Re: [kvm-unit-tests PATCH 2/2] Link with "-z noexecstack" to avoid warning from newer versions of ld

[Sean Christopherson <seanjc@google.com>]

On Fri, Jun 23, 2023, Thomas Huth wrote:
> On 23/06/2023 16.24, Sean Christopherson wrote:
> > On Fri, Jun 23, 2023, Thomas Huth wrote:
> > > Newer versions of ld (from binutils 2.40) complain on s390x and x86:
> > > 
> > >   ld: warning: s390x/cpu.o: missing .note.GNU-stack section implies
> > >                executable stack
> > >   ld: NOTE: This behaviour is deprecated and will be removed in a
> > >             future version of the linker
> > > 
> > > We can silence these warnings by using "-z noexecstack" for linking
> > > (which should not have any real influence on the kvm-unit-tests since
> > > the information from the ELF header is not used here anyway, so it's
> > > just cosmetics).
> > > 
> > > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > > ---
> > >   Makefile | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/Makefile b/Makefile
> > > index 0e5d85a1..20f7137c 100644
> > > --- a/Makefile
> > > +++ b/Makefile
> > > @@ -96,7 +96,7 @@ CFLAGS += -Woverride-init -Wmissing-prototypes -Wstrict-prototypes
> > >   autodepend-flags = -MMD -MF $(dir $*).$(notdir $*).d
> > > -LDFLAGS += -nostdlib
> > > +LDFLAGS += -nostdlib -z noexecstack
> > 
> > Drat, the pull request[1] I sent to Paolo yesterday only fixes x86[2].
> 
> Oops, sorry, I did not notice that patch in my overcrowded mailboxes (or
> forgot about it during KVM forum...) :-/

Heh, you gave a Reviewed-by[*], so either its the latter, or you've got a clone
running around :-)

[*] https://lore.kernel.org/all/916aac4f-97b8-70c2-de39-87438eb4aea4@redhat.com

> > Paolo, want me to redo the pull request to drop the x86-specific patch?
> 
> I can also respin my patch on top of your series later ... the problem
> currently also only seems to happen on x86 and s390x, on ppc64 and aarch64,
> the linker does not complain ... so maybe it's even better to do it
> per-architecture only anyway? Opinions?

I don't think it makes sense to do this per-arch, other architectures likely aren't
problematic purely because of linker specific behavior, e.g. see

https://patches.linaro.org/project/binutils/patch/1506025575-1559-1-git-send-email-jim.wilson@linaro.org