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126 lines
4.5 KiB
126 lines
4.5 KiB
4 months ago
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#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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#
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# Copyright (C) 2019 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Helper tool to generate cross-compiled syscall and constant tables to JSON.
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This script takes the LLVM IR of libconstants.gen.c and libsyscalls.gen.c and
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generates the `constants.json` file with that. LLVM IR files are moderately
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architecture-neutral (at least for this case).
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"""
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import argparse
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import collections
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import json
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import re
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import sys
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_STRING_CONSTANT_RE = re.compile(r'(@[a-zA-Z0-9.]+) = .*c"([^"\\]+)\\00".*')
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_TABLE_ENTRY_RE = re.compile(
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r'%struct.(?:constant|syscall)_entry\s*{\s*([^}]+)\s*}')
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# This looks something like
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#
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# i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.5, i32 0, i32 0), i32 5
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#
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# For arm-v7a. What we are interested in are the @.str.x and the very last
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# number.
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_TABLE_ENTRY_CONTENTS = re.compile(r'.*?(null|@[a-zA-Z0-9.]+).* (-?\d+)')
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ParseResults = collections.namedtuple('ParseResults', ['table_name',
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'table_entries'])
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HELP_EPILOG = """Generate LLVM IR: clang -S -emit-llvm libconstants.gen.c libsyscalls.gen.c
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"""
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def parse_llvm_ir(ir):
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"""Parses a single LLVM IR file."""
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string_constants = collections.OrderedDict()
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table_entries = collections.OrderedDict()
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table_name = ''
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for line in ir:
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string_constant_match = _STRING_CONSTANT_RE.match(line)
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if string_constant_match:
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string_constants[string_constant_match.group(
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1)] = string_constant_match.group(2)
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continue
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if '@syscall_table' in line or '@constant_table' in line:
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if '@syscall_table' in line:
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table_name = 'syscalls'
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else:
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table_name = 'constants'
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for entry in _TABLE_ENTRY_RE.findall(line):
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groups = _TABLE_ENTRY_CONTENTS.match(entry)
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if not groups:
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raise ValueError('Failed to parse table entry %r' % entry)
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name, value = groups.groups()
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if name == 'null':
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# This is the end-of-table marker.
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break
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table_entries[string_constants[name]] = int(value)
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return ParseResults(table_name=table_name, table_entries=table_entries)
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def main(argv=None):
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"""Main entrypoint."""
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if argv is None:
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argv = sys.argv[1:]
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parser = argparse.ArgumentParser(description=__doc__, epilog=HELP_EPILOG)
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parser.add_argument('--output',
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help='The path of the generated constants.json file.',
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type=argparse.FileType('w'),
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required=True)
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parser.add_argument(
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'llvm_ir_files',
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help='An LLVM IR file with one of the {constants,syscall} table.',
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metavar='llvm_ir_file',
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nargs='+',
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type=argparse.FileType('r'))
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opts = parser.parse_args(argv)
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constants_json = {}
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for ir in opts.llvm_ir_files:
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parse_results = parse_llvm_ir(ir)
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constants_json[parse_results.table_name] = parse_results.table_entries
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# Populate the top-level fields.
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constants_json['arch_nr'] = constants_json['constants']['MINIJAIL_ARCH_NR']
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constants_json['bits'] = constants_json['constants']['MINIJAIL_ARCH_BITS']
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# It is a bit more complicated to generate the arch_name, since the
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# constants can only output numeric values. Use a hardcoded mapping instead.
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if constants_json['arch_nr'] == 0xC000003E:
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constants_json['arch_name'] = 'x86_64'
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elif constants_json['arch_nr'] == 0x40000003:
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constants_json['arch_name'] = 'x86'
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elif constants_json['arch_nr'] == 0xC00000B7:
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constants_json['arch_name'] = 'arm64'
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elif constants_json['arch_nr'] == 0x40000028:
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constants_json['arch_name'] = 'arm'
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else:
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raise ValueError('Unknown architecture: 0x%08X' %
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constants_json['arch_nr'])
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json.dump(constants_json, opts.output, indent=' ')
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return 0
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if __name__ == '__main__':
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sys.exit(main(sys.argv[1:]))
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