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)	\
16do {								\
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)	\
30do {								\
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
48static __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;
77Efault:
78	user_access_end();
79	return -EFAULT;
80}
81
82static 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