Refactor: Move memory initialization to memory::init function

src/lib.rs

@@ -24,37 +24,23 @@ mod vga_buffer;
 mod memory;
 
 #[no_mangle]
-pub extern fn rust_main(multiboot_information_address: usize) {
-    use memory::FrameAllocator;
-
+pub extern "C" fn rust_main(multiboot_information_address: usize) {
+    // ATTENTION: we have a very small stack and no guard page
     vga_buffer::clear_screen();
     println!("Hello World{}", "!");
 
-    let boot_info = unsafe{ multiboot2::load(multiboot_information_address) };
-    let memory_map_tag = boot_info.memory_map_tag()
-        .expect("Memory map tag required");
-    let elf_sections_tag = boot_info.elf_sections_tag()
-        .expect("Elf sections tag required");
-
-    let kernel_start = elf_sections_tag.sections().map(|s| s.addr)
-        .min().unwrap();
-    let kernel_end = elf_sections_tag.sections().map(|s| s.addr + s.size)
-        .max().unwrap();
-    let multiboot_start = multiboot_information_address;
-    let multiboot_end = multiboot_start + (boot_info.total_size as usize);
+    let boot_info = unsafe {
+        multiboot2::load(multiboot_information_address)
+    };
+    enable_nxe_bit();
+    enable_write_protect_bit();
 
-    println!("kernel start: 0x{:x}, kernel end: 0x{:x}",
-        kernel_start, kernel_end);
-    println!("multiboot start: 0x{:x}, multiboot end: 0x{:x}",
-        multiboot_start, multiboot_end);
+    // set up guard page and map the heap pages
+    memory::init(boot_info);
 
-    let mut frame_allocator = memory::AreaFrameAllocator::new(
-        kernel_start as usize, kernel_end as usize, multiboot_start,
-        multiboot_end, memory_map_tag.memory_areas());
+    use alloc::boxed::Box;
+    let heap_test = Box::new(42);
 
-    enable_nxe_bit();
-    enable_write_protect_bit();
-    memory::remap_the_kernel(&mut frame_allocator, boot_info);
     println!("It did not crash!");
 
     loop {}

src/memory/mod.rs

@@ -1,6 +1,7 @@
 pub use self::area_frame_allocator::AreaFrameAllocator;
 pub use self::paging::remap_the_kernel;
 use self::paging::PhysicalAddress;
+use multiboot2::BootInformation;
 
 mod area_frame_allocator;
 pub mod heap_allocator;
@@ -8,6 +9,34 @@ mod paging;
 
 pub const PAGE_SIZE: usize = 4096;
 
+
+pub fn init(boot_info: &BootInformation) {
+    let memory_map_tag = boot_info.memory_map_tag().expect(
+        "Memory map tag required");
+    let elf_sections_tag = boot_info.elf_sections_tag().expect(
+        "Elf sections tag required");
+
+    let kernel_start = elf_sections_tag.sections()
+        .filter(|s| s.is_allocated()).map(|s| s.addr).min().unwrap();
+    let kernel_end = elf_sections_tag.sections()
+        .filter(|s| s.is_allocated()).map(|s| s.addr + s.size).max()
+        .unwrap();
+
+    println!("kernel start: {:#x}, kernel end: {:#x}",
+             kernel_start,
+             kernel_end);
+    println!("multiboot start: {:#x}, multiboot end: {:#x}",
+             boot_info.start_address(),
+             boot_info.end_address());
+
+    let mut frame_allocator = AreaFrameAllocator::new(
+        kernel_start as usize, kernel_end as usize,
+        boot_info.start_address(), boot_info.end_address(),
+        memory_map_tag.memory_areas());
+
+    paging::remap_the_kernel(&mut frame_allocator, boot_info);
+}
+
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Frame {
     number: usize,