The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d85be8a49e733dcd23674aa6202870d54bf5600d Mon Sep 17 00:00:00 2001

From: Mathieu Desnoyers mathieu.desnoyers@efficios.com Date: Thu, 22 Oct 2020 09:29:20 +0000 Subject: [PATCH] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at

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@vger.kernel.org # v2.6.28+ Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Signed-off-by: Christophe Leroy christophe.leroy@csgroup.eu Acked-by: Segher Boessenkool segher@kernel.crashing.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/96354bd77977a6a933fe9020da57629007fdb920.160335894...

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h index 36443cda8dcf..41d8bc6db303 100644 --- a/arch/powerpc/include/asm/book3s/32/pgtable.h +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h @@ -522,9 +522,9 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, if (pte_val(*ptep) & _PAGE_HASHPTE) flush_hash_entry(mm, ptep, addr); __asm__ __volatile__("\ - stw%U0%X0 %2,%0\n\ + stw%X0 %2,%0\n\ eieio\n\ - stw%U0%X0 %L2,%1" + stw%X1 %L2,%1" : "=m" (*ptep), "=m" (*((unsigned char *)ptep+4)) : "r" (pte) : "memory");

diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h index 6277e7596ae5..ac75f4ab0dba 100644 --- a/arch/powerpc/include/asm/nohash/pgtable.h +++ b/arch/powerpc/include/asm/nohash/pgtable.h @@ -192,9 +192,9 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, */ if (IS_ENABLED(CONFIG_PPC32) && IS_ENABLED(CONFIG_PTE_64BIT) && !percpu) { __asm__ __volatile__("\ - stw%U0%X0 %2,%0\n\ + stw%X0 %2,%0\n\ eieio\n\ - stw%U0%X0 %L2,%1" + stw%X1 %L2,%1" : "=m" (*ptep), "=m" (*((unsigned char *)ptep+4)) : "r" (pte) : "memory"); return;