Meta: Add Serenity Kernel to gn build

Meta/gn/secondary/Kernel/post_process_kernel.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+
+import argparse
+import shutil
+import subprocess
+import sys
+from functools import cmp_to_key
+from pathlib import Path
+
+
+def main():
+    parser = argparse.ArgumentParser(
+                 epilog=__doc__,
+                 formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument('kernel', help='kernel binary location')
+    parser.add_argument('-n', '--nm', required=True, help='path to nm')
+    parser.add_argument('-o', '--objcopy', required=True, help='path to objcopy')
+    args = parser.parse_args()
+
+    kernel_path = Path(args.kernel)
+    binary_directory = kernel_path.parent
+
+    # Write out kernel.map, which contains kernel symbols and their addresses
+    symbols = subprocess.check_output([args.nm, '-C', '-n', str(kernel_path)])
+    if not symbols:
+        print(f"Unable to dump symbols from {kernel_path}", file=sys.stderr)
+        return 1
+
+    def filter_symbol(s):
+        return s and not (".Lubsan_data" in s or s.split()[1] == "a")
+
+    symbols = filter(filter_symbol, symbols.decode().split('\n'))
+    symbols = list(set(symbols))
+
+    def sort_symbols(s1, s2):
+        return int(s1.split()[0], base=16) - int(s2.split()[0], base=16)
+    symbols = sorted(symbols, key=cmp_to_key(sort_symbols))
+
+    kernel_map = binary_directory / "kernel.map"
+    with open(kernel_map, 'w') as out:
+        out.write(f'{len(symbols):#x}\n')
+        out.write('\n'.join(symbols))
+        out.write('\0')
+
+    kernel_final = binary_directory / "Kernel"
+
+    shutil.copyfile(kernel_path, kernel_final)
+
+    kernel_final = str(kernel_final)
+
+    subprocess.check_call([args.objcopy, "--update-section", f".ksyms={kernel_map}", kernel_final])
+    subprocess.check_call([args.objcopy, "--only-keep-debug", kernel_final, kernel_final + ".debug"])
+    subprocess.check_call([args.objcopy, "--strip-debug", kernel_final])
+    subprocess.check_call([args.objcopy, f"--add-gnu-debuglink={kernel_final}.debug", kernel_final])
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())