exec with interpreter

libkernel/src/memory/proc_vm/memory_map/mod.rs

@@ -13,7 +13,7 @@ const MMAP_BASE: usize = 0x4000_0000_0000;
 
 /// Manages mappings in a process's address space.
 pub struct MemoryMap<AS: UserAddressSpace> {
-    vmas: BTreeMap<VA, VMArea>,
+    pub(super) vmas: BTreeMap<VA, VMArea>,
     address_space: AS,
 }
 

libkernel/src/memory/proc_vm/mod.rs

@@ -48,10 +48,21 @@ impl<AS: UserAddressSpace> ProcessVM<AS> {
         Ok(Self { mm, brk })
     }
 
-    pub fn from_map(map: MemoryMap<AS>, brk: VA) -> Self {
+    pub fn from_map(map: MemoryMap<AS>) -> Self {
+        // Last entry will be the VMA with the highest address.
+        let brk = map
+            .vmas
+            .last_key_value()
+            .expect("No VMAs in map")
+            .1
+            .region
+            .end_address()
+            // VMAs should already be page-aligned, but just in case.
+            .align_up(PAGE_SIZE);
+
         Self {
             mm: map,
-            brk: VirtMemoryRegion::new(brk.align_up(PAGE_SIZE), 0),
+            brk: VirtMemoryRegion::new(brk, 0),
         }
     }
 

libkernel/src/memory/proc_vm/vmarea.rs

@@ -172,7 +172,7 @@ impl VMAreaKind {
 /// managing a process's memory layout.
 #[derive(Clone, PartialEq)]
 pub struct VMArea {
-    pub(super) region: VirtMemoryRegion,
+    pub region: VirtMemoryRegion,
     pub(super) kind: VMAreaKind,
     pub(super) permissions: VMAPermissions,
 }
@@ -205,11 +205,15 @@ impl VMArea {
     /// * `f`: A handle to the ELF file's inode.
     /// * `hdr`: The ELF program header (`LOAD` segment) to create the VMA from.
     /// * `endian`: The endianness of the ELF file, for correctly parsing header fields.
+    /// * `address_bias`: A bias added to the VAs of the segment.
     pub fn from_pheader<E: Endian>(
         f: Arc<dyn Inode>,
         hdr: ProgramHeader64<E>,
         endian: E,
+        address_bias: Option<usize>,
     ) -> VMArea {
+        let address_bias = address_bias.unwrap_or(0);
+
         let mut permissions = VMAPermissions {
             read: false,
             write: false,
@@ -229,7 +233,7 @@ impl VMArea {
         }
 
         let mappable_region = VirtMemoryRegion::new(
-            VA::from_value(hdr.p_vaddr(endian) as usize),
+            VA::from_value(hdr.p_vaddr(endian) as usize + address_bias),
             hdr.p_memsz(endian) as usize,
         )
         .to_mappable_region();
@@ -446,6 +450,11 @@ impl VMArea {
             VMAreaKind::Anon => new_vma,
         }
     }
+
+    /// Return the virtual memory region managed by this VMA.
+    pub fn region(&self) -> VirtMemoryRegion {
+        self.region
+    }
 }
 
 #[cfg(test)]