tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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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#ifdef __KERNEL__
9
10#include <linux/futex.h>
11#include <linux/uaccess.h>
12
13#include <asm/errno.h>
14
15#define FUTEX_MAX_LOOPS 128 /* What's the largest number you can think of? */
16
17#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
18do { \
19 unsigned int loops = FUTEX_MAX_LOOPS; \
20 \
21 uaccess_enable(); \
22 asm volatile( \
23" prfm pstl1strm, %2\n" \
24"1: ldxr %w1, %2\n" \
25 insn "\n" \
26"2: stlxr %w0, %w3, %2\n" \
27" cbz %w0, 3f\n" \
28" sub %w4, %w4, %w0\n" \
29" cbnz %w4, 1b\n" \
30" mov %w0, %w7\n" \
31"3:\n" \
32" dmb ish\n" \
33" .pushsection .fixup,\"ax\"\n" \
34" .align 2\n" \
35"4: mov %w0, %w6\n" \
36" b 3b\n" \
37" .popsection\n" \
38 _ASM_EXTABLE(1b, 4b) \
39 _ASM_EXTABLE(2b, 4b) \
40 : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp), \
41 "+r" (loops) \
42 : "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN) \
43 : "memory"); \
44 uaccess_disable(); \
45} while (0)
46
47static inline int
48arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
49{
50 int oldval = 0, ret, tmp;
51 u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
52
53 pagefault_disable();
54
55 switch (op) {
56 case FUTEX_OP_SET:
57 __futex_atomic_op("mov %w3, %w5",
58 ret, oldval, uaddr, tmp, oparg);
59 break;
60 case FUTEX_OP_ADD:
61 __futex_atomic_op("add %w3, %w1, %w5",
62 ret, oldval, uaddr, tmp, oparg);
63 break;
64 case FUTEX_OP_OR:
65 __futex_atomic_op("orr %w3, %w1, %w5",
66 ret, oldval, uaddr, tmp, oparg);
67 break;
68 case FUTEX_OP_ANDN:
69 __futex_atomic_op("and %w3, %w1, %w5",
70 ret, oldval, uaddr, tmp, ~oparg);
71 break;
72 case FUTEX_OP_XOR:
73 __futex_atomic_op("eor %w3, %w1, %w5",
74 ret, oldval, uaddr, tmp, oparg);
75 break;
76 default:
77 ret = -ENOSYS;
78 }
79
80 pagefault_enable();
81
82 if (!ret)
83 *oval = oldval;
84
85 return ret;
86}
87
88static inline int
89futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
90 u32 oldval, u32 newval)
91{
92 int ret = 0;
93 unsigned int loops = FUTEX_MAX_LOOPS;
94 u32 val, tmp;
95 u32 __user *uaddr;
96
97 if (!access_ok(_uaddr, sizeof(u32)))
98 return -EFAULT;
99
100 uaddr = __uaccess_mask_ptr(_uaddr);
101 uaccess_enable();
102 asm volatile("// futex_atomic_cmpxchg_inatomic\n"
103" prfm pstl1strm, %2\n"
104"1: ldxr %w1, %2\n"
105" sub %w3, %w1, %w5\n"
106" cbnz %w3, 4f\n"
107"2: stlxr %w3, %w6, %2\n"
108" cbz %w3, 3f\n"
109" sub %w4, %w4, %w3\n"
110" cbnz %w4, 1b\n"
111" mov %w0, %w8\n"
112"3:\n"
113" dmb ish\n"
114"4:\n"
115" .pushsection .fixup,\"ax\"\n"
116"5: mov %w0, %w7\n"
117" b 4b\n"
118" .popsection\n"
119 _ASM_EXTABLE(1b, 5b)
120 _ASM_EXTABLE(2b, 5b)
121 : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
122 : "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
123 : "memory");
124 uaccess_disable();
125
126 if (!ret)
127 *uval = val;
128
129 return ret;
130}
131
132#endif /* __KERNEL__ */
133#endif /* __ASM_FUTEX_H */