Merge branch 'uaccess.futex' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs into locking/core

Pull uaccess futex cleanups for Al Viro:

     Consolidate access_ok() usage and the futex uaccess function zoo.

2 files changed, 63 insertions, 129 deletions

diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index 13c83fe97988..f9c00110a69a 100644
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -12,76 +12,103 @@
 #include <asm/processor.h>
 #include <asm/smap.h>
 
-#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)	\
-	asm volatile("\t" ASM_STAC "\n"				\
-		     "1:\t" insn "\n"				\
-		     "2:\t" ASM_CLAC "\n"			\
+#define unsafe_atomic_op1(insn, oval, uaddr, oparg, label)	\
+do {								\
+	int oldval = 0, ret;					\
+	asm volatile("1:\t" insn "\n"				\
+		     "2:\n"					\
 		     "\t.section .fixup,\"ax\"\n"		\
 		     "3:\tmov\t%3, %1\n"			\
 		     "\tjmp\t2b\n"				\
 		     "\t.previous\n"				\
 		     _ASM_EXTABLE_UA(1b, 3b)			\
 		     : "=r" (oldval), "=r" (ret), "+m" (*uaddr)	\
-		     : "i" (-EFAULT), "0" (oparg), "1" (0))
+		     : "i" (-EFAULT), "0" (oparg), "1" (0));	\
+	if (ret)						\
+		goto label;					\
+	*oval = oldval;						\
+} while(0)
 
-#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)	\
-	asm volatile("\t" ASM_STAC "\n"				\
-		     "1:\tmovl	%2, %0\n"			\
-		     "\tmovl\t%0, %3\n"				\
+
+#define unsafe_atomic_op2(insn, oval, uaddr, oparg, label)	\
+do {								\
+	int oldval = 0, ret, tem;				\
+	asm volatile("1:\tmovl	%2, %0\n"			\
+		     "2:\tmovl\t%0, %3\n"			\
 		     "\t" insn "\n"				\
-		     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
-		     "\tjnz\t1b\n"				\
-		     "3:\t" ASM_CLAC "\n"			\
+		     "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
+		     "\tjnz\t2b\n"				\
+		     "4:\n"					\
 		     "\t.section .fixup,\"ax\"\n"		\
-		     "4:\tmov\t%5, %1\n"			\
-		     "\tjmp\t3b\n"				\
+		     "5:\tmov\t%5, %1\n"			\
+		     "\tjmp\t4b\n"				\
 		     "\t.previous\n"				\
-		     _ASM_EXTABLE_UA(1b, 4b)			\
-		     _ASM_EXTABLE_UA(2b, 4b)			\
+		     _ASM_EXTABLE_UA(1b, 5b)			\
+		     _ASM_EXTABLE_UA(3b, 5b)			\
 		     : "=&a" (oldval), "=&r" (ret),		\
 		       "+m" (*uaddr), "=&r" (tem)		\
-		     : "r" (oparg), "i" (-EFAULT), "1" (0))
+		     : "r" (oparg), "i" (-EFAULT), "1" (0));	\
+	if (ret)						\
+		goto label;					\
+	*oval = oldval;						\
+} while(0)
 
-static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
+static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		u32 __user *uaddr)
 {
-	int oldval = 0, ret, tem;
-
-	pagefault_disable();
+	if (!user_access_begin(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
-		__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_ADD:
-		__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
-				   uaddr, oparg);
+		unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
+				   uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_OR:
-		__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_ANDN:
-		__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
+		unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
 		break;
 	case FUTEX_OP_XOR:
-		__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
 		break;
 	default:
-		ret = -ENOSYS;
+		user_access_end();
+		return -ENOSYS;
 	}
-
-	pagefault_enable();
-
-	if (!ret)
-		*oval = oldval;
-
-	return ret;
+	user_access_end();
+	return 0;
+Efault:
+	user_access_end();
+	return -EFAULT;
 }
 
 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 						u32 oldval, u32 newval)
 {
-	return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);
+	int ret = 0;
+
+	if (!user_access_begin(uaddr, sizeof(u32)))
+		return -EFAULT;
+	asm volatile("\n"
+		"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
+		"2:\n"
+		"\t.section .fixup, \"ax\"\n"
+		"3:\tmov     %3, %0\n"
+		"\tjmp     2b\n"
+		"\t.previous\n"
+		_ASM_EXTABLE_UA(1b, 3b)
+		: "+r" (ret), "=a" (oldval), "+m" (*uaddr)
+		: "i" (-EFAULT), "r" (newval), "1" (oldval)
+		: "memory"
+	);
+	user_access_end();
+	*uval = oldval;
+	return ret;
 }
 
 #endif
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 61d93f062a36..ea6fc643ccfe 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -584,99 +584,6 @@ extern __must_check long strnlen_user(const char __user *str, long n);
 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 
-extern void __cmpxchg_wrong_size(void)
-	__compiletime_error("Bad argument size for cmpxchg");
-
-#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)	\
-({									\
-	int __ret = 0;							\
-	__typeof__(*(ptr)) __old = (old);				\
-	__typeof__(*(ptr)) __new = (new);				\
-	__uaccess_begin_nospec();					\
-	switch (size) {							\
-	case 1:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "q" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 2:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 4:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 8:								\
-	{								\
-		if (!IS_ENABLED(CONFIG_X86_64))				\
-			__cmpxchg_wrong_size();				\
-									\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	default:							\
-		__cmpxchg_wrong_size();					\
-	}								\
-	__uaccess_end();						\
-	*(uval) = __old;						\
-	__ret;								\
-})
-
-#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)		\
-({									\
-	access_ok((ptr), sizeof(*(ptr))) ?		\
-		__user_atomic_cmpxchg_inatomic((uval), (ptr),		\
-				(old), (new), sizeof(*(ptr))) :		\
-		-EFAULT;						\
-})
-
 /*
  * movsl can be slow when source and dest are not both 8-byte aligned
  */