Subject: [PATCH v2 02/18] uaccess: fix nios2 and microblaze get_user_8()

From: Arnd Bergmann <[email-masked]>
Date: Wed, 16 Feb 2022 14:13:16 +0100

From: Arnd Bergmann <[email-masked]>

These two architectures implement 8-byte get_user() through
a memcpy() into a four-byte variable, which won't fit.

Use a temporary 64-bit variable instead here, and use a double
cast the way that risc-v and openrisc do to avoid compile-time
warnings.

Fixes: 6a090e97972d ("arch/microblaze: support get_user() of size 8 bytes")
Fixes: 5ccc6af5e88e ("nios2: Memory management")
Signed-off-by: Arnd Bergmann <[email-masked]>
---
 arch/microblaze/include/asm/uaccess.h | 18 +++++++++---------
 arch/nios2/include/asm/uaccess.h      | 26 ++++++++++++++++----------
 2 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index 5b6e0e7788f4..3fe96979d2c6 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -130,27 +130,27 @@ extern long __user_bad(void);
 
 #define __get_user(x, ptr)						\
 ({									\
-	unsigned long __gu_val = 0;					\
 	long __gu_err;							\
 	switch (sizeof(*(ptr))) {					\
 	case 1:								\
-		__get_user_asm("lbu", (ptr), __gu_val, __gu_err);	\
+		__get_user_asm("lbu", (ptr), x, __gu_err);		\
 		break;							\
 	case 2:								\
-		__get_user_asm("lhu", (ptr), __gu_val, __gu_err);	\
+		__get_user_asm("lhu", (ptr), x, __gu_err);		\
 		break;							\
 	case 4:								\
-		__get_user_asm("lw", (ptr), __gu_val, __gu_err);	\
+		__get_user_asm("lw", (ptr), x, __gu_err);		\
 		break;							\
-	case 8:								\
-		__gu_err = __copy_from_user(&__gu_val, ptr, 8);		\
-		if (__gu_err)						\
-			__gu_err = -EFAULT;				\
+	case 8: {							\
+		__u64 __x = 0;						\
+		__gu_err = raw_copy_from_user(&__x, ptr, 8) ?		\
+							-EFAULT : 0;	\
+		(x) = (typeof(x))(typeof((x) - (x)))__x;		\
 		break;							\
+	}								\
 	default:							\
 		/* __gu_val = 0; __gu_err = -EINVAL;*/ __gu_err = __user_bad();\
 	}								\
-	x = (__force __typeof__(*(ptr))) __gu_val;			\
 	__gu_err;							\
 })
 
diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
index ba9340e96fd4..ca9285a915ef 100644
--- a/arch/nios2/include/asm/uaccess.h
+++ b/arch/nios2/include/asm/uaccess.h
@@ -88,6 +88,7 @@ extern __must_check long strnlen_user(const char __user *s, long n);
 /* Optimized macros */
 #define __get_user_asm(val, insn, addr, err)				\
 {									\
+	unsigned long __gu_val;						\
 	__asm__ __volatile__(						\
 	"       movi    %0, %3\n"					\
 	"1:   " insn " %1, 0(%2)\n"					\
@@ -96,14 +97,20 @@ extern __must_check long strnlen_user(const char __user *s, long n);
 	"       .section __ex_table,\"a\"\n"				\
 	"       .word 1b, 2b\n"						\
 	"       .previous"						\
-	: "=&r" (err), "=r" (val)					\
+	: "=&r" (err), "=r" (__gu_val)					\
 	: "r" (addr), "i" (-EFAULT));					\
+	val = (__force __typeof__(*(addr)))__gu_val;			\
 }
 
-#define __get_user_unknown(val, size, ptr, err) do {			\
+extern void __get_user_unknown(void);
+
+#define __get_user_8(val, ptr, err) do {				\
+	u64 __val = 0;							\
 	err = 0;							\
-	if (__copy_from_user(&(val), ptr, size)) {			\
+	if (raw_copy_from_user(&(__val), ptr, sizeof(val))) {		\
 		err = -EFAULT;						\
+	} else {							\
+		val = (typeof(val))(typeof((val) - (val)))__val;	\
 	}								\
 	} while (0)
 
@@ -119,8 +126,11 @@ do {									\
 	case 4:								\
 		__get_user_asm(val, "ldw", ptr, err);			\
 		break;							\
+	case 8:								\
+		__get_user_8(val, ptr, err);				\
+		break;							\
 	default:							\
-		__get_user_unknown(val, size, ptr, err);		\
+		__get_user_unknown();					\
 		break;							\
 	}								\
 } while (0)
@@ -129,9 +139,7 @@ do {									\
 	({								\
 	long __gu_err = -EFAULT;					\
 	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
-	unsigned long __gu_val = 0;					\
-	__get_user_common(__gu_val, sizeof(*(ptr)), __gu_ptr, __gu_err);\
-	(x) = (__force __typeof__(x))__gu_val;				\
+	__get_user_common(x, sizeof(*(ptr)), __gu_ptr, __gu_err);	\
 	__gu_err;							\
 	})
 
@@ -139,11 +147,9 @@ do {									\
 ({									\
 	long __gu_err = -EFAULT;					\
 	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
-	unsigned long __gu_val = 0;					\
 	if (access_ok( __gu_ptr, sizeof(*__gu_ptr)))	\
-		__get_user_common(__gu_val, sizeof(*__gu_ptr),		\
+		__get_user_common(x, sizeof(*__gu_ptr),			\
 			__gu_ptr, __gu_err);				\
-	(x) = (__force __typeof__(x))__gu_val;				\
 	__gu_err;							\
 })
 
-- 
2.29.2