From 3d532a5a7ace06d49ed8227843f72ddc081627f0 Mon Sep 17 00:00:00 2001
From: Jack Halford <jack@crans.org>
Date: Mon, 5 Mar 2018 11:18:30 +0100
Subject: [PATCH] memory stuff

---
 kernel-rs/Cargo.toml                 |  9 +++---
 kernel-rs/src/context.rs             |  2 +-
 kernel-rs/src/lib.rs                 |  5 ++-
 kernel-rs/src/memory/mod.rs          |  6 ++++
 kernel-rs/src/memory/paging/entry.rs | 47 ++++++++++++++++++++++++++++
 kernel-rs/src/memory/paging/mod.rs   | 10 ++++++
 kernel-rs/src/memory/paging/table.rs | 28 +++++++++++++++++
 7 files changed, 99 insertions(+), 8 deletions(-)
 create mode 100644 kernel-rs/src/memory/paging/entry.rs
 create mode 100644 kernel-rs/src/memory/paging/mod.rs
 create mode 100644 kernel-rs/src/memory/paging/table.rs

diff --git a/kernel-rs/Cargo.toml b/kernel-rs/Cargo.toml
index 84dde790..f7771995 100644
--- a/kernel-rs/Cargo.toml
+++ b/kernel-rs/Cargo.toml
@@ -8,9 +8,10 @@ crate-type = ["staticlib"]
 
 [dependencies]
 rlibc = "1.0"
-spin = "0.4.5"
+bitflags = "1.0.1"
+# spin = "0.4.5"
 multiboot2 = { path = "multiboot2-elf64" }
 
-[dependencies.lazy_static]
-version = "0.2.4"
-features = ["spin_no_std"]
+# [dependencies.lazy_static]
+# version = "0.2.4"
+# features = ["spin_no_std"]
diff --git a/kernel-rs/src/context.rs b/kernel-rs/src/context.rs
index fddab663..6569012d 100644
--- a/kernel-rs/src/context.rs
+++ b/kernel-rs/src/context.rs
@@ -19,7 +19,7 @@ pub struct Context {
 impl Context
 {
     pub fn new(multiboot_start: usize) -> Context {
-        let boot_info = multiboot2::load(multiboot_start);
+        let boot_info = unsafe { multiboot2::load(multiboot_start) };
         let multiboot_end = multiboot_start + boot_info.total_size();
 
         let elf_sections_tag = boot_info.elf_sections_tag().unwrap();
diff --git a/kernel-rs/src/lib.rs b/kernel-rs/src/lib.rs
index bbf6f05c..89dca7fa 100644
--- a/kernel-rs/src/lib.rs
+++ b/kernel-rs/src/lib.rs
@@ -8,9 +8,7 @@
 
 extern crate rlibc;
 extern crate multiboot2;        //slightly modified fork from official 0.3.2
-#[macro_use]
-extern crate lazy_static;
-extern crate spin;
+#[macro_use] extern crate bitflags;
 
 /// 80x25 screen and simplistic terminal driver
 #[macro_use] pub mod vga;
@@ -28,6 +26,7 @@ pub mod acpi;
 pub mod memory;
 
 use context::*;
+use memory::*;
 
 use vga::{Color, ColorCode};
 
diff --git a/kernel-rs/src/memory/mod.rs b/kernel-rs/src/memory/mod.rs
index aa2b620e..68b3abd9 100644
--- a/kernel-rs/src/memory/mod.rs
+++ b/kernel-rs/src/memory/mod.rs
@@ -1,8 +1,10 @@
 pub const PAGE_SIZE: usize = 4096;
 
 mod area_allocator;
+mod paging;
 
 pub use self::area_allocator::*;
+use self::paging::PhysicalAddress;
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Frame {
@@ -13,6 +15,10 @@ impl Frame {
     fn containing_address(address: usize) -> Frame {
         Frame{ number: address / PAGE_SIZE }
     }
+
+    fn start_address(&self) -> PhysicalAddress {
+        self.number * PAGE_SIZE
+    }
 }
 
 pub trait FrameAllocator {
diff --git a/kernel-rs/src/memory/paging/entry.rs b/kernel-rs/src/memory/paging/entry.rs
new file mode 100644
index 00000000..506bbf6a
--- /dev/null
+++ b/kernel-rs/src/memory/paging/entry.rs
@@ -0,0 +1,47 @@
+use memory::Frame;
+
+pub struct Entry(u64);
+
+bitflags! {
+    pub struct EntryFlags: u64 {
+        const PRESENT =         1 << 0;
+        const WRITABLE =        1 << 1;
+        const USER_ACCESSIBLE = 1 << 2;
+        const WRITE_THROUGH =   1 << 3;
+        const NO_CACHE =        1 << 4;
+        const ACCESSED =        1 << 5;
+        const DIRTY =           1 << 6;
+        const HUGE_PAGE =       1 << 7;
+        const GLOBAL =          1 << 8;
+        const NO_EXECUTE =      1 << 63;
+    }
+}
+
+impl Entry {
+    pub fn is_unused(&self) -> bool {
+        self.0 == 0;
+    }
+
+    pub fn set_unused(&mut self) {
+        self.0 = 0;
+    }
+
+    pub fn flags(&self) -> EntryFlags {
+        EntryFlags::from_bits_truncate(self.0);
+    }
+
+    pub fn pointed_frame(&self) -> Option<Frame> {
+        if self.flags().contains(PRESENT) {
+            Some(Frame::containing_address(
+                    self.0 as usize & 0x000fffff_fffff000   // actual addr is bits 12-51
+                    ))
+        } else {
+            None
+        }
+    }
+
+    pub fn set(&mut self, frame: Frame, flags: EntryFlags) {
+        assert!!(frame.start_address() & !0x000fffff_fffff000 == 0);
+        self.0 = (frame.start_address() as u64) | flags.bits();
+    }
+}
diff --git a/kernel-rs/src/memory/paging/mod.rs b/kernel-rs/src/memory/paging/mod.rs
new file mode 100644
index 00000000..17896565
--- /dev/null
+++ b/kernel-rs/src/memory/paging/mod.rs
@@ -0,0 +1,10 @@
+use memory::PAGE_SIZE;
+
+const ENTRY_COUNT: usize = 512;
+
+pub type PhysicalAddress = usize;
+pub type VirtualAddress = usize;
+
+pub struct Page {
+    number: usize,
+}
diff --git a/kernel-rs/src/memory/paging/table.rs b/kernel-rs/src/memory/paging/table.rs
new file mode 100644
index 00000000..aa11a3ab
--- /dev/null
+++ b/kernel-rs/src/memory/paging/table.rs
@@ -0,0 +1,28 @@
+use memory::paging::entry::*;
+use memory::paging::ENTRY_COUNT;
+
+use core::ops::{Index, IndexMut};
+
+pub struct Table {
+    entries: [Entry; ENTRY_COUNT],
+}
+
+impl Table {
+    for entry in self.entries.iter_mut() {
+        entry.set_unused();
+    }
+}
+
+impl Index<usize> for Table {
+    type Output = Entry;
+
+    fn index(&self, index: usize) -> &Entry {
+        &self.entries[index]
+    }
+}
+
+impl IndexMut<usize> for Table {
+    fn index(&self, index: usize) -> &mut Entry {
+        &mut self.entries[index]
+    }
+}