linux-kernel - [PATCH v3 3/3] powerpc: Fix update form addressing in inline assembly

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Message-Id: <62eab5ca595485c192de1765bdac099f633a21d0.1603358942.git.christophe.leroy@csgroup.eu>
Date:   Thu, 22 Oct 2020 09:29:21 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        mathieu.desnoyers@...icios.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3 3/3] powerpc: Fix update form addressing in inline assembly

In several places, inline assembly uses the "%Un" modifier
to enable the use of instruction with update form addressing,
but the associated "<>" constraint is missing.

As mentioned in previous patch, this fails with gcc 4.9, so
"<>" can't be used directly.

Use UPD_CONSTR macro everywhere %Un modifier is used.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
Reviewed-by: Segher Boessenkool <segher@...nel.crashing.org>
---
v3: __set_pte_at() not impacted anymore (%U0 removed in previous patch)
v2: Build failure (circular inclusion) fixed by change in patch 1
---
 arch/powerpc/include/asm/atomic.h | 9 +++++----
 arch/powerpc/include/asm/io.h     | 4 ++--
 arch/powerpc/kvm/powerpc.c        | 4 ++--
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index 8a55eb8cc97b..61c6e8b200e8 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -10,6 +10,7 @@
 #include <linux/types.h>
 #include <asm/cmpxchg.h>
 #include <asm/barrier.h>
+#include <asm/asm-const.h>
 
 /*
  * Since *_return_relaxed and {cmp}xchg_relaxed are implemented with
@@ -26,14 +27,14 @@ static __inline__ int atomic_read(const atomic_t *v)
 {
 	int t;
 
-	__asm__ __volatile__("lwz%U1%X1 %0,%1" : "=r"(t) : "m"(v->counter));
+	__asm__ __volatile__("lwz%U1%X1 %0,%1" : "=r"(t) : "m"UPD_CONSTR(v->counter));
 
 	return t;
 }
 
 static __inline__ void atomic_set(atomic_t *v, int i)
 {
-	__asm__ __volatile__("stw%U0%X0 %1,%0" : "=m"(v->counter) : "r"(i));
+	__asm__ __volatile__("stw%U0%X0 %1,%0" : "=m"UPD_CONSTR(v->counter) : "r"(i));
 }
 
 #define ATOMIC_OP(op, asm_op)						\
@@ -316,14 +317,14 @@ static __inline__ s64 atomic64_read(const atomic64_t *v)
 {
 	s64 t;
 
-	__asm__ __volatile__("ld%U1%X1 %0,%1" : "=r"(t) : "m"(v->counter));
+	__asm__ __volatile__("ld%U1%X1 %0,%1" : "=r"(t) : "m"UPD_CONSTR(v->counter));
 
 	return t;
 }
 
 static __inline__ void atomic64_set(atomic64_t *v, s64 i)
 {
-	__asm__ __volatile__("std%U0%X0 %1,%0" : "=m"(v->counter) : "r"(i));
+	__asm__ __volatile__("std%U0%X0 %1,%0" : "=m"UPD_CONSTR(v->counter) : "r"(i));
 }
 
 #define ATOMIC64_OP(op, asm_op)						\
diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index 58635960403c..87964dfb838e 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -122,7 +122,7 @@ static inline u##size name(const volatile u##size __iomem *addr)	\
 {									\
 	u##size ret;							\
 	__asm__ __volatile__("sync;"#insn"%U1%X1 %0,%1;twi 0,%0,0;isync"\
-		: "=r" (ret) : "m" (*addr) : "memory");			\
+		: "=r" (ret) : "m"UPD_CONSTR (*addr) : "memory");	\
 	return ret;							\
 }
 
@@ -130,7 +130,7 @@ static inline u##size name(const volatile u##size __iomem *addr)	\
 static inline void name(volatile u##size __iomem *addr, u##size val)	\
 {									\
 	__asm__ __volatile__("sync;"#insn"%U0%X0 %1,%0"			\
-		: "=m" (*addr) : "r" (val) : "memory");			\
+		: "=m"UPD_CONSTR (*addr) : "r" (val) : "memory");	\
 	mmiowb_set_pending();						\
 }
 
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 13999123b735..cf52d26f49cd 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -1087,7 +1087,7 @@ static inline u64 sp_to_dp(u32 fprs)
 
 	preempt_disable();
 	enable_kernel_fp();
-	asm ("lfs%U1%X1 0,%1; stfd%U0%X0 0,%0" : "=m" (fprd) : "m" (fprs)
+	asm ("lfs%U1%X1 0,%1; stfd%U0%X0 0,%0" : "=m"UPD_CONSTR (fprd) : "m"UPD_CONSTR (fprs)
 	     : "fr0");
 	preempt_enable();
 	return fprd;
@@ -1099,7 +1099,7 @@ static inline u32 dp_to_sp(u64 fprd)
 
 	preempt_disable();
 	enable_kernel_fp();
-	asm ("lfd%U1%X1 0,%1; stfs%U0%X0 0,%0" : "=m" (fprs) : "m" (fprd)
+	asm ("lfd%U1%X1 0,%1; stfs%U0%X0 0,%0" : "=m"UPD_CONSTR (fprs) : "m"UPD_CONSTR (fprd)
 	     : "fr0");
 	preempt_enable();
 	return fprs;
-- 
2.25.0