Bug#808246: Potentially interesting difference in module header symbol order
On Mon, Dec 21, 2015 at 02:55:16PM -0500, wrote:
> I tried various binutils versions, and any version starting from
> 2.25.51.20151014-1 seems to be reordering the sections, even though
> the arch/powerpc/kernel/vmlinux.lds file explicitly says to use the
> order with .toc at the end. So somehow binutils 2.25.51+ is ignoring
> instructions about which order to put things in the file, which seems
> like it is causing the kernel to not be able to load modules.
>
> Simply reverting to binutils 2.25.1-7 makes the modules build like they
> did before, so it does not seem to be gcc or anything else at fault,
> just the new binutils.
>
> Since most architectures probably don't have anything like the .toc,
> it is likely only powerpc64 is affected.
It looks related to the -z relro support patches for powerpc64 in
binutils. Sections are being reordered to allow more sections to be
made read only, and it could be that the kernel's module loading code
is making invalid assumptions about the section order.
--
Len Sorensen
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