Add rust bpf allocator (#4426)

programs/bpf_loader/src/allocator_bump.rs

@@ -0,0 +1,32 @@
+use crate::alloc;
+
+use alloc::{Alloc, AllocErr};
+use std::alloc::Layout;
+
+#[derive(Debug)]
+pub struct BPFAllocator {
+    heap: Vec<u8>,
+    pos: usize,
+}
+
+impl BPFAllocator {
+    pub fn new(heap: Vec<u8>) -> Self {
+        Self { heap, pos: 0 }
+    }
+}
+
+impl Alloc for BPFAllocator {
+    fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+        if self.pos + layout.size() <= self.heap.len() {
+            let ptr = unsafe { self.heap.as_mut_ptr().add(self.pos) };
+            self.pos += layout.size();
+            Ok(ptr)
+        } else {
+            Err(AllocErr)
+        }
+    }
+
+    fn dealloc(&mut self, _ptr: *mut u8, _layout: Layout) {
+        // It's a bump allocator, free not supported
+    }
+}