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Diffstat (limited to 'vendor/portable-atomic/src/imp/arm_linux.rs')
| -rw-r--r-- | vendor/portable-atomic/src/imp/arm_linux.rs | 471 |
1 files changed, 0 insertions, 471 deletions
diff --git a/vendor/portable-atomic/src/imp/arm_linux.rs b/vendor/portable-atomic/src/imp/arm_linux.rs deleted file mode 100644 index 623a282..0000000 --- a/vendor/portable-atomic/src/imp/arm_linux.rs +++ /dev/null @@ -1,471 +0,0 @@ -// SPDX-License-Identifier: Apache-2.0 OR MIT - -// 64-bit atomic implementation using kuser_cmpxchg64 on pre-v6 ARM Linux/Android. -// -// Refs: -// - https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt -// - https://github.com/rust-lang/compiler-builtins/blob/0.1.88/src/arm_linux.rs -// -// Note: On Miri and ThreadSanitizer which do not support inline assembly, we don't use -// this module and use fallback implementation instead. - -// TODO: Since Rust 1.64, the Linux kernel requirement for Rust when using std is 3.2+, so it should -// be possible to omit the dynamic kernel version check if the std feature is enabled on Rust 1.64+. -// https://blog.rust-lang.org/2022/08/01/Increasing-glibc-kernel-requirements.html - -#[path = "fallback/outline_atomics.rs"] -mod fallback; - -use core::{arch::asm, cell::UnsafeCell, mem, sync::atomic::Ordering}; - -use crate::utils::{Pair, U64}; - -// https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt -const KUSER_HELPER_VERSION: usize = 0xFFFF0FFC; -// __kuser_helper_version >= 5 (kernel version 3.1+) -const KUSER_CMPXCHG64: usize = 0xFFFF0F60; -#[inline] -fn __kuser_helper_version() -> i32 { - use core::sync::atomic::AtomicI32; - - static CACHE: AtomicI32 = AtomicI32::new(0); - let mut v = CACHE.load(Ordering::Relaxed); - if v != 0 { - return v; - } - // SAFETY: core assumes that at least __kuser_memory_barrier (__kuser_helper_version >= 3) is - // available on this platform. __kuser_helper_version is always available on such a platform. - v = unsafe { (KUSER_HELPER_VERSION as *const i32).read() }; - CACHE.store(v, Ordering::Relaxed); - v -} -#[inline] -fn has_kuser_cmpxchg64() -> bool { - // Note: detect_false cfg is intended to make it easy for portable-atomic developers to - // test cases such as has_cmpxchg16b == false, has_lse == false, - // __kuser_helper_version < 5, etc., and is not a public API. - if cfg!(portable_atomic_test_outline_atomics_detect_false) { - return false; - } - __kuser_helper_version() >= 5 -} -#[inline] -unsafe fn __kuser_cmpxchg64(old_val: *const u64, new_val: *const u64, ptr: *mut u64) -> bool { - // SAFETY: the caller must uphold the safety contract. - unsafe { - let f: extern "C" fn(*const u64, *const u64, *mut u64) -> u32 = - mem::transmute(KUSER_CMPXCHG64 as *const ()); - f(old_val, new_val, ptr) == 0 - } -} - -// 64-bit atomic load by two 32-bit atomic loads. -#[inline] -unsafe fn byte_wise_atomic_load(src: *const u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { - let (out_lo, out_hi); - asm!( - "ldr {out_lo}, [{src}]", - "ldr {out_hi}, [{src}, #4]", - src = in(reg) src, - out_lo = out(reg) out_lo, - out_hi = out(reg) out_hi, - options(pure, nostack, preserves_flags, readonly), - ); - U64 { pair: Pair { lo: out_lo, hi: out_hi } }.whole - } -} - -#[inline(always)] -unsafe fn atomic_update_kuser_cmpxchg64<F>(dst: *mut u64, mut f: F) -> u64 -where - F: FnMut(u64) -> u64, -{ - debug_assert!(dst as usize % 8 == 0); - debug_assert!(has_kuser_cmpxchg64()); - // SAFETY: the caller must uphold the safety contract. - unsafe { - loop { - // This is not single-copy atomic reads, but this is ok because subsequent - // CAS will check for consistency. - // - // Note that the C++20 memory model does not allow mixed-sized atomic access, - // so we must use inline assembly to implement byte_wise_atomic_load. - // (i.e., byte-wise atomic based on the standard library's atomic types - // cannot be used here). - let prev = byte_wise_atomic_load(dst); - let next = f(prev); - if __kuser_cmpxchg64(&prev, &next, dst) { - return prev; - } - } - } -} - -macro_rules! atomic_with_ifunc { - ( - unsafe fn $name:ident($($arg:tt)*) $(-> $ret_ty:ty)? { $($kuser_cmpxchg64_fn_body:tt)* } - fallback = $seqcst_fallback_fn:ident - ) => { - #[inline] - unsafe fn $name($($arg)*) $(-> $ret_ty)? { - unsafe fn kuser_cmpxchg64_fn($($arg)*) $(-> $ret_ty)? { - $($kuser_cmpxchg64_fn_body)* - } - // SAFETY: the caller must uphold the safety contract. - // we only calls __kuser_cmpxchg64 if it is available. - unsafe { - ifunc!(unsafe fn($($arg)*) $(-> $ret_ty)? { - if has_kuser_cmpxchg64() { - kuser_cmpxchg64_fn - } else { - // Use SeqCst because __kuser_cmpxchg64 is always SeqCst. - // https://github.com/torvalds/linux/blob/v6.1/arch/arm/kernel/entry-armv.S#L918-L925 - fallback::$seqcst_fallback_fn - } - }) - } - } - }; -} - -atomic_with_ifunc! { - unsafe fn atomic_load(src: *mut u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(src, |old| old) } - } - fallback = atomic_load_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_store(dst: *mut u64, val: u64) { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |_| val); } - } - fallback = atomic_store_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_swap(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |_| val) } - } - fallback = atomic_swap_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_compare_exchange(dst: *mut u64, old: u64, new: u64) -> (u64, bool) { - // SAFETY: the caller must uphold the safety contract. - let prev = unsafe { - atomic_update_kuser_cmpxchg64(dst, |v| if v == old { new } else { v }) - }; - (prev, prev == old) - } - fallback = atomic_compare_exchange_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_add(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| x.wrapping_add(val)) } - } - fallback = atomic_add_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_sub(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| x.wrapping_sub(val)) } - } - fallback = atomic_sub_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_and(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| x & val) } - } - fallback = atomic_and_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_nand(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| !(x & val)) } - } - fallback = atomic_nand_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_or(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| x | val) } - } - fallback = atomic_or_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_xor(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| x ^ val) } - } - fallback = atomic_xor_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_max(dst: *mut u64, val: u64) -> u64 { - #[allow(clippy::cast_possible_wrap, clippy::cast_sign_loss)] - // SAFETY: the caller must uphold the safety contract. - unsafe { - atomic_update_kuser_cmpxchg64(dst, |x| core::cmp::max(x as i64, val as i64) as u64) - } - } - fallback = atomic_max_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_umax(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| core::cmp::max(x, val)) } - } - fallback = atomic_umax_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_min(dst: *mut u64, val: u64) -> u64 { - #[allow(clippy::cast_possible_wrap, clippy::cast_sign_loss)] - // SAFETY: the caller must uphold the safety contract. - unsafe { - atomic_update_kuser_cmpxchg64(dst, |x| core::cmp::min(x as i64, val as i64) as u64) - } - } - fallback = atomic_min_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_umin(dst: *mut u64, val: u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| core::cmp::min(x, val)) } - } - fallback = atomic_umin_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_not(dst: *mut u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, |x| !x) } - } - fallback = atomic_not_seqcst -} -atomic_with_ifunc! { - unsafe fn atomic_neg(dst: *mut u64) -> u64 { - // SAFETY: the caller must uphold the safety contract. - unsafe { atomic_update_kuser_cmpxchg64(dst, u64::wrapping_neg) } - } - fallback = atomic_neg_seqcst -} - -macro_rules! atomic64 { - ($atomic_type:ident, $int_type:ident, $atomic_max:ident, $atomic_min:ident) => { - #[repr(C, align(8))] - pub(crate) struct $atomic_type { - v: UnsafeCell<$int_type>, - } - - // Send is implicitly implemented. - // SAFETY: any data races are prevented by the kernel user helper or the lock. - unsafe impl Sync for $atomic_type {} - - impl_default_no_fetch_ops!($atomic_type, $int_type); - impl_default_bit_opts!($atomic_type, $int_type); - impl $atomic_type { - #[inline] - pub(crate) const fn new(v: $int_type) -> Self { - Self { v: UnsafeCell::new(v) } - } - - #[inline] - pub(crate) fn is_lock_free() -> bool { - has_kuser_cmpxchg64() - } - #[inline] - pub(crate) const fn is_always_lock_free() -> bool { - false - } - - #[inline] - pub(crate) fn get_mut(&mut self) -> &mut $int_type { - // SAFETY: the mutable reference guarantees unique ownership. - // (UnsafeCell::get_mut requires Rust 1.50) - unsafe { &mut *self.v.get() } - } - - #[inline] - pub(crate) fn into_inner(self) -> $int_type { - self.v.into_inner() - } - - #[inline] - #[cfg_attr(all(debug_assertions, not(portable_atomic_no_track_caller)), track_caller)] - pub(crate) fn load(&self, order: Ordering) -> $int_type { - crate::utils::assert_load_ordering(order); - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_load(self.v.get().cast::<u64>()) as $int_type } - } - - #[inline] - #[cfg_attr(all(debug_assertions, not(portable_atomic_no_track_caller)), track_caller)] - pub(crate) fn store(&self, val: $int_type, order: Ordering) { - crate::utils::assert_store_ordering(order); - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_store(self.v.get().cast::<u64>(), val as u64) } - } - - #[inline] - pub(crate) fn swap(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_swap(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - #[cfg_attr(all(debug_assertions, not(portable_atomic_no_track_caller)), track_caller)] - pub(crate) fn compare_exchange( - &self, - current: $int_type, - new: $int_type, - success: Ordering, - failure: Ordering, - ) -> Result<$int_type, $int_type> { - crate::utils::assert_compare_exchange_ordering(success, failure); - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { - let (prev, ok) = atomic_compare_exchange( - self.v.get().cast::<u64>(), - current as u64, - new as u64, - ); - if ok { - Ok(prev as $int_type) - } else { - Err(prev as $int_type) - } - } - } - - #[inline] - #[cfg_attr(all(debug_assertions, not(portable_atomic_no_track_caller)), track_caller)] - pub(crate) fn compare_exchange_weak( - &self, - current: $int_type, - new: $int_type, - success: Ordering, - failure: Ordering, - ) -> Result<$int_type, $int_type> { - self.compare_exchange(current, new, success, failure) - } - - #[inline] - pub(crate) fn fetch_add(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_add(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_sub(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_sub(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_and(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_and(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_nand(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_nand(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_or(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_or(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_xor(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_xor(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_max(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { $atomic_max(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_min(&self, val: $int_type, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { $atomic_min(self.v.get().cast::<u64>(), val as u64) as $int_type } - } - - #[inline] - pub(crate) fn fetch_not(&self, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_not(self.v.get().cast::<u64>()) as $int_type } - } - #[inline] - pub(crate) fn not(&self, order: Ordering) { - self.fetch_not(order); - } - - #[inline] - pub(crate) fn fetch_neg(&self, _order: Ordering) -> $int_type { - // SAFETY: any data races are prevented by the kernel user helper or the lock - // and the raw pointer passed in is valid because we got it from a reference. - unsafe { atomic_neg(self.v.get().cast::<u64>()) as $int_type } - } - #[inline] - pub(crate) fn neg(&self, order: Ordering) { - self.fetch_neg(order); - } - - #[inline] - pub(crate) const fn as_ptr(&self) -> *mut $int_type { - self.v.get() - } - } - }; -} - -atomic64!(AtomicI64, i64, atomic_max, atomic_min); -atomic64!(AtomicU64, u64, atomic_umax, atomic_umin); - -#[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::*; - - #[test] - fn kuser_helper_version() { - let version = __kuser_helper_version(); - assert!(version >= 5, "{:?}", version); - assert_eq!(version, unsafe { (KUSER_HELPER_VERSION as *const i32).read() }); - } - - test_atomic_int!(i64); - test_atomic_int!(u64); - - // load/store/swap implementation is not affected by signedness, so it is - // enough to test only unsigned types. - stress_test!(u64); -} |