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

[Yury Khrustalev]

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:
> 
> On 31/10/25 16:37, Yury Khrustalev wrote:
> > Check that the new tunable changes behaviour correctly:
> > 
> >  * When BTI is enforced, any unmarked binary that is loaded
> >    results in an error: either an abort or dlopen error when
> >    this binary is loaded via dlopen.
> >  * When BTI is not enforced, it is OK to load an unmarked
> >    binary.
> > ...
> >
> > +tests += \
> > +  tst-bti-abort-imm \
> > +  tst-bti-abort-transitive \
> > +  tst-bti-abort-unprot \
> > +  tst-bti-dep-prot \
> > +  tst-bti-dlopen-imm \
> > +  tst-bti-dlopen-prot \
> > +  tst-bti-dlopen-transitive \
> > +  tst-bti-permissive-dlopen \
> > +  tst-bti-permissive-imm \
> > +  tst-bti-permissive-transitive \
> > +  # tests
> 
> 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?

> I think we will need to use -mbranch-protection=bti for the aforementioned
> tests.

This won't work unfortunately.

Thanks,
Yury