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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""
+Use this to convert qtest log info from a generic fuzzer input into a qtest
+trace that you can feed into a standard qemu-system process. Example usage:
+
+QEMU_FUZZ_ARGS="-machine q35,accel=qtest" QEMU_FUZZ_OBJECTS="*" \
+ ./i386-softmmu/qemu-fuzz-i386 --fuzz-target=general-pci-fuzz
+# .. Finds some crash
+QTEST_LOG=1 FUZZ_SERIALIZE_QTEST=1 \
+QEMU_FUZZ_ARGS="-machine q35,accel=qtest" QEMU_FUZZ_OBJECTS="*" \
+ ./i386-softmmu/qemu-fuzz-i386 --fuzz-target=general-pci-fuzz
+ /path/to/crash 2> qtest_log_output
+scripts/oss-fuzz/reorder_fuzzer_qtest_trace.py qtest_log_output > qtest_trace
+./i386-softmmu/qemu-fuzz-i386 -machine q35,accel=qtest \
+ -qtest stdin < qtest_trace
+
+### Details ###
+
+Some fuzzer make use of hooks that allow us to populate some memory range, just
+before a DMA read from that range. This means that the fuzzer can produce
+activity that looks like:
+ [start] read from mmio addr
+ [end] read from mmio addr
+ [start] write to pio addr
+ [start] fill a DMA buffer just in time
+ [end] fill a DMA buffer just in time
+ [start] fill a DMA buffer just in time
+ [end] fill a DMA buffer just in time
+ [end] write to pio addr
+ [start] read from mmio addr
+ [end] read from mmio addr
+
+We annotate these "nested" DMA writes, so with QTEST_LOG=1 the QTest trace
+might look something like:
+[R +0.028431] readw 0x10000
+[R +0.028434] outl 0xc000 0xbeef # Triggers a DMA read from 0xbeef and 0xbf00
+[DMA][R +0.034639] write 0xbeef 0x2 0xAAAA
+[DMA][R +0.034639] write 0xbf00 0x2 0xBBBB
+[R +0.028431] readw 0xfc000
+
+This script would reorder the above trace so it becomes:
+readw 0x10000
+write 0xbeef 0x2 0xAAAA
+write 0xbf00 0x2 0xBBBB
+outl 0xc000 0xbeef
+readw 0xfc000
+
+I.e. by the time, 0xc000 tries to read from DMA, those DMA buffers have already
+been set up, removing the need for the DMA hooks. We can simply provide this
+reordered trace via -qtest stdio to reproduce the input
+
+Note: this won't work for traces where the device tries to read from the same
+DMA region twice in between MMIO/PIO commands. E.g:
+ [R +0.028434] outl 0xc000 0xbeef
+ [DMA][R +0.034639] write 0xbeef 0x2 0xAAAA
+ [DMA][R +0.034639] write 0xbeef 0x2 0xBBBB
+
+The fuzzer will annotate suspected double-fetches with [DOUBLE-FETCH]. This
+script looks for these tags and warns the users that the resulting trace might
+not reproduce the bug.
+"""
+
+import sys
+
+__author__ = "Alexander Bulekov <alxndr@bu.edu>"
+__copyright__ = "Copyright (C) 2020, Red Hat, Inc."
+__license__ = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Alexander Bulekov"
+__email__ = "alxndr@bu.edu"
+
+
+def usage():
+ sys.exit("Usage: {} /path/to/qtest_log_output".format((sys.argv[0])))
+
+
+def main(filename):
+ with open(filename, "r") as f:
+ trace = f.readlines()
+
+ # Leave only lines that look like logged qtest commands
+ trace[:] = [x.strip() for x in trace if "[R +" in x
+ or "[S +" in x and "CLOSED" not in x]
+
+ for i in range(len(trace)):
+ if i+1 < len(trace):
+ if "[DMA]" in trace[i+1]:
+ if "[DOUBLE-FETCH]" in trace[i+1]:
+ sys.stderr.write("Warning: Likely double fetch on line {}.\n"
+ "There will likely be problems reproducing "
+ "behavior with the "
+ "resulting qtest trace\n\n".format(i+1))
+ trace[i], trace[i+1] = trace[i+1], trace[i]
+ for line in trace:
+ print(line.split("]")[-1].strip())
+
+
+if __name__ == '__main__':
+ if len(sys.argv) == 1:
+ usage()
+ main(sys.argv[1])