1 files changed, 397 insertions, 0 deletions
diff --git a/vendor/rustix/src/imp/linux_raw/vdso_wrappers.rs b/vendor/rustix/src/imp/linux_raw/vdso_wrappers.rs
new file mode 100644
index 000000000..80c8dbefd
--- /dev/null
+++ b/vendor/rustix/src/imp/linux_raw/vdso_wrappers.rs
@@ -0,0 +1,397 @@
+//! Implement syscalls using the vDSO.
+//!
+//! <https://man7.org/linux/man-pages/man7/vdso.7.html>
+//!
+//! # Safety
+//!
+//! Similar to syscalls.rs, this file performs raw system calls, and sometimes
+//! passes them uninitialized memory buffers. This file also calls vDSO
+//! functions.
+#![allow(unsafe_code)]
+
+use super::conv::{c_int, ret};
+#[cfg(target_arch = "x86")]
+use super::reg::{ArgReg, RetReg, SyscallNumber, A0, A1, A2, A3, A4, A5, R0};
+use super::time::types::{ClockId, DynamicClockId, Timespec};
+use super::{c, vdso};
+use crate::io;
+#[cfg(all(asm, target_arch = "x86"))]
+use core::arch::asm;
+use core::mem::{transmute, MaybeUninit};
+use core::ptr::null_mut;
+use core::sync::atomic::AtomicPtr;
+use core::sync::atomic::Ordering::Relaxed;
+#[cfg(target_pointer_width = "32")]
+use linux_raw_sys::general::timespec as __kernel_old_timespec;
+use linux_raw_sys::general::{__kernel_clockid_t, __kernel_timespec};
+
+#[inline]
+pub(crate) fn clock_gettime(which_clock: ClockId) -> __kernel_timespec {
+    // Safety: `CLOCK_GETTIME` contains either null or the address of a
+    // function with an ABI like libc `clock_gettime`, and calling it has
+    // the side effect of writing to the result buffer, and no others.
+    unsafe {
+        let mut result = MaybeUninit::<__kernel_timespec>::uninit();
+        let callee = match transmute(CLOCK_GETTIME.load(Relaxed)) {
+            Some(callee) => callee,
+            None => init_clock_gettime(),
+        };
+        let r0 = callee(which_clock as c::c_int, result.as_mut_ptr());
+        assert_eq!(r0, 0);
+        result.assume_init()
+    }
+}
+
+#[inline]
+pub(crate) fn clock_gettime_dynamic(which_clock: DynamicClockId<'_>) -> io::Result<Timespec> {
+    let id = match which_clock {
+        DynamicClockId::Known(id) => id as __kernel_clockid_t,
+
+        DynamicClockId::Dynamic(fd) => {
+            // See `FD_TO_CLOCKID` in Linux's `clock_gettime` documentation.
+            use crate::imp::fd::AsRawFd;
+            const CLOCKFD: i32 = 3;
+            ((!fd.as_raw_fd() << 3) | CLOCKFD) as __kernel_clockid_t
+        }
+
+        DynamicClockId::RealtimeAlarm => {
+            linux_raw_sys::general::CLOCK_REALTIME_ALARM as __kernel_clockid_t
+        }
+        DynamicClockId::Tai => linux_raw_sys::general::CLOCK_TAI as __kernel_clockid_t,
+        DynamicClockId::Boottime => linux_raw_sys::general::CLOCK_BOOTTIME as __kernel_clockid_t,
+        DynamicClockId::BoottimeAlarm => {
+            linux_raw_sys::general::CLOCK_BOOTTIME_ALARM as __kernel_clockid_t
+        }
+    };
+
+    // Safety: `CLOCK_GETTIME` contains either null or the address of a
+    // function with an ABI like libc `clock_gettime`, and calling it has
+    // the side effect of writing to the result buffer, and no others.
+    unsafe {
+        const EINVAL: c::c_int = -(c::EINVAL as c::c_int);
+        let mut timespec = MaybeUninit::<Timespec>::uninit();
+        let callee = match transmute(CLOCK_GETTIME.load(Relaxed)) {
+            Some(callee) => callee,
+            None => init_clock_gettime(),
+        };
+        match callee(id, timespec.as_mut_ptr()) {
+            0 => (),
+            EINVAL => return Err(io::Errno::INVAL),
+            _ => _rustix_clock_gettime_via_syscall(id, timespec.as_mut_ptr())?,
+        }
+        Ok(timespec.assume_init())
+    }
+}
+
+#[cfg(target_arch = "x86")]
+pub(super) mod x86_via_vdso {
+    use super::{transmute, ArgReg, Relaxed, RetReg, SyscallNumber, A0, A1, A2, A3, A4, A5, R0};
+    use crate::imp::arch::asm;
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall0(nr: SyscallNumber<'_>) -> RetReg<R0> {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall0(callee, nr)
+    }
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall1<'a>(
+        nr: SyscallNumber<'a>,
+        a0: ArgReg<'a, A0>,
+    ) -> RetReg<R0> {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall1(callee, nr, a0)
+    }
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall1_noreturn<'a>(
+        nr: SyscallNumber<'a>,
+        a0: ArgReg<'a, A0>,
+    ) -> ! {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall1_noreturn(callee, nr, a0)
+    }
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall2<'a>(
+        nr: SyscallNumber<'a>,
+        a0: ArgReg<'a, A0>,
+        a1: ArgReg<'a, A1>,
+    ) -> RetReg<R0> {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall2(callee, nr, a0, a1)
+    }
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall3<'a>(
+        nr: SyscallNumber<'a>,
+        a0: ArgReg<'a, A0>,
+        a1: ArgReg<'a, A1>,
+        a2: ArgReg<'a, A2>,
+    ) -> RetReg<R0> {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall3(callee, nr, a0, a1, a2)
+    }
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall4<'a>(
+        nr: SyscallNumber<'a>,
+        a0: ArgReg<'a, A0>,
+        a1: ArgReg<'a, A1>,
+        a2: ArgReg<'a, A2>,
+        a3: ArgReg<'a, A3>,
+    ) -> RetReg<R0> {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall4(callee, nr, a0, a1, a2, a3)
+    }
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall5<'a>(
+        nr: SyscallNumber<'a>,
+        a0: ArgReg<'a, A0>,
+        a1: ArgReg<'a, A1>,
+        a2: ArgReg<'a, A2>,
+        a3: ArgReg<'a, A3>,
+        a4: ArgReg<'a, A4>,
+    ) -> RetReg<R0> {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall5(callee, nr, a0, a1, a2, a3, a4)
+    }
+
+    #[inline]
+    pub(in crate::imp) unsafe fn syscall6<'a>(
+        nr: SyscallNumber<'a>,
+        a0: ArgReg<'a, A0>,
+        a1: ArgReg<'a, A1>,
+        a2: ArgReg<'a, A2>,
+        a3: ArgReg<'a, A3>,
+        a4: ArgReg<'a, A4>,
+        a5: ArgReg<'a, A5>,
+    ) -> RetReg<R0> {
+        let callee = match transmute(super::SYSCALL.load(Relaxed)) {
+            Some(callee) => callee,
+            None => super::init_syscall(),
+        };
+        asm::indirect_syscall6(callee, nr, a0, a1, a2, a3, a4, a5)
+    }
+
+    // With the indirect call, it isn't meaningful to do a separate
+    // `_readonly` optimization.
+    pub(in crate::imp) use {
+        syscall0 as syscall0_readonly, syscall1 as syscall1_readonly,
+        syscall2 as syscall2_readonly, syscall3 as syscall3_readonly,
+        syscall4 as syscall4_readonly, syscall5 as syscall5_readonly,
+        syscall6 as syscall6_readonly,
+    };
+}
+
+type ClockGettimeType = unsafe extern "C" fn(c::c_int, *mut Timespec) -> c::c_int;
+
+/// The underlying syscall functions are only called from asm, using the
+/// special syscall calling convention to pass arguments and return values,
+/// which the signature here doesn't reflect.
+#[cfg(target_arch = "x86")]
+pub(super) type SyscallType = unsafe extern "C" fn();
+
+fn init_clock_gettime() -> ClockGettimeType {
+    init();
+    // Safety: Load the function address from static storage that we
+    // just initialized.
+    unsafe { transmute(CLOCK_GETTIME.load(Relaxed)) }
+}
+
+#[cfg(target_arch = "x86")]
+fn init_syscall() -> SyscallType {
+    init();
+    // Safety: Load the function address from static storage that we
+    // just initialized.
+    unsafe { transmute(SYSCALL.load(Relaxed)) }
+}
+
+/// `AtomicPtr` can't hold a `fn` pointer, so we use a `*` pointer to this
+/// placeholder type, and cast it as needed.
+struct Function;
+static mut CLOCK_GETTIME: AtomicPtr<Function> = AtomicPtr::new(null_mut());
+#[cfg(target_arch = "x86")]
+static mut SYSCALL: AtomicPtr<Function> = AtomicPtr::new(null_mut());
+
+unsafe extern "C" fn rustix_clock_gettime_via_syscall(
+    clockid: c::c_int,
+    res: *mut Timespec,
+) -> c::c_int {
+    match _rustix_clock_gettime_via_syscall(clockid, res) {
+        Ok(()) => 0,
+        Err(e) => e.raw_os_error().wrapping_neg(),
+    }
+}
+
+#[cfg(target_pointer_width = "32")]
+unsafe fn _rustix_clock_gettime_via_syscall(
+    clockid: c::c_int,
+    res: *mut Timespec,
+) -> io::Result<()> {
+    let r0 = syscall!(__NR_clock_gettime64, c_int(clockid), res);
+    match ret(r0) {
+        Err(io::Errno::NOSYS) => _rustix_clock_gettime_via_syscall_old(clockid, res),
+        otherwise => otherwise,
+    }
+}
+
+#[cfg(target_pointer_width = "32")]
+unsafe fn _rustix_clock_gettime_via_syscall_old(
+    clockid: c::c_int,
+    res: *mut Timespec,
+) -> io::Result<()> {
+    // Ordinarily `rustix` doesn't like to emulate system calls, but in
+    // the case of time APIs, it's specific to Linux, specific to
+    // 32-bit architectures *and* specific to old kernel versions, and
+    // it's not that hard to fix up here, so that no other code needs
+    // to worry about this.
+    let mut old_result = MaybeUninit::<__kernel_old_timespec>::uninit();
+    let r0 = syscall!(__NR_clock_gettime, c_int(clockid), &mut old_result);
+    match ret(r0) {
+        Ok(()) => {
+            let old_result = old_result.assume_init();
+            *res = Timespec {
+                tv_sec: old_result.tv_sec.into(),
+                tv_nsec: old_result.tv_nsec.into(),
+            };
+            Ok(())
+        }
+        otherwise => otherwise,
+    }
+}
+
+#[cfg(target_pointer_width = "64")]
+unsafe fn _rustix_clock_gettime_via_syscall(
+    clockid: c::c_int,
+    res: *mut Timespec,
+) -> io::Result<()> {
+    ret(syscall!(__NR_clock_gettime, c_int(clockid), res))
+}
+
+/// A symbol pointing to an `int 0x80` instruction. This "function" is only
+/// called from assembly, and only with the x86 syscall calling convention,
+/// so its signature here is not its true signature.
+#[cfg(all(asm, target_arch = "x86"))]
+#[naked]
+unsafe extern "C" fn rustix_int_0x80() {
+    asm!("int $$0x80", "ret", options(noreturn))
+}
+
+// The outline version of the `rustix_int_0x80` above.
+#[cfg(all(not(asm), target_arch = "x86"))]
+extern "C" {
+    fn rustix_int_0x80();
+}
+
+fn minimal_init() {
+    // Safety: Store default function addresses in static storage so that if we
+    // end up making any system calls while we read the vDSO, they'll work.
+    // If the memory happens to already be initialized, this is redundant, but
+    // not harmful.
+    unsafe {
+        CLOCK_GETTIME
+            .compare_exchange(
+                null_mut(),
+                rustix_clock_gettime_via_syscall as *mut Function,
+                Relaxed,
+                Relaxed,
+            )
+            .ok();
+        #[cfg(target_arch = "x86")]
+        {
+            SYSCALL
+                .compare_exchange(
+                    null_mut(),
+                    rustix_int_0x80 as *mut Function,
+                    Relaxed,
+                    Relaxed,
+                )
+                .ok();
+        }
+    }
+}
+
+fn init() {
+    minimal_init();
+
+    if let Some(vdso) = vdso::Vdso::new() {
+        // Look up the platform-specific `clock_gettime` symbol as documented
+        // [here], except on 32-bit platforms where we look up the
+        // `64`-suffixed variant and fail if we don't find it.
+        //
+        // [here]: https://man7.org/linux/man-pages/man7/vdso.7.html
+        #[cfg(target_arch = "x86_64")]
+        let ptr = vdso.sym(cstr!("LINUX_2.6"), cstr!("__vdso_clock_gettime"));
+        #[cfg(target_arch = "arm")]
+        let ptr = vdso.sym(cstr!("LINUX_2.6"), cstr!("__vdso_clock_gettime64"));
+        #[cfg(target_arch = "aarch64")]
+        let ptr = vdso.sym(cstr!("LINUX_2.6.39"), cstr!("__kernel_clock_gettime"));
+        #[cfg(target_arch = "x86")]
+        let ptr = vdso.sym(cstr!("LINUX_2.6"), cstr!("__vdso_clock_gettime64"));
+        #[cfg(target_arch = "riscv64")]
+        let ptr = vdso.sym(cstr!("LINUX_4.15"), cstr!("__vdso_clock_gettime"));
+        #[cfg(target_arch = "powerpc64")]
+        let ptr = vdso.sym(cstr!("LINUX_2.6.15"), cstr!("__kernel_clock_gettime"));
+        #[cfg(target_arch = "mips")]
+        let ptr = vdso.sym(cstr!("LINUX_2.6"), cstr!("__vdso_clock_gettime64"));
+        #[cfg(target_arch = "mips64")]
+        let ptr = vdso.sym(cstr!("LINUX_2.6"), cstr!("__vdso_clock_gettime"));
+
+        // On all 64-bit platforms, the 64-bit `clock_gettime` symbols are
+        // always available.
+        #[cfg(any(target_pointer_width = "64"))]
+        let ok = true;
+
+        // On some 32-bit platforms, the 64-bit `clock_gettime` symbols are not
+        // available on older kernel versions.
+        #[cfg(any(target_arch = "arm", target_arch = "mips", target_arch = "x86"))]
+        let ok = !ptr.is_null();
+
+        if ok {
+            assert!(!ptr.is_null());
+
+            // Safety: Store the computed function addresses in static storage
+            // so that we don't need to compute it again (but if we do, it doesn't
+            // hurt anything).
+            unsafe {
+                CLOCK_GETTIME.store(ptr.cast(), Relaxed);
+            }
+        }
+
+        // On x86, also look up the vsyscall entry point.
+        #[cfg(target_arch = "x86")]
+        {
+            let ptr = vdso.sym(cstr!("LINUX_2.5"), cstr!("__kernel_vsyscall"));
+            assert!(!ptr.is_null());
+
+            // Safety: As above, store the computed function addresses in
+            // static storage.
+            unsafe {
+                SYSCALL.store(ptr.cast(), Relaxed);
+            }
+        }
+    }
+}