crates/sel4-stack: Introduce

Signed-off-by: Nick Spinale <nick@nickspinale.com>

Author: nspin

Cargo.lock

@@ -135,6 +135,7 @@ members = [
     "crates/sel4-shared-ring-buffer/block-io/types",
     "crates/sel4-shared-ring-buffer/bookkeeping",
     "crates/sel4-shared-ring-buffer/smoltcp",
+    "crates/sel4-stack",
     "crates/sel4-sync",
     "crates/sel4-test-harness",
     "crates/sel4/bitfield-ops",

Cargo.toml

@@ -14,6 +14,7 @@ mk {
       sel4
       sel4-root-task
       sel4-elf-header
+      sel4-stack
       sel4-initialize-tls
     ;
   };

crates/examples/root-task/spawn-thread/Cargo.nix

@@ -22,3 +22,4 @@ sel4 = { path = "../../../sel4" }
 sel4-elf-header = { path = "../../../sel4-elf-header" }
 sel4-initialize-tls = { path = "../../../sel4-initialize-tls" }
 sel4-root-task = { path = "../../../sel4-root-task" }
+sel4-stack = { path = "../../../sel4-stack" }

crates/examples/root-task/spawn-thread/Cargo.toml

@@ -24,6 +24,7 @@ use sel4_initialize_tls::{TlsImage, TlsReservationLayout, UncheckedTlsImage};
 use sel4_root_task::{
     abort, panicking::catch_unwind, root_task, set_global_allocator_mutex_notification, Never,
 };
+use sel4_stack::Stack;
 
 static SECONDARY_THREAD_STACK: Stack<4096> = Stack::new();
 
@@ -133,7 +134,9 @@ fn find_largest_kernel_untyped(bootinfo: &sel4::BootInfo) -> sel4::cap::Untyped
 fn create_user_context(f: SecondaryThreadFn) -> sel4::UserContext {
     let mut ctx = sel4::UserContext::default();
 
-    *ctx.sp_mut() = SECONDARY_THREAD_STACK.top().try_into().unwrap();
+    *ctx.sp_mut() = (SECONDARY_THREAD_STACK.top().ptr() as usize)
+        .try_into()
+        .unwrap();
     *ctx.pc_mut() = (secondary_thread_entrypoint as usize).try_into().unwrap();
     *ctx.c_param_mut(0) = f.into_arg();
 
@@ -253,23 +256,6 @@ fn get_tls_image() -> TlsImage {
 
 // // //
 
-#[repr(C, align(16))]
-struct Stack<const N: usize>(UnsafeCell<[u8; N]>);
-
-unsafe impl<const N: usize> Sync for Stack<N> {}
-
-impl<const N: usize> Stack<N> {
-    const fn new() -> Self {
-        Self(UnsafeCell::new([0; N]))
-    }
-
-    fn top(&self) -> usize {
-        (self.0.get() as usize) + N
-    }
-}
-
-// // //
-
 #[repr(C, align(4096))]
 struct IpcBufferFrame(UnsafeCell<[u8; GRANULE_SIZE]>);
 

crates/examples/root-task/spawn-thread/src/main.rs

@@ -20,6 +20,7 @@ mk {
       sel4-config
       sel4-kernel-loader-embed-page-tables-runtime
       sel4-immutable-cell
+      sel4-stack
     ;
     sel4-kernel-loader-payload-types = localCrates.sel4-kernel-loader-payload-types // { features = [ "serde" ]; };
   };

crates/sel4-kernel-loader/Cargo.nix

@@ -28,6 +28,7 @@ sel4-kernel-loader-embed-page-tables-runtime = { path = "embed-page-tables/runti
 sel4-kernel-loader-payload-types = { path = "payload-types", features = ["serde"] }
 sel4-logging = { path = "../sel4-logging" }
 sel4-platform-info = { path = "../sel4-platform-info" }
+sel4-stack = { path = "../sel4-stack" }
 spin = { version = "0.9.4", features = ["lock_api"] }
 
 [build-dependencies]

crates/sel4-kernel-loader/Cargo.toml

@@ -55,26 +55,7 @@ pub(crate) mod stacks {
     use core::cell::UnsafeCell;
 
     use sel4_config::sel4_cfg_usize;
-
-    #[repr(C, align(16))]
-    struct Stack<const N: usize>(UnsafeCell<[u8; N]>);
-
-    unsafe impl<const N: usize> Sync for Stack<N> {}
-
-    impl<const N: usize> Stack<N> {
-        pub const fn new() -> Self {
-            Self(UnsafeCell::new([0; N]))
-        }
-
-        pub const fn top(&self) -> StackTop {
-            StackTop(self.0.get().cast::<u8>().wrapping_add(N))
-        }
-    }
-
-    #[repr(transparent)]
-    pub struct StackTop(#[allow(dead_code)] *mut u8);
-
-    unsafe impl Sync for StackTop {}
+    use sel4_stack::{Stack, StackTop};
 
     const PRIMARY_STACK_SIZE: usize = 4096 * 8; // TODO this is excessive
 

crates/sel4-kernel-loader/src/this_image.rs

@@ -4,11 +4,12 @@
 # SPDX-License-Identifier: BSD-2-Clause
 #
 
-{ mk, versions }:
+{ mk, versions, localCrates }:
 
 mk {
   package.name = "sel4-reset";
   dependencies = {
     inherit (versions) cfg-if;
+    inherit (localCrates) sel4-stack;
   };
 }

crates/sel4-reset/Cargo.nix

@@ -18,3 +18,4 @@ license = "BSD-2-Clause"
 
 [dependencies]
 cfg-if = "1.0.0"
+sel4-stack = { path = "../sel4-stack" }