From fad48af98563da297bb2032ce9170a7fc049e969 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jeremy@system76.com>
Date: Wed, 13 Jan 2021 10:47:35 -0700
Subject: [PATCH] WIP: aarch64 support

---
 src/arch/aarch64.rs | 70 +++++++++++++++++++++++++++++++++++++++++++++
 src/arch/mod.rs     |  2 ++
 2 files changed, 72 insertions(+)
 create mode 100644 src/arch/aarch64.rs

diff --git a/src/arch/aarch64.rs b/src/arch/aarch64.rs
new file mode 100644
index 0000000000..7a22a5a9d8
--- /dev/null
+++ b/src/arch/aarch64.rs
@@ -0,0 +1,70 @@
+use crate::{
+    Arch,
+    MemoryArea,
+    PhysicalAddress,
+    VirtualAddress,
+};
+
+#[derive(Clone, Copy)]
+pub struct AArch64Arch;
+
+impl Arch for AArch64Arch {
+    const PAGE_SHIFT: usize = 12; // 4096 bytes
+    const PAGE_ENTRY_SHIFT: usize = 9; // 512 entries, 8 bytes each
+    const PAGE_LEVELS: usize = 4; // PML4, PDP, PD, PT
+
+    //TODO
+    const ENTRY_ADDRESS_SHIFT: usize = 52;
+    const ENTRY_FLAG_PRESENT: usize = 1 << 0;
+    const ENTRY_FLAG_WRITABLE: usize = 1 << 1;
+    const ENTRY_FLAG_USER: usize = 1 << 2;
+    const ENTRY_FLAG_HUGE: usize = 1 << 7;
+    const ENTRY_FLAG_GLOBAL: usize = 1 << 8;
+    const ENTRY_FLAG_NO_EXEC: usize = 1 << 63;
+
+    const PHYS_OFFSET: usize = Self::PAGE_NEGATIVE_MASK + (Self::PAGE_ADDRESS_SIZE >> 1); // PML4 slot 256 and onwards
+
+    unsafe fn init() -> &'static [MemoryArea] {
+        unimplemented!("AArch64Arch::init unimplemented");
+    }
+
+    #[inline(always)]
+    unsafe fn invalidate(address: VirtualAddress) {
+        unimplemented!()
+    }
+
+    #[inline(always)]
+    unsafe fn table() -> PhysicalAddress {
+        unimplemented!()
+    }
+
+    #[inline(always)]
+    unsafe fn set_table(address: PhysicalAddress) {
+        unimplemented!()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Arch;
+    use super::AArch64Arch;
+
+    #[test]
+    fn constants() {
+        assert_eq!(AArch64Arch::PAGE_SIZE, 4096);
+        assert_eq!(AArch64Arch::PAGE_OFFSET_MASK, 0xFFF);
+        assert_eq!(AArch64Arch::PAGE_ADDRESS_SHIFT, 48);
+        assert_eq!(AArch64Arch::PAGE_ADDRESS_SIZE, 0x0001_0000_0000_0000);
+        assert_eq!(AArch64Arch::PAGE_ADDRESS_MASK, 0x0000_FFFF_FFFF_F000);
+        assert_eq!(AArch64Arch::PAGE_ENTRY_SIZE, 8);
+        assert_eq!(AArch64Arch::PAGE_ENTRIES, 512);
+        assert_eq!(AArch64Arch::PAGE_ENTRY_MASK, 0x1FF);
+        assert_eq!(AArch64Arch::PAGE_NEGATIVE_MASK, 0xFFFF_0000_0000_0000);
+
+        assert_eq!(AArch64Arch::ENTRY_ADDRESS_SIZE, 0x0010_0000_0000_0000);
+        assert_eq!(AArch64Arch::ENTRY_ADDRESS_MASK, 0x000F_FFFF_FFFF_F000);
+        assert_eq!(AArch64Arch::ENTRY_FLAGS_MASK, 0xFFF0_0000_0000_0FFF);
+
+        assert_eq!(AArch64Arch::PHYS_OFFSET, 0xFFFF_8000_0000_0000);
+    }
+}
diff --git a/src/arch/mod.rs b/src/arch/mod.rs
index 27681785ce..5825bdc987 100644
--- a/src/arch/mod.rs
+++ b/src/arch/mod.rs
@@ -6,10 +6,12 @@ use crate::{
     VirtualAddress,
 };
 
+pub use self::aarch64::AArch64Arch;
 #[cfg(feature = "std")]
 pub use self::emulate::EmulateArch;
 pub use self::x86_64::X8664Arch;
 
+mod aarch64;
 #[cfg(feature = "std")]
 mod emulate;
 mod x86_64;