Re: [PATCH for 4.9/4.14] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at

[Sasha Levin]

On Wed, Jan 13, 2021 at 07:12:44AM +0000, Christophe Leroy wrote:
> From: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
>
> Backport for 4.9 and 4.14
>
> (cherry picked from commit d85be8a49e733dcd23674aa6202870d54bf5600d)
>
> The placeholder for instruction selection should use the second
> argument's operand, which is %1, not %0. This could generate incorrect
> assembly code if the memory addressing of operand %0 is a different
> form from that of operand %1.
>
> Also remove the %Un placeholder because having %Un placeholders
> for two operands which are based on the same local var (ptep) doesn't
> make much sense. By the way, it doesn't change the current behaviour
> because "<>" constraint is missing for the associated "=m".
>
> [chleroy: revised commit log iaw segher's comments and removed %U0]
>
> Fixes: 9bf2b5cdc5fe ("powerpc: Fixes for CONFIG_PTE_64BIT for SMP support")
> Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.28+
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> Acked-by: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/96354bd77977a6a933fe9020da57629007fdb920.1603358942.git.christophe.leroy@xxxxxxxxxx

I took this and the 4.4 backport, thanks!

--
Thanks,
Sasha