feat(loader, kernel): impl part of loader and initialize kernel structure

arch/x86_64/boot/relocate.zig

@@ -0,0 +1,20 @@
+const std = @import("std");
+const elf = std.elf;
+
+extern var __rela_dyn_start: u8;
+extern var __rela_dyn_end: u8;
+
+pub fn relocateSelf(base_addr: usize) callconv(.c) void {
+    const rela_size = (@intFromPtr(&__rela_dyn_end) - @intFromPtr(&__rela_dyn_start)) / @sizeOf(elf.Elf64_Rela);
+    const relas = @as([*]elf.Elf64_Rela, @ptrCast(@alignCast(&__rela_dyn_start)))[0..rela_size];
+    for (relas) |rela| {
+        const offset = rela.r_offset;
+        const addend = rela.r_addend;
+        // const sym_index = rela.r_info >> 32;
+        const type_ = rela.r_info & 0xffffffff;
+        if (type_ == @intFromEnum(elf.R_X86_64.RELATIVE)) {
+            const reloc_addr: *u64 = @ptrFromInt(offset + base_addr);
+            reloc_addr.* = base_addr + @as(usize, @intCast(addend));
+        }
+    }
+}