detect: Support run-time detection on aarch64 Fuchsia

src/imp/atomic128/aarch64.rs

@@ -54,13 +54,15 @@ include!("macros.rs");
 )]
 #[cfg_attr(target_os = "windows", path = "detect/aarch64_windows.rs")]
 #[cfg_attr(any(target_os = "freebsd", target_os = "openbsd"), path = "detect/aarch64_aa64reg.rs")]
+#[cfg_attr(target_os = "fuchsia", path = "detect/aarch64_fuchsia.rs")]
 #[cfg_attr(
     not(any(
         all(target_os = "linux", target_env = "gnu"),
         target_os = "android",
         target_os = "windows",
         target_os = "freebsd",
         target_os = "openbsd",
+        target_os = "fuchsia",
     )),
     path = "detect/aarch64_std.rs"
 )]
@@ -309,6 +311,7 @@ unsafe fn atomic_compare_exchange(
             target_os = "windows",
             target_os = "freebsd",
             target_os = "openbsd",
+            target_os = "fuchsia",
         )
     )))]
     #[cfg(not(any(target_feature = "lse", portable_atomic_target_feature = "lse")))]
@@ -324,6 +327,7 @@ unsafe fn atomic_compare_exchange(
             target_os = "windows",
             target_os = "freebsd",
             target_os = "openbsd",
+            target_os = "fuchsia",
         )
     ))]
     #[cfg(not(any(target_feature = "lse", portable_atomic_target_feature = "lse")))]

src/imp/atomic128/detect/aarch64_fuchsia.rs

@@ -0,0 +1,89 @@
+// Run-time feature detection on aarch64 Fuchsia by using zx_system_get_features.
+//
+// As of nightly-2023-01-23, is_aarch64_feature_detected doesn't support run-time detection on Fuchsia.
+// https://github.com/rust-lang/stdarch/blob/a0c30f3e3c75adcd6ee7efc94014ebcead61c507/crates/std_detect/src/detect/mod.rs
+//
+// Refs:
+// - https://fuchsia.dev/fuchsia-src/reference/syscalls/system_get_features
+// - https://github.com/llvm/llvm-project/commit/4e731abc55681751b5d736b613f7720e50eb1ad4
+
+#![cfg_attr(
+    any(
+        portable_atomic_no_aarch64_target_feature,
+        any(target_feature = "lse", portable_atomic_target_feature = "lse")
+    ),
+    allow(dead_code)
+)]
+
+include!("common.rs");
+
+#[allow(non_camel_case_types, clippy::upper_case_acronyms)]
+mod ffi {
+    // https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/system/public/zircon/types.h
+    pub(crate) type zx_status_t = i32;
+
+    // https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/system/public/zircon/errors.h
+    pub(crate) const ZX_OK: zx_status_t = 0;
+    // https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/system/public/zircon/features.h
+    pub(crate) const ZX_FEATURE_KIND_CPU: u32 = 0;
+    pub(crate) const ZX_ARM64_FEATURE_ISA_ATOMICS: u32 = 1 << 8;
+
+    #[link(name = "zircon")]
+    extern "C" {
+        // https://fuchsia.dev/fuchsia-src/reference/syscalls/system_get_features
+        pub(crate) fn zx_system_get_features(kind: u32, features: *mut u32) -> zx_status_t;
+    }
+}
+
+#[inline]
+fn _detect(info: &mut CpuInfo) {
+    let mut features: u32 = 0;
+    // SAFETY: we've passed a valid pointer.
+    let res = unsafe { ffi::zx_system_get_features(ffi::ZX_FEATURE_KIND_CPU, &mut features) };
+    if res != ffi::ZX_OK {
+        return;
+    }
+    if (features & ffi::ZX_ARM64_FEATURE_ISA_ATOMICS) != 0 {
+        info.set(CpuInfo::HAS_LSE);
+    }
+}
+
+#[allow(
+    clippy::alloc_instead_of_core,
+    clippy::std_instead_of_alloc,
+    clippy::std_instead_of_core,
+    clippy::undocumented_unsafe_blocks,
+    clippy::wildcard_imports
+)]
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // Static assertions for FFI bindings.
+    // This checks that FFI bindings defined in this crate and FFI bindings
+    // generated for the platform's latest header file using bindgen have
+    // compatible signatures (or the same values if constants).
+    // Since this is static assertion, we can detect problems with
+    // `cargo check --tests --target <target>` run in CI (via TESTS=1 build.sh)
+    // without actually running tests on these platforms.
+    // See also tools/codegen/src/ffi.rs.
+    // TODO: auto-generate this test
+    #[allow(
+        clippy::cast_possible_wrap,
+        clippy::cast_sign_loss,
+        clippy::cast_possible_truncation,
+        clippy::no_effect_underscore_binding
+    )]
+    const _: fn() = || {
+        use crate::tests::sys::*;
+        // TODO: zx_status_t, zx_system_get_features
+        let [] = [(); (ffi::ZX_OK - zircon_system_public_zircon_errors::ZX_OK as ffi::zx_status_t)
+            as usize];
+        let [] = [(); (ffi::ZX_FEATURE_KIND_CPU
+            - zircon_system_public_zircon_features::ZX_FEATURE_KIND_CPU)
+            as usize];
+        let [] = [(); (ffi::ZX_ARM64_FEATURE_ISA_ATOMICS
+            - zircon_system_public_zircon_features::ZX_ARM64_FEATURE_ISA_ATOMICS)
+            as usize];
+    };
+}

src/imp/atomic128/detect/aarch64_windows.rs

@@ -42,7 +42,13 @@ fn _detect(info: &mut CpuInfo) {
     }
 }
 
-#[allow(clippy::undocumented_unsafe_blocks)]
+#[allow(
+    clippy::alloc_instead_of_core,
+    clippy::std_instead_of_alloc,
+    clippy::std_instead_of_core,
+    clippy::undocumented_unsafe_blocks,
+    clippy::wildcard_imports
+)]
 #[cfg(test)]
 mod tests {
     use super::*;

tools/build.sh

@@ -56,6 +56,7 @@ default_targets=(
     aarch64-pc-windows-gnullvm
     aarch64-pc-windows-msvc
     aarch64-unknown-freebsd
+    aarch64-unknown-fuchsia
     aarch64-unknown-linux-gnu
     aarch64-unknown-linux-musl
     aarch64-unknown-linux-uclibc # custom target

tools/codegen/patches/fuchsia.diff

@@ -0,0 +1,21 @@
+diff --git a/zircon/system/public/zircon/features.h b/zircon/system/public/zircon/features.h
+--- a/zircon/system/public/zircon/features.h
++++ b/zircon/system/public/zircon/features.h
+@@ -8,7 +8,7 @@
+ // clang-format off
+
+ // types of features that can be retrieved via |zx_system_get_features|
+-#define ZX_FEATURE_KIND_CPU                   ((uint32_t)0)
++#define ZX_FEATURE_KIND_CPU                   0
+ #define ZX_FEATURE_KIND_HW_BREAKPOINT_COUNT   ((uint32_t)1)
+ #define ZX_FEATURE_KIND_HW_WATCHPOINT_COUNT   ((uint32_t)2)
+ #define ZX_FEATURE_KIND_ADDRESS_TAGGING       ((uint32_t)3)
+@@ -35,7 +35,7 @@
+ #define ZX_ARM64_FEATURE_ISA_SHA1      ((uint32_t)(1u << 5))
+ #define ZX_ARM64_FEATURE_ISA_SHA256    ((uint32_t)(1u << 6))
+ #define ZX_ARM64_FEATURE_ISA_CRC32     ((uint32_t)(1u << 7))
+-#define ZX_ARM64_FEATURE_ISA_ATOMICS   ((uint32_t)(1u << 8))
++#define ZX_ARM64_FEATURE_ISA_ATOMICS   (1u << 8)
+ #define ZX_ARM64_FEATURE_ISA_RDM       ((uint32_t)(1u << 9))
+ #define ZX_ARM64_FEATURE_ISA_SHA3      ((uint32_t)(1u << 10))
+ #define ZX_ARM64_FEATURE_ISA_SM3       ((uint32_t)(1u << 11))

tools/codegen/src/ffi.rs

@@ -2,8 +2,9 @@
 // platform APIs, and we define our own FFI bindings to those APIs.
 //
 // We use only one function and a few constants per platform, but
-// technically OS can change these APIs so it is preferable to be able
-// to detect them.
+// technically OS can change these APIs (unfortunately, some operating
+// systems don't care about breaking API/ABI between releases), so it is
+// preferable to be able to detect them.
 //
 // See also https://github.com/rust-lang/libc/issues/570.
 
@@ -29,15 +30,9 @@ static TARGETS: &[Target] = &[
             "aarch64-linux-android",
         ],
         headers: &[
-            // TODO
-            // Header {
-            //     // https://github.com/bminor/glibc/blob/HEAD/misc/sys/auxv.h
-            //     // https://github.com/bminor/musl/blob/HEAD/include/sys/auxv.h
-            //     path: "sys/auxv.h",
-            //     types: &[],
-            //     vars: &[],
-            //     functions: &["getauxval"],
-            // },
+            // TODO: getauxval
+            // https://github.com/bminor/glibc/blob/HEAD/misc/sys/auxv.h
+            // https://github.com/bminor/musl/blob/HEAD/include/sys/auxv.h
             Header {
                 // https://github.com/torvalds/linux/blob/HEAD/include/uapi/linux/auxvec.h
                 path: "include/uapi/linux/auxvec.h",
@@ -73,6 +68,28 @@ static TARGETS: &[Target] = &[
             },
         ],
     },
+    Target {
+        triples: &["aarch64-unknown-fuchsia"],
+        headers: &[
+            // TODO: zx_system_get_features
+            // TODO: zx_status_t
+            // https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/system/public/zircon/types.h
+            Header {
+                // https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/system/public/zircon/errors.h
+                path: "zircon/system/public/zircon/errors.h",
+                types: &[],
+                vars: &["ZX_OK"],
+                functions: &[],
+            },
+            Header {
+                // https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/system/public/zircon/features.h
+                path: "zircon/system/public/zircon/features.h",
+                types: &[],
+                vars: &["ZX_FEATURE_KIND_CPU", "ZX_ARM64_FEATURE_ISA_ATOMICS"],
+                functions: &[],
+            },
+        ],
+    },
 ];
 
 #[derive(Clone, Copy)]
@@ -139,6 +156,7 @@ pub(crate) fn gen() -> Result<()> {
                     vec![src_dir.join("arch").join(arch).join("include/uapi")]
                 }
                 openbsd => vec![src_dir.join("sys")],
+                fuchsia => vec![src_dir.join("zircon/system/public")],
                 _ => todo!("{target:?}"),
             };
             for include in &include {
@@ -158,6 +176,7 @@ pub(crate) fn gen() -> Result<()> {
                 let header_path = match target.os {
                     linux | android => src_dir.join(header.path),
                     openbsd => src_dir.join(format!("sys/{}", header.path)),
+                    fuchsia => src_dir.join(header.path),
                     _ => todo!("{target:?}"),
                 };
 
@@ -205,28 +224,24 @@ pub(crate) fn gen() -> Result<()> {
 
 fn git_clone(target: &TargetSpec, download_cache_dir: &Utf8Path) -> Result<Utf8PathBuf> {
     fn clone(download_cache_dir: &Utf8Path, repository: &str) -> Result<Utf8PathBuf> {
-        let src_dir = download_cache_dir.join(repository.replace('/', "-"));
+        let name = repository.strip_suffix(".git").unwrap_or(repository);
+        let name = name.strip_prefix("https://github.com/").unwrap_or(name);
+        let name = name.strip_prefix("https://fuchsia.googlesource.com/").unwrap_or(name);
+        let src_dir = download_cache_dir.join(name.replace('/', "-"));
         if src_dir.exists() {
             cmd!("git", "clean", "-df",).dir(&src_dir).run()?;
             // TODO: use stash?
             cmd!("git", "checkout", ".",).dir(&src_dir).run()?;
         } else {
             // TODO: use sparse-checkout
-            cmd!(
-                "git",
-                "clone",
-                "--depth",
-                "1",
-                format!("https://github.com/{repository}.git"),
-                &src_dir
-            )
-            .run()?;
+            cmd!("git", "clone", "--depth", "1", repository, &src_dir).run()?;
         }
         Ok(src_dir)
     }
     let src_dir = match target.os {
-        linux | android => clone(download_cache_dir, "torvalds/linux")?,
-        openbsd => clone(download_cache_dir, "openbsd/src")?,
+        linux | android => clone(download_cache_dir, "https://github.com/torvalds/linux.git")?,
+        openbsd => clone(download_cache_dir, "https://github.com/openbsd/src.git")?,
+        fuchsia => clone(download_cache_dir, "https://fuchsia.googlesource.com/fuchsia")?,
         _ => todo!("{target:?}"),
     };
     // TODO: remove needs of patches.
@@ -254,6 +269,7 @@ fn arch_symlink(target: &TargetSpec, src_dir: &Utf8Path) -> Result<()> {
             let link = &src_dir.join("sys/machine");
             fs::os::unix::fs::symlink(src_dir.join("sys/arch").join(arch).join("include"), link)?;
         }
+        fuchsia => {}
         _ => todo!("{target:?}"),
     }
     Ok(())

tools/codegen/src/main.rs

@@ -1,5 +1,10 @@
 #![warn(rust_2018_idioms, single_use_lifetimes)]
-#![allow(clippy::match_on_vec_items, clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
+#![allow(
+    clippy::match_on_vec_items,
+    clippy::needless_pass_by_value,
+    clippy::single_match,
+    clippy::unnecessary_wraps
+)]
 
 #[cfg(unix)]
 #[macro_use]