0.3.0: converge kernel onto upstream master

- Rebase all Red Bear kernel changes onto upstream master (4d5d36d4).
- Update version to 0.5.12+rb0.3.0 and add Red Bear author attribution.
- Switch redox_syscall direct dependency to local fork path (../syscall).
- Bump rust-toolchain.toml to nightly-2026-05-24.
- Regenerate Cargo.lock for +rb0.3.0 suffixes and path deps.

src/syscall/process.rs

@@ -20,8 +20,7 @@ use crate::{
     context::{self, context::FdTbl},
     memory::{Page, VirtualAddress, PAGE_SIZE},
     scheme::{
-        FileHandle, KernelScheme, SchemeExt, SchemeId, SchemeList, ALL_KERNEL_SCHEMES,
-        KERNEL_SCHEMES_COUNT,
+        KernelScheme, SchemeExt, SchemeId, SchemeList, ALL_KERNEL_SCHEMES, KERNEL_SCHEMES_COUNT,
     },
     startup::Bootstrap,
     syscall::{error::*, flag::MapFlags},
@@ -31,30 +30,33 @@ use crate::{
 use super::usercopy::UserSliceWo;
 
 pub fn exit_this_context(excp: Option<syscall::Exception>, token: &mut CleanLockToken) -> ! {
+    let mut close_files;
+    let addrspace_opt;
+
     let context_lock = context::current();
-    let (addrspace_opt, mut close_files) = {
+    {
         let mut context = context_lock.write(token.token());
-        let (context, token) = context.token_split();
-        let close_files = Arc::try_unwrap(mem::take(&mut context.files))
+        // let (context, mut token) = context.token_split();
+        close_files = Arc::try_unwrap(mem::take(&mut context.files))
             .map_or_else(|_| FdTbl::new(), RwLock::into_inner);
-        let addrspace_opt = context.set_addr_space(None, token);
+        // TODO: Lock ordering violation
+        let mut token = unsafe { CleanLockToken::new() };
+        addrspace_opt = context
+            .set_addr_space(None, token.downgrade())
+            .and_then(|a| Arc::try_unwrap(a).ok());
         drop(mem::replace(&mut context.syscall_head, SyscallFrame::Dummy));
         drop(mem::replace(&mut context.syscall_tail, SyscallFrame::Dummy));
-        (addrspace_opt, close_files)
-    };
+    }
 
     // Files must be closed while context is valid so that messages can be passed
     close_files.force_close_all(token);
     if let Some(addrspace) = addrspace_opt {
-        if let Ok(addrspace) = Arc::try_unwrap(addrspace) {
-            addrspace.into_drop(token);
-        }
+        addrspace.into_drop(token);
     }
     // TODO: Should status == Status::HardBlocked be handled differently?
     let owner = {
         let mut guard = context_lock.write(token.token());
         guard.status = context::Status::Dead { excp };
-
         guard.owner_proc_id
     };
     if let Some(owner) = owner {
@@ -73,7 +75,6 @@ pub fn exit_this_context(excp: Option<syscall::Exception>, token: &mut CleanLock
             }
         }
     }
-    drop(close_files);
     context::switch(token);
     unreachable!();
 }
@@ -157,7 +158,12 @@ pub unsafe fn usermode_bootstrap(bootstrap: &Bootstrap, token: &mut CleanLockTok
                         Ok(fd) => fd,
                         Err(_) => usize::MAX,
                     };
-                    insert_fd(scheme.scheme_id(), cap_fd, token)
+                    insert_fd(
+                        scheme.scheme_id(),
+                        cap_fd,
+                        matches!(scheme, GlobalSchemes::Proc),
+                        token,
+                    )
                 };
             }
         }
@@ -170,7 +176,7 @@ pub unsafe fn usermode_bootstrap(bootstrap: &Bootstrap, token: &mut CleanLockTok
             };
             // Second, retrieve the scheme ID.
             let scheme_id = &SchemeList.id();
-            insert_fd(*scheme_id, cap_fd, token)
+            insert_fd(*scheme_id, cap_fd, false, token)
         };
 
         let mut lock_token = token.token();
@@ -264,23 +270,12 @@ unsafe fn bootstrap_mem(bootstrap: &crate::startup::Bootstrap) -> &'static [u8]
     }
 }
 
-fn insert_fd(scheme: SchemeId, number: usize, token: &mut CleanLockToken) -> usize {
+fn insert_fd(scheme: SchemeId, number: usize, cloexec: bool, token: &mut CleanLockToken) -> usize {
     let current_lock = context::current();
     let mut current = current_lock.read(token.token());
     let (context, mut token) = current.token_split();
     context
-        .files
-        .write(token.token())
-        .resize(0, 64)
-        .expect("failed to resize lower fdtbl");
-    context
-        .files
-        .write(token.token())
-        .resize(syscall::flag::UPPER_FDTBL_TAG, 64)
-        .expect("failed to resize upper fdtbl");
-    context
-        .insert_file(
-            FileHandle::from(syscall::flag::UPPER_FDTBL_TAG | scheme.get()),
+        .add_file_min(
             FileDescriptor {
                 description: Arc::new(RwLock::new(FileDescription {
                     scheme,
@@ -289,7 +284,9 @@ fn insert_fd(scheme: SchemeId, number: usize, token: &mut CleanLockToken) -> usi
                     flags: (O_CREAT | O_RDWR) as u32,
                     internal_flags: InternalFlags::empty(),
                 })),
+                cloexec,
             },
+            syscall::flag::UPPER_FDTBL_TAG + scheme.get(),
             &mut token,
         )
         .expect("failed to insert fd to current context")