Merge pull request #346 from devsnek/x/kernel-image-fields

kernel image fields & zero out rbp

api/src/info.rs

@@ -56,6 +56,12 @@ pub struct BootInfo {
  pub ramdisk_addr: Optional<u64>,
  /// Ramdisk image size, set to 0 if addr is None
  pub ramdisk_len: u64,
+ /// Physical address of the kernel ELF in memory.
+ pub kernel_addr: u64,
+ /// Size of the kernel ELF in memory.
+ pub kernel_len: u64,
+ /// Virtual address of the loaded kernel image.
+ pub kernel_image_offset: u64,
 
  #[doc(hidden)]
  pub _test_sentinel: u64,
@@ -76,6 +82,9 @@ impl BootInfo {
  tls_template: Optional::None,
  ramdisk_addr: Optional::None,
  ramdisk_len: 0,
+ kernel_addr: 0,
+ kernel_len: 0,
+ kernel_image_offset: 0,
  _test_sentinel: 0,
  }
  }

common/src/legacy_memory_region.rs

@@ -110,10 +110,11 @@ where
  pub fn construct_memory_map(
  self,
  regions: &mut [MaybeUninit<MemoryRegion>],
- kernel_slice_start: u64,
+ kernel_slice_start: PhysAddr,
  kernel_slice_len: u64,
  ) -> &mut [MemoryRegion] {
  let mut next_index = 0;
+ let kernel_slice_start = kernel_slice_start.as_u64();
 
  for descriptor in self.original {
  let mut start = descriptor.start();

common/src/lib.rs

@@ -39,7 +39,7 @@ pub mod serial;
 
 const PAGE_SIZE: u64 = 4096;
 
-/// Initialize a text-based logger using the given pixel-based framebuffer as output. 
+/// Initialize a text-based logger using the given pixel-based framebuffer as output.
 pub fn init_logger(
  framebuffer: &'static mut [u8],
  info: FrameBufferInfo,
@@ -195,10 +195,10 @@ where
  enable_write_protect_bit();
 
  let config = kernel.config;
- let kernel_slice_start = kernel.start_address as u64;
+ let kernel_slice_start = PhysAddr::new(kernel.start_address as _);
  let kernel_slice_len = u64::try_from(kernel.len).unwrap();
 
- let (entry_point, tls_template) = load_kernel::load_kernel(
+ let (kernel_image_offset, entry_point, tls_template) = load_kernel::load_kernel(
  kernel,
  kernel_page_table,
  frame_allocator,
@@ -402,6 +402,8 @@ where
 
  kernel_slice_start,
  kernel_slice_len,
+ kernel_image_offset,
+
  ramdisk_slice_start,
  ramdisk_slice_len,
  }
@@ -426,9 +428,11 @@ pub struct Mappings {
  pub tls_template: Option<TlsTemplate>,
 
  /// Start address of the kernel slice allocation in memory.
- pub kernel_slice_start: u64,
+ pub kernel_slice_start: PhysAddr,
  /// Size of the kernel slice allocation in memory.
  pub kernel_slice_len: u64,
+ /// Relocation offset of the kernel image in virtual memory.
+ pub kernel_image_offset: VirtAddr,
  pub ramdisk_slice_start: Option<VirtAddr>,
  pub ramdisk_slice_len: u64,
 }
@@ -543,6 +547,9 @@ where
  .map(|addr| addr.as_u64())
  .into();
  info.ramdisk_len = mappings.ramdisk_slice_len;
+ info.kernel_addr = mappings.kernel_slice_start.as_u64();
+ info.kernel_len = mappings.kernel_slice_len as _;
+ info.kernel_image_offset = mappings.kernel_image_offset.as_u64();
  info._test_sentinel = boot_config._test_sentinel;
  info
  });
@@ -587,15 +594,21 @@ pub struct PageTables {
  ///
  /// Must be the page table that the `kernel` field of this struct refers to.
  ///
- /// This frame is loaded into the `CR3` register on the final context switch to the kernel. 
+ /// This frame is loaded into the `CR3` register on the final context switch to the kernel.
  pub kernel_level_4_frame: PhysFrame,
 }
 
 /// Performs the actual context switch.
 unsafe fn context_switch(addresses: Addresses) -> ! {
  unsafe {
  asm!(
- "mov cr3, {}; mov rsp, {}; push 0; jmp {}",
+ r#"
+ xor rbp, rbp
+ mov cr3, {}
+ mov rsp, {}
+ push 0
+ jmp {}
+ "#,
  in(reg) addresses.page_table.start_address().as_u64(),
  in(reg) addresses.stack_top.as_u64(),
  in(reg) addresses.entry_point.as_u64(),

common/src/load_kernel.rs

@@ -721,11 +721,15 @@ pub fn load_kernel(
  page_table: &mut (impl MapperAllSizes + Translate),
  frame_allocator: &mut impl FrameAllocator<Size4KiB>,
  used_entries: &mut UsedLevel4Entries,
-) -> Result<(VirtAddr, Option<TlsTemplate>), &'static str> {
+) -> Result<(VirtAddr, VirtAddr, Option<TlsTemplate>), &'static str> {
  let mut loader = Loader::new(kernel, page_table, frame_allocator, used_entries)?;
  let tls_template = loader.load_segments()?;
 
- Ok((loader.entry_point(), tls_template))
+ Ok((
+ VirtAddr::new(loader.inner.virtual_address_offset.virtual_address_offset() as u64),
+ loader.entry_point(),
+ tls_template,
+ ))
 }
 
 /// A helper type used to offset virtual addresses for position independent