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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2012 ARM Ltd.
4 */
5#ifndef __ASM_FUTEX_H
6#define __ASM_FUTEX_H
7
8#include <linux/futex.h>
9#include <linux/uaccess.h>
10
11#include <asm/errno.h>
12
13#define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */
14
15#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
16do { \
17 unsigned int loops = FUTEX_MAX_LOOPS; \
18 \
19 uaccess_enable(); \
20 asm volatile( \
21" prfm pstl1strm, %2\n" \
22"1: ldxr %w1, %2\n" \
23 insn "\n" \
24"2: stlxr %w0, %w3, %2\n" \
25" cbz %w0, 3f\n" \
26" sub %w4, %w4, %w0\n" \
27" cbnz %w4, 1b\n" \
28" mov %w0, %w7\n" \
29"3:\n" \
30" dmb ish\n" \
31" .pushsection .fixup,\"ax\"\n" \
32" .align 2\n" \
33"4: mov %w0, %w6\n" \
34" b 3b\n" \
35" .popsection\n" \
36 _ASM_EXTABLE(1b, 4b) \
37 _ASM_EXTABLE(2b, 4b) \
38 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \
39 "+r" (loops) \
40 : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN) \
41 : "memory"); \
42 uaccess_disable(); \
43} while (0)
44
45static inline int
46arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
47{
48 int oldval = 0, ret, tmp;
49 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
50
51 pagefault_disable();
52
53 switch (op) {
54 case FUTEX_OP_SET:
55 __futex_atomic_op("mov %w3, %w5",
56 ret, oldval, uaddr, tmp, oparg);
57 break;
58 case FUTEX_OP_ADD:
59 __futex_atomic_op("add %w3, %w1, %w5",
60 ret, oldval, uaddr, tmp, oparg);
61 break;
62 case FUTEX_OP_OR:
63 __futex_atomic_op("orr %w3, %w1, %w5",
64 ret, oldval, uaddr, tmp, oparg);
65 break;
66 case FUTEX_OP_ANDN:
67 __futex_atomic_op("and %w3, %w1, %w5",
68 ret, oldval, uaddr, tmp, ~oparg);
69 break;
70 case FUTEX_OP_XOR:
71 __futex_atomic_op("eor %w3, %w1, %w5",
72 ret, oldval, uaddr, tmp, oparg);
73 break;
74 default:
75 ret = -ENOSYS;
76 }
77
78 pagefault_enable();
79
80 if (!ret)
81 *oval = oldval;
82
83 return ret;
84}
85
86static inline int
87futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
88 u32 oldval, u32 newval)
89{
90 int ret = 0;
91 unsigned int loops = FUTEX_MAX_LOOPS;
92 u32 val, tmp;
93 u32 __user *uaddr;
94
95 if (!access_ok(_uaddr, sizeof(u32)))
96 return -EFAULT;
97
98 uaddr = __uaccess_mask_ptr(_uaddr);
99 uaccess_enable();
100 asm volatile("// futex_atomic_cmpxchg_inatomic\n"
101" prfm pstl1strm, %2\n"
102"1: ldxr %w1, %2\n"
103" sub %w3, %w1, %w5\n"
104" cbnz %w3, 4f\n"
105"2: stlxr %w3, %w6, %2\n"
106" cbz %w3, 3f\n"
107" sub %w4, %w4, %w3\n"
108" cbnz %w4, 1b\n"
109" mov %w0, %w8\n"
110"3:\n"
111" dmb ish\n"
112"4:\n"
113" .pushsection .fixup,\"ax\"\n"
114"5: mov %w0, %w7\n"
115" b 4b\n"
116" .popsection\n"
117 _ASM_EXTABLE(1b, 5b)
118 _ASM_EXTABLE(2b, 5b)
119 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
120 : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
121 : "memory");
122 uaccess_disable();
123
124 if (!ret)
125 *uval = val;
126
127 return ret;
128}
129
130#endif /* __ASM_FUTEX_H */