196 lines
7.3 KiB
Python
Executable File
196 lines
7.3 KiB
Python
Executable File
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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"""
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This takes a crashing qtest trace and tries to remove superflous operations
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"""
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import sys
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import os
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import subprocess
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import time
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import struct
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QEMU_ARGS = None
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QEMU_PATH = None
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TIMEOUT = 5
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CRASH_TOKEN = None
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write_suffix_lookup = {"b": (1, "B"),
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"w": (2, "H"),
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"l": (4, "L"),
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"q": (8, "Q")}
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def usage():
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sys.exit("""\
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Usage: QEMU_PATH="/path/to/qemu" QEMU_ARGS="args" {} input_trace output_trace
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By default, will try to use the second-to-last line in the output to identify
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whether the crash occred. Optionally, manually set a string that idenitifes the
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crash by setting CRASH_TOKEN=
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""".format((sys.argv[0])))
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deduplication_note = """\n\
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Note: While trimming the input, sometimes the mutated trace triggers a different
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type crash but indicates the same bug. Under this situation, our minimizer is
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incapable of recognizing and stopped from removing it. In the future, we may
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use a more sophisticated crash case deduplication method.
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\n"""
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def check_if_trace_crashes(trace, path):
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with open(path, "w") as tracefile:
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tracefile.write("".join(trace))
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rc = subprocess.Popen("timeout -s 9 {timeout}s {qemu_path} {qemu_args} 2>&1\
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< {trace_path}".format(timeout=TIMEOUT,
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qemu_path=QEMU_PATH,
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qemu_args=QEMU_ARGS,
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trace_path=path),
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shell=True,
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stdin=subprocess.PIPE,
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stdout=subprocess.PIPE,
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encoding="utf-8")
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global CRASH_TOKEN
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if CRASH_TOKEN is None:
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try:
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outs, _ = rc.communicate(timeout=5)
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CRASH_TOKEN = " ".join(outs.splitlines()[-2].split()[0:3])
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except subprocess.TimeoutExpired:
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print("subprocess.TimeoutExpired")
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return False
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print("Identifying Crashes by this string: {}".format(CRASH_TOKEN))
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global deduplication_note
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print(deduplication_note)
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return True
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for line in iter(rc.stdout.readline, ""):
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if "CLOSED" in line:
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return False
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if CRASH_TOKEN in line:
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return True
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print("\nWarning:")
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print(" There is no 'CLOSED'or CRASH_TOKEN in the stdout of subprocess.")
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print(" Usually this indicates a different type of crash.\n")
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return False
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def minimize_trace(inpath, outpath):
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global TIMEOUT
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with open(inpath) as f:
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trace = f.readlines()
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start = time.time()
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if not check_if_trace_crashes(trace, outpath):
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sys.exit("The input qtest trace didn't cause a crash...")
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end = time.time()
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print("Crashed in {} seconds".format(end-start))
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TIMEOUT = (end-start)*5
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print("Setting the timeout for {} seconds".format(TIMEOUT))
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i = 0
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newtrace = trace[:]
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remove_step = 1
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while i < len(newtrace):
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# 1.) Try to remove lines completely and reproduce the crash.
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# If it works, we're done.
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if (i+remove_step) >= len(newtrace):
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remove_step = 1
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prior = newtrace[i:i+remove_step]
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for j in range(i, i+remove_step):
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newtrace[j] = ""
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print("Removing {lines} ...\n".format(lines=prior))
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if check_if_trace_crashes(newtrace, outpath):
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i += remove_step
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# Double the number of lines to remove for next round
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remove_step *= 2
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continue
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# Failed to remove multiple IOs, fast recovery
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if remove_step > 1:
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for j in range(i, i+remove_step):
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newtrace[j] = prior[j-i]
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remove_step = 1
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continue
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newtrace[i] = prior[0] # remove_step = 1
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# 2.) Try to replace write{bwlq} commands with a write addr, len
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# command. Since this can require swapping endianness, try both LE and
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# BE options. We do this, so we can "trim" the writes in (3)
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if (newtrace[i].startswith("write") and not
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newtrace[i].startswith("write ")):
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suffix = newtrace[i].split()[0][-1]
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assert(suffix in write_suffix_lookup)
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addr = int(newtrace[i].split()[1], 16)
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value = int(newtrace[i].split()[2], 16)
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for endianness in ['<', '>']:
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data = struct.pack("{end}{size}".format(end=endianness,
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size=write_suffix_lookup[suffix][1]),
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value)
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newtrace[i] = "write {addr} {size} 0x{data}\n".format(
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addr=hex(addr),
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size=hex(write_suffix_lookup[suffix][0]),
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data=data.hex())
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if(check_if_trace_crashes(newtrace, outpath)):
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break
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else:
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newtrace[i] = prior[0]
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# 3.) If it is a qtest write command: write addr len data, try to split
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# it into two separate write commands. If splitting the data operand
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# from length/2^n bytes to the left does not work, try to move the pivot
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# to the right side, then add one to n, until length/2^n == 0. The idea
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# is to prune unneccessary bytes from long writes, while accommodating
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# arbitrary MemoryRegion access sizes and alignments.
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# This algorithm will fail under some rare situations.
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# e.g., xxxxxxxxxuxxxxxx (u is the unnecessary byte)
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if newtrace[i].startswith("write "):
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addr = int(newtrace[i].split()[1], 16)
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length = int(newtrace[i].split()[2], 16)
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data = newtrace[i].split()[3][2:]
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if length > 1:
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leftlength = int(length/2)
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rightlength = length - leftlength
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newtrace.insert(i+1, "")
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power = 1
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while leftlength > 0:
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newtrace[i] = "write {addr} {size} 0x{data}\n".format(
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addr=hex(addr),
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size=hex(leftlength),
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data=data[:leftlength*2])
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newtrace[i+1] = "write {addr} {size} 0x{data}\n".format(
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addr=hex(addr+leftlength),
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size=hex(rightlength),
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data=data[leftlength*2:])
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if check_if_trace_crashes(newtrace, outpath):
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break
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# move the pivot to right side
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if leftlength < rightlength:
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rightlength, leftlength = leftlength, rightlength
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continue
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power += 1
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leftlength = int(length/pow(2, power))
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rightlength = length - leftlength
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if check_if_trace_crashes(newtrace, outpath):
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i -= 1
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else:
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newtrace[i] = prior[0]
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del newtrace[i+1]
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i += 1
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check_if_trace_crashes(newtrace, outpath)
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if __name__ == '__main__':
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if len(sys.argv) < 3:
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usage()
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QEMU_PATH = os.getenv("QEMU_PATH")
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QEMU_ARGS = os.getenv("QEMU_ARGS")
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if QEMU_PATH is None or QEMU_ARGS is None:
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usage()
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# if "accel" not in QEMU_ARGS:
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# QEMU_ARGS += " -accel qtest"
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CRASH_TOKEN = os.getenv("CRASH_TOKEN")
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QEMU_ARGS += " -qtest stdio -monitor none -serial none "
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minimize_trace(sys.argv[1], sys.argv[2])
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