MIPS: asm: uaccess: Add EVA support for str*_user operations

The str*_user functions are used to securely access NULL terminated strings from userland. Therefore, it's necessary to use the appropriate EVA function. However, if the string is in kernel space, then the normal instructions are being used to access it. The __str*_kernel_asm and __str*_user_asm symbols are the same for non-EVA mode so there is no functional change for the non-EVA kernels. Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
mariux64 · Mar 26, 2014 · e3a9b07 · e3a9b07
1 parent 05c6516
commit e3a9b07
Showing 1 changed file with 119 additions and 53 deletions.
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
@@ -1246,16 +1246,28 @@ __strncpy_from_user(char *__to, const char __user *__from, long __len)
 {
 	long res;
 
-	might_fault();
-	__asm__ __volatile__(
-		"move\t$4, %1\n\t"
-		"move\t$5, %2\n\t"
-		"move\t$6, %3\n\t"
-		__MODULE_JAL(__strncpy_from_user_nocheck_asm)
-		"move\t%0, $2"
-		: "=r" (res)
-		: "r" (__to), "r" (__from), "r" (__len)
-		: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
+	if (segment_eq(get_fs(), get_ds())) {
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			"move\t$6, %3\n\t"
+			__MODULE_JAL(__strncpy_from_kernel_nocheck_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (__to), "r" (__from), "r" (__len)
+			: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
+	} else {
+		might_fault();
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			"move\t$6, %3\n\t"
+			__MODULE_JAL(__strncpy_from_user_nocheck_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (__to), "r" (__from), "r" (__len)
+			: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
+	}
 
 	return res;
 }
@@ -1283,16 +1295,28 @@ strncpy_from_user(char *__to, const char __user *__from, long __len)
 {
 	long res;
 
-	might_fault();
-	__asm__ __volatile__(
-		"move\t$4, %1\n\t"
-		"move\t$5, %2\n\t"
-		"move\t$6, %3\n\t"
-		__MODULE_JAL(__strncpy_from_user_asm)
-		"move\t%0, $2"
-		: "=r" (res)
-		: "r" (__to), "r" (__from), "r" (__len)
-		: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
+	if (segment_eq(get_fs(), get_ds())) {
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			"move\t$6, %3\n\t"
+			__MODULE_JAL(__strncpy_from_kernel_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (__to), "r" (__from), "r" (__len)
+			: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
+	} else {
+		might_fault();
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			"move\t$6, %3\n\t"
+			__MODULE_JAL(__strncpy_from_user_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (__to), "r" (__from), "r" (__len)
+			: "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
+	}
 
 	return res;
 }
@@ -1302,14 +1326,24 @@ static inline long __strlen_user(const char __user *s)
 {
 	long res;
 
-	might_fault();
-	__asm__ __volatile__(
-		"move\t$4, %1\n\t"
-		__MODULE_JAL(__strlen_user_nocheck_asm)
-		"move\t%0, $2"
-		: "=r" (res)
-		: "r" (s)
-		: "$2", "$4", __UA_t0, "$31");
+	if (segment_eq(get_fs(), get_ds())) {
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			__MODULE_JAL(__strlen_kernel_nocheck_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s)
+			: "$2", "$4", __UA_t0, "$31");
+	} else {
+		might_fault();
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			__MODULE_JAL(__strlen_user_nocheck_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s)
+			: "$2", "$4", __UA_t0, "$31");
+	}
 
 	return res;
 }
@@ -1332,14 +1366,24 @@ static inline long strlen_user(const char __user *s)
 {
 	long res;
 
-	might_fault();
-	__asm__ __volatile__(
-		"move\t$4, %1\n\t"
-		__MODULE_JAL(__strlen_user_asm)
-		"move\t%0, $2"
-		: "=r" (res)
-		: "r" (s)
-		: "$2", "$4", __UA_t0, "$31");
+	if (segment_eq(get_fs(), get_ds())) {
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			__MODULE_JAL(__strlen_kernel_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s)
+			: "$2", "$4", __UA_t0, "$31");
+	} else {
+		might_fault();
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			__MODULE_JAL(__strlen_kernel_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s)
+			: "$2", "$4", __UA_t0, "$31");
+	}
 
 	return res;
 }
@@ -1349,15 +1393,26 @@ static inline long __strnlen_user(const char __user *s, long n)
 {
 	long res;
 
-	might_fault();
-	__asm__ __volatile__(
-		"move\t$4, %1\n\t"
-		"move\t$5, %2\n\t"
-		__MODULE_JAL(__strnlen_user_nocheck_asm)
-		"move\t%0, $2"
-		: "=r" (res)
-		: "r" (s), "r" (n)
-		: "$2", "$4", "$5", __UA_t0, "$31");
+	if (segment_eq(get_fs(), get_ds())) {
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			__MODULE_JAL(__strnlen_kernel_nocheck_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s), "r" (n)
+			: "$2", "$4", "$5", __UA_t0, "$31");
+	} else {
+		might_fault();
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			__MODULE_JAL(__strnlen_user_nocheck_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s), "r" (n)
+			: "$2", "$4", "$5", __UA_t0, "$31");
+	}
 
 	return res;
 }
@@ -1381,14 +1436,25 @@ static inline long strnlen_user(const char __user *s, long n)
 	long res;
 
 	might_fault();
-	__asm__ __volatile__(
-		"move\t$4, %1\n\t"
-		"move\t$5, %2\n\t"
-		__MODULE_JAL(__strnlen_user_asm)
-		"move\t%0, $2"
-		: "=r" (res)
-		: "r" (s), "r" (n)
-		: "$2", "$4", "$5", __UA_t0, "$31");
+	if (segment_eq(get_fs(), get_ds())) {
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			__MODULE_JAL(__strnlen_kernel_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s), "r" (n)
+			: "$2", "$4", "$5", __UA_t0, "$31");
+	} else {
+		__asm__ __volatile__(
+			"move\t$4, %1\n\t"
+			"move\t$5, %2\n\t"
+			__MODULE_JAL(__strnlen_user_asm)
+			"move\t%0, $2"
+			: "=r" (res)
+			: "r" (s), "r" (n)
+			: "$2", "$4", "$5", __UA_t0, "$31");
+	}
 
 	return res;
 }