s390/uaccess: use exception handler to zero result on get_user() failure

Historically the uaccess code pre-initializes the result of get_user()
(and now also __get_kernel_nofault()) to zero and uses the result as
input parameter for inline assemblies. This is different to what most,
if not all, other architectures are doing, which set the result to
zero within the exception handler in case of a fault.

Use the new extable mechanism and handle zeroing of the result within
the exception handler in case of a fault.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 45 insertions, 27 deletions

diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index 5ffb88b3fdee..2d8d9e89d48f 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -80,8 +80,12 @@ union oac {
 	};
 };
 
-#define __put_get_user_asm(to, from, size, oac_spec)			\
+#define __put_user_asm(to, from, size)					\
 ({									\
+	union oac __oac_spec = {					\
+		.oac1.as = PSW_BITS_AS_SECONDARY,			\
+		.oac1.a = 1,						\
+	};								\
 	int __rc;							\
 									\
 	asm volatile(							\
@@ -89,26 +93,15 @@ union oac {
 		"0:	mvcos	%[_to],%[_from],%[_size]\n"		\
 		"1:	xr	%[rc],%[rc]\n"				\
 		"2:\n"							\
-		EX_TABLE_UA(0b,2b,%[rc]) EX_TABLE_UA(1b,2b,%[rc])	\
+		EX_TABLE_UA_STORE(0b, 2b, %[rc])			\
+		EX_TABLE_UA_STORE(1b, 2b, %[rc])			\
 		: [rc] "=&d" (__rc), [_to] "+Q" (*(to))			\
 		: [_size] "d" (size), [_from] "Q" (*(from)),		\
-		  [spec] "d" (oac_spec.val)				\
+		  [spec] "d" (__oac_spec.val)				\
 		: "cc", "0");						\
 	__rc;								\
 })
 
-#define __put_user_asm(to, from, size)				\
-	__put_get_user_asm(to, from, size, ((union oac) {	\
-		.oac1.as = PSW_BITS_AS_SECONDARY,		\
-		.oac1.a = 1					\
-	}))
-
-#define __get_user_asm(to, from, size)				\
-	__put_get_user_asm(to, from, size, ((union oac) {	\
-		.oac2.as = PSW_BITS_AS_SECONDARY,		\
-		.oac2.a = 1					\
-	}))							\
-
 static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
 {
 	int rc;
@@ -141,6 +134,29 @@ static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned lon
 	return rc;
 }
 
+#define __get_user_asm(to, from, size)					\
+({									\
+	union oac __oac_spec = {					\
+		.oac2.as = PSW_BITS_AS_SECONDARY,			\
+		.oac2.a = 1,						\
+	};								\
+	int __rc;							\
+									\
+	asm volatile(							\
+		"	lr	0,%[spec]\n"				\
+		"0:	mvcos	0(%[_to]),%[_from],%[_size]\n"		\
+		"1:	xr	%[rc],%[rc]\n"				\
+		"2:\n"							\
+		EX_TABLE_UA_LOAD_MEM(0b, 2b, %[rc], %[_to], %[_ksize])	\
+		EX_TABLE_UA_LOAD_MEM(1b, 2b, %[rc], %[_to], %[_ksize])	\
+		: [rc] "=&d" (__rc), "=Q" (*(to))			\
+		: [_size] "d" (size), [_from] "Q" (*(from)),		\
+		  [spec] "d" (__oac_spec.val), [_to] "a" (to),		\
+		  [_ksize] "K" (size)					\
+		: "cc", "0");						\
+	__rc;								\
+})
+
 static __always_inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
 {
 	int rc;
@@ -210,28 +226,28 @@ static __always_inline int __get_user_fn(void *x, const void __user *ptr, unsign
 	__chk_user_ptr(ptr);					\
 	switch (sizeof(*(ptr))) {				\
 	case 1: {						\
-		unsigned char __x = 0;				\
+		unsigned char __x;				\
 		__gu_err = __get_user_fn(&__x, ptr,		\
 					 sizeof(*(ptr)));	\
 		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
 		break;						\
 	};							\
 	case 2: {						\
-		unsigned short __x = 0;				\
+		unsigned short __x;				\
 		__gu_err = __get_user_fn(&__x, ptr,		\
 					 sizeof(*(ptr)));	\
 		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
 		break;						\
 	};							\
 	case 4: {						\
-		unsigned int __x = 0;				\
+		unsigned int __x;				\
 		__gu_err = __get_user_fn(&__x, ptr,		\
 					 sizeof(*(ptr)));	\
 		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
 		break;						\
 	};							\
 	case 8: {						\
-		unsigned long long __x = 0;			\
+		unsigned long __x;				\
 		__gu_err = __get_user_fn(&__x, ptr,		\
 					 sizeof(*(ptr)));	\
 		(x) = *(__force __typeof__(*(ptr)) *) &__x;	\
@@ -281,7 +297,8 @@ int __noreturn __put_kernel_bad(void);
 		"0:   " insn "  %[_val],%[_to]\n"			\
 		"1:	xr	%[rc],%[rc]\n"				\
 		"2:\n"							\
-		EX_TABLE_UA(0b,2b,%0) EX_TABLE_UA(1b,2b,%0)		\
+		EX_TABLE_UA_STORE(0b, 2b, %[rc])			\
+		EX_TABLE_UA_STORE(1b, 2b, %[rc])			\
 		: [rc] "=d" (__rc), [_to] "+Q" (*(to))			\
 		: [_val] "d" (val)					\
 		: "cc");						\
@@ -290,7 +307,7 @@ int __noreturn __put_kernel_bad(void);
 
 #define __put_kernel_nofault(dst, src, type, err_label)			\
 do {									\
-	u64 __x = (u64)(*((type *)(src)));				\
+	unsigned long __x = (unsigned long)(*((type *)(src)));		\
 	int __pk_err;							\
 									\
 	switch (sizeof(type)) {						\
@@ -324,8 +341,9 @@ int __noreturn __get_kernel_bad(void);
 		"0:   " insn "  %[_val],%[_from]\n"			\
 		"1:	xr	%[rc],%[rc]\n"				\
 		"2:\n"							\
-		EX_TABLE_UA(0b,2b,%0) EX_TABLE_UA(1b,2b,%0)		\
-		: [rc] "=d" (__rc), [_val] "+d" (val)			\
+		EX_TABLE_UA_LOAD_REG(0b, 2b, %[rc], %[_val])		\
+		EX_TABLE_UA_LOAD_REG(1b, 2b, %[rc], %[_val])		\
+		: [rc] "=d" (__rc), [_val] "=d" (val)			\
 		: [_from] "Q" (*(from))					\
 		: "cc");						\
 	__rc;								\
@@ -337,28 +355,28 @@ do {									\
 									\
 	switch (sizeof(type)) {						\
 	case 1: {							\
-		u8 __x = 0;						\
+		unsigned char __x;					\
 									\
 		__gk_err = __get_kernel_asm(__x, (type *)(src), "ic");	\
 		*((type *)(dst)) = (type)__x;				\
 		break;							\
 	};								\
 	case 2: {							\
-		u16 __x = 0;						\
+		unsigned short __x;					\
 									\
 		__gk_err = __get_kernel_asm(__x, (type *)(src), "lh");	\
 		*((type *)(dst)) = (type)__x;				\
 		break;							\
 	};								\
 	case 4: {							\
-		u32 __x = 0;						\
+		unsigned int __x;					\
 									\
 		__gk_err = __get_kernel_asm(__x, (type *)(src), "l");	\
 		*((type *)(dst)) = (type)__x;				\
 		break;							\
 	};								\
 	case 8: {							\
-		u64 __x = 0;						\
+		unsigned long __x;					\
 									\
 		__gk_err = __get_kernel_asm(__x, (type *)(src), "lg");	\
 		*((type *)(dst)) = (type)__x;				\