xref: /openbmc/linux/arch/riscv/include/asm/futex.h (revision 20802d8d)
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
arch_futex_atomic_op_inuser(int op,int oparg,int * oval,u32 __user * uaddr)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
futex_atomic_cmpxchg_inatomic(u32 * uval,u32 __user * uaddr,u32 oldval,u32 newval)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