Converts a level 2 BPF verifier log into an annotated control flow graph (CFG) and outputs it in DOT format. BPF instructions and corresponding C lines are grouped into basic blocks, with each instruction annotated by the number of times the verifier has visited it.

Output Conventions:

• More intense basic block colors indicate more frequent visits.
• Blue edges represent true branches in conditionals.
• Bold edges indicate back-edges.

Usage:

log2dot [-h] [-o dot_file] [log_file]

Parameters:

• log_file: A verifier log produced with BPF_LOG_LEVEL2. If omitted, input is read from stdin.
• dot_file: The output file name. If omitted, output is written to stdout.

Dependencies:

• The pydot package is required to generate the graph. It can be installed via:

  pip3 install pydot
  

  or using a distribution package manager, e.g.:

  dnf install python3-pydot  # Fedora
  

Example Usage:

$ veristat -vl2 -f iter_nested_deeply_iters iters.bpf.o > test.log
$ log2dot.py test.log | xdot -

Here, xdot is used for interactive visualization of the generated DOT file.