Hardened paging into a real VMM

src/root.zig

@@ -76,9 +76,22 @@ pub const MemoryMap = extern struct {
     len: usize,
 };
 
+/// One PT_LOAD segment of the kernel image, so the kernel can re-map itself with
+/// correct permissions (code R+X, rodata R, data R+W+NX). `flags` are raw ELF
+/// segment flags: PF_X=1, PF_W=2, PF_R=4.
+pub const KernelSegment = extern struct {
+    virt: u64,
+    pages: u64,
+    flags: u32,
+    _pad: u32 = 0,
+};
+
 /// Handoff structure the bootloader fills in and passes to the kernel's
 /// `_start` in RDI (the first argument under the SysV AMD64 C ABI).
 pub const BootInfo = extern struct {
     framebuffer: Framebuffer,
     memory_map: MemoryMap,
+    /// The kernel's own PT_LOAD segments (it has three: text, rodata, data).
+    kernel_segments: [8]KernelSegment,
+    kernel_segment_count: u32,
 };