Move memory layout helpers to new module.

Bug: 223166344
Test: atest vmbase_example.integration_test
Change-Id: I2e819594bc6110783b5e64fa6485052b0f01e062
diff --git a/vmbase/example/src/main.rs b/vmbase/example/src/main.rs
index 3a1de08..6b110cf 100644
--- a/vmbase/example/src/main.rs
+++ b/vmbase/example/src/main.rs
@@ -19,13 +19,14 @@
 #![feature(default_alloc_error_handler)]
 
 mod exceptions;
+mod layout;
 
 extern crate alloc;
 
-use aarch64_paging::{
-    idmap::IdMap,
-    paging::{Attributes, MemoryRegion},
+use crate::layout::{
+    dtb_range, print_addresses, rodata_range, text_range, writable_region, DEVICE_REGION,
 };
+use aarch64_paging::{idmap::IdMap, paging::Attributes};
 use alloc::{vec, vec::Vec};
 use buddy_system_allocator::LockedHeap;
 use vmbase::{main, println};
@@ -42,9 +43,6 @@
 
 static mut HEAP: [u8; 65536] = [0; 65536];
 
-/// The first 1 GiB of memory are used for MMIO.
-const DEVICE_REGION: MemoryRegion = MemoryRegion::new(0, 0x40000000);
-
 main!(main);
 
 /// Entry point for VM bootloader.
@@ -52,9 +50,7 @@
     println!("Hello world");
     println!("x0={:#018x}, x1={:#018x}, x2={:#018x}, x3={:#018x}", arg0, arg1, arg2, arg3);
     print_addresses();
-    unsafe {
-        assert_eq!(arg0, &dtb_begin as *const u8 as u64);
-    }
+    assert_eq!(arg0, dtb_range().start.0 as u64);
     check_data();
 
     unsafe {
@@ -67,13 +63,13 @@
     idmap.map_range(&DEVICE_REGION, Attributes::DEVICE_NGNRE | Attributes::EXECUTE_NEVER).unwrap();
     idmap
         .map_range(
-            &text_region(),
+            &text_range().into(),
             Attributes::NORMAL | Attributes::NON_GLOBAL | Attributes::READ_ONLY,
         )
         .unwrap();
     idmap
         .map_range(
-            &rodata_region(),
+            &rodata_range().into(),
             Attributes::NORMAL
                 | Attributes::NON_GLOBAL
                 | Attributes::READ_ONLY
@@ -95,67 +91,6 @@
     check_data();
 }
 
-/// Executable code.
-fn text_region() -> MemoryRegion {
-    unsafe { MemoryRegion::new(&text_begin as *const u8 as usize, &text_end as *const u8 as usize) }
-}
-
-/// Read-only data.
-fn rodata_region() -> MemoryRegion {
-    unsafe {
-        MemoryRegion::new(&rodata_begin as *const u8 as usize, &rodata_end as *const u8 as usize)
-    }
-}
-
-/// Writable data, including the stack.
-fn writable_region() -> MemoryRegion {
-    unsafe {
-        MemoryRegion::new(&data_begin as *const u8 as usize, &boot_stack_end as *const u8 as usize)
-    }
-}
-
-fn print_addresses() {
-    unsafe {
-        println!(
-            "dtb:        {:#010x}-{:#010x} ({} bytes)",
-            &dtb_begin as *const u8 as usize,
-            &dtb_end as *const u8 as usize,
-            &dtb_end as *const u8 as usize - &dtb_begin as *const u8 as usize,
-        );
-        println!(
-            "text:       {:#010x}-{:#010x} ({} bytes)",
-            &text_begin as *const u8 as usize,
-            &text_end as *const u8 as usize,
-            &text_end as *const u8 as usize - &text_begin as *const u8 as usize,
-        );
-        println!(
-            "rodata:     {:#010x}-{:#010x} ({} bytes)",
-            &rodata_begin as *const u8 as usize,
-            &rodata_end as *const u8 as usize,
-            &rodata_end as *const u8 as usize - &rodata_begin as *const u8 as usize,
-        );
-        println!(
-            "data:       {:#010x}-{:#010x} ({} bytes, loaded at {:#010x})",
-            &data_begin as *const u8 as usize,
-            &data_end as *const u8 as usize,
-            &data_end as *const u8 as usize - &data_begin as *const u8 as usize,
-            &data_lma as *const u8 as usize,
-        );
-        println!(
-            "bss:        {:#010x}-{:#010x} ({} bytes)",
-            &bss_begin as *const u8 as usize,
-            &bss_end as *const u8 as usize,
-            &bss_end as *const u8 as usize - &bss_begin as *const u8 as usize,
-        );
-        println!(
-            "boot_stack: {:#010x}-{:#010x} ({} bytes)",
-            &boot_stack_begin as *const u8 as usize,
-            &boot_stack_end as *const u8 as usize,
-            &boot_stack_end as *const u8 as usize - &boot_stack_begin as *const u8 as usize,
-        );
-    }
-}
-
 fn check_data() {
     println!("INITIALISED_DATA: {:#010x}", &INITIALISED_DATA as *const u32 as usize);
     unsafe {
@@ -201,19 +136,3 @@
     assert_eq!(vector[2], 42);
     println!("Vec seems to work.");
 }
-
-extern "C" {
-    static dtb_begin: u8;
-    static dtb_end: u8;
-    static text_begin: u8;
-    static text_end: u8;
-    static rodata_begin: u8;
-    static rodata_end: u8;
-    static data_begin: u8;
-    static data_end: u8;
-    static data_lma: u8;
-    static bss_begin: u8;
-    static bss_end: u8;
-    static boot_stack_begin: u8;
-    static boot_stack_end: u8;
-}