[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 at efficios.com>
>
>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 at vger.kernel.org> # v2.6.28+
>Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
>Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
>Acked-by: Segher Boessenkool <segher at kernel.crashing.org>
>Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
>Link: https://lore.kernel.org/r/96354bd77977a6a933fe9020da57629007fdb920.1603358942.git.christophe.leroy@csgroup.eu

I took this and the 4.4 backport, thanks!

-- 
Thanks,
Sasha