable in
configure.ac.
* Add the function to the AC_CHECK_FUNCS lists just after the
setting of the funcs shell variable. These AC_CHECK_FUNCS calls
are never executed; they are there to make autoheader work
better.
* Consider the special cases of building libiberty; as of this
writing, the special cases are newlib and VxWorks. If a
particular special case provides the function, you do not need
to do anything. If it does not provide the function, add the
object file to LIBOBJS, and add the function name to the case
controlling whether to define HAVE_func.
Finally, in the build directory of libiberty, configure with
"--enable-maintainer-mode", run "make maint-deps" to update
Makefile.in, and run 'make stamp-functions' to regenerate
functions.texi.
The optional file you've added (e.g. getcwd.c) should compile and work
on all hosts where it is needed. It does not have to work or even
compile on hosts where it is not needed.
ADDING A NEW CONFIGURATION
==========================
On most hosts you should be able to use the scheme for automatically
figuring out which files are needed. In that case, you probably
don't need a special Makefile stub for that configuration.
If the fully automatic scheme doesn't work, you may be able to get
by with defining EXTRA_OFILES in your Makefile stub. This is
a list of object file names that should be treated as required
for this configuration - they will be included in libiberty.a,
regardless of whatever might be in the C library.