Start designing Serialize trait

src/abi.rs

@@ -1,5 +1,21 @@
+extern crate alloc;
+use alloc::string::String;
+use alloc::vec::Vec;
 use uefi::proto::console::gop::{GraphicsOutput, PixelFormat};
 
+/// Serialize object into a buffer for FreeBSD
+pub trait Serialize {
+    /// Output buffer must be aligned to this size
+    fn alignment() -> usize;
+
+    /// Calculate output size of object, from base address to final byte written
+    fn size(&self) -> usize;
+
+    /// Serliaze data into a buffer. Buffer must be aligned at alignment.
+    fn serialize(&self, out: &mut [u8]);
+}
+
+#[derive(Debug, Copy, Clone)]
 #[repr(C)]
 pub struct EFIFramebufferParams {
     pub addr: u64,
@@ -45,76 +61,142 @@ impl EFIFramebufferParams {
     }
 }
 
-/// Single TLV in the metadata buffer.
+impl Serialize for EFIFramebufferParams {
-/// In the FreeBSD kernel would be placed in `preload_metadata`
+    fn alignment() -> usize {
-pub enum PreloadDirectoryElem<'a> {
+        4
-    /// Module name (MOD_NAME)
+    }
-    Name(&'a str),
+
-    /// Module type (MOD_TYPE)
+    fn size(&self) -> usize {
-    Type(&'a str),
+        core::mem::size_of::<Self>()
-    /// Module parameters (MOD_ARGS)
+    }
-    Args(&'a str),
+
+    fn serialize(&self, out: &mut [u8]) {
+        // we're already repr(C) so just copy
+        out.copy_from_slice(unsafe {
+            core::slice::from_raw_parts(
+                self as *const Self as *const u8,
+                core::mem::size_of_val(self),
+            )
+        })
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[repr(u32)]
+/// Tag in the module info TLV
+pub enum ModuleInfoType {
+    /// Module name (MODINFO_NAME)
+    Name = 0x1,
+    /// Module type (MODINFO_TYPE)
+    Type = 0x2,
     // TODO: figure out how to make this pointer safer
-    /// Module address (MOD_ADDR)
+    /// Module address (MODINFO_ADDR)
-    LoadAddress(*const u8),
+    LoadAddress = 0x3,
-    /// Module size (MOD_SIZE)
+    /// Module size (MODINFO_SIZE)
+    Size = 0x4,
+    /// Module parameters (MODINFO_ARGS)
+    Args = 0x6,
+
+    /// a.out header (MODINFOMD_AOUTEXEC)
+    AoutExecHeader = 0x8001,
+    /// ELF header (MODINFOMD_ELFHDR)
+    ElfHeader = 0x8002,
+    /// Start virtual address of symtab/strtab (MODINFOMD_SSYM)
+    StartSymbols = 0x8003,
+    /// End virtual address of symtab/strtab (MODINFOMD_SSYM)
+    EndSymbols = 0x8004,
+    /// Base virtual address of `PT_DYNAMIC` segment (MODINFOMD_DYNAMIC)
+    Dynamic = 0x8005,
+    /// Section header table (MODINFOMD_SHDR)
+    SectionHeader = 0x8009,
+    /// Base virtual address of constructors (MODINFOMD_CTORS_ADDR)
+    CtorsAddress = 0x800a,
+    /// Size of constructors (MODINFOMD_CTORS_SIZE)
+    CtorsSize = 0x800b,
+    /// Pointer to firmware object, on EFI this means Runtime SystemTable (MODINFOMD_FW_HANDLE)
+    FirmwareHandle = 0x800c,
+    /// Crypto key buffer, used for geli (MODINFOMD_KEYBUF)
+    KeyBuffer = 0x800d,
+    /// Console font (MODINFOMD_FONT)
+    Font = 0x800e,
+
+    #[cfg(target_arch = "x86_64")]
+    /// Base virtual address of device tree (MODINFOMD_DTBP)
+    DeviceTreePointer = 0x9003,
+
+    #[cfg(target_arch = "x86_64")]
+    /// EFI memory map (MODINFOMD_EFI_MAP)
+    EFIMemoryMap = 0x9004,
+
+    #[cfg(target_arch = "x86_64")]
+    /// EFI framebuffer metadata (MODINFOMD_EFI_FB)
+    EFIFrameBuffer = 0x9005,
+}
+
+/// Value in the module info TLV
+#[derive(Debug, Clone)]
+pub enum ModuleInfoValue {
+    StaticString(&'static str),
+    String(String),
+    // TODO: figure out how to make this pointer safer
+    Pointer(*const u8),
     Size(usize),
-    /// Type-speicfic metadata (MOD_METADATA)
+    Buffer(Vec<u8>),
-    Metadata(FileMetadataType, &'a [u8]),
-    End,
 }
 
-impl<'a> PreloadDirectoryElem<'a> {
+impl ModuleInfoValue {
-    fn copy_str(data: &str, output: &mut [u8]) -> Option<u32> {
+    fn serialize_str(s: &str, out: &mut [u8]) {
-        output[..data.len()].copy_from_slice(data.as_bytes());
+        out[..s.len()].copy_from_slice(s.as_bytes());
-        output[data.len()] = 0;
+        out[s.len()] = 0;
-        data.len().checked_add(1)?.try_into().ok()
-    }
-
-    pub fn copy_to_output<'b>(&'a self, output: &'b mut [u8]) -> Option<&'b mut [u8]> {
-        let usize_size = core::mem::size_of::<usize>();
-
-        let (tag, length) = match self {
-            Self::Name(name) => (1u32, Self::copy_str(name, &mut output[8..])?),
-            Self::Type(typ) => (2u32, Self::copy_str(typ, &mut output[8..])?),
-            Self::Args(args) => (6u32, Self::copy_str(args, &mut output[8..])?),
-            Self::LoadAddress(addr) => {
-                output[8..(8 + usize_size)].copy_from_slice(&(*addr as usize).to_ne_bytes());
-                (3u32, usize_size as u32)
-            }
-            Self::Size(size) => {
-                output[8..(8 + usize_size)].copy_from_slice(&size.to_ne_bytes());
-                (4u32, usize_size as u32)
-            }
-            Self::Metadata(typ, metadata) => {
-                output[8..(8 + metadata.len())].copy_from_slice(metadata);
-                (0x8000 | (*typ as u32), metadata.len() as u32)
-            }
-            Self::End => (0u32, 0u32),
-        };
-
-        output[..4].copy_from_slice(&tag.to_ne_bytes());
-        output[4..8].copy_from_slice(&length.to_ne_bytes());
-
-        let aligned_length = ((length as usize + usize_size - 1) / usize_size) * usize_size;
-
-        Some(&mut output[(aligned_length + 8)..])
     }
 }
 
-#[derive(Debug, Copy, Clone)]
+impl Serialize for ModuleInfoValue {
-#[repr(u16)]
+    fn alignment() -> usize {
-pub enum FileMetadataType {
+        4
-    AoutExecHeader = 1,
+    }
-    ElfHeader = 2,
+
-    StartSymbols = 3,
+    fn size(&self) -> usize {
-    EndSymbols = 4,
+        match self {
-    Dynamic = 5,
+            ModuleInfoValue::StaticString(s) => s.len() + 1,
-    MB2Header = 6,
+            ModuleInfoValue::String(s) => s.len() + 1,
-    SectionHeader = 9,
+            ModuleInfoValue::Pointer(obj) => core::mem::size_of_val(obj),
-    CtorsAddress = 10,
+            ModuleInfoValue::Size(obj) => core::mem::size_of_val(obj),
-    CtorsSize = 11,
+            ModuleInfoValue::Buffer(buf) => buf.len(),
-    FirmwareHandle = 12,
+        }
-    KeyBuffer = 13,
+    }
-    Font = 14,
+
+    fn serialize(&self, out: &mut [u8]) {
+        match self {
+            ModuleInfoValue::StaticString(s) => Self::serialize_str(s, out),
+            ModuleInfoValue::String(s) => Self::serialize_str(s, out),
+            ModuleInfoValue::Pointer(p) => out.copy_from_slice(&usize::to_ne_bytes(*p as usize)),
+            ModuleInfoValue::Size(p) => out.copy_from_slice(&usize::to_ne_bytes(*p)),
+            ModuleInfoValue::Buffer(buf) => out.copy_from_slice(buf),
+        }
+    }
+}
+
+/// Key and value in the module info TLV
+/// TODO: figure out how to make this properly typesafe
+#[derive(Debug, Clone)]
+pub struct ModuleInfoItem {
+    tag: ModuleInfoType,
+    value: ModuleInfoValue,
+}
+
+impl Serialize for ModuleInfoItem {
+    fn alignment() -> usize {
+        core::mem::size_of::<usize>()
+    }
+
+    fn size(&self) -> usize {
+        8 + self.value.size()
+    }
+
+    fn serialize(&self, out: &mut [u8]) {
+        out[..4].copy_from_slice(&u32::to_ne_bytes(self.tag as u32));
+        out[4..8].copy_from_slice(&u32::to_ne_bytes(self.value.size().try_into().unwrap()));
+        self.value.serialize(&mut out[8..]);
+    }
 }

src/main.rs

@@ -32,7 +32,7 @@ fn main(image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
     staging_buf[..kernel.len()].copy_from_slice(&kernel);
 
     let header =
-        elf::ElfBytes::<NativeEndian>::minimal_parse(&staging_buf).expect("Failed to parse kernel");
+        elf::ElfBytes::<NativeEndian>::minimal_parse(staging_buf).expect("Failed to parse kernel");
 
     info!("Kernel is {:?}", header.ehdr.class);