1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright (c) 2006 Ralf Baechle (ralf@linux-mips.org)
4 * Copyright (c) 2018 Jim Wilson (jimw@sifive.com)
5 */
6
7 #ifndef _ASM_RISCV_FUTEX_H
8 #define _ASM_RISCV_FUTEX_H
9
10 #include <linux/futex.h>
11 #include <linux/uaccess.h>
12 #include <linux/errno.h>
13 #include <asm/asm.h>
14 #include <asm/asm-extable.h>
15
16 /* We don't even really need the extable code, but for now keep it simple */
17 #ifndef CONFIG_MMU
18 #define __enable_user_access() do { } while (0)
19 #define __disable_user_access() do { } while (0)
20 #endif
21
22 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
23 { \
24 __enable_user_access(); \
25 __asm__ __volatile__ ( \
26 "1: " insn " \n" \
27 "2: \n" \
28 _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %[r]) \
29 : [r] "+r" (ret), [ov] "=&r" (oldval), \
30 [u] "+m" (*uaddr) \
31 : [op] "Jr" (oparg) \
32 : "memory"); \
33 __disable_user_access(); \
34 }
35
36 static inline int
37 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
38 {
39 int oldval = 0, ret = 0;
40
41 if (!access_ok(uaddr, sizeof(u32)))
42 return -EFAULT;
43
44 switch (op) {
45 case FUTEX_OP_SET:
46 __futex_atomic_op("amoswap.w.aqrl %[ov],%z[op],%[u]",
47 ret, oldval, uaddr, oparg);
48 break;
49 case FUTEX_OP_ADD:
50 __futex_atomic_op("amoadd.w.aqrl %[ov],%z[op],%[u]",
51 ret, oldval, uaddr, oparg);
52 break;
53 case FUTEX_OP_OR:
54 __futex_atomic_op("amoor.w.aqrl %[ov],%z[op],%[u]",
55 ret, oldval, uaddr, oparg);
56 break;
57 case FUTEX_OP_ANDN:
58 __futex_atomic_op("amoand.w.aqrl %[ov],%z[op],%[u]",
59 ret, oldval, uaddr, ~oparg);
60 break;
61 case FUTEX_OP_XOR:
62 __futex_atomic_op("amoxor.w.aqrl %[ov],%z[op],%[u]",
63 ret, oldval, uaddr, oparg);
64 break;
65 default:
66 ret = -ENOSYS;
67 }
68
69 if (!ret)
70 *oval = oldval;
71
72 return ret;
73 }
74
75 static inline int
76 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
77 u32 oldval, u32 newval)
78 {
79 int ret = 0;
80 u32 val;
81 uintptr_t tmp;
82
83 if (!access_ok(uaddr, sizeof(u32)))
84 return -EFAULT;
85
86 __enable_user_access();
87 __asm__ __volatile__ (
88 "1: lr.w.aqrl %[v],%[u] \n"
89 " bne %[v],%z[ov],3f \n"
90 "2: sc.w.aqrl %[t],%z[nv],%[u] \n"
91 " bnez %[t],1b \n"
92 "3: \n"
93 _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %[r]) \
94 _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %[r]) \
95 : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)
96 : [ov] "Jr" (oldval), [nv] "Jr" (newval)
97 : "memory");
98 __disable_user_access();
99
100 *uval = val;
101 return ret;
102 }
103
104 #endif /* _ASM_RISCV_FUTEX_H */
105
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