| 1 | #!/usr/bin/env python3 |
| 2 | # |
| 3 | # Copyright (C) 2017 Francis Deslauriers <francis.deslauriers@efficios.com> |
| 4 | # |
| 5 | # SPDX-License-Identifier: LGPL-2.1-only |
| 6 | # |
| 7 | |
| 8 | import sys |
| 9 | import bisect |
| 10 | import subprocess |
| 11 | import re |
| 12 | |
| 13 | |
| 14 | def addr2line(executable, addr): |
| 15 | """ |
| 16 | Uses binutils' addr2line to get function containing a given address |
| 17 | """ |
| 18 | cmd = ["addr2line"] |
| 19 | |
| 20 | cmd += ["-e", executable] |
| 21 | |
| 22 | # Print function names |
| 23 | cmd += ["--functions"] |
| 24 | |
| 25 | # Expand inlined functions |
| 26 | cmd += ["--addresses", addr] |
| 27 | |
| 28 | status = subprocess.run(cmd, stdout=subprocess.PIPE, check=True) |
| 29 | |
| 30 | addr2line_output = status.stdout.decode("utf-8").splitlines() |
| 31 | # addr2line's output is made of 3-tuples: |
| 32 | # - address |
| 33 | # - function name |
| 34 | # - source location |
| 35 | if len(addr2line_output) % 3 != 0: |
| 36 | raise Exception( |
| 37 | "Unexpected addr2line output:\n\t{}".format("\n\t".join(addr2line_output)) |
| 38 | ) |
| 39 | |
| 40 | function_names = [] |
| 41 | for address_line_number in range(0, len(addr2line_output), 3): |
| 42 | function_name = addr2line_output[address_line_number + 1] |
| 43 | |
| 44 | # Filter-out unresolved functions |
| 45 | if "??" not in function_name: |
| 46 | function_names.append(addr2line_output[address_line_number + 1]) |
| 47 | |
| 48 | return function_names |
| 49 | |
| 50 | |
| 51 | def extract_user_func_names(executable, raw_callstack): |
| 52 | """ |
| 53 | Given a callstack from the Babeltrace CLI output, returns a set |
| 54 | containing the name of the functions. This assumes that the binary have |
| 55 | not changed since the execution. |
| 56 | """ |
| 57 | recorded_callstack = set() |
| 58 | |
| 59 | # Remove commas and split on spaces |
| 60 | for index, addr in enumerate(raw_callstack.replace(",", "").split(" ")): |
| 61 | # Consider only the elements starting with '0x' which are the |
| 62 | # addresses recorded in the callstack |
| 63 | if "0x" in addr[:2]: |
| 64 | funcs = addr2line(executable, addr) |
| 65 | recorded_callstack.update(funcs) |
| 66 | |
| 67 | return recorded_callstack |
| 68 | |
| 69 | |
| 70 | def extract_kernel_func_names(raw_callstack): |
| 71 | """ |
| 72 | Given a callstack from the Babeltrace CLI output, returns a set |
| 73 | containing the name of the functions. |
| 74 | Uses the /proc/kallsyms procfile to find the symbol associated with an |
| 75 | address. This function should only be used if the user is root or has |
| 76 | access to /proc/kallsyms. |
| 77 | """ |
| 78 | recorded_callstack = set() |
| 79 | syms = [] |
| 80 | addresses = [] |
| 81 | # We read kallsyms file and save the output |
| 82 | with open("/proc/kallsyms") as kallsyms_f: |
| 83 | for line in kallsyms_f: |
| 84 | line_tokens = line.split() |
| 85 | addr = line_tokens[0] |
| 86 | symbol = line_tokens[2] |
| 87 | addresses.append(int(addr, 16)) |
| 88 | syms.append({"addr": int(addr, 16), "symbol": symbol}) |
| 89 | |
| 90 | # Save the address and symbol in a sorted list of tupple |
| 91 | syms = sorted(syms, key=lambda k: k["addr"]) |
| 92 | # We save the list of addresses in a seperate sorted list to easily bisect |
| 93 | # the closer address of a symbol. |
| 94 | addresses = sorted(addresses) |
| 95 | |
| 96 | # Remove commas and split on spaces |
| 97 | for addr in raw_callstack.replace(",", "").split(" "): |
| 98 | if "0x" in addr[:2]: |
| 99 | # Search the location of the address in the addresses list and |
| 100 | # deference this location in the syms list to add the associated |
| 101 | # symbol. |
| 102 | loc = bisect.bisect(addresses, int(addr, 16)) |
| 103 | recorded_callstack.add(syms[loc - 1]["symbol"]) |
| 104 | |
| 105 | return recorded_callstack |
| 106 | |
| 107 | |
| 108 | # Regex capturing the callstack_user and callstack_kernel context |
| 109 | user_cs_rexp = ".*callstack_user\ \=\ \[(.*)\]\ .*\}, \{.*\}" |
| 110 | kernel_cs_rexp = ".*callstack_kernel\ \=\ \[(.*)\]\ .*\}, \{.*\}" |
| 111 | |
| 112 | |
| 113 | def main(): |
| 114 | """ |
| 115 | Reads a line from stdin and expect it to be a wellformed Babeltrace CLI |
| 116 | output containing containing a callstack context of the domain passed |
| 117 | as argument. |
| 118 | """ |
| 119 | expected_callstack = set() |
| 120 | recorded_callstack = set() |
| 121 | cs_type = None |
| 122 | |
| 123 | if len(sys.argv) <= 2: |
| 124 | print(sys.argv) |
| 125 | raise ValueError( |
| 126 | "USAGE: ./{} (--kernel|--user EXE) FUNC-NAMES".format(sys.argv[0]) |
| 127 | ) |
| 128 | |
| 129 | # If the `--user` option is passed, save the next argument as the path |
| 130 | # to the executable |
| 131 | argc = 1 |
| 132 | executable = None |
| 133 | if sys.argv[argc] in "--kernel": |
| 134 | rexp = kernel_cs_rexp |
| 135 | cs_type = "kernel" |
| 136 | elif sys.argv[argc] in "--user": |
| 137 | rexp = user_cs_rexp |
| 138 | cs_type = "user" |
| 139 | argc += 1 |
| 140 | executable = sys.argv[argc] |
| 141 | else: |
| 142 | raise Exception("Unknown domain") |
| 143 | |
| 144 | argc += 1 |
| 145 | |
| 146 | # Extract the function names that are expected to be found call stack of |
| 147 | # the current events |
| 148 | for func in sys.argv[argc:]: |
| 149 | expected_callstack.add(func) |
| 150 | |
| 151 | # Read the tested line for STDIN |
| 152 | event_line = None |
| 153 | for line in sys.stdin: |
| 154 | event_line = line |
| 155 | break |
| 156 | |
| 157 | # Extract the userspace callstack context of the event |
| 158 | m = re.match(rexp, event_line) |
| 159 | |
| 160 | # If there is no match, exit with error |
| 161 | if m is None: |
| 162 | raise re.error("Callstack not found in event line") |
| 163 | else: |
| 164 | raw_callstack = str(m.group(1)) |
| 165 | if cs_type in "user": |
| 166 | recorded_callstack = extract_user_func_names(executable, raw_callstack) |
| 167 | elif cs_type in "kernel": |
| 168 | recorded_callstack = extract_kernel_func_names(raw_callstack) |
| 169 | else: |
| 170 | raise Exception("Unknown domain") |
| 171 | |
| 172 | # Verify that all expected function are present in the callstack |
| 173 | for e in expected_callstack: |
| 174 | if e not in recorded_callstack: |
| 175 | raise Exception("Expected function name not found in recorded callstack") |
| 176 | |
| 177 | sys.exit(0) |
| 178 | |
| 179 | |
| 180 | if __name__ == "__main__": |
| 181 | main() |