set pagetable, doesn't work

Cargo.lock

@@ -27,6 +27,7 @@ dependencies = [
  "goblin",
  "log",
  "uefi",
+ "x86_64",
 ]
 
 [[package]]
@@ -90,6 +91,12 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rustversion"
+version = "1.0.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "955d28af4278de8121b7ebeb796b6a45735dc01436d898801014aced2773a3d6"
+
 [[package]]
 name = "scroll"
 version = "0.12.0"
@@ -190,3 +197,21 @@ name = "unicode-ident"
 version = "1.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
+
+[[package]]
+name = "volatile"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "442887c63f2c839b346c192d047a7c87e73d0689c9157b00b53dcc27dd5ea793"
+
+[[package]]
+name = "x86_64"
+version = "0.15.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4bc79523af8abf92fb1a970c3e086c5a343f6bcc1a0eb890f575cbb3b45743df"
+dependencies = [
+ "bit_field",
+ "bitflags",
+ "rustversion",
+ "volatile",
+]

Cargo.toml

@@ -7,3 +7,4 @@ edition = "2021"
 uefi = { version = "0.29.0", default-features = false, features = [ "alloc", "global_allocator", "panic_handler", "logger" ] }
 log = { version = "0.4.22", default-features = false }
 goblin = { version = "0.8.2", default-features = false, features = [ "elf64", "elf32", "endian_fd" ] }
+x86_64 = { version = "0.15.1", default-features = false }

src/boot.rs

@@ -3,10 +3,13 @@ pub use x86_64::boot_kernel;
 
 #[cfg(target_arch = "x86_64")]
 mod x86_64 {
-    use core::{arch::global_asm, ptr::null, slice};
+    use core::{arch::global_asm, slice};
 
-    
-    use uefi::table::{Boot, SystemTable};
+    use uefi::table::{boot::PAGE_SIZE, Boot, SystemTable};
+    use x86_64::{
+        structures::paging::{PageTable, PageTableFlags},
+        PhysAddr,
+    };
 
     use crate::{object::Kernel, staging::allocate_code};
 
@@ -38,7 +41,7 @@ trampoline_size:
 
         fn trampoline_code(
             stack: *const u8,
-            pagetable: *const u8,
+            pagetable: *const PageTable,
             modinfo_base: *const u8,
             free_ptr: *const u8,
             entry: *const u8,
@@ -46,7 +49,17 @@ trampoline_size:
     }
 
     type TrampolineFunction =
-        extern "sysv64" fn(*const u8, *const u8, *const u8, *const u8, *const u8);
+        extern "sysv64" fn(*const u8, *const PageTable, *const u8, *const u8, *const u8);
+
+    #[repr(C, align(4096))]
+    struct MiscBuf {
+        stack: [u8; PAGE_SIZE],
+        trampoline: [u8; PAGE_SIZE],
+        pt4: PageTable,
+        pt3_lower: PageTable,
+        pt3_upper: PageTable,
+        pt2_upper: PageTable,
+    }
 
     pub fn boot_kernel(
         system_table: SystemTable<Boot>,
@@ -55,19 +68,56 @@ trampoline_size:
         modinfo_base: *const u8,
         free_ptr: *const u8,
     ) {
-        let trampoline_code_size = unsafe { trampoline_size } as usize;
-        let misc_buf = allocate_code(system_table.boot_services(), trampoline_code_size + 64);
+        let misc_alloc = allocate_code(
+            system_table.boot_services(),
+            core::mem::size_of::<MiscBuf>(),
+        );
+        // allocate_code is always page aligned, so we'll always meet 4096 alignment for MiscBuf
+        let misc_buf = unsafe { (misc_alloc.as_mut_ptr() as *mut MiscBuf).as_mut().unwrap() };
 
-        let (stack_buf, trampoline_buf) = misc_buf.split_at_mut(64);
-        trampoline_buf[..trampoline_code_size].copy_from_slice(unsafe {
+        let trampoline_code_size = unsafe { trampoline_size } as usize;
+        misc_buf.trampoline[..trampoline_code_size].copy_from_slice(unsafe {
             slice::from_raw_parts(trampoline_code as *const u8, trampoline_code_size)
         });
 
+        // Map the lower 512G of RAM identity-mapped with 1GiB pages
+        for (idx, pte) in misc_buf.pt3_lower.iter_mut().enumerate() {
+            pte.set_addr(
+                PhysAddr::new((idx as u64) << 30),
+                PageTableFlags::PRESENT | PageTableFlags::HUGE_PAGE | PageTableFlags::WRITABLE,
+            );
+        }
+
+        misc_buf.pt4[0].set_addr(
+            PhysAddr::new(&misc_buf.pt3_lower as *const PageTable as usize as u64),
+            PageTableFlags::PRESENT | PageTableFlags::WRITABLE,
+        );
+
+        // Map the kernel to 2GiB from the top of RAM with 2MiB pages
+        for (idx, pte) in misc_buf.pt2_upper.iter_mut().enumerate() {
+            let addr = kernel_base as usize + (idx << 21);
+            pte.set_addr(
+                PhysAddr::new(addr as u64),
+                PageTableFlags::PRESENT | PageTableFlags::HUGE_PAGE | PageTableFlags::WRITABLE,
+            );
+        }
+        // 512 entries, each pt3 entry represents 1GiB
+        misc_buf.pt3_upper[510].set_addr(
+            PhysAddr::new(&misc_buf.pt2_upper as *const PageTable as usize as u64),
+            PageTableFlags::PRESENT | PageTableFlags::WRITABLE,
+        );
+        // 512 entries, each pt4 entry represents 512GiB
+        misc_buf.pt4[511].set_addr(
+            PhysAddr::new(&misc_buf.pt3_upper as *const PageTable as usize as u64),
+            PageTableFlags::PRESENT | PageTableFlags::WRITABLE,
+        );
+
         unsafe {
-            let trampoline_func: TrampolineFunction = core::mem::transmute(trampoline_buf.as_ptr());
+            let trampoline_func: TrampolineFunction =
+                core::mem::transmute(misc_buf.trampoline.as_ptr());
             trampoline_func(
-                stack_buf.as_ptr(),
-                null(),
+                &misc_buf.stack[PAGE_SIZE - 8] as *const u8,
+                &misc_buf.pt4 as *const PageTable,
                 modinfo_base,
                 free_ptr,
                 kernel.entry_addr(kernel_base),