Add executable analaysis tool for floating point checks.

hugueskamba · hugueskamba · commit 4f1a7c24589a · 2019-08-30T11:21:15.000+01:00
diff --git a/tools/executable_analysis_tools/elf-float-checker.py b/tools/executable_analysis_tools/elf-float-checker.py
@@ -0,0 +1,168 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Script for checking for floating point symbols in ELF files."""
+
+import argparse
+import logging
+import re
+import subprocess
+import sys
+
+log = logging.getLogger(__name__)
+
+LOG_FORMAT = "%(asctime)s - %(levelname)s - %(message)s"
+FLOATING_POINT_SYMBOL_REGEX = r"__aeabi_(cd.+|cf.+|h2f.+|d.+|f.+|.+2d|.+2f)"
+OBJECT_FILE_ANALYSIS_CMD = ["objdump", "-t"]
+
+class SymbolParser:
+    """Parse the given ELF format file."""
+
+    def get_symbols_from_table(self, symbol_table, symbol_regex):
+        """Get symbols matching a regular expression pattern from a table."""
+        pattern = re.compile(symbol_regex, re.X)
+        matched_symbols = []
+        symbol_table_lines = symbol_table.split("\n")
+        for symbol_table_line in symbol_table_lines:
+            match = pattern.search(symbol_table_line)
+            if match:
+                log.debug("Symbol line: {}".format(symbol_table_line))
+                log.debug("Match found: {}".format(match))
+                matched_symbols.append(match.group(0))
+
+        log.debug("Symbols found:\n'{}'".format(matched_symbols))
+        return matched_symbols
+
+    def get_symbol_table(self, elf_file):
+        """Get the symbol table from an ELF format file."""
+        log.debug(
+            "Get the symbol table for ELF format file '{}'".format(elf_file)
+        )
+
+        cmd = [*OBJECT_FILE_ANALYSIS_CMD, elf_file]
+        log.debug("command: '{}'".format(cmd))
+        try:
+            process = subprocess.run(
+                cmd,
+                check=True,
+                stdin=None,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.STDOUT,
+            )
+        except subprocess.CalledProcessError as error:
+            err_output = error.stdout.decode()
+            msg = (
+                "Getting symbol table for ELF format file '{}' failed,"
+                " error: {}".format(elf_file, err_output)
+            )
+            raise SymbolTableError(msg)
+
+        symbol_table = process.stdout.decode()
+        log.debug("Symbol table:\n{}\n".format(symbol_table))
+
+        return symbol_table
+
+
+class SymbolTableError(Exception):
+    """An exception for a failure to obtain a symbol table."""
+
+
+class ArgumentParserWithDefaultHelp(argparse.ArgumentParser):
+    """Subclass that always shows the help message on invalid arguments."""
+
+    def error(self, message):
+        """Error handler."""
+        sys.stderr.write("error: {}\n".format(message))
+        self.print_help()
+
+
+def set_log_verbosity(increase_verbosity):
+    """Set the verbosity of the log output."""
+    log_level = logging.DEBUG if increase_verbosity else logging.INFO
+
+    log.setLevel(log_level)
+    logging.basicConfig(level=log_level, format=LOG_FORMAT)
+
+
+def check_float_symbols(elf_file):
+    """Check for floating point symbols in ELF format file.
+
+    Return the floating point symbols found.
+    """
+    parser = SymbolParser()
+    symbol_table = parser.get_symbol_table(elf_file)
+
+    float_symbols = parser.get_symbols_from_table(
+        symbol_table, FLOATING_POINT_SYMBOL_REGEX
+    )
+
+    return float_symbols
+
+
+def check_action(args):
+    """Entry point for checking the ELF file."""
+    float_symbols = check_float_symbols(args.elf_file)
+    if float_symbols:
+        print("Found float symbols:")
+        for float_symbol in float_symbols:
+            print(float_symbol)
+    else:
+        print("No float symbols found.")
+
+
+def parse_args():
+    """Parse the command line args."""
+    parser = ArgumentParserWithDefaultHelp(
+        description="ELF floats checker",
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+    )
+
+    parser.add_argument(
+        "elf_file",
+        type=str,
+        help=(
+            "the Executable and Linkable Format (ELF) file to check"
+            " for floating point instruction inclusion."
+        ),
+    )
+
+    parser.add_argument(
+        "-v",
+        "--verbose",
+        action="store_true",
+        help="increase verbosity of status information.",
+    )
+
+    parser.set_defaults(func=check_action)
+
+    args_namespace = parser.parse_args()
+
+    # We want to fail gracefully, with a consistent
+    # help message, in the no argument case.
+    # So here's an obligatory hasattr hack.
+    if not hasattr(args_namespace, "func"):
+        parser.error("No arguments given!")
+    else:
+        return args_namespace
+
+
+def run_elf_floats_checker():
+    """Application main algorithm."""
+    args = parse_args()
+
+    set_log_verbosity(args.verbose)
+
+    log.debug("Starting elf-floats-checker")
+    log.debug("Command line arguments:{}".format(args))
+
+    args.func(args)
+
+
+if __name__ == "__main__":
+    """Run elf-floats-checker."""
+    try:
+        run_elf_floats_checker()
+    except Exception as error:
+        print(error)
diff --git a/tools/executable_analysis_tools/test_elf-float-checker.py b/tools/executable_analysis_tools/test_elf-float-checker.py
@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Pytest for testing elf-float-checker."""
+
+import importlib
+import mock
+import subprocess
+from pathlib import Path
+
+
+TARGET = importlib.import_module("elf-float-checker")
+
+SYMBOL_TABLE_WITHOUT_FLOATS = (
+    " Symbol table '.symtab' contains 2723 entries:\n"
+    "Num:    Value  Size Type    Bind   Vis      Ndx Name\n"
+    "  0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND \n"
+    "  1: 000045fd    16 FUNC    GLOBAL HIDDEN     3 lp_ticker_clear_interrupt\n"
+    "  2: 00004609    16 FUNC    GLOBAL HIDDEN     3 __aeabi_uwrite4\n"
+    "  3: 00004615    16 FUNC    GLOBAL HIDDEN     3 lp_ticker_fire_interrupt\n"
+    "  4: 00004625    36 FUNC    GLOBAL HIDDEN     3 lp_ticker_free\n"
+    "  5: 00004645     8 FUNC    GLOBAL HIDDEN     3 lp_ticker_get_info\n"
+    "  6: 0000464d   116 FUNC    GLOBAL HIDDEN     3 __aeabi_lasr\n"
+    "  7: 000046bd    20 FUNC    GLOBAL HIDDEN     3 lp_ticker_irq_handler\n"
+    "  8: 000046d1    16 FUNC    GLOBAL HIDDEN     3 lp_ticker_read\n"
+    "  9: 000046e1    52 FUNC    GLOBAL HIDDEN     3 __aeabi_lmul\n"
+)
+
+FLOAT_SYMBOLS = [
+    "__aeabi_cdcmpeq",
+    "__aeabi_cfcmpeq",
+    "__aeabi_f2iz",
+    "__aeabi_h2f_alt",
+    "__aeabi_i2d",
+    "__aeabi_d2iz",
+    "__aeabi_i2f",
+]
+
+SYMBOL_TABLE_WITH_FLOATS = (
+    " Symbol table '.symtab' contains 2723 entries:\n"
+    "Num:    Value  Size Type    Bind   Vis      Ndx Name\n"
+    f"  0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND \n"
+    f"  1: 000045fd    16 FUNC    GLOBAL HIDDEN     3 {FLOAT_SYMBOLS[0]}\n"
+    f"  2: 00004609    16 FUNC    GLOBAL HIDDEN     3 lp_ticker_disable_interrupt\n"
+    f"  3: 00004615    16 FUNC    GLOBAL HIDDEN     3 {FLOAT_SYMBOLS[1]}\n"
+    f"  4: 00004625    36 FUNC    GLOBAL HIDDEN     3 {FLOAT_SYMBOLS[2]}\n"
+    f"  5: 00004645     8 FUNC    GLOBAL HIDDEN     3 lp_ticker_get_info\n"
+    f"  6: 0000464d   116 FUNC    GLOBAL HIDDEN     3 {FLOAT_SYMBOLS[3]}\n"
+    f"  7: 000046bd    20 FUNC    GLOBAL HIDDEN     3 lp_ticker_irq_handler\n"
+    f"  8: 000046d1    16 FUNC    GLOBAL HIDDEN     3 {FLOAT_SYMBOLS[4]}\n"
+    f"  9: 000046e1    52 FUNC    GLOBAL HIDDEN     3 {FLOAT_SYMBOLS[5]}\n"
+    f" 10: 000046f1    52 FUNC    GLOBAL HIDDEN     3 {FLOAT_SYMBOLS[6]}\n"
+)
+
+
+ELF_FORMAT_FILE = "mbed-os-example.elf"
+OBJECT_FILE_ANALYSIS_CMD = [*(TARGET.OBJECT_FILE_ANALYSIS_CMD), f"{ELF_FORMAT_FILE}"]
+
+class TestElfFloatChecker:
+    """Test class"""
+
+    @classmethod
+    def setup_class(cls):
+        # Create a dummy ELF format file
+        Path(ELF_FORMAT_FILE).touch()
+
+    @classmethod
+    def teardown_class(cls):
+        # Remove the dummy ELF format file
+        Path(ELF_FORMAT_FILE).unlink()
+
+    @mock.patch("subprocess.run")
+    def test_correctly_detect_absence_of_float_symbols(
+        self, mock_subprocess_run
+    ):
+        """Test that no false positive occur."""
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args=(
+                f"{OBJECT_FILE_ANALYSIS_CMD}"
+                " check=True, stderr=-2, stdin=None, stdout=-1"
+            ),
+            returncode=0,
+            stdout=SYMBOL_TABLE_WITHOUT_FLOATS.encode(),
+            stderr=None,
+        )
+        assert [] == TARGET.check_float_symbols(ELF_FORMAT_FILE)
+        mock_subprocess_run.assert_called_with(
+            OBJECT_FILE_ANALYSIS_CMD,
+            check=True,
+            stdin=None,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+        )
+
+    @mock.patch("subprocess.run")
+    def test_correctly_detect_presence_of_float_symbols(
+        self, mock_subprocess_run
+    ):
+        """Test that float symbols can be discovered in a symbol table."""
+        mock_subprocess_run.return_value = subprocess.CompletedProcess(
+            args=(
+                f"{OBJECT_FILE_ANALYSIS_CMD}"
+                " check=True, stderr=-2, stdin=None, stdout=-1"
+            ),
+            returncode=0,
+            stdout=SYMBOL_TABLE_WITH_FLOATS.encode(),
+            stderr=None,
+        )
+        assert FLOAT_SYMBOLS == TARGET.check_float_symbols(
+            ELF_FORMAT_FILE
+        )
+        mock_subprocess_run.assert_called_with(
+            OBJECT_FILE_ANALYSIS_CMD,
+            check=True,
+            stdin=None,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+        )
