diff options
Diffstat (limited to 'library/std_detect/src/detect/os/linux/riscv.rs')
| -rw-r--r-- | library/std_detect/src/detect/os/linux/riscv.rs | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/library/std_detect/src/detect/os/linux/riscv.rs b/library/std_detect/src/detect/os/linux/riscv.rs new file mode 100644 index 00000000000..dbb3664890e --- /dev/null +++ b/library/std_detect/src/detect/os/linux/riscv.rs @@ -0,0 +1,321 @@ +//! Run-time feature detection for RISC-V on Linux. +//! +//! On RISC-V, detection using auxv only supports single-letter extensions. +//! So, we use riscv_hwprobe that supports multi-letter extensions if available. +//! <https://www.kernel.org/doc/html/latest/arch/riscv/hwprobe.html> + +use core::ptr; + +use super::super::riscv::imply_features; +use super::auxvec; +use crate::detect::{Feature, bit, cache}; + +// See <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/prctl.h?h=v6.15> +// for runtime status query constants. +const PR_RISCV_V_GET_CONTROL: libc::c_int = 70; +const PR_RISCV_V_VSTATE_CTRL_ON: libc::c_int = 2; +const PR_RISCV_V_VSTATE_CTRL_CUR_MASK: libc::c_int = 3; + +// See <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/riscv/include/uapi/asm/hwprobe.h?h=v6.15> +// for riscv_hwprobe struct and hardware probing constants. + +#[repr(C)] +struct riscv_hwprobe { + key: i64, + value: u64, +} + +impl riscv_hwprobe { + // key is overwritten to -1 if not supported by riscv_hwprobe syscall. + pub fn get(&self) -> Option<u64> { + (self.key != -1).then_some(self.value) + } +} + +#[allow(non_upper_case_globals)] +const __NR_riscv_hwprobe: libc::c_long = 258; + +const RISCV_HWPROBE_KEY_BASE_BEHAVIOR: i64 = 3; +const RISCV_HWPROBE_BASE_BEHAVIOR_IMA: u64 = 1 << 0; + +const RISCV_HWPROBE_KEY_IMA_EXT_0: i64 = 4; +const RISCV_HWPROBE_IMA_FD: u64 = 1 << 0; +const RISCV_HWPROBE_IMA_C: u64 = 1 << 1; +const RISCV_HWPROBE_IMA_V: u64 = 1 << 2; +const RISCV_HWPROBE_EXT_ZBA: u64 = 1 << 3; +const RISCV_HWPROBE_EXT_ZBB: u64 = 1 << 4; +const RISCV_HWPROBE_EXT_ZBS: u64 = 1 << 5; +const RISCV_HWPROBE_EXT_ZICBOZ: u64 = 1 << 6; +const RISCV_HWPROBE_EXT_ZBC: u64 = 1 << 7; +const RISCV_HWPROBE_EXT_ZBKB: u64 = 1 << 8; +const RISCV_HWPROBE_EXT_ZBKC: u64 = 1 << 9; +const RISCV_HWPROBE_EXT_ZBKX: u64 = 1 << 10; +const RISCV_HWPROBE_EXT_ZKND: u64 = 1 << 11; +const RISCV_HWPROBE_EXT_ZKNE: u64 = 1 << 12; +const RISCV_HWPROBE_EXT_ZKNH: u64 = 1 << 13; +const RISCV_HWPROBE_EXT_ZKSED: u64 = 1 << 14; +const RISCV_HWPROBE_EXT_ZKSH: u64 = 1 << 15; +const RISCV_HWPROBE_EXT_ZKT: u64 = 1 << 16; +const RISCV_HWPROBE_EXT_ZVBB: u64 = 1 << 17; +const RISCV_HWPROBE_EXT_ZVBC: u64 = 1 << 18; +const RISCV_HWPROBE_EXT_ZVKB: u64 = 1 << 19; +const RISCV_HWPROBE_EXT_ZVKG: u64 = 1 << 20; +const RISCV_HWPROBE_EXT_ZVKNED: u64 = 1 << 21; +const RISCV_HWPROBE_EXT_ZVKNHA: u64 = 1 << 22; +const RISCV_HWPROBE_EXT_ZVKNHB: u64 = 1 << 23; +const RISCV_HWPROBE_EXT_ZVKSED: u64 = 1 << 24; +const RISCV_HWPROBE_EXT_ZVKSH: u64 = 1 << 25; +const RISCV_HWPROBE_EXT_ZVKT: u64 = 1 << 26; +const RISCV_HWPROBE_EXT_ZFH: u64 = 1 << 27; +const RISCV_HWPROBE_EXT_ZFHMIN: u64 = 1 << 28; +const RISCV_HWPROBE_EXT_ZIHINTNTL: u64 = 1 << 29; +const RISCV_HWPROBE_EXT_ZVFH: u64 = 1 << 30; +const RISCV_HWPROBE_EXT_ZVFHMIN: u64 = 1 << 31; +const RISCV_HWPROBE_EXT_ZFA: u64 = 1 << 32; +const RISCV_HWPROBE_EXT_ZTSO: u64 = 1 << 33; +const RISCV_HWPROBE_EXT_ZACAS: u64 = 1 << 34; +const RISCV_HWPROBE_EXT_ZICOND: u64 = 1 << 35; +const RISCV_HWPROBE_EXT_ZIHINTPAUSE: u64 = 1 << 36; +const RISCV_HWPROBE_EXT_ZVE32X: u64 = 1 << 37; +const RISCV_HWPROBE_EXT_ZVE32F: u64 = 1 << 38; +const RISCV_HWPROBE_EXT_ZVE64X: u64 = 1 << 39; +const RISCV_HWPROBE_EXT_ZVE64F: u64 = 1 << 40; +const RISCV_HWPROBE_EXT_ZVE64D: u64 = 1 << 41; +const RISCV_HWPROBE_EXT_ZIMOP: u64 = 1 << 42; +const RISCV_HWPROBE_EXT_ZCA: u64 = 1 << 43; +const RISCV_HWPROBE_EXT_ZCB: u64 = 1 << 44; +const RISCV_HWPROBE_EXT_ZCD: u64 = 1 << 45; +const RISCV_HWPROBE_EXT_ZCF: u64 = 1 << 46; +const RISCV_HWPROBE_EXT_ZCMOP: u64 = 1 << 47; +const RISCV_HWPROBE_EXT_ZAWRS: u64 = 1 << 48; +// Excluded because it only reports the existence of `prctl`-based pointer masking control. +// const RISCV_HWPROBE_EXT_SUPM: u64 = 1 << 49; +const RISCV_HWPROBE_EXT_ZICNTR: u64 = 1 << 50; +const RISCV_HWPROBE_EXT_ZIHPM: u64 = 1 << 51; +const RISCV_HWPROBE_EXT_ZFBFMIN: u64 = 1 << 52; +const RISCV_HWPROBE_EXT_ZVFBFMIN: u64 = 1 << 53; +const RISCV_HWPROBE_EXT_ZVFBFWMA: u64 = 1 << 54; +const RISCV_HWPROBE_EXT_ZICBOM: u64 = 1 << 55; +const RISCV_HWPROBE_EXT_ZAAMO: u64 = 1 << 56; +const RISCV_HWPROBE_EXT_ZALRSC: u64 = 1 << 57; + +const RISCV_HWPROBE_KEY_CPUPERF_0: i64 = 5; +const RISCV_HWPROBE_MISALIGNED_FAST: u64 = 3; +const RISCV_HWPROBE_MISALIGNED_MASK: u64 = 7; + +const RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF: i64 = 9; +const RISCV_HWPROBE_MISALIGNED_SCALAR_FAST: u64 = 3; + +const RISCV_HWPROBE_KEY_MISALIGNED_VECTOR_PERF: i64 = 10; +const RISCV_HWPROBE_MISALIGNED_VECTOR_FAST: u64 = 3; + +// syscall returns an unsupported error if riscv_hwprobe is not supported, +// so we can safely use this function on older versions of Linux. +fn _riscv_hwprobe(out: &mut [riscv_hwprobe]) -> bool { + unsafe fn __riscv_hwprobe( + pairs: *mut riscv_hwprobe, + pair_count: libc::size_t, + cpu_set_size: libc::size_t, + cpus: *mut libc::c_ulong, + flags: libc::c_uint, + ) -> libc::c_long { + unsafe { libc::syscall(__NR_riscv_hwprobe, pairs, pair_count, cpu_set_size, cpus, flags) } + } + + unsafe { __riscv_hwprobe(out.as_mut_ptr(), out.len(), 0, ptr::null_mut(), 0) == 0 } +} + +/// Read list of supported features from (1) the auxiliary vector +/// and (2) the results of `riscv_hwprobe` and `prctl` system calls. +pub(crate) fn detect_features() -> cache::Initializer { + let mut value = cache::Initializer::default(); + let mut enable_feature = |feature, enable| { + if enable { + value.set(feature as u32); + } + }; + + // Use auxiliary vector to enable single-letter ISA extensions. + // The values are part of the platform-specific [asm/hwcap.h][hwcap] + // + // [hwcap]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/riscv/include/uapi/asm/hwcap.h?h=v6.15 + let auxv = auxvec::auxv().expect("read auxvec"); // should not fail on RISC-V platform + let mut has_i = bit::test(auxv.hwcap, (b'i' - b'a').into()); + #[allow(clippy::eq_op)] + enable_feature(Feature::a, bit::test(auxv.hwcap, (b'a' - b'a').into())); + enable_feature(Feature::c, bit::test(auxv.hwcap, (b'c' - b'a').into())); + enable_feature(Feature::d, bit::test(auxv.hwcap, (b'd' - b'a').into())); + enable_feature(Feature::f, bit::test(auxv.hwcap, (b'f' - b'a').into())); + enable_feature(Feature::m, bit::test(auxv.hwcap, (b'm' - b'a').into())); + let has_v = bit::test(auxv.hwcap, (b'v' - b'a').into()); + let mut is_v_set = false; + + // Use riscv_hwprobe syscall to query more extensions and + // performance-related capabilities. + 'hwprobe: { + macro_rules! init { + { $($name: ident : $key: expr),* $(,)? } => { + #[repr(usize)] + enum Indices { $($name),* } + let mut t = [$(riscv_hwprobe { key: $key, value: 0 }),*]; + macro_rules! data_mut { () => { &mut t } } + macro_rules! query { [$idx: ident] => { t[Indices::$idx as usize].get() } } + } + } + init! { + BaseBehavior: RISCV_HWPROBE_KEY_BASE_BEHAVIOR, + Extensions: RISCV_HWPROBE_KEY_IMA_EXT_0, + MisalignedScalarPerf: RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF, + MisalignedVectorPerf: RISCV_HWPROBE_KEY_MISALIGNED_VECTOR_PERF, + MisalignedScalarPerfFallback: RISCV_HWPROBE_KEY_CPUPERF_0, + }; + if !_riscv_hwprobe(data_mut!()) { + break 'hwprobe; + } + + // Query scalar misaligned behavior. + if let Some(value) = query![MisalignedScalarPerf] { + enable_feature( + Feature::unaligned_scalar_mem, + value == RISCV_HWPROBE_MISALIGNED_SCALAR_FAST, + ); + } else if let Some(value) = query![MisalignedScalarPerfFallback] { + // Deprecated method for fallback + enable_feature( + Feature::unaligned_scalar_mem, + value & RISCV_HWPROBE_MISALIGNED_MASK == RISCV_HWPROBE_MISALIGNED_FAST, + ); + } + + // Query vector misaligned behavior. + if let Some(value) = query![MisalignedVectorPerf] { + enable_feature( + Feature::unaligned_vector_mem, + value == RISCV_HWPROBE_MISALIGNED_VECTOR_FAST, + ); + } + + // Query whether "I" base and extensions "M" and "A" (as in the ISA + // manual version 2.2) are enabled. "I" base at that time corresponds + // to "I", "Zicsr", "Zicntr" and "Zifencei" (as in the ISA manual version + // 20240411). + // This is a current requirement of + // `RISCV_HWPROBE_KEY_IMA_EXT_0`-based tests. + if query![BaseBehavior].is_none_or(|value| value & RISCV_HWPROBE_BASE_BEHAVIOR_IMA == 0) { + break 'hwprobe; + } + has_i = true; + enable_feature(Feature::zicsr, true); + enable_feature(Feature::zicntr, true); + enable_feature(Feature::zifencei, true); + enable_feature(Feature::m, true); + enable_feature(Feature::a, true); + + // Enable features based on `RISCV_HWPROBE_KEY_IMA_EXT_0`. + let Some(ima_ext_0) = query![Extensions] else { + break 'hwprobe; + }; + let test = |mask| (ima_ext_0 & mask) != 0; + + enable_feature(Feature::d, test(RISCV_HWPROBE_IMA_FD)); // F is implied. + enable_feature(Feature::c, test(RISCV_HWPROBE_IMA_C)); + + enable_feature(Feature::zicntr, test(RISCV_HWPROBE_EXT_ZICNTR)); + enable_feature(Feature::zihpm, test(RISCV_HWPROBE_EXT_ZIHPM)); + + enable_feature(Feature::zihintntl, test(RISCV_HWPROBE_EXT_ZIHINTNTL)); + enable_feature(Feature::zihintpause, test(RISCV_HWPROBE_EXT_ZIHINTPAUSE)); + enable_feature(Feature::zimop, test(RISCV_HWPROBE_EXT_ZIMOP)); + enable_feature(Feature::zicbom, test(RISCV_HWPROBE_EXT_ZICBOM)); + enable_feature(Feature::zicboz, test(RISCV_HWPROBE_EXT_ZICBOZ)); + enable_feature(Feature::zicond, test(RISCV_HWPROBE_EXT_ZICOND)); + + enable_feature(Feature::zalrsc, test(RISCV_HWPROBE_EXT_ZALRSC)); + enable_feature(Feature::zaamo, test(RISCV_HWPROBE_EXT_ZAAMO)); + enable_feature(Feature::zawrs, test(RISCV_HWPROBE_EXT_ZAWRS)); + enable_feature(Feature::zacas, test(RISCV_HWPROBE_EXT_ZACAS)); + enable_feature(Feature::ztso, test(RISCV_HWPROBE_EXT_ZTSO)); + + enable_feature(Feature::zba, test(RISCV_HWPROBE_EXT_ZBA)); + enable_feature(Feature::zbb, test(RISCV_HWPROBE_EXT_ZBB)); + enable_feature(Feature::zbs, test(RISCV_HWPROBE_EXT_ZBS)); + enable_feature(Feature::zbc, test(RISCV_HWPROBE_EXT_ZBC)); + + enable_feature(Feature::zbkb, test(RISCV_HWPROBE_EXT_ZBKB)); + enable_feature(Feature::zbkc, test(RISCV_HWPROBE_EXT_ZBKC)); + enable_feature(Feature::zbkx, test(RISCV_HWPROBE_EXT_ZBKX)); + enable_feature(Feature::zknd, test(RISCV_HWPROBE_EXT_ZKND)); + enable_feature(Feature::zkne, test(RISCV_HWPROBE_EXT_ZKNE)); + enable_feature(Feature::zknh, test(RISCV_HWPROBE_EXT_ZKNH)); + enable_feature(Feature::zksed, test(RISCV_HWPROBE_EXT_ZKSED)); + enable_feature(Feature::zksh, test(RISCV_HWPROBE_EXT_ZKSH)); + enable_feature(Feature::zkt, test(RISCV_HWPROBE_EXT_ZKT)); + + enable_feature(Feature::zcmop, test(RISCV_HWPROBE_EXT_ZCMOP)); + enable_feature(Feature::zca, test(RISCV_HWPROBE_EXT_ZCA)); + enable_feature(Feature::zcf, test(RISCV_HWPROBE_EXT_ZCF)); + enable_feature(Feature::zcd, test(RISCV_HWPROBE_EXT_ZCD)); + enable_feature(Feature::zcb, test(RISCV_HWPROBE_EXT_ZCB)); + + enable_feature(Feature::zfh, test(RISCV_HWPROBE_EXT_ZFH)); + enable_feature(Feature::zfhmin, test(RISCV_HWPROBE_EXT_ZFHMIN)); + enable_feature(Feature::zfa, test(RISCV_HWPROBE_EXT_ZFA)); + enable_feature(Feature::zfbfmin, test(RISCV_HWPROBE_EXT_ZFBFMIN)); + + // Use prctl (if any) to determine whether the vector extension + // is enabled on the current thread (assuming the entire process + // share the same status). If prctl fails (e.g. QEMU userland emulator + // as of version 9.2.3), use auxiliary vector to retrieve the default + // vector status on the process startup. + let has_vectors = { + let v_status = unsafe { libc::prctl(PR_RISCV_V_GET_CONTROL) }; + if v_status >= 0 { + (v_status & PR_RISCV_V_VSTATE_CTRL_CUR_MASK) == PR_RISCV_V_VSTATE_CTRL_ON + } else { + has_v + } + }; + if has_vectors { + enable_feature(Feature::v, test(RISCV_HWPROBE_IMA_V)); + enable_feature(Feature::zve32x, test(RISCV_HWPROBE_EXT_ZVE32X)); + enable_feature(Feature::zve32f, test(RISCV_HWPROBE_EXT_ZVE32F)); + enable_feature(Feature::zve64x, test(RISCV_HWPROBE_EXT_ZVE64X)); + enable_feature(Feature::zve64f, test(RISCV_HWPROBE_EXT_ZVE64F)); + enable_feature(Feature::zve64d, test(RISCV_HWPROBE_EXT_ZVE64D)); + + enable_feature(Feature::zvbb, test(RISCV_HWPROBE_EXT_ZVBB)); + enable_feature(Feature::zvbc, test(RISCV_HWPROBE_EXT_ZVBC)); + enable_feature(Feature::zvkb, test(RISCV_HWPROBE_EXT_ZVKB)); + enable_feature(Feature::zvkg, test(RISCV_HWPROBE_EXT_ZVKG)); + enable_feature(Feature::zvkned, test(RISCV_HWPROBE_EXT_ZVKNED)); + enable_feature(Feature::zvknha, test(RISCV_HWPROBE_EXT_ZVKNHA)); + enable_feature(Feature::zvknhb, test(RISCV_HWPROBE_EXT_ZVKNHB)); + enable_feature(Feature::zvksed, test(RISCV_HWPROBE_EXT_ZVKSED)); + enable_feature(Feature::zvksh, test(RISCV_HWPROBE_EXT_ZVKSH)); + enable_feature(Feature::zvkt, test(RISCV_HWPROBE_EXT_ZVKT)); + + enable_feature(Feature::zvfh, test(RISCV_HWPROBE_EXT_ZVFH)); + enable_feature(Feature::zvfhmin, test(RISCV_HWPROBE_EXT_ZVFHMIN)); + enable_feature(Feature::zvfbfmin, test(RISCV_HWPROBE_EXT_ZVFBFMIN)); + enable_feature(Feature::zvfbfwma, test(RISCV_HWPROBE_EXT_ZVFBFWMA)); + } + is_v_set = true; + }; + + // Set V purely depending on the auxiliary vector + // only if no fine-grained vector extension detection is available. + if !is_v_set { + enable_feature(Feature::v, has_v); + } + + // Handle base ISA. + // If future RV128I is supported, implement with `enable_feature` here. + // Note that we should use `target_arch` instead of `target_pointer_width` + // to avoid misdetection caused by experimental ABIs such as RV64ILP32. + #[cfg(target_arch = "riscv64")] + enable_feature(Feature::rv64i, has_i); + #[cfg(target_arch = "riscv32")] + enable_feature(Feature::rv32i, has_i); + + imply_features(value) +} |