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 : "" (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
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
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
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