130 lines · python
1#!/usr/bin/env python32 3# Generates a version script for an architecture so that it can be incorporated4# into gcc_s.ver.5 6from collections import defaultdict7from itertools import chain8import argparse, subprocess, sys, os9 10 11def split_suffix(symbol):12 """13 Splits a symbol such as `__gttf2@GCC_3.0` into a triple representing its14 function name (__gttf2), version name (GCC_3.0), and version number (300).15 16 The version number acts as a priority. Since earlier versions are more17 accessible and are likely to be used more, the lower the number is, the higher18 its priortiy. A symbol that has a '@@' instead of '@' has been designated by19 the linker as the default symbol, and is awarded a priority of -1.20 """21 if "@" not in symbol:22 return None23 data = [i for i in filter(lambda s: s, symbol.split("@"))]24 _, version = data[-1].split("_")25 version = version.replace(".", "")26 priority = -1 if "@@" in symbol else int(version + "0" * (3 - len(version)))27 return data[0], data[1], priority28 29 30def invert_mapping(symbol_map):31 """Transforms a map from Key->Value to Value->Key."""32 store = defaultdict(list)33 for symbol, (version, _) in symbol_map.items():34 store[version].append(symbol)35 result = []36 for k, v in store.items():37 v.sort()38 result.append((k, v))39 result.sort(key=lambda x: x[0])40 return result41 42 43def intersection(llvm, gcc):44 """45 Finds the intersection between the symbols extracted from compiler-rt.a/libunwind.a46 and libgcc_s.so.1.47 """48 common_symbols = {}49 for i in gcc:50 suffix_triple = split_suffix(i)51 if not suffix_triple:52 continue53 54 symbol, version_name, version_number = suffix_triple55 if symbol in llvm:56 if symbol not in common_symbols:57 common_symbols[symbol] = (version_name, version_number)58 continue59 if version_number < common_symbols[symbol][1]:60 common_symbols[symbol] = (version_name, version_number)61 return invert_mapping(common_symbols)62 63 64def find_function_names(path):65 """66 Runs readelf on a binary and reduces to only defined functions. Equivalent to67 `llvm-readelf --wide ${path} | grep 'FUNC' | grep -v 'UND' | awk '{print $8}'`.68 """69 result = subprocess.run(args=["llvm-readelf", "-su", path], capture_output=True)70 71 if result.returncode != 0:72 print(result.stderr.decode("utf-8"), file=sys.stderr)73 sys.exit(1)74 75 stdout = result.stdout.decode("utf-8")76 stdout = filter(lambda x: "FUNC" in x and "UND" not in x, stdout.split("\n"))77 stdout = chain(map(lambda x: filter(None, x), (i.split(" ") for i in stdout)))78 79 return [list(i)[7] for i in stdout]80 81 82def to_file(versioned_symbols):83 path = f"{os.path.dirname(os.path.realpath(__file__))}/new-gcc_s-symbols"84 with open(path, "w") as f:85 f.write(86 "Do not check this version script in: you should instead work "87 "out which symbols are missing in `lib/gcc_s.ver` and then "88 "integrate them into `lib/gcc_s.ver`. For more information, "89 "please see `doc/LLVMLibgcc.rst`.\n"90 )91 for version, symbols in versioned_symbols:92 f.write(f"{version} {{\n")93 for i in symbols:94 f.write(f" {i};\n")95 f.write("};\n\n")96 97 98def read_args():99 parser = argparse.ArgumentParser()100 parser.add_argument(101 "--compiler_rt",102 type=str,103 help="Path to `libclang_rt.builtins-${ARCH}.a`.",104 required=True,105 )106 parser.add_argument(107 "--libunwind", type=str, help="Path to `libunwind.a`.", required=True108 )109 parser.add_argument(110 "--libgcc_s",111 type=str,112 help="Path to `libgcc_s.so.1`. Note that unlike the other two arguments, this is a dynamic library.",113 required=True,114 )115 return parser.parse_args()116 117 118def main():119 args = read_args()120 llvm = find_function_names(args.compiler_rt) + find_function_names(args.libunwind)121 gcc = find_function_names(args.libgcc_s)122 versioned_symbols = intersection(llvm, gcc)123 # TODO(cjdb): work out a way to integrate new symbols in with the existing124 # ones125 to_file(versioned_symbols)126 127 128if __name__ == "__main__":129 main()130