[PATCH 2/3] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at

From: Christophe Leroy
Date: Mon Oct 19 2020 - 08:13:03 EST


From: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>

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 instruction selection for argument %0 ever differs
from argument %1.

Fixes: 9bf2b5cdc5fe ("powerpc: Fixes for CONFIG_PTE_64BIT for SMP support")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.28+
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/include/asm/book3s/32/pgtable.h | 2 +-
arch/powerpc/include/asm/nohash/pgtable.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 36443cda8dcf..34f5ca391f0c 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -524,7 +524,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
__asm__ __volatile__("\
stw%U0%X0 %2,%0\n\
eieio\n\
- stw%U0%X0 %L2,%1"
+ stw%U1%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 4b7c3472eab1..a00e4c1746d6 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -199,7 +199,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
__asm__ __volatile__("\
stw%U0%X0 %2,%0\n\
eieio\n\
- stw%U0%X0 %L2,%1"
+ stw%U1%X1 %L2,%1"
: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
: "r" (pte) : "memory");
return;
--
2.25.0