From 2134146bb6f77d3ef757b224693238e5ee2629aa Mon Sep 17 00:00:00 2001
From: Andre Richter <andre.o.richter@gmail.com>
Date: Sun, 24 Nov 2019 22:04:34 +0100
Subject: [PATCH] Clean up mmu.rs

---
 11_virtual_memory/README.md                   |  82 +++++++-----------
 11_virtual_memory/kernel                      | Bin 147064 -> 147056 bytes
 11_virtual_memory/src/arch/aarch64/mmu.rs     |  80 +++++++----------
 12_cpu_exceptions_part1/README.md             |  20 ++---
 12_cpu_exceptions_part1/kernel                | Bin 151424 -> 151392 bytes
 12_cpu_exceptions_part1/kernel8.img           | Bin 65560 -> 65560 bytes
 .../src/arch/aarch64/mmu.rs                   |  80 +++++++----------
 7 files changed, 107 insertions(+), 155 deletions(-)

diff --git a/11_virtual_memory/README.md b/11_virtual_memory/README.md
index 4d8b8d01..df126ca8 100644
--- a/11_virtual_memory/README.md
+++ b/11_virtual_memory/README.md
@@ -265,7 +265,7 @@ make chainbot
 diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/aarch64/mmu.rs
 --- 10_privilege_level/src/arch/aarch64/mmu.rs
 +++ 11_virtual_memory/src/arch/aarch64/mmu.rs
-@@ -0,0 +1,316 @@
+@@ -0,0 +1,300 @@
 +// SPDX-License-Identifier: MIT
 +//
 +// Copyright (c) 2018-2019 Andre Richter <andre.o.richter@gmail.com>
@@ -347,18 +347,22 @@ diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/
 +    ]
 +}
 +
-+// Two newtypes for added type safety, so that you cannot accidentally place a TableDescriptor into
-+// a PageDescriptor slot in `struct PageTables`, and vice versa.
++const SIXTYFOUR_KIB_SHIFT: usize = 16; //  log2(64 * 1024)
++const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
++
++/// A table descriptor for 64 KiB aperture.
++///
++/// The output points to the next table.
 +#[derive(Copy, Clone)]
 +#[repr(transparent)]
-+struct RawTableDescriptor(u64);
++struct TableDescriptor(u64);
 +
++/// A page descriptor with 64 KiB aperture.
++///
++/// The output points to physical memory.
 +#[derive(Copy, Clone)]
 +#[repr(transparent)]
-+struct RawPageDescriptor(u64);
-+
-+const SIXTYFOUR_KIB_SHIFT: usize = 16; //  log2(64 * 1024)
-+const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
++struct PageDescriptor(u64);
 +
 +/// Big monolithic struct for storing the page tables. Individual levels must be 64 KiB aligned,
 +/// hence the "reverse" order of appearance.
@@ -366,9 +370,9 @@ diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/
 +#[repr(align(65536))]
 +struct PageTables<const N: usize> {
 +    // Page descriptors, covering 64 KiB windows per entry.
-+    lvl3: [[RawPageDescriptor; 8192]; N],
++    lvl3: [[PageDescriptor; 8192]; N],
 +    // Table descriptors, covering 512 MiB windows.
-+    lvl2: [RawTableDescriptor; N],
++    lvl2: [TableDescriptor; N],
 +}
 +
 +/// Usually evaluates to 1 GiB for RPi3 and 4 GiB for RPi 4.
@@ -378,8 +382,8 @@ diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/
 +///
 +/// Supposed to land in `.bss`. Therefore, ensure that they boil down to all "0" entries.
 +static mut TABLES: PageTables<{ ENTRIES_512_MIB }> = PageTables {
-+    lvl3: [[RawPageDescriptor(0); 8192]; ENTRIES_512_MIB],
-+    lvl2: [RawTableDescriptor(0); ENTRIES_512_MIB],
++    lvl3: [[PageDescriptor(0); 8192]; ENTRIES_512_MIB],
++    lvl2: [TableDescriptor(0); ENTRIES_512_MIB],
 +};
 +
 +trait BaseAddr {
@@ -397,24 +401,15 @@ diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/
 +    }
 +}
 +
-+/// A descriptor pointing to the next page table.
-+struct TableDescriptor(register::FieldValue<u64, STAGE1_TABLE_DESCRIPTOR::Register>);
-+
-+impl TableDescriptor {
-+    fn new(next_lvl_table_addr: usize) -> TableDescriptor {
++impl convert::From<usize> for TableDescriptor {
++    fn from(next_lvl_table_addr: usize) -> Self {
 +        let shifted = next_lvl_table_addr >> SIXTYFOUR_KIB_SHIFT;
++        let val = (STAGE1_TABLE_DESCRIPTOR::VALID::True
++            + STAGE1_TABLE_DESCRIPTOR::TYPE::Table
++            + STAGE1_TABLE_DESCRIPTOR::NEXT_LEVEL_TABLE_ADDR_64KiB.val(shifted as u64))
++        .value;
 +
-+        TableDescriptor(
-+            STAGE1_TABLE_DESCRIPTOR::VALID::True
-+                + STAGE1_TABLE_DESCRIPTOR::TYPE::Table
-+                + STAGE1_TABLE_DESCRIPTOR::NEXT_LEVEL_TABLE_ADDR_64KiB.val(shifted as u64),
-+        )
-+    }
-+}
-+
-+impl convert::From<TableDescriptor> for RawTableDescriptor {
-+    fn from(desc: TableDescriptor) -> Self {
-+        RawTableDescriptor(desc.0.value)
++        TableDescriptor(val)
 +    }
 +}
 +
@@ -452,28 +447,17 @@ diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/
 +    }
 +}
 +
-+/// A page descriptor with 64 KiB aperture.
-+///
-+/// The output points to physical memory.
-+struct PageDescriptor(register::FieldValue<u64, STAGE1_PAGE_DESCRIPTOR::Register>);
-+
 +impl PageDescriptor {
 +    fn new(output_addr: usize, attribute_fields: AttributeFields) -> PageDescriptor {
 +        let shifted = output_addr >> SIXTYFOUR_KIB_SHIFT;
-+
-+        PageDescriptor(
-+            STAGE1_PAGE_DESCRIPTOR::VALID::True
-+                + STAGE1_PAGE_DESCRIPTOR::AF::True
-+                + attribute_fields.into()
-+                + STAGE1_PAGE_DESCRIPTOR::TYPE::Table
-+                + STAGE1_PAGE_DESCRIPTOR::OUTPUT_ADDR_64KiB.val(shifted as u64),
-+        )
-+    }
-+}
-+
-+impl convert::From<PageDescriptor> for RawPageDescriptor {
-+    fn from(desc: PageDescriptor) -> Self {
-+        RawPageDescriptor(desc.0.value)
++        let val = (STAGE1_PAGE_DESCRIPTOR::VALID::True
++            + STAGE1_PAGE_DESCRIPTOR::AF::True
++            + attribute_fields.into()
++            + STAGE1_PAGE_DESCRIPTOR::TYPE::Table
++            + STAGE1_PAGE_DESCRIPTOR::OUTPUT_ADDR_64KiB.val(shifted as u64))
++        .value;
++
++        PageDescriptor(val)
 +    }
 +}
 +
@@ -505,7 +489,7 @@ diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/
 +/// - Modifies a `static mut`. Ensure it only happens from here.
 +unsafe fn populate_pt_entries() -> Result<(), &'static str> {
 +    for (l2_nr, l2_entry) in TABLES.lvl2.iter_mut().enumerate() {
-+        *l2_entry = TableDescriptor::new(TABLES.lvl3[l2_nr].base_addr_usize()).into();
++        *l2_entry = TABLES.lvl3[l2_nr].base_addr_usize().into();
 +
 +        for (l3_nr, l3_entry) in TABLES.lvl3[l2_nr].iter_mut().enumerate() {
 +            let virt_addr = (l2_nr << FIVETWELVE_MIB_SHIFT) + (l3_nr << SIXTYFOUR_KIB_SHIFT);
@@ -513,7 +497,7 @@ diff -uNr 10_privilege_level/src/arch/aarch64/mmu.rs 11_virtual_memory/src/arch/
 +            let (output_addr, attribute_fields) =
 +                bsp::virt_mem_layout().get_virt_addr_properties(virt_addr)?;
 +
-+            *l3_entry = PageDescriptor::new(output_addr, attribute_fields).into();
++            *l3_entry = PageDescriptor::new(output_addr, attribute_fields);
 +        }
 +    }
 +
diff --git a/11_virtual_memory/kernel b/11_virtual_memory/kernel
index a319a0bd74bfb09b01afe0ac568767bf17959580..5d93985302ea1fca150b9636d79332d957d69f22 100755
GIT binary patch
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diff --git a/11_virtual_memory/src/arch/aarch64/mmu.rs b/11_virtual_memory/src/arch/aarch64/mmu.rs
index a81e68de..34d5f71e 100644
--- a/11_virtual_memory/src/arch/aarch64/mmu.rs
+++ b/11_virtual_memory/src/arch/aarch64/mmu.rs
@@ -79,18 +79,22 @@ register_bitfields! {u64,
     ]
 }
 
-// Two newtypes for added type safety, so that you cannot accidentally place a TableDescriptor into
-// a PageDescriptor slot in `struct PageTables`, and vice versa.
+const SIXTYFOUR_KIB_SHIFT: usize = 16; //  log2(64 * 1024)
+const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
+
+/// A table descriptor for 64 KiB aperture.
+///
+/// The output points to the next table.
 #[derive(Copy, Clone)]
 #[repr(transparent)]
-struct RawTableDescriptor(u64);
+struct TableDescriptor(u64);
 
+/// A page descriptor with 64 KiB aperture.
+///
+/// The output points to physical memory.
 #[derive(Copy, Clone)]
 #[repr(transparent)]
-struct RawPageDescriptor(u64);
-
-const SIXTYFOUR_KIB_SHIFT: usize = 16; //  log2(64 * 1024)
-const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
+struct PageDescriptor(u64);
 
 /// Big monolithic struct for storing the page tables. Individual levels must be 64 KiB aligned,
 /// hence the "reverse" order of appearance.
@@ -98,9 +102,9 @@ const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
 #[repr(align(65536))]
 struct PageTables<const N: usize> {
     // Page descriptors, covering 64 KiB windows per entry.
-    lvl3: [[RawPageDescriptor; 8192]; N],
+    lvl3: [[PageDescriptor; 8192]; N],
     // Table descriptors, covering 512 MiB windows.
-    lvl2: [RawTableDescriptor; N],
+    lvl2: [TableDescriptor; N],
 }
 
 /// Usually evaluates to 1 GiB for RPi3 and 4 GiB for RPi 4.
@@ -110,8 +114,8 @@ const ENTRIES_512_MIB: usize = bsp::addr_space_size() >> FIVETWELVE_MIB_SHIFT;
 ///
 /// Supposed to land in `.bss`. Therefore, ensure that they boil down to all "0" entries.
 static mut TABLES: PageTables<{ ENTRIES_512_MIB }> = PageTables {
-    lvl3: [[RawPageDescriptor(0); 8192]; ENTRIES_512_MIB],
-    lvl2: [RawTableDescriptor(0); ENTRIES_512_MIB],
+    lvl3: [[PageDescriptor(0); 8192]; ENTRIES_512_MIB],
+    lvl2: [TableDescriptor(0); ENTRIES_512_MIB],
 };
 
 trait BaseAddr {
@@ -129,24 +133,15 @@ impl<T, const N: usize> BaseAddr for [T; N] {
     }
 }
 
-/// A descriptor pointing to the next page table.
-struct TableDescriptor(register::FieldValue<u64, STAGE1_TABLE_DESCRIPTOR::Register>);
-
-impl TableDescriptor {
-    fn new(next_lvl_table_addr: usize) -> TableDescriptor {
+impl convert::From<usize> for TableDescriptor {
+    fn from(next_lvl_table_addr: usize) -> Self {
         let shifted = next_lvl_table_addr >> SIXTYFOUR_KIB_SHIFT;
+        let val = (STAGE1_TABLE_DESCRIPTOR::VALID::True
+            + STAGE1_TABLE_DESCRIPTOR::TYPE::Table
+            + STAGE1_TABLE_DESCRIPTOR::NEXT_LEVEL_TABLE_ADDR_64KiB.val(shifted as u64))
+        .value;
 
-        TableDescriptor(
-            STAGE1_TABLE_DESCRIPTOR::VALID::True
-                + STAGE1_TABLE_DESCRIPTOR::TYPE::Table
-                + STAGE1_TABLE_DESCRIPTOR::NEXT_LEVEL_TABLE_ADDR_64KiB.val(shifted as u64),
-        )
-    }
-}
-
-impl convert::From<TableDescriptor> for RawTableDescriptor {
-    fn from(desc: TableDescriptor) -> Self {
-        RawTableDescriptor(desc.0.value)
+        TableDescriptor(val)
     }
 }
 
@@ -184,28 +179,17 @@ impl convert::From<AttributeFields>
     }
 }
 
-/// A page descriptor with 64 KiB aperture.
-///
-/// The output points to physical memory.
-struct PageDescriptor(register::FieldValue<u64, STAGE1_PAGE_DESCRIPTOR::Register>);
-
 impl PageDescriptor {
     fn new(output_addr: usize, attribute_fields: AttributeFields) -> PageDescriptor {
         let shifted = output_addr >> SIXTYFOUR_KIB_SHIFT;
-
-        PageDescriptor(
-            STAGE1_PAGE_DESCRIPTOR::VALID::True
-                + STAGE1_PAGE_DESCRIPTOR::AF::True
-                + attribute_fields.into()
-                + STAGE1_PAGE_DESCRIPTOR::TYPE::Table
-                + STAGE1_PAGE_DESCRIPTOR::OUTPUT_ADDR_64KiB.val(shifted as u64),
-        )
-    }
-}
-
-impl convert::From<PageDescriptor> for RawPageDescriptor {
-    fn from(desc: PageDescriptor) -> Self {
-        RawPageDescriptor(desc.0.value)
+        let val = (STAGE1_PAGE_DESCRIPTOR::VALID::True
+            + STAGE1_PAGE_DESCRIPTOR::AF::True
+            + attribute_fields.into()
+            + STAGE1_PAGE_DESCRIPTOR::TYPE::Table
+            + STAGE1_PAGE_DESCRIPTOR::OUTPUT_ADDR_64KiB.val(shifted as u64))
+        .value;
+
+        PageDescriptor(val)
     }
 }
 
@@ -237,7 +221,7 @@ fn set_up_mair() {
 /// - Modifies a `static mut`. Ensure it only happens from here.
 unsafe fn populate_pt_entries() -> Result<(), &'static str> {
     for (l2_nr, l2_entry) in TABLES.lvl2.iter_mut().enumerate() {
-        *l2_entry = TableDescriptor::new(TABLES.lvl3[l2_nr].base_addr_usize()).into();
+        *l2_entry = TABLES.lvl3[l2_nr].base_addr_usize().into();
 
         for (l3_nr, l3_entry) in TABLES.lvl3[l2_nr].iter_mut().enumerate() {
             let virt_addr = (l2_nr << FIVETWELVE_MIB_SHIFT) + (l3_nr << SIXTYFOUR_KIB_SHIFT);
@@ -245,7 +229,7 @@ unsafe fn populate_pt_entries() -> Result<(), &'static str> {
             let (output_addr, attribute_fields) =
                 bsp::virt_mem_layout().get_virt_addr_properties(virt_addr)?;
 
-            *l3_entry = PageDescriptor::new(output_addr, attribute_fields).into();
+            *l3_entry = PageDescriptor::new(output_addr, attribute_fields);
         }
     }
 
diff --git a/12_cpu_exceptions_part1/README.md b/12_cpu_exceptions_part1/README.md
index d0874c53..fda1281f 100644
--- a/12_cpu_exceptions_part1/README.md
+++ b/12_cpu_exceptions_part1/README.md
@@ -459,9 +459,9 @@ General purpose register:
 ## Diff to previous
 ```diff
 
-diff -uNr 11_virtual_memory/src/arch/aarch64/exception.rs 12_exceptions_part1/src/arch/aarch64/exception.rs
+diff -uNr 11_virtual_memory/src/arch/aarch64/exception.rs 12_cpu_exceptions_part1/src/arch/aarch64/exception.rs
 --- 11_virtual_memory/src/arch/aarch64/exception.rs
-+++ 12_exceptions_part1/src/arch/aarch64/exception.rs
++++ 12_cpu_exceptions_part1/src/arch/aarch64/exception.rs
 @@ -4,12 +4,248 @@
 
  //! Exception handling.
@@ -713,9 +713,9 @@ diff -uNr 11_virtual_memory/src/arch/aarch64/exception.rs 12_exceptions_part1/sr
      fn daif_field() -> register::Field<u32, DAIF::Register>;
  }
 
-diff -uNr 11_virtual_memory/src/arch/aarch64/exception.S 12_exceptions_part1/src/arch/aarch64/exception.S
+diff -uNr 11_virtual_memory/src/arch/aarch64/exception.S 12_cpu_exceptions_part1/src/arch/aarch64/exception.S
 --- 11_virtual_memory/src/arch/aarch64/exception.S
-+++ 12_exceptions_part1/src/arch/aarch64/exception.S
++++ 12_cpu_exceptions_part1/src/arch/aarch64/exception.S
 @@ -0,0 +1,135 @@
 +// SPDX-License-Identifier: MIT
 +//
@@ -853,9 +853,9 @@ diff -uNr 11_virtual_memory/src/arch/aarch64/exception.S 12_exceptions_part1/src
 +
 +    eret
 
-diff -uNr 11_virtual_memory/src/arch/aarch64.rs 12_exceptions_part1/src/arch/aarch64.rs
+diff -uNr 11_virtual_memory/src/arch/aarch64.rs 12_cpu_exceptions_part1/src/arch/aarch64.rs
 --- 11_virtual_memory/src/arch/aarch64.rs
-+++ 12_exceptions_part1/src/arch/aarch64.rs
++++ 12_cpu_exceptions_part1/src/arch/aarch64.rs
 @@ -106,6 +106,15 @@
      }
  }
@@ -873,9 +873,9 @@ diff -uNr 11_virtual_memory/src/arch/aarch64.rs 12_exceptions_part1/src/arch/aar
  pub fn mmu() -> &'static impl interface::mm::MMU {
      &MMU
 
-diff -uNr 11_virtual_memory/src/bsp.rs 12_exceptions_part1/src/bsp.rs
+diff -uNr 11_virtual_memory/src/bsp.rs 12_cpu_exceptions_part1/src/bsp.rs
 --- 11_virtual_memory/src/bsp.rs
-+++ 12_exceptions_part1/src/bsp.rs
++++ 12_cpu_exceptions_part1/src/bsp.rs
 @@ -4,7 +4,7 @@
 
  //! Conditional exporting of Board Support Packages.
@@ -886,9 +886,9 @@ diff -uNr 11_virtual_memory/src/bsp.rs 12_exceptions_part1/src/bsp.rs
  #[cfg(any(feature = "bsp_rpi3", feature = "bsp_rpi4"))]
  mod rpi;
 
-diff -uNr 11_virtual_memory/src/main.rs 12_exceptions_part1/src/main.rs
+diff -uNr 11_virtual_memory/src/main.rs 12_cpu_exceptions_part1/src/main.rs
 --- 11_virtual_memory/src/main.rs
-+++ 12_exceptions_part1/src/main.rs
++++ 12_cpu_exceptions_part1/src/main.rs
 @@ -22,6 +22,7 @@
  #![allow(incomplete_features)]
  #![feature(const_generics)]
diff --git a/12_cpu_exceptions_part1/kernel b/12_cpu_exceptions_part1/kernel
index 238fb8087c45bd77c24c20fbac21a3bd1c312109..f0b221c2ad7559ee3e77b6bea22f0f7f24146eb5 100755
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diff --git a/12_cpu_exceptions_part1/src/arch/aarch64/mmu.rs b/12_cpu_exceptions_part1/src/arch/aarch64/mmu.rs
index a81e68de..34d5f71e 100644
--- a/12_cpu_exceptions_part1/src/arch/aarch64/mmu.rs
+++ b/12_cpu_exceptions_part1/src/arch/aarch64/mmu.rs
@@ -79,18 +79,22 @@ register_bitfields! {u64,
     ]
 }
 
-// Two newtypes for added type safety, so that you cannot accidentally place a TableDescriptor into
-// a PageDescriptor slot in `struct PageTables`, and vice versa.
+const SIXTYFOUR_KIB_SHIFT: usize = 16; //  log2(64 * 1024)
+const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
+
+/// A table descriptor for 64 KiB aperture.
+///
+/// The output points to the next table.
 #[derive(Copy, Clone)]
 #[repr(transparent)]
-struct RawTableDescriptor(u64);
+struct TableDescriptor(u64);
 
+/// A page descriptor with 64 KiB aperture.
+///
+/// The output points to physical memory.
 #[derive(Copy, Clone)]
 #[repr(transparent)]
-struct RawPageDescriptor(u64);
-
-const SIXTYFOUR_KIB_SHIFT: usize = 16; //  log2(64 * 1024)
-const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
+struct PageDescriptor(u64);
 
 /// Big monolithic struct for storing the page tables. Individual levels must be 64 KiB aligned,
 /// hence the "reverse" order of appearance.
@@ -98,9 +102,9 @@ const FIVETWELVE_MIB_SHIFT: usize = 29; // log2(512 * 1024 * 1024)
 #[repr(align(65536))]
 struct PageTables<const N: usize> {
     // Page descriptors, covering 64 KiB windows per entry.
-    lvl3: [[RawPageDescriptor; 8192]; N],
+    lvl3: [[PageDescriptor; 8192]; N],
     // Table descriptors, covering 512 MiB windows.
-    lvl2: [RawTableDescriptor; N],
+    lvl2: [TableDescriptor; N],
 }
 
 /// Usually evaluates to 1 GiB for RPi3 and 4 GiB for RPi 4.
@@ -110,8 +114,8 @@ const ENTRIES_512_MIB: usize = bsp::addr_space_size() >> FIVETWELVE_MIB_SHIFT;
 ///
 /// Supposed to land in `.bss`. Therefore, ensure that they boil down to all "0" entries.
 static mut TABLES: PageTables<{ ENTRIES_512_MIB }> = PageTables {
-    lvl3: [[RawPageDescriptor(0); 8192]; ENTRIES_512_MIB],
-    lvl2: [RawTableDescriptor(0); ENTRIES_512_MIB],
+    lvl3: [[PageDescriptor(0); 8192]; ENTRIES_512_MIB],
+    lvl2: [TableDescriptor(0); ENTRIES_512_MIB],
 };
 
 trait BaseAddr {
@@ -129,24 +133,15 @@ impl<T, const N: usize> BaseAddr for [T; N] {
     }
 }
 
-/// A descriptor pointing to the next page table.
-struct TableDescriptor(register::FieldValue<u64, STAGE1_TABLE_DESCRIPTOR::Register>);
-
-impl TableDescriptor {
-    fn new(next_lvl_table_addr: usize) -> TableDescriptor {
+impl convert::From<usize> for TableDescriptor {
+    fn from(next_lvl_table_addr: usize) -> Self {
         let shifted = next_lvl_table_addr >> SIXTYFOUR_KIB_SHIFT;
+        let val = (STAGE1_TABLE_DESCRIPTOR::VALID::True
+            + STAGE1_TABLE_DESCRIPTOR::TYPE::Table
+            + STAGE1_TABLE_DESCRIPTOR::NEXT_LEVEL_TABLE_ADDR_64KiB.val(shifted as u64))
+        .value;
 
-        TableDescriptor(
-            STAGE1_TABLE_DESCRIPTOR::VALID::True
-                + STAGE1_TABLE_DESCRIPTOR::TYPE::Table
-                + STAGE1_TABLE_DESCRIPTOR::NEXT_LEVEL_TABLE_ADDR_64KiB.val(shifted as u64),
-        )
-    }
-}
-
-impl convert::From<TableDescriptor> for RawTableDescriptor {
-    fn from(desc: TableDescriptor) -> Self {
-        RawTableDescriptor(desc.0.value)
+        TableDescriptor(val)
     }
 }
 
@@ -184,28 +179,17 @@ impl convert::From<AttributeFields>
     }
 }
 
-/// A page descriptor with 64 KiB aperture.
-///
-/// The output points to physical memory.
-struct PageDescriptor(register::FieldValue<u64, STAGE1_PAGE_DESCRIPTOR::Register>);
-
 impl PageDescriptor {
     fn new(output_addr: usize, attribute_fields: AttributeFields) -> PageDescriptor {
         let shifted = output_addr >> SIXTYFOUR_KIB_SHIFT;
-
-        PageDescriptor(
-            STAGE1_PAGE_DESCRIPTOR::VALID::True
-                + STAGE1_PAGE_DESCRIPTOR::AF::True
-                + attribute_fields.into()
-                + STAGE1_PAGE_DESCRIPTOR::TYPE::Table
-                + STAGE1_PAGE_DESCRIPTOR::OUTPUT_ADDR_64KiB.val(shifted as u64),
-        )
-    }
-}
-
-impl convert::From<PageDescriptor> for RawPageDescriptor {
-    fn from(desc: PageDescriptor) -> Self {
-        RawPageDescriptor(desc.0.value)
+        let val = (STAGE1_PAGE_DESCRIPTOR::VALID::True
+            + STAGE1_PAGE_DESCRIPTOR::AF::True
+            + attribute_fields.into()
+            + STAGE1_PAGE_DESCRIPTOR::TYPE::Table
+            + STAGE1_PAGE_DESCRIPTOR::OUTPUT_ADDR_64KiB.val(shifted as u64))
+        .value;
+
+        PageDescriptor(val)
     }
 }
 
@@ -237,7 +221,7 @@ fn set_up_mair() {
 /// - Modifies a `static mut`. Ensure it only happens from here.
 unsafe fn populate_pt_entries() -> Result<(), &'static str> {
     for (l2_nr, l2_entry) in TABLES.lvl2.iter_mut().enumerate() {
-        *l2_entry = TableDescriptor::new(TABLES.lvl3[l2_nr].base_addr_usize()).into();
+        *l2_entry = TABLES.lvl3[l2_nr].base_addr_usize().into();
 
         for (l3_nr, l3_entry) in TABLES.lvl3[l2_nr].iter_mut().enumerate() {
             let virt_addr = (l2_nr << FIVETWELVE_MIB_SHIFT) + (l3_nr << SIXTYFOUR_KIB_SHIFT);
@@ -245,7 +229,7 @@ unsafe fn populate_pt_entries() -> Result<(), &'static str> {
             let (output_addr, attribute_fields) =
                 bsp::virt_mem_layout().get_virt_addr_properties(virt_addr)?;
 
-            *l3_entry = PageDescriptor::new(output_addr, attribute_fields).into();
+            *l3_entry = PageDescriptor::new(output_addr, attribute_fields);
         }
     }