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std_detect: Only check features that are known to be available on armv8.0 cores if CPU is Exynos 9810

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This commit is contained in:
Taiki Endo 2023-02-12 16:25:13 +09:00 • committed by Amanieu d'Antras
parent e9d18c6b18
commit 2ebd1395ec
1 changed files with 28 additions and 8 deletions
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36
library/stdarch/crates/std_detect/src/detect/os/linux/aarch64.rs
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@ -7,7 +7,7 @@ use crate::detect::{bit, cache, Feature};
/// to read them from /proc/cpuinfo.
pub(crate) fn detect_features() -> cache::Initializer {
#[cfg(all(target_arch = "aarch64", target_os = "android"))]
{
let is_exynos9810 = {
// Samsung Exynos 9810 has a bug that big and little cores have different
// ISAs. And on older Android (pre-9), the kernel incorrectly reports
// that features available only on some cores are available on all cores.
@ -21,18 +21,19 @@ pub(crate) fn detect_features() -> cache::Initializer {
};
// On Exynos, ro.arch is not available on Android 12+, but it is fine
// because Android 9+ includes the fix.
if len > 0 && arch.starts_with(b"exynos9810") {
return cache::Initializer::default();
}
}
len > 0 && arch.starts_with(b"exynos9810")
};
#[cfg(not(all(target_arch = "aarch64", target_os = "android")))]
let is_exynos9810 = false;
if let Ok(auxv) = auxvec::auxv() {
let hwcap: AtHwcap = auxv.into();
return hwcap.cache();
return hwcap.cache(is_exynos9810);
}
#[cfg(feature = "std_detect_file_io")]
if let Ok(c) = super::cpuinfo::CpuInfo::new() {
let hwcap: AtHwcap = c.into();
return hwcap.cache();
return hwcap.cache(is_exynos9810);
}
cache::Initializer::default()
}
@ -228,7 +229,7 @@ impl AtHwcap {
///
/// The feature dependencies here come directly from LLVM's feature definintions:
/// https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/AArch64/AArch64.td
fn cache(self) -> cache::Initializer {
fn cache(self, is_exynos9810: bool) -> cache::Initializer {
let mut value = cache::Initializer::default();
{
let mut enable_feature = |f, enable| {
@ -237,6 +238,25 @@ impl AtHwcap {
}
};
// Samsung Exynos 9810 has a bug that big and little cores have different
// ISAs. And on older Android (pre-9), the kernel incorrectly reports
// that features available only on some cores are available on all cores.
// So, only check features that are known to be available on exynos-m3:
// $ rustc --print cfg --target aarch64-linux-android -C target-cpu=exynos-m3 | grep target_feature
// See also https://github.com/rust-lang/stdarch/pull/1378#discussion_r1103748342.
if is_exynos9810 {
enable_feature(Feature::fp, self.fp);
enable_feature(Feature::crc, self.crc32);
// ASIMD support requires float support - if half-floats are
// supported, it also requires half-float support:
let asimd = self.fp && self.asimd && (!self.fphp | self.asimdhp);
enable_feature(Feature::asimd, asimd);
// Cryptographic extensions require ASIMD
enable_feature(Feature::aes, self.aes && asimd);
enable_feature(Feature::sha2, self.sha1 && self.sha2 && asimd);
return value;
}
enable_feature(Feature::fp, self.fp);
// Half-float support requires float support
enable_feature(Feature::fp16, self.fp && self.fphp);