0.3.0: converge relibc to upstream 0.6.0 + Red Bear patches

generic-rt/src/lib.rs

@@ -0,0 +1,133 @@
+#![no_std]
+#![allow(internal_features)]
+#![feature(core_intrinsics)]
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use core::{
+    arch::asm,
+    mem::{self, offset_of},
+};
+
+#[derive(Debug)]
+#[repr(C)]
+pub struct GenericTcb<Os> {
+    /// Pointer to the end of static TLS. Must be the first member
+    pub tls_end: *mut u8,
+    /// Size of the memory allocated for the static TLS in bytes (multiple of page size)
+    pub tls_len: usize,
+    /// Pointer to this structure
+    pub tcb_ptr: *mut Self,
+    /// Size of the memory allocated for this structure in bytes (should be same as page size)
+    pub tcb_len: usize,
+    pub os_specific: Os,
+}
+impl<Os> GenericTcb<Os> {
+    /// Architecture specific code to read a usize from the TCB - aarch64
+    #[allow(unsafe_op_in_unsafe_fn)]
+    #[inline(always)]
+    #[cfg(target_arch = "aarch64")]
+    pub unsafe fn arch_read(offset: usize) -> usize {
+        let abi_ptr: usize;
+        asm!(
+            "mrs {}, tpidr_el0",
+            out(reg) abi_ptr,
+        );
+
+        let tcb_ptr = *(abi_ptr as *const usize);
+        *((tcb_ptr + offset) as *const usize)
+    }
+
+    /// Architecture specific code to read a usize from the TCB - x86
+    #[allow(unsafe_op_in_unsafe_fn)]
+    #[inline(always)]
+    #[cfg(target_arch = "x86")]
+    pub unsafe fn arch_read(offset: usize) -> usize {
+        let value;
+        asm!(
+            "
+            mov {}, gs:[{}]
+            ",
+            out(reg) value,
+            in(reg) offset,
+        );
+        value
+    }
+
+    /// Architecture specific code to read a usize from the TCB - x86_64
+    #[allow(unsafe_op_in_unsafe_fn)]
+    #[inline(always)]
+    #[cfg(target_arch = "x86_64")]
+    pub unsafe fn arch_read(offset: usize) -> usize {
+        let value;
+        asm!(
+            "
+            mov {}, fs:[{}]
+            ",
+            out(reg) value,
+            in(reg) offset,
+        );
+        value
+    }
+
+    /// Architecture specific code to read a usize from the TCB - riscv64
+    #[allow(unsafe_op_in_unsafe_fn)]
+    #[inline(always)]
+    #[cfg(target_arch = "riscv64")]
+    unsafe fn arch_read(offset: usize) -> usize {
+        let value;
+        asm!(
+            "ld {value}, -8(tp)", // TCB
+            "add {value}, {value}, {offset}",
+            "ld {value}, 0({value})",
+            value = out(reg) value,
+            offset = in(reg) offset,
+        );
+        value
+    }
+
+    pub unsafe fn current_ptr() -> Option<*mut Self> {
+        let tcb_ptr = unsafe { Self::arch_read(offset_of!(Self, tcb_ptr)) as *mut Self };
+        let tcb_len = unsafe { Self::arch_read(offset_of!(Self, tcb_len)) };
+        if tcb_ptr.is_null() || tcb_len < mem::size_of::<Self>() {
+            None
+        } else {
+            Some(tcb_ptr)
+        }
+    }
+    pub unsafe fn current() -> Option<&'static mut Self> {
+        unsafe { Some(&mut *Self::current_ptr()?) }
+    }
+}
+pub fn panic_notls(_msg: impl core::fmt::Display) -> ! {
+    // TODO: actually print _msg, perhaps by having panic_notls take a `T: DebugBackend` that can
+    // propagate until called by e.g. relibc start
+    core::intrinsics::abort();
+}
+
+pub trait ExpectTlsFree {
+    type Unwrapped;
+
+    fn expect_notls(self, msg: &str) -> Self::Unwrapped;
+}
+impl<T, E: core::fmt::Debug> ExpectTlsFree for Result<T, E> {
+    type Unwrapped = T;
+
+    fn expect_notls(self, msg: &str) -> T {
+        match self {
+            Ok(t) => t,
+            Err(err) => panic_notls(format_args!(
+                "{msg}: expect failed for Result with err: {err:?}",
+            )),
+        }
+    }
+}
+impl<T> ExpectTlsFree for Option<T> {
+    type Unwrapped = T;
+
+    fn expect_notls(self, msg: &str) -> T {
+        match self {
+            Some(t) => t,
+            None => panic_notls(format_args!("{msg}: expect failed for Option")),
+        }
+    }
+}