[PATCH 4/4] aarch64: add tests for glibc.cpu.aarch64_bti behaviour

[Yury Khrustalev]

On Mon, Nov 17, 2025 at 10:03:05AM -0300, Adhemerval Zanella Netto wrote:
> 
> On 14/11/25 11:58, Yury Khrustalev wrote:
> > Hi Adhemerval,
> > 
> > Thank you for your comments, all will be fixed in the next version of
> > this patch series.
> > 
> > On Mon, Nov 10, 2025 at 12:02:50PM -0300, Adhemerval Zanella Netto wrote:
> >>
> >> ...
> >>
> >> I am seeing these failures when the toolchain does not have 
> >> --enable-standard-branch-protection:
> >>
> >> FAIL: misc/tst-bti-dep-prot
> >> FAIL: misc/tst-bti-dlopen-imm
> >> FAIL: misc/tst-bti-dlopen-prot
> >> FAIL: misc/tst-bti-dlopen-transitive
> >>
> >> It is because the binaries do not have the BTI property:
> > 
> > A similar problem exists with some of the GCS tests too. In case when
> > the toolchain's CC and LD support BTI (or GCS, etc) but we do not
> > enable corresponding branch protection for the Glibc itself, we are
> > going to see such test errors simply because libc.so won't have the
> > marking.
> > 
> > Ideally, we need a way to know if branch protection is enabled when
> > compiling and linking libc.so and only then activate the corresponding
> > tests.
> > 
> > Perhaps before running the test we could check properties of libc.so
> > and let these tests to fail as UNSUPPORTED?
> 
> This can be a configure check that enabled Makefile flag.

I'm not sure how this can be a configure check. When we run configure,
Glibc is not built yet, so we can't probe ELF properties of libc.so.

During configure run, is it possible to get a full compiler and linker
commands that will be used to build libc.so that will take into account
environment variables and various configure flags? We could use that to
link a dummy binary and probe its properties perhaps?

Thanks,
Yury