std_detect/detect/os/linux/
loongarch.rs

1//! Run-time feature detection for LoongArch on Linux.
2
3use core::arch::asm;
4
5use super::auxvec;
6use crate::detect::{Feature, bit, cache};
7
8/// Try to read the features from the auxiliary vector.
9pub(crate) fn detect_features() -> cache::Initializer {
10    let mut value = cache::Initializer::default();
11    let enable_feature = |value: &mut cache::Initializer, feature, enable| {
12        if enable {
13            value.set(feature as u32);
14        }
15    };
16
17    // The values are part of the platform-specific [cpucfg]
18    //
19    // [cpucfg]: LoongArch Reference Manual Volume 1: Basic Architecture v1.1
20    let cpucfg2: usize;
21    unsafe {
22        asm!(
23            "cpucfg {}, {}",
24            out(reg) cpucfg2, in(reg) 2,
25            options(pure, nomem, preserves_flags, nostack)
26        );
27    }
28    let cpucfg3: usize;
29    unsafe {
30        asm!(
31            "cpucfg {}, {}",
32            out(reg) cpucfg3, in(reg) 3,
33            options(pure, nomem, preserves_flags, nostack)
34        );
35    }
36    enable_feature(&mut value, Feature::frecipe, bit::test(cpucfg2, 25));
37    enable_feature(&mut value, Feature::div32, bit::test(cpucfg2, 26));
38    enable_feature(&mut value, Feature::lam_bh, bit::test(cpucfg2, 27));
39    enable_feature(&mut value, Feature::lamcas, bit::test(cpucfg2, 28));
40    enable_feature(&mut value, Feature::scq, bit::test(cpucfg2, 30));
41    enable_feature(&mut value, Feature::ld_seq_sa, bit::test(cpucfg3, 23));
42
43    // The values are part of the platform-specific [asm/hwcap.h][hwcap]
44    //
45    // [hwcap]: https://github.com/torvalds/linux/blob/master/arch/loongarch/include/uapi/asm/hwcap.h
46    if let Ok(auxv) = auxvec::auxv() {
47        enable_feature(&mut value, Feature::f, bit::test(cpucfg2, 1) && bit::test(auxv.hwcap, 3));
48        enable_feature(&mut value, Feature::d, bit::test(cpucfg2, 2) && bit::test(auxv.hwcap, 3));
49        enable_feature(&mut value, Feature::lsx, bit::test(auxv.hwcap, 4));
50        enable_feature(&mut value, Feature::lasx, bit::test(auxv.hwcap, 5));
51        enable_feature(
52            &mut value,
53            Feature::lbt,
54            bit::test(auxv.hwcap, 10) && bit::test(auxv.hwcap, 11) && bit::test(auxv.hwcap, 12),
55        );
56        enable_feature(&mut value, Feature::lvz, bit::test(auxv.hwcap, 9));
57        enable_feature(&mut value, Feature::ual, bit::test(auxv.hwcap, 2));
58        return value;
59    }
60    value
61}
std_detect/detect/os/linux/loongarch.rs

std_detect/detect/os/linux/
loongarch.rs
