| #!/usr/bin/env python3 |
| # |
| # Copyright 2019 The Hafnium Authors. |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # https://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """Check ELF file for assembly-level regressions. |
| |
| Objdumps the given ELF file and detects known assembly patterns, checking for |
| regressions on bugs such as CPU erratas. Throws an exception if a broken pattern |
| is detected. |
| """ |
| |
| import argparse |
| import os |
| import re |
| import subprocess |
| import sys |
| |
| HF_ROOT = os.path.dirname(os.path.dirname(os.path.dirname(__file__))) |
| CLANG_ROOT = os.path.join(HF_ROOT, "prebuilts", "linux-x64", "clang") |
| OBJDUMP = os.path.join(CLANG_ROOT, "bin", "llvm-objdump") |
| NM = os.path.join(CLANG_ROOT, "bin", "llvm-nm") |
| |
| def check_eret_speculation_barrier(args): |
| """ |
| Some ARM64 CPUs speculatively execute instructions after ERET. |
| Check that every ERET is followed by DSB NSH and ISB. |
| """ |
| |
| objdump_stdout = subprocess\ |
| .check_output([ OBJDUMP, "-d", args.input_elf ])\ |
| .decode("utf-8")\ |
| .splitlines() |
| |
| found_eret = False |
| |
| STATE_DEFAULT = 1 |
| STATE_EXPECT_DSB_NSH = 2 |
| STATE_EXPECT_ISB = 3 |
| |
| REGEX_ERET = re.compile(r"^\s*[0-9a-f]+:\s*e0 03 9f d6\s+eret$") |
| REGEX_DSB_NSH = re.compile(r"^\s*[0-9a-f]+:\s*9f 37 03 d5\s*dsb\s+nsh$") |
| REGEX_ISB = re.compile(r"^\s*[0-9a-f]+:\s*df 3f 03 d5\s+isb$") |
| |
| state = STATE_DEFAULT |
| for line in objdump_stdout: |
| if state == STATE_DEFAULT: |
| if re.match(REGEX_ERET, line): |
| found_eret = True |
| state = STATE_EXPECT_DSB_NSH |
| elif state == STATE_EXPECT_DSB_NSH: |
| if re.match(REGEX_DSB_NSH, line): |
| state = STATE_EXPECT_ISB |
| else: |
| raise Exception("ERET not followed by DSB NSH") |
| elif state == STATE_EXPECT_ISB: |
| if re.match(REGEX_ISB, line): |
| state = STATE_DEFAULT |
| else: |
| raise Exception("ERET not followed by ISB") |
| |
| # Ensure that at least one instance was found, otherwise the regexes are |
| # probably wrong. |
| if not found_eret: |
| raise Exception("Could not find any ERET instructions") |
| |
| def check_max_image_size(args): |
| """ |
| Check that the ELF's effective image size does not exceed maximum |
| allowed image size, if specified in command-line arguments. |
| """ |
| |
| if args.max_image_size <= 0: |
| return |
| |
| nm_stdout = subprocess\ |
| .check_output([ NM, args.input_elf ])\ |
| .decode("utf-8")\ |
| .splitlines() |
| |
| COLUMN_COUNT = 3 |
| COLUMN_IDX_VALUE = 0 |
| COLUMN_IDX_TYPE = 1 |
| COLUMN_IDX_NAME = 2 |
| |
| image_size = None |
| for line in nm_stdout: |
| line = line.split() |
| if len(line) != COLUMN_COUNT: |
| raise Exception( |
| "Unexpected number of columns in NM output") |
| |
| if line[COLUMN_IDX_NAME] == "image_size": |
| if line[COLUMN_IDX_TYPE] != "A": |
| raise Exception( |
| "Unexpected type of image_size symbol") |
| image_size = int(line[COLUMN_IDX_VALUE], 16) |
| break |
| |
| if image_size is None: |
| raise Exception("Could not find value of image_size symbol") |
| elif image_size > args.max_image_size: |
| raise Exception( |
| "Image size exceeds maximum allowed image size " + |
| "({}B > {}B)".format(image_size, args.max_image_size)) |
| |
| def Main(): |
| parser = argparse.ArgumentParser() |
| parser.add_argument("input_elf", |
| help="ELF file to analyze") |
| parser.add_argument("stamp_file", |
| help="file to be touched if successful") |
| parser.add_argument("--max-image-size", |
| required=False, type=int, default=0, |
| help="maximum allowed image size in bytes") |
| args = parser.parse_args() |
| |
| check_eret_speculation_barrier(args) |
| check_max_image_size(args) |
| |
| # Touch `stamp_file`. |
| with open(args.stamp_file, "w"): |
| pass |
| |
| return 0 |
| |
| if __name__ == "__main__": |
| sys.exit(Main()) |