1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_FUTEX_H
3 #define _ASM_X86_FUTEX_H
4 
5 #ifdef __KERNEL__
6 
7 #include <linux/futex.h>
8 #include <linux/uaccess.h>
9 
10 #include <asm/asm.h>
11 #include <asm/errno.h>
12 #include <asm/processor.h>
13 #include <asm/smap.h>
14 
15 #define unsafe_atomic_op1(insn, oval, uaddr, oparg, label)	\
16 do {								\
17 	int oldval = 0, ret;					\
18 	asm volatile("1:\t" insn "\n"				\
19 		     "2:\n"					\
20 		     _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %1) \
21 		     : "=r" (oldval), "=r" (ret), "+m" (*uaddr)	\
22 		     : "0" (oparg), "1" (0));	\
23 	if (ret)						\
24 		goto label;					\
25 	*oval = oldval;						\
26 } while(0)
27 
28 
29 #define unsafe_atomic_op2(insn, oval, uaddr, oparg, label)	\
30 do {								\
31 	int oldval = 0, ret, tem;				\
32 	asm volatile("1:\tmovl	%2, %0\n"			\
33 		     "2:\tmovl\t%0, %3\n"			\
34 		     "\t" insn "\n"				\
35 		     "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
36 		     "\tjnz\t2b\n"				\
37 		     "4:\n"					\
38 		     _ASM_EXTABLE_TYPE_REG(1b, 4b, EX_TYPE_EFAULT_REG, %1) \
39 		     _ASM_EXTABLE_TYPE_REG(3b, 4b, EX_TYPE_EFAULT_REG, %1) \
40 		     : "=&a" (oldval), "=&r" (ret),		\
41 		       "+m" (*uaddr), "=&r" (tem)		\
42 		     : "r" (oparg), "1" (0));			\
43 	if (ret)						\
44 		goto label;					\
45 	*oval = oldval;						\
46 } while(0)
47 
arch_futex_atomic_op_inuser(int op,int oparg,int * oval,u32 __user * uaddr)48 static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
49 		u32 __user *uaddr)
50 {
51 	if (!user_access_begin(uaddr, sizeof(u32)))
52 		return -EFAULT;
53 
54 	switch (op) {
55 	case FUTEX_OP_SET:
56 		unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
57 		break;
58 	case FUTEX_OP_ADD:
59 		unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
60 				   uaddr, oparg, Efault);
61 		break;
62 	case FUTEX_OP_OR:
63 		unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
64 		break;
65 	case FUTEX_OP_ANDN:
66 		unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
67 		break;
68 	case FUTEX_OP_XOR:
69 		unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
70 		break;
71 	default:
72 		user_access_end();
73 		return -ENOSYS;
74 	}
75 	user_access_end();
76 	return 0;
77 Efault:
78 	user_access_end();
79 	return -EFAULT;
80 }
81 
futex_atomic_cmpxchg_inatomic(u32 * uval,u32 __user * uaddr,u32 oldval,u32 newval)82 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
83 						u32 oldval, u32 newval)
84 {
85 	int ret = 0;
86 
87 	if (!user_access_begin(uaddr, sizeof(u32)))
88 		return -EFAULT;
89 	asm volatile("\n"
90 		"1:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"
91 		"2:\n"
92 		_ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %0) \
93 		: "+r" (ret), "=a" (oldval), "+m" (*uaddr)
94 		: "r" (newval), "1" (oldval)
95 		: "memory"
96 	);
97 	user_access_end();
98 	*uval = oldval;
99 	return ret;
100 }
101 
102 #endif
103 #endif /* _ASM_X86_FUTEX_H */
104