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 (can_do_masked_user_access())
52 uaddr = masked_user_access_begin(uaddr);
53 else if (!user_access_begin(uaddr, sizeof(u32)))
54 return -EFAULT;
55
56 switch (op) {
57 case FUTEX_OP_SET:
58 unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
59 break;
60 case FUTEX_OP_ADD:
61 unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
62 uaddr, oparg, Efault);
63 break;
64 case FUTEX_OP_OR:
65 unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
66 break;
67 case FUTEX_OP_ANDN:
68 unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
69 break;
70 case FUTEX_OP_XOR:
71 unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
72 break;
73 default:
74 user_access_end();
75 return -ENOSYS;
76 }
77 user_access_end();
78 return 0;
79Efault:
80 user_access_end();
81 return -EFAULT;
82}
83
84static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
85 u32 oldval, u32 newval)
86{
87 int ret = 0;
88
89 if (can_do_masked_user_access())
90 uaddr = masked_user_access_begin(uaddr);
91 else if (!user_access_begin(uaddr, sizeof(u32)))
92 return -EFAULT;
93 asm volatile("\n"
94 "1:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"
95 "2:\n"
96 _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %0) \
97 : "+r" (ret), "=a" (oldval), "+m" (*uaddr)
98 : "r" (newval), "1" (oldval)
99 : "memory"
100 );
101 user_access_end();
102 *uval = oldval;
103 return ret;
104}
105
106#endif
107#endif /* _ASM_X86_FUTEX_H */
108