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//! ARM64 CPU feature detection support.
//!
//! Unfortunately ARM instructions to detect CPU features cannot be called from
//! unprivileged userspace code, so this implementation relies on OS-specific
//! APIs for feature detection.
// Evaluate the given `$body` expression any of the supplied target features
// are not enabled. Otherwise returns true.
#[macro_export]
#[doc(hidden)]
macro_rules! __unless_target_features {
($($tf:tt),+ => $body:expr ) => {
{
#[cfg(not(all($(target_feature=$tf,)*)))]
$body
#[cfg(all($(target_feature=$tf,)*))]
true
}
};
}
// Linux runtime detection of target CPU features using `getauxval`.
#[cfg(any(target_os = "linux", target_os = "android"))]
#[macro_export]
#[doc(hidden)]
macro_rules! __detect_target_features {
($($tf:tt),+) => {{
let hwcaps = $crate::aarch64::getauxval_hwcap();
$($crate::check!(hwcaps, $tf) & )+ true
}};
}
/// Linux helper function for calling `getauxval` to get `AT_HWCAP`.
#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn getauxval_hwcap() -> u64 {
unsafe { libc::getauxval(libc::AT_HWCAP) }
}
// Apple platform's runtime detection of target CPU features using `sysctlbyname`.
#[cfg(target_vendor = "apple")]
#[macro_export]
#[doc(hidden)]
macro_rules! __detect_target_features {
($($tf:tt),+) => {{
$($crate::check!($tf) & )+ true
}};
}
// Linux `expand_check_macro`
#[cfg(any(target_os = "linux", target_os = "android"))]
macro_rules! __expand_check_macro {
($(($name:tt, $hwcap:ident)),* $(,)?) => {
#[macro_export]
#[doc(hidden)]
macro_rules! check {
$(
($hwcaps:expr, $name) => {
(($hwcaps & $crate::aarch64::hwcaps::$hwcap) != 0)
};
)*
}
};
}
// Linux `expand_check_macro`
#[cfg(any(target_os = "linux", target_os = "android"))]
__expand_check_macro! {
("aes", AES), // Enable AES support.
("sha2", SHA2), // Enable SHA1 and SHA256 support.
("sha3", SHA3), // Enable SHA512 and SHA3 support.
}
/// Linux hardware capabilities mapped to target features.
///
/// Note that LLVM target features are coarser grained than what Linux supports
/// and imply more capabilities under each feature. This module attempts to
/// provide that mapping accordingly.
///
#[cfg(any(target_os = "linux", target_os = "android"))]
pub mod hwcaps {
use libc::c_ulong;
pub const AES: c_ulong = libc::HWCAP_AES | libc::HWCAP_PMULL;
pub const SHA2: c_ulong = libc::HWCAP_SHA2;
pub const SHA3: c_ulong = libc::HWCAP_SHA3 | libc::HWCAP_SHA512;
}
// Apple OS (macOS, iOS, watchOS, and tvOS) `check!` macro.
//
// NOTE: several of these instructions (e.g. `aes`, `sha2`) can be assumed to
// be present on all Apple ARM64 hardware.
//
// Newer CPU instructions now have nodes within sysctl's `hw.optional`
// namespace, however the ones that do not can safely be assumed to be
// present on all Apple ARM64 devices, now and for the foreseeable future.
//
// See discussion on this issue for more information:
#[cfg(target_vendor = "apple")]
#[macro_export]
#[doc(hidden)]
macro_rules! check {
("aes") => {
true
};
("sha2") => {
true
};
("sha3") => {
unsafe {
// `sha3` target feature implies SHA-512 as well
$crate::aarch64::sysctlbyname(b"hw.optional.armv8_2_sha512\0")
&& $crate::aarch64::sysctlbyname(b"hw.optional.armv8_2_sha3\0")
}
};
}
/// Apple helper function for calling `sysctlbyname`.
#[cfg(target_vendor = "apple")]
pub unsafe fn sysctlbyname(name: &[u8]) -> bool {
assert_eq!(
name.last().cloned(),
Some(0),
"name is not NUL terminated: {:?}",
name
);
let mut value: u32 = 0;
let mut size = core::mem::size_of::<u32>();
let rc = libc::sysctlbyname(
name.as_ptr() as *const i8,
&mut value as *mut _ as *mut libc::c_void,
&mut size,
core::ptr::null_mut(),
0,
);
assert_eq!(size, 4, "unexpected sysctlbyname(3) result size");
assert_eq!(rc, 0, "sysctlbyname returned error code: {}", rc);
value != 0
}
// On other targets, runtime CPU feature detection is unavailable
#[cfg(not(any(target_vendor = "apple", target_os = "linux", target_os = "android",)))]
#[macro_export]
#[doc(hidden)]
macro_rules! __detect_target_features {
($($tf:tt),+) => {
false
};
}