From 66a3c6852242f322d7b5cf0e45a9a126969b1610 Mon Sep 17 00:00:00 2001
From: Erin <erin@erindesu.cz>
Date: Wed, 15 Nov 2023 19:33:21 +0100
Subject: [PATCH] Stack for programs

---
 Cargo.lock                   |  4 ++--
 kernel/src/holeybytes/mod.rs | 39 ++++++++++++++++++++++++++++++------
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 6bf0825..068da5c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -467,7 +467,7 @@ dependencies = [
 [[package]]
 name = "hbbytecode"
 version = "0.1.0"
-source = "git+https://git.ablecorp.us/ableos/holey-bytes#0f619887c613be3fb3a7dd8c970b7ee76ad0d23b"
+source = "git+https://git.ablecorp.us/ableos/holey-bytes#4fb203aa4d96483a3cfd5890717e96d00f9b5c3f"
 dependencies = [
  "with_builtin_macros",
 ]
@@ -475,7 +475,7 @@ dependencies = [
 [[package]]
 name = "hbvm"
 version = "0.1.0"
-source = "git+https://git.ablecorp.us/ableos/holey-bytes#0f619887c613be3fb3a7dd8c970b7ee76ad0d23b"
+source = "git+https://git.ablecorp.us/ableos/holey-bytes#4fb203aa4d96483a3cfd5890717e96d00f9b5c3f"
 dependencies = [
  "hbbytecode",
 ]
diff --git a/kernel/src/holeybytes/mod.rs b/kernel/src/holeybytes/mod.rs
index 7161648..fa3bb72 100644
--- a/kernel/src/holeybytes/mod.rs
+++ b/kernel/src/holeybytes/mod.rs
@@ -1,3 +1,5 @@
+use core::ptr::NonNull;
+
 mod ecah;
 mod mem;
 
@@ -20,6 +22,7 @@ type Vm = hbvm::Vm<mem::Memory, TIMER_QUOTIENT>;
 
 pub struct ExecThread<'p> {
     vm: Vm,
+    stack_top: *mut u8,
     _phantom: PhantomData<&'p [u8]>,
 }
 
@@ -31,18 +34,30 @@ impl<'p> ExecThread<'p> {
     }
 
     pub unsafe fn new(program: &'p [u8], entrypoint: Address) -> Self {
+        let mut vm = unsafe {
+            Vm::new(
+                mem::Memory,
+                Address::new(program.as_ptr() as u64 + entrypoint.get()),
+            )
+        };
+
+        let stack_top = allocate_stack().as_ptr();
+        vm.write_reg(254, stack_top as u64);
+
         ExecThread {
-            vm: unsafe {
-                Vm::new(
-                    mem::Memory,
-                    Address::new(program.as_ptr() as u64 + entrypoint.get()),
-                )
-            },
+            vm,
+            stack_top,
             _phantom: Default::default(),
         }
     }
 }
 
+impl<'p> Drop for ExecThread<'p> {
+    fn drop(&mut self) {
+        unsafe { alloc::alloc::dealloc(self.stack_top, stack_layout()) };
+    }
+}
+
 impl<'p> Future for ExecThread<'p> {
     type Output = Result<(), VmRunError>;
 
@@ -94,3 +109,15 @@ impl HandlePageFault for PageFaultHandler {
         false
     }
 }
+
+const fn stack_layout() -> core::alloc::Layout {
+    unsafe { alloc::alloc::Layout::from_size_align_unchecked(1024 * 1024, 4096) }
+}
+
+fn allocate_stack() -> NonNull<u8> {
+    let layout = stack_layout();
+    match NonNull::new(unsafe { alloc::alloc::alloc_zeroed(layout) }) {
+        Some(ptr) => ptr,
+        None => alloc::alloc::handle_alloc_error(layout),
+    }
+}