* [PATCH for 4.9/4.14] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at
@ 2021-01-13 7:12 Christophe Leroy
2021-01-13 16:48 ` Sasha Levin
0 siblings, 1 reply; 2+ messages in thread
From: Christophe Leroy @ 2021-01-13 7:12 UTC (permalink / raw)
To: stable; +Cc: linux-kernel, linuxppc-dev
From: Mathieu Desnoyers <mathieu.desnoyers@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@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/96354bd77977a6a933fe9020da57629007fdb920.1603358942.git.christophe.leroy@csgroup.eu
---
arch/powerpc/include/asm/book3s/32/pgtable.h | 4 ++--
arch/powerpc/include/asm/nohash/pgtable.h | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 016579ef16d3..ec98abca0df0 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -414,9 +414,9 @@ 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 5c68f4a59f75..e9171b8242e4 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -157,9 +157,9 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
flush_hash_entry(mm, ptep, addr);
#endif
__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");
--
2.25.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH for 4.9/4.14] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at
2021-01-13 7:12 [PATCH for 4.9/4.14] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at Christophe Leroy
@ 2021-01-13 16:48 ` Sasha Levin
0 siblings, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2021-01-13 16:48 UTC (permalink / raw)
To: Christophe Leroy; +Cc: stable, linux-kernel, linuxppc-dev
On Wed, Jan 13, 2021 at 07:12:44AM +0000, Christophe Leroy wrote:
>From: Mathieu Desnoyers <mathieu.desnoyers@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@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/96354bd77977a6a933fe9020da57629007fdb920.1603358942.git.christophe.leroy@csgroup.eu
I took this and the 4.4 backport, thanks!
--
Thanks,
Sasha
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