On Fri, Jul 19, 2024 at 2:10 AM John Stultz <jstultz@xxxxxxxxxx> wrote:
>
> On Tue, Sep 26, 2023 at 9:09 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
> >
> > The 32-bit ARM kernel stops working if the kernel grows to the point
> > where veneers for __get_user_* are created.
> >
> > AAPCS32 [1] states, "Register r12 (IP) may be used by a linker as a
> > scratch register between a routine and any subroutine it calls. It
> > can also be used within a routine to hold intermediate values between
> > subroutine calls."
> >
> > However, bl instructions buried within the inline asm are unpredictable
> > for compilers; hence, "ip" must be added to the clobber list.
> >
> > This becomes critical when veneers for __get_user_* are created because
> > veneers use the ip register since commit 02e541db0540 ("ARM: 8323/1:
> > force linker to use PIC veneers").
> >
> > [1]: https://github.com/ARM-software/abi-aa/blob/2023Q1/aapcs32/aapcs32.rst
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> > Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
>
> + stable@xxxxxxxxxxxxxxx
> It seems like this (commit 24d3ba0a7b44c1617c27f5045eecc4f34752ab03
> upstream) would be a good candidate for -stable?
Yes.
This one should be back-ported. Thanks.
--
Best Regards
Masahiro Yamada
