Re: [edk2-devel] [PATCH] BaseTools/GenFw: Change opcode when converting ADR to ADRP

["Jake Garver via groups.io" <jake=nvidia.com@groups.io>]

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Totally understand and agree, Ard.

In the meantime, I've now experienced the issue with Ubuntu22's GCC 12.3.  Originally, we didn't see the issue on this toolchain, but a developer ran into when preparing a change.  Even more concerning, when I instrumented that change, it went away.  So, it seems to be very sensitive to the input, which will make it hard to reproduce.

Specifically, like the Ubuntu20 10.5 toolchain, the Ubuntu 12.3 toolchain generated an R_AARCH64_ADR_GOT_PAGE relocation against an ADR instruction.  Further, it was when loading the value of __stack_chk_guard.

I was again unable to reproduce this using a crosstool-ng build of GCC 12.3, even when matching the ./configure arguments.

Since it's now reproducible in a toolchain we're actively using, I'll continue looking at it.  I'll let you know what I find.

Thanks,
Jake
________________________________
From: Ard Biesheuvel <ardb@kernel.org>
Sent: Tuesday, December 12, 2023 4:22 AM
To: Jake Garver <jake@nvidia.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>; devel@edk2.groups.io <devel@edk2.groups.io>; rebecca@bsdio.com <rebecca@bsdio.com>; gaoliming@byosoft.com.cn <gaoliming@byosoft.com.cn>; bob.c.feng@intel.com <bob.c.feng@intel.com>; yuwei.chen@intel.com <yuwei.chen@intel.com>
Subject: Re: [edk2-devel] [PATCH] BaseTools/GenFw: Change opcode when converting ADR to ADRP

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On Wed, 6 Dec 2023 at 17:51, Jake Garver <jake@nvidia.com> wrote:
>
> Thanks, Pedro and Ard,
>
> An update on this issue:
>
> It seems to be very specific to Ubuntu20's 10.5 build of GCC.
> I could not reproduce it using a crosstool-ng build of 10.5, even after trying to configure it identically to Ubuntu20's.  It might be something in Ubuntu's patchset, but nothing stuck out to me there.
> We have migrated to Ubuntu22 as a preferred platform.  Their build of GCC 12.1 and 12.3 do not have this issue.  As a result, this issue is no longer a high runner for us.
>
>
> Next step: Try reproducing it by rebuilding Ubuntu's GCC debs.  I still want to get to the bottom of this, just to make sure it doesn't pop-up in later builds on GCC on Ubuntu.
>
> Pedro: I haven't attempted to build without LTO yet.  That looked painful to setup, so I didn't make it a priority.
>

Thanks for the update. If this appears to be specific to Ubuntu's GCC
build, and the issue is no longer reproducible on more recent builds,
I'd be inclined not to bother. But if you do insist and find the
culprit, I'd be happy to take another look.

--
Ard.


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