Re: [PATCH 2/2] [RFC] iommu: io-pgtable-arm-v7s: avoid gcc-16.0.1 section mismatch

[Will Deacon <will@kernel.org>]

On Tue, Mar 10, 2026 at 08:26:40PM +0100, Arnd Bergmann wrote:
> On Tue, Mar 10, 2026, at 17:40, Will Deacon wrote:
> > On Tue, Feb 03, 2026 at 05:24:00PM +0100, Arnd Bergmann wrote:
> >> From: Arnd Bergmann <arnd@arndb.de>
> >> 
> >> gcc-16 has gained some more advanced inlining techniques that enable
> >> it to inline the dummy_tlb_add_page() and dummy_tlb_flush() function
> >> pointers into a specialized version of __arm_v7s_unmap:
> >> 
> >> WARNING: modpost: vmlinux: section mismatch in reference: __arm_v7s_unmap+0x2cc (section: .text) -> dummy_tlb_add_page (section: .init.text)
> >> 
> >> From what I can tell, the transformation is correct, as this
> >> is only called when __arm_v7s_unmap() is called from
> >> arm_v7s_do_selftests(), which is also __init.
> >> 
> >> I have not come up with a good workaround, so this simply marks
> >> dummy_tlb_add_page() as not __init. Since there are currently only two
> >> files where this happens, that may be an easy way out.
> >> 
> >> If anyone has a better idea for how to deal with that, let me know!
> >
> > Can we mark the dummy_* functions as 'noinline' instead? We shouldn't
> > have to keep the selftest code kicking around in memory after boot.
> 
> I think that would work as well, but I'd have to test it properly,
> as the gcc behavior was already not what I had expected.
> 
> Another option may be to take this a bit further and do the
> same for the arm_v7s selftest that Mostafa did in the lpae
> selftest with 7e06063a43d3 ("iommu/io-pgtable-arm-selftests:
> Use KUnit") and a3c24b6d7cd6 ("iommu/io-pgtable-arm-selftests:
> Modularize the test").
> 
> I think that would be the most logical step, but it's also
> beyond what I can do as a simple build fix.

tbh, I'm happy to take the noinline variant as a quick hack if it works.

Will