1// Copyright (C) 2023 Intel Corporation.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3// Qt-Security score:significant reason:default
4
5#ifndef QFUTEX_LINUX_P_H
6#define QFUTEX_LINUX_P_H
7
8//
9// W A R N I N G
10// -------------
11//
12// This file is not part of the Qt API. It exists purely as an
13// implementation detail. This header file may change from version to
14// version without notice, or even be removed.
15//
16// We mean it.
17//
18
19#include <private/qcore_unix_p.h>
20#include <qdeadlinetimer.h>
21#include <qtsan_impl.h>
22
23#include <asm/unistd.h>
24#include <errno.h>
25#include <limits.h>
26#include <linux/futex.h>
27#include <sys/syscall.h>
28#include <unistd.h>
29
30// RISC-V does not supply __NR_futex
31#ifndef __NR_futex
32# define __NR_futex __NR_futex_time64
33#endif
34
35#define QT_ALWAYS_USE_FUTEX
36
37QT_BEGIN_NAMESPACE
38
39namespace QtLinuxFutex {
40constexpr inline bool futexAvailable() { return true; }
41
42inline long _q_futex(int *addr, int op, int val, quintptr val2 = 0,
43 int *addr2 = nullptr, int val3 = 0) noexcept
44{
45 QtTsan::futexRelease(addr, addr2);
46
47 // we use __NR_futex because some libcs (like Android's bionic) don't
48 // provide SYS_futex etc.
49 long result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
50
51 QtTsan::futexAcquire(addr, addr2);
52
53 return result;
54}
55template <typename T> int *addr(T *ptr)
56{
57 int *int_addr = reinterpret_cast<int *>(ptr);
58#if Q_BYTE_ORDER == Q_BIG_ENDIAN
59 if (sizeof(T) > sizeof(int))
60 int_addr++; //We want a pointer to the least significant half
61#endif
62 return int_addr;
63}
64
65template <typename Atomic>
66inline void futexWait(Atomic &futex, typename Atomic::Type expectedValue)
67{
68 _q_futex(addr(&futex), FUTEX_WAIT, qintptr(expectedValue));
69}
70template <typename Atomic>
71inline bool futexWait(Atomic &futex, typename Atomic::Type expectedValue, QDeadlineTimer deadline)
72{
73 auto timeout = deadline.deadline<std::chrono::steady_clock>().time_since_epoch();
74 struct timespec ts = durationToTimespec(timeout);
75 long r = _q_futex(addr(&futex), FUTEX_WAIT_BITSET, qintptr(expectedValue), quintptr(&ts),
76 nullptr, FUTEX_BITSET_MATCH_ANY);
77 return r == 0 || errno != ETIMEDOUT;
78}
79template <typename Atomic> inline void futexWakeOne(Atomic &futex)
80{
81 _q_futex(addr(&futex), FUTEX_WAKE, 1);
82}
83template <typename Atomic> inline void futexWakeAll(Atomic &futex)
84{
85 _q_futex(addr(&futex), FUTEX_WAKE, INT_MAX);
86}
87template <typename Atomic> inline
88void futexWakeOp(Atomic &futex1, int wake1, int wake2, Atomic &futex2, quint32 op)
89{
90 _q_futex(addr(&futex1), FUTEX_WAKE_OP, wake1, wake2, addr(&futex2), op);
91}} // namespace QtLinuxFutex
92namespace QtFutex = QtLinuxFutex;
93
94QT_END_NAMESPACE
95
96#endif // QFUTEX_LINUX_P_H
97

source code of qtbase/src/corelib/thread/qfutex_linux_p.h