FreeBSD starts loading, lots of unclean code

src/boot.rs

@@ -33,7 +33,7 @@ trampoline_code:
     cli
     mov rsp,rdi
     push rcx
-    sal rdx, #32
+    sal rdx, 32
     push rdx
     push r8
     mov cr3,rsi
@@ -54,14 +54,14 @@ trampoline_size:
         fn trampoline_code(
             stack: *const u8,
             pagetable: *const PageTable,
-            modinfo_base: *const u8,
+            modinfo_offset: usize,
-            free_ptr: *const u8,
+            free_offset: usize,
             entry: *const u8,
         );
     }
 
     type TrampolineFunction =
-        extern "sysv64" fn(*const u8, *const PageTable, *const u8, *const u8, *const u8);
+        extern "sysv64" fn(*const u8, *const PageTable, usize, usize, *const u8);
 
     #[repr(C, align(4096))]
     struct MiscBuf {
@@ -76,11 +76,15 @@ trampoline_size:
     pub fn boot_kernel(
         system_table: SystemTable<Boot>,
         kernel: Kernel,
-        kernel_base: *const u8,
+        kernel_start: *const u8,
         modinfo_base: *const u8,
         free_ptr: *const u8,
         staging: &mut [u8],
     ) {
+        // FreeBSD x86_64 makes stuff relative to KERNBASE,
+        // 2MiB before the first mapping (KERNSTART)
+        let kernel_base = unsafe { kernel_start.byte_offset(-(1 << 21)) };
+
         let misc_alloc = allocate_code(
             system_table.boot_services(),
             core::mem::size_of::<MiscBuf>(),
@@ -126,6 +130,18 @@ trampoline_size:
         );
 
         unsafe {
+            let entry_addr = kernel.entry_addr(kernel_start);
+            log::debug!(
+                "Calling trampoline at {:#x} for kernel at {:#x}",
+                misc_buf.trampoline.as_ptr() as usize,
+                entry_addr as usize
+            );
+            log::debug!(
+                "modinfo_base={:#x}, free_ptr={:#x}",
+                modinfo_base as usize,
+                free_ptr as usize
+            );
+
             // Serialize some final metadata. Calls exit boot services.
             add_efi_metadata(system_table, staging);
 
@@ -134,9 +150,9 @@ trampoline_size:
             trampoline_func(
                 &misc_buf.stack[PAGE_SIZE - 8] as *const u8,
                 &misc_buf.pt4 as *const PageTable,
-                modinfo_base,
+                modinfo_base.byte_offset_from(kernel_base) as usize,
-                free_ptr,
+                free_ptr.byte_offset_from(kernel_base) as usize,
-                kernel.entry_addr(kernel_base),
+                entry_addr,
             );
         }
     }
@@ -178,7 +194,7 @@ trampoline_size:
 
         item.serialize_unaligned(staging)
     }
-    fn parse_efi_framebuffer_params<'a>(
+    fn parse_efi_framebuffer_params(
         boot_services: &BootServices,
     ) -> Result<EFIFramebufferParams, uefi::Error> {
         let gop_handle = boot_services.get_handle_for_protocol::<GraphicsOutput>()?;

src/main.rs

@@ -12,7 +12,7 @@ use abi::{Environment, Howto, ModuleInfoItem, ModuleInfoType, ModuleInfoValue, S
 use alloc::{collections::btree_map::BTreeMap, string::ToString};
 use log::info;
 use object::{Kernel, Module};
-use uefi::{fs::FileSystem, prelude::*, proto::loaded_image::LoadedImage};
+use uefi::{fs::FileSystem, prelude::*, proto::loaded_image::LoadedImage, table::boot::PAGE_SIZE};
 
 #[entry]
 fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
@@ -45,7 +45,6 @@ fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
 
     let kernel = Kernel::from_elf_bytes(&kernel_data);
     let mut kernel_metadata = kernel.metadata();
-    info!("Kernel metadata is {:x?}", kernel_metadata);
 
     let environment = Environment(BTreeMap::from([(
         "kernel".to_string(),
@@ -68,7 +67,11 @@ fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
 
     kernel_metadata.push(abi::ModuleInfoItem {
         tag: ModuleInfoType::Environment,
-        value: ModuleInfoValue::Pointer(environ_base),
+        value: ModuleInfoValue::Size(
+            (environ_base as usize)
+                .wrapping_sub(kernel_base as usize)
+                .wrapping_add(1 << 21),
+        ),
     });
 
     kernel_metadata.push(abi::ModuleInfoItem {
@@ -76,12 +79,18 @@ fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
         value: ModuleInfoValue::Howto(Howto::VERBOSE | Howto::SERIAL),
     });
 
-    let free_ptr = unsafe { next.as_ptr().byte_add(metadata_size) };
+    let free_ptr = unsafe {
+        let base = next.as_ptr().byte_add(metadata_size);
+        let offset = base.align_offset(PAGE_SIZE);
+        base.byte_add(offset)
+    };
     kernel_metadata.push(ModuleInfoItem {
         tag: ModuleInfoType::FreeAddress,
         value: ModuleInfoValue::Pointer(free_ptr),
     });
 
+    info!("Kernel metadata is {:x?}", kernel_metadata);
+
     let modinfo_base = next.as_ptr();
     for item in kernel_metadata.iter() {
         next = item.serialize_unaligned(next);