1 //! The Linux `membarrier` syscall.
2 //!
3 //! # Safety
4 //!
5 //! This file defines an enum and a bitflags type that represent the same
6 //! set of values and are kept in sync.
7 #![allow(unsafe_code)]
8
9 use crate::process::Cpuid;
10 use crate::{backend, io};
11
12 pub use backend::process::types::MembarrierCommand;
13
14 #[cfg(any(target_os = "android", target_os = "linux"))]
15 bitflags::bitflags! {
16 /// A result from [`membarrier_query`].
17 ///
18 /// These flags correspond to values of [`MembarrierCommand`] which are
19 /// supported in the OS.
20 pub struct MembarrierQuery: u32 {
21 /// `MEMBARRIER_CMD_GLOBAL`
22 #[doc(alias = "SHARED")]
23 #[doc(alias = "MEMBARRIER_CMD_SHARED")]
24 const GLOBAL = MembarrierCommand::Global as _;
25 /// `MEMBARRIER_CMD_GLOBAL_EXPEDITED`
26 const GLOBAL_EXPEDITED = MembarrierCommand::GlobalExpedited as _;
27 /// `MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED`
28 const REGISTER_GLOBAL_EXPEDITED = MembarrierCommand::RegisterGlobalExpedited as _;
29 /// `MEMBARRIER_CMD_PRIVATE_EXPEDITED`
30 const PRIVATE_EXPEDITED = MembarrierCommand::PrivateExpedited as _;
31 /// `MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED`
32 const REGISTER_PRIVATE_EXPEDITED = MembarrierCommand::RegisterPrivateExpedited as _;
33 /// `MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE`
34 const PRIVATE_EXPEDITED_SYNC_CORE = MembarrierCommand::PrivateExpeditedSyncCore as _;
35 /// `MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE`
36 const REGISTER_PRIVATE_EXPEDITED_SYNC_CORE = MembarrierCommand::RegisterPrivateExpeditedSyncCore as _;
37 /// `MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ` (since Linux 5.10)
38 const PRIVATE_EXPEDITED_RSEQ = MembarrierCommand::PrivateExpeditedRseq as _;
39 /// `MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ` (since Linux 5.10)
40 const REGISTER_PRIVATE_EXPEDITED_RSEQ = MembarrierCommand::RegisterPrivateExpeditedRseq as _;
41 }
42 }
43
44 #[cfg(any(target_os = "android", target_os = "linux"))]
45 impl MembarrierQuery {
46 /// Test whether this query result contains the given command.
47 #[inline]
contains_command(self, cmd: MembarrierCommand) -> bool48 pub fn contains_command(self, cmd: MembarrierCommand) -> bool {
49 // Safety: `MembarrierCommand` is an enum that only contains values
50 // also valid in `MembarrierQuery`.
51 self.contains(unsafe { Self::from_bits_unchecked(cmd as _) })
52 }
53 }
54
55 /// `membarrier(MEMBARRIER_CMD_QUERY, 0, 0)`—Query the supported `membarrier`
56 /// commands.
57 ///
58 /// This function doesn't return a `Result` because it always succeeds; if
59 /// the underlying OS doesn't support the `membarrier` syscall, it returns
60 /// an empty `MembarrierQuery` value.
61 ///
62 /// # References
63 /// - [Linux]
64 ///
65 /// [Linux]: https://man7.org/linux/man-pages/man2/membarrier.2.html
66 #[inline]
67 #[doc(alias = "MEMBARRIER_CMD_QUERY")]
membarrier_query() -> MembarrierQuery68 pub fn membarrier_query() -> MembarrierQuery {
69 backend::process::syscalls::membarrier_query()
70 }
71
72 /// `membarrier(cmd, 0, 0)`—Perform a memory barrier.
73 ///
74 /// # References
75 /// - [Linux]
76 ///
77 /// [Linux]: https://man7.org/linux/man-pages/man2/membarrier.2.html
78 #[inline]
membarrier(cmd: MembarrierCommand) -> io::Result<()>79 pub fn membarrier(cmd: MembarrierCommand) -> io::Result<()> {
80 backend::process::syscalls::membarrier(cmd)
81 }
82
83 /// `membarrier(cmd, MEMBARRIER_CMD_FLAG_CPU, cpu)`—Perform a memory barrier
84 /// with a specific CPU.
85 ///
86 /// # References
87 /// - [Linux]
88 ///
89 /// [Linux]: https://man7.org/linux/man-pages/man2/membarrier.2.html
90 #[inline]
membarrier_cpu(cmd: MembarrierCommand, cpu: Cpuid) -> io::Result<()>91 pub fn membarrier_cpu(cmd: MembarrierCommand, cpu: Cpuid) -> io::Result<()> {
92 backend::process::syscalls::membarrier_cpu(cmd, cpu)
93 }
94