Re: [PATCH 0/5] aarch64 BTI stub fixes

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

The 11/07/2023 13:08, Szabolcs Nagy wrote:
> The 11/07/2023 11:38, Nick Clifton wrote:
> > FYI - I did find one regression in the linker testsuite with the patch applied:
> > 
> >   FAIL: Check linker stubs with indirect calls handle BTI (exe).
> > 
> > However there are mitigating circumstances:
> > 
> >   * The failure was for an unusual toolchain configuration:
> > 
> >       --target=aarch64_be-linux-gnu_ilp32
> > 
> >   * The three other tests in this part of the testsuite also fail, both
> >     with and without your patch applied:
> > 
> >       FAIL: Check linker stubs with indirect calls handle BTI (shared lib).
> >       FAIL: Check linker stubs with indirect calls handle BTI (exe).
> >       FAIL: Check linker stubs with indirect calls handle BTI when target has BTI.
> > 
> >    Note: there appear to be *two* tests called "check linker stubs with indirect calls handle BTI (exe)."
> > 
> > I leave it up to you to decide if it is worth fixing these tests.
> 
> thanks for looking at this.
> i will have to check what's going on.

i will change the name of the new test to be unique.

cleaning up ilp32 test issues will be a fair bit of work.

i can commit a followup patch to force the tests i added to use
lp64 abi, like we do on other tests, but this is not ideal.

> > PS.  My gut feeling at the moment is that we do not need a 2.41.1 release
> > for this patch, since AArch64 systems with BTI enabled are not yet the norm,
> > and those that do exist are being used to test for problems like this rather
> > than general use.  Since your patch will be in the 2.42 release, due January
> > next year, I think that that will be a reasonable timescale for getting the
> > fix out there.  Do you agree ?
> 
> makes sense,
> unless it affects hardened kernel builds.
> i will have to check if that's an issue.

in practice i think the kernel should be fine.
(it's hard to say conclusively)

but i plan to backport the patches even if we don't arrange
a new release.