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USAGE.md

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Plugin: llvm_trace

Summary

The llvm_trace plugin creates an instruction trace from a replay. This trace includes not only the instructions executed, lifted to LLVM, but also the dynamic values necessary for following dataflow throughout the trace, including all memory loads and stores, and the result of all branch operations taken in LLVM code.

These traces can then be processed by other tools; for example, the dynslice tool performs dynamic slicing on

llvm_trace produces several files that together make up a trace. In its legacy log format, it produces:

  • $BASEDIR/llvm-memlog.log : the memory operations and dynamic values needed to reconstruct dataflow
  • $BASEDIR/llvm-functions.log : a list of LLVM basic blocks executed
  • $BASEDIR/llvm-mod.bc : the LLVM bitcode for all basic blocks executed

If the newer TUBTF (Tim's Uncomplicated Binary Trace Format) format is used (by specifying the tubtf option), then the files written will be:

  • $BASEDIR/tubtf.log : the trace and dynamic value log, in TUBTF format
  • $BASEDIR/llvm-mod.bc : the LLVM bitcode for all basic blocks executed

Here, $BASEDIR refers to the base directory specified with the base option.

For more information on TUBTF, see tubtf.h in the qemu/panda subdirectory.

Arguments

  • base: string, defaults to "/tmp". The directory where trace logs should be stored.
  • tubtf: boolean, whether to use use TUBTF format for logging

Dependencies

None.

APIs and Callbacks

None.

Example

To create a trace in the current directory in TUBTF format:

$PANDA_PATH/x86_64-softmmu/qemu-system-x86_64 -replay foo \
    -panda llvm_trace:base=.,tubtf