atlas_define_syscall/
lib.rs

1#![no_std]
2#![cfg_attr(docsrs, feature(doc_cfg))]
3
4pub mod definitions;
5
6#[cfg(any(
7    target_feature = "static-syscalls",
8    all(target_arch = "bpf", feature = "unstable-static-syscalls")
9))]
10#[macro_export]
11macro_rules! define_syscall {
12    (fn $name:ident($($arg:ident: $typ:ty),*) -> $ret:ty) => {
13        #[inline]
14        pub unsafe fn $name($($arg: $typ),*) -> $ret {
15            // this enum is used to force the hash to be computed in a const context
16            #[repr(usize)]
17            enum Syscall {
18                Code = $crate::sys_hash(stringify!($name)),
19            }
20
21            let syscall: extern "C" fn($($arg: $typ),*) -> $ret = core::mem::transmute(Syscall::Code);
22            syscall($($arg),*)
23        }
24
25    };
26    (fn $name:ident($($arg:ident: $typ:ty),*)) => {
27        define_syscall!(fn $name($($arg: $typ),*) -> ());
28    }
29}
30
31#[cfg(not(any(
32    target_feature = "static-syscalls",
33    all(target_arch = "bpf", feature = "unstable-static-syscalls")
34)))]
35#[macro_export]
36macro_rules! define_syscall {
37    (fn $name:ident($($arg:ident: $typ:ty),*) -> $ret:ty) => {
38        extern "C" {
39            pub fn $name($($arg: $typ),*) -> $ret;
40        }
41    };
42    (fn $name:ident($($arg:ident: $typ:ty),*)) => {
43        define_syscall!(fn $name($($arg: $typ),*) -> ());
44    }
45}
46
47#[cfg(any(
48    target_feature = "static-syscalls",
49    all(target_arch = "bpf", feature = "unstable-static-syscalls")
50))]
51pub const fn sys_hash(name: &str) -> usize {
52    murmur3_32(name.as_bytes(), 0) as usize
53}
54
55#[cfg(any(
56    target_feature = "static-syscalls",
57    all(target_arch = "bpf", feature = "unstable-static-syscalls")
58))]
59const fn murmur3_32(buf: &[u8], seed: u32) -> u32 {
60    const fn pre_mix(buf: [u8; 4]) -> u32 {
61        u32::from_le_bytes(buf)
62            .wrapping_mul(0xcc9e2d51)
63            .rotate_left(15)
64            .wrapping_mul(0x1b873593)
65    }
66
67    let mut hash = seed;
68
69    let mut i = 0;
70    while i < buf.len() / 4 {
71        let buf = [buf[i * 4], buf[i * 4 + 1], buf[i * 4 + 2], buf[i * 4 + 3]];
72        hash ^= pre_mix(buf);
73        hash = hash.rotate_left(13);
74        hash = hash.wrapping_mul(5).wrapping_add(0xe6546b64);
75
76        i += 1;
77    }
78
79    match buf.len() % 4 {
80        0 => {}
81        1 => {
82            hash = hash ^ pre_mix([buf[i * 4], 0, 0, 0]);
83        }
84        2 => {
85            hash = hash ^ pre_mix([buf[i * 4], buf[i * 4 + 1], 0, 0]);
86        }
87        3 => {
88            hash = hash ^ pre_mix([buf[i * 4], buf[i * 4 + 1], buf[i * 4 + 2], 0]);
89        }
90        _ => { /* unreachable!() */ }
91    }
92
93    hash = hash ^ buf.len() as u32;
94    hash = hash ^ (hash.wrapping_shr(16));
95    hash = hash.wrapping_mul(0x85ebca6b);
96    hash = hash ^ (hash.wrapping_shr(13));
97    hash = hash.wrapping_mul(0xc2b2ae35);
98    hash = hash ^ (hash.wrapping_shr(16));
99
100    hash
101}
atlas_define_syscall/lib.rs

atlas_define_syscall/
lib.rs
