[PATCH v2 1/3] powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9

[PATCH v2 1/3] powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9

[Christophe Leroy]

GCC 4.9 sometimes fails to build with "m<>" constraint in
inline assembly.

  CC      lib/iov_iter.o
In file included from ./arch/powerpc/include/asm/cmpxchg.h:6:0,
                 from ./arch/powerpc/include/asm/atomic.h:11,
                 from ./include/linux/atomic.h:7,
                 from ./include/linux/crypto.h:15,
                 from ./include/crypto/hash.h:11,
                 from lib/iov_iter.c:2:
lib/iov_iter.c: In function 'iovec_from_user.part.30':
./arch/powerpc/include/asm/uaccess.h:287:2: error: 'asm' operand has impossible constraints
  __asm__ __volatile__(    \
  ^
./include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
 # define unlikely(x) __builtin_expect(!!(x), 0)
                                          ^
./arch/powerpc/include/asm/uaccess.h:583:34: note: in expansion of macro 'unsafe_op_wrap'
 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
                                  ^
./arch/powerpc/include/asm/uaccess.h:329:10: note: in expansion of macro '__get_user_asm'
  case 4: __get_user_asm(x, (u32 __user *)ptr, retval, "lwz"); break; \
          ^
./arch/powerpc/include/asm/uaccess.h:363:3: note: in expansion of macro '__get_user_size_allowed'
   __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \
   ^
./arch/powerpc/include/asm/uaccess.h:100:2: note: in expansion of macro '__get_user_nocheck'
  __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false)
  ^
./arch/powerpc/include/asm/uaccess.h:583:49: note: in expansion of macro '__get_user_allowed'
 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
                                                 ^
lib/iov_iter.c:1663:3: note: in expansion of macro 'unsafe_get_user'
   unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
   ^
make[1]: *** [scripts/Makefile.build:283: lib/iov_iter.o] Error 1

Define a UPD_CONSTR macro that is "<>" by default and
only "" with GCC prior to GCC 5.

Fixes: fcf1f26895a4 ("powerpc/uaccess: Add pre-update addressing to __put_user_asm_goto()")
Fixes: 2f279eeb68b8 ("powerpc/uaccess: Add pre-update addressing to __get_user_asm() and __put_user_asm()")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
---
v2: Moved UPD_CONSTR to asm-const.h to avoid circular inclusion issues with patch 3.
---
 arch/powerpc/include/asm/asm-const.h | 13 +++++++++++++
 arch/powerpc/include/asm/uaccess.h   |  4 ++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
index 082c1538c562..0ce2368bd20f 100644
--- a/arch/powerpc/include/asm/asm-const.h
+++ b/arch/powerpc/include/asm/asm-const.h
@@ -11,4 +11,17 @@
 #  define __ASM_CONST(x)	x##UL
 #  define ASM_CONST(x)		__ASM_CONST(x)
 #endif
+
+/*
+ * Inline assembly memory constraint
+ *
+ * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
+ *
+ */
+#if defined(GCC_VERSION) && GCC_VERSION < 50000
+#define UPD_CONSTR ""
+#else
+#define UPD_CONSTR "<>"
+#endif
+
 #endif /* _ASM_POWERPC_ASM_CONST_H */
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 604d705f1bb8..8f27ea48fadb 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -223,7 +223,7 @@ do {								\
 		"1:	" op "%U1%X1 %0,%1	# put_user\n"	\
 		EX_TABLE(1b, %l2)				\
 		:						\
-		: "r" (x), "m<>" (*addr)				\
+		: "r" (x), "m"UPD_CONSTR (*addr)		\
 		:						\
 		: label)
 
@@ -294,7 +294,7 @@ extern long __get_user_bad(void);
 		".previous\n"				\
 		EX_TABLE(1b, 3b)			\
 		: "=r" (err), "=r" (x)			\
-		: "m<>" (*addr), "i" (-EFAULT), "0" (err))
+		: "m"UPD_CONSTR (*addr), "i" (-EFAULT), "0" (err))
 
 #ifdef __powerpc64__
 #define __get_user_asm2(x, addr, err)			\
-- 
2.25.0

[PATCH v2 1/3] powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9

[Christophe Leroy]

GCC 4.9 sometimes fails to build with "m<>" constraint in
inline assembly.

  CC      lib/iov_iter.o
In file included from ./arch/powerpc/include/asm/cmpxchg.h:6:0,
                 from ./arch/powerpc/include/asm/atomic.h:11,
                 from ./include/linux/atomic.h:7,
                 from ./include/linux/crypto.h:15,
                 from ./include/crypto/hash.h:11,
                 from lib/iov_iter.c:2:
lib/iov_iter.c: In function 'iovec_from_user.part.30':
./arch/powerpc/include/asm/uaccess.h:287:2: error: 'asm' operand has impossible constraints
  __asm__ __volatile__(    \
  ^
./include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
 # define unlikely(x) __builtin_expect(!!(x), 0)
                                          ^
./arch/powerpc/include/asm/uaccess.h:583:34: note: in expansion of macro 'unsafe_op_wrap'
 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
                                  ^
./arch/powerpc/include/asm/uaccess.h:329:10: note: in expansion of macro '__get_user_asm'
  case 4: __get_user_asm(x, (u32 __user *)ptr, retval, "lwz"); break; \
          ^
./arch/powerpc/include/asm/uaccess.h:363:3: note: in expansion of macro '__get_user_size_allowed'
   __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \
   ^
./arch/powerpc/include/asm/uaccess.h:100:2: note: in expansion of macro '__get_user_nocheck'
  __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false)
  ^
./arch/powerpc/include/asm/uaccess.h:583:49: note: in expansion of macro '__get_user_allowed'
 #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
                                                 ^
lib/iov_iter.c:1663:3: note: in expansion of macro 'unsafe_get_user'
   unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
   ^
make[1]: *** [scripts/Makefile.build:283: lib/iov_iter.o] Error 1

Define a UPD_CONSTR macro that is "<>" by default and
only "" with GCC prior to GCC 5.

Fixes: fcf1f26895a4 ("powerpc/uaccess: Add pre-update addressing to __put_user_asm_goto()")
Fixes: 2f279eeb68b8 ("powerpc/uaccess: Add pre-update addressing to __get_user_asm() and __put_user_asm()")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
---
v2: Moved UPD_CONSTR to asm-const.h to avoid circular inclusion issues with patch 3.
---
 arch/powerpc/include/asm/asm-const.h | 13 +++++++++++++
 arch/powerpc/include/asm/uaccess.h   |  4 ++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
index 082c1538c562..0ce2368bd20f 100644
--- a/arch/powerpc/include/asm/asm-const.h
+++ b/arch/powerpc/include/asm/asm-const.h
@@ -11,4 +11,17 @@
 #  define __ASM_CONST(x)	x##UL
 #  define ASM_CONST(x)		__ASM_CONST(x)
 #endif
+
+/*
+ * Inline assembly memory constraint
+ *
+ * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
+ *
+ */
+#if defined(GCC_VERSION) && GCC_VERSION < 50000
+#define UPD_CONSTR ""
+#else
+#define UPD_CONSTR "<>"
+#endif
+
 #endif /* _ASM_POWERPC_ASM_CONST_H */
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 604d705f1bb8..8f27ea48fadb 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -223,7 +223,7 @@ do {								\
 		"1:	" op "%U1%X1 %0,%1	# put_user\n"	\
 		EX_TABLE(1b, %l2)				\
 		:						\
-		: "r" (x), "m<>" (*addr)				\
+		: "r" (x), "m"UPD_CONSTR (*addr)		\
 		:						\
 		: label)
 
@@ -294,7 +294,7 @@ extern long __get_user_bad(void);
 		".previous\n"				\
 		EX_TABLE(1b, 3b)			\
 		: "=r" (err), "=r" (x)			\
-		: "m<>" (*addr), "i" (-EFAULT), "0" (err))
+		: "m"UPD_CONSTR (*addr), "i" (-EFAULT), "0" (err))
 
 #ifdef __powerpc64__
 #define __get_user_asm2(x, addr, err)			\
-- 
2.25.0

[PATCH v2 2/3] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at

[Christophe Leroy]

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

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.

Fixes: 9bf2b5cdc5fe ("powerpc: Fixes for CONFIG_PTE_64BIT for SMP support")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: <stable@vger.kernel.org> # v2.6.28+
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
[chleroy: revised commit log iaw segher's comment]
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v2: Changed commit log.
---
 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

[PATCH v2 2/3] powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at

[Christophe Leroy]

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

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.

Fixes: 9bf2b5cdc5fe ("powerpc: Fixes for CONFIG_PTE_64BIT for SMP support")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: <stable@vger.kernel.org> # v2.6.28+
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
[chleroy: revised commit log iaw segher's comment]
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v2: Changed commit log.
---
 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

[PATCH v2 3/3] powerpc: Fix update form addressing in inline assembly

[Christophe Leroy]

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@csgroup.eu>
---
v2: Build failure (circular inclusion) fixed by change in patch 1
---
 arch/powerpc/include/asm/atomic.h            | 9 +++++----
 arch/powerpc/include/asm/book3s/32/pgtable.h | 2 +-
 arch/powerpc/include/asm/io.h                | 4 ++--
 arch/powerpc/include/asm/nohash/pgtable.h    | 2 +-
 arch/powerpc/kvm/powerpc.c                   | 4 ++--
 5 files changed, 11 insertions(+), 10 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/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 34f5ca391f0c..0e1b6e020cef 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -525,7 +525,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 		stw%U0%X0 %2,%0\n\
 		eieio\n\
 		stw%U1%X1 %L2,%1"
-	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
+	: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
 	: "r" (pte) : "memory");
 
 #else
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/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index a00e4c1746d6..55ef2112ed00 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -200,7 +200,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 			stw%U0%X0 %2,%0\n\
 			eieio\n\
 			stw%U1%X1 %L2,%1"
-		: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
+		: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
 		: "r" (pte) : "memory");
 		return;
 	}
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

[PATCH v2 3/3] powerpc: Fix update form addressing in inline assembly

[Christophe Leroy]

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@csgroup.eu>
---
v2: Build failure (circular inclusion) fixed by change in patch 1
---
 arch/powerpc/include/asm/atomic.h            | 9 +++++----
 arch/powerpc/include/asm/book3s/32/pgtable.h | 2 +-
 arch/powerpc/include/asm/io.h                | 4 ++--
 arch/powerpc/include/asm/nohash/pgtable.h    | 2 +-
 arch/powerpc/kvm/powerpc.c                   | 4 ++--
 5 files changed, 11 insertions(+), 10 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/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 34f5ca391f0c..0e1b6e020cef 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -525,7 +525,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 		stw%U0%X0 %2,%0\n\
 		eieio\n\
 		stw%U1%X1 %L2,%1"
-	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
+	: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
 	: "r" (pte) : "memory");
 
 #else
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/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index a00e4c1746d6..55ef2112ed00 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -200,7 +200,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 			stw%U0%X0 %2,%0\n\
 			eieio\n\
 			stw%U1%X1 %L2,%1"
-		: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
+		: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
 		: "r" (pte) : "memory");
 		return;
 	}
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

Re: [PATCH v2 3/3] powerpc: Fix update form addressing in inline assembly

[Segher Boessenkool]

Hi!

On Tue, Oct 20, 2020 at 07:40:09AM +0000, Christophe Leroy wrote:
> 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@csgroup.eu>

Oh well, it will be easy enough to remove this wart later, so

Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>

> --- a/arch/powerpc/include/asm/book3s/32/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
> @@ -525,7 +525,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
>  		stw%U0%X0 %2,%0\n\
>  		eieio\n\
>  		stw%U1%X1 %L2,%1"
> -	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
> +	: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
>  	: "r" (pte) : "memory");

Here it would pre-increment ptep+4.  That can never be something useful
afaics?  The order the two operands are (either or not) pre-modified in
the asm is not specified (GCC does not parse the asm template, by
design), so I fail to see how this could ever work.

> --- a/arch/powerpc/include/asm/nohash/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/pgtable.h
> @@ -200,7 +200,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
>  			stw%U0%X0 %2,%0\n\
>  			eieio\n\
>  			stw%U1%X1 %L2,%1"
> -		: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
> +		: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
>  		: "r" (pte) : "memory");

Same here.

The rest looks fine.


Segher

Re: [PATCH v2 3/3] powerpc: Fix update form addressing in inline assembly

[Segher Boessenkool]

Hi!

On Tue, Oct 20, 2020 at 07:40:09AM +0000, Christophe Leroy wrote:
> 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@csgroup.eu>

Oh well, it will be easy enough to remove this wart later, so

Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>

> --- a/arch/powerpc/include/asm/book3s/32/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
> @@ -525,7 +525,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
>  		stw%U0%X0 %2,%0\n\
>  		eieio\n\
>  		stw%U1%X1 %L2,%1"
> -	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
> +	: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
>  	: "r" (pte) : "memory");

Here it would pre-increment ptep+4.  That can never be something useful
afaics?  The order the two operands are (either or not) pre-modified in
the asm is not specified (GCC does not parse the asm template, by
design), so I fail to see how this could ever work.

> --- a/arch/powerpc/include/asm/nohash/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/pgtable.h
> @@ -200,7 +200,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
>  			stw%U0%X0 %2,%0\n\
>  			eieio\n\
>  			stw%U1%X1 %L2,%1"
> -		: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
> +		: "=m"UPD_CONSTR (*ptep), "=m"UPD_CONSTR (*((unsigned char *)ptep+4))
>  		: "r" (pte) : "memory");

Same here.

The rest looks fine.


Segher

Re: [PATCH v2 1/3] powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9

[Michael Ellerman]

On Tue, 20 Oct 2020 07:40:07 +0000 (UTC), Christophe Leroy wrote:
> GCC 4.9 sometimes fails to build with "m<>" constraint in
> inline assembly.
> 
>   CC      lib/iov_iter.o
> In file included from ./arch/powerpc/include/asm/cmpxchg.h:6:0,
>                  from ./arch/powerpc/include/asm/atomic.h:11,
>                  from ./include/linux/atomic.h:7,
>                  from ./include/linux/crypto.h:15,
>                  from ./include/crypto/hash.h:11,
>                  from lib/iov_iter.c:2:
> lib/iov_iter.c: In function 'iovec_from_user.part.30':
> ./arch/powerpc/include/asm/uaccess.h:287:2: error: 'asm' operand has impossible constraints
>   __asm__ __volatile__(    \
>   ^
> ./include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
>  # define unlikely(x) __builtin_expect(!!(x), 0)
>                                           ^
> ./arch/powerpc/include/asm/uaccess.h:583:34: note: in expansion of macro 'unsafe_op_wrap'
>  #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
>                                   ^
> ./arch/powerpc/include/asm/uaccess.h:329:10: note: in expansion of macro '__get_user_asm'
>   case 4: __get_user_asm(x, (u32 __user *)ptr, retval, "lwz"); break; \
>           ^
> ./arch/powerpc/include/asm/uaccess.h:363:3: note: in expansion of macro '__get_user_size_allowed'
>    __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \
>    ^
> ./arch/powerpc/include/asm/uaccess.h:100:2: note: in expansion of macro '__get_user_nocheck'
>   __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false)
>   ^
> ./arch/powerpc/include/asm/uaccess.h:583:49: note: in expansion of macro '__get_user_allowed'
>  #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e)
>                                                  ^
> lib/iov_iter.c:1663:3: note: in expansion of macro 'unsafe_get_user'
>    unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
>    ^
> make[1]: *** [scripts/Makefile.build:283: lib/iov_iter.o] Error 1
> 
> [...]

Patch 1 applied to powerpc/fixes.

[1/3] powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9
      https://git.kernel.org/powerpc/c/592bbe9c505d9a0ef69260f8c8263df47da2698e

cheers