PR28827 testcase

[H.J. Lu]

On Sun, Feb 6, 2022 at 2:54 PM Alan Modra <amodra@gmail.com> wrote:
>
> On Sat, Feb 05, 2022 at 08:26:55PM -0800, H.J. Lu wrote:
> > On Sun, Feb 06, 2022 at 02:47:19PM +1030, Alan Modra via Binutils wrote:
> > > On Sat, Feb 05, 2022 at 10:39:50AM +0000, Nick Clifton wrote:
> > > > Hi Alan, Hi Fangrui,
> > > >
> > > > > This testcase triggers a stub sizing error with the patches applied
> > > > > for PR28743 (commit 2f83249c13d8 and c804c6f98d34).
> > > > >
> > > > >         PR 28827
> > > > >         * testsuite/ld-powerpc/pr28827-1.s,
> > > > >         * testsuite/ld-powerpc/pr28827-1.d: New test.
> > > > >         * testsuite/ld-powerpc/powerpc.exp: Run it.
> > > >
> > > > Given the importance of the PowerPC target, I am going to hold
> > > > off from creating the 2.38 release until this issue is fixed.
> > >
> > > Thanks, I appreciate it.
> > >
> > > >  I do hope however that it can be resolved soon....
> > >
> > > The solution is to revert HJ's two relro patches on the branch.  That
> > > will let you immediately make a release.  Despite being raised by
> > > Florian, I don't believe PR28743 is an important bug to fix just
> > > before a release.  Our relro support has sometimes created a hole for
> > > *years*.
> > >
> > > Of course, the patches ought to be reverted on mainline too,
> > > separately from whatever solution we finally adopt for PR28743.
> > >
> >
> > Why make removing the 1-page gap before the PT_GNU_RELRO segment opt-in?
> >
> > https://sourceware.org/pipermail/binutils/2022-February/119625.html
>
> I happen to think your changes to lang_size_relro_segment_1 are wrong.
> Making them optional doesn't fix that.

So far, it has been working for x86.   Do you have a testcase to show
otherwise?

> The major reason is that I question the premise behind the patch.  Is
> it really worth wasting up to maxpagesize-1 in memory at the end of

My patches shouldn't create a gap of more than 1-page at the end.
If it isn't the case, do you have a testcase for x86?  I don't see the
value of a 1-page gap before RELRO segment on x86.  I'd like to
avoid it on x86 if possible.

> the relro segment in order to remove a page gap at the beginning of
> the relro segment?  That seems a dubious trade-off to me.  If process
> memory is an issue then it would be better to increase disk image size
> for reduced memory size.
>
> There is also the fact that we now hit the do_reset code path in
> lang_size_relro_segment when running multiple ld tests.  I think that
> says the current implementation is broken.
>

-- 
H.J.