LLFI

LLFI is an LLVM based fault injection tool, that injects faults into the LLVM IR of the application source code. The faults can be injected into specific program points, and the effect can be easily tracked back to the source code. LLFI is typically used to map fault characteristics back to source code, and hence understand source level or program characteristics for various kinds of fault outcomes.

Please join the following Google Groups for information related to LLFI development: llfi-development@googlegroups.com

Dependencies

32/64 bit Linux or OS X
CMake (minimum v2.8)
Python
Python YAML library (PyYAML)
Clang v3.3
LLVM v3.3, built with CMake * Build llvm-3.3 WITH CMAKE using flag -DLLVM_REQUIRES_RTTI=1. Instructions * Remember to run make in the llvm build directory after running cmake.

Building

Run ./setup --help for build instructions.

$ ./setup --help

Usage: setup OPTIONS
List of options:
  -LLVM_DST_ROOT <LLVM CMake build root dir>:
      Make sure you build LLVM with CMake and pass build root directory here
  -LLVM_SRC_ROOT <LLVM source root dir>
  -LLVM_GXX_BIN_DIR <clang's parent dir> (optional):
      You don't need to set it if it is in system path
  -LLFI_BUILD_ROOT <path where you want to build LLFI>

--help(-h): show help information

Here is a sample build command if clang is already in $PATH:

./setup -LLFI_BUILD_ROOT $BUILD/LLFI -LLVM_SRC_ROOT $SRC/llvm-3.3 -LLVM_DST_ROOT $BUILD/llvm-3.3

Running

You can use example programs in the test_programs directory to test LLFI, including:

min: find the minimum number from five input numbers
factorial: compute the factorial of 6
sum: compute the sum of positive integers between 1 and N

Example program: factorial

Go to test_programs/factorial.
Build a single IR file with the LLFI tool compiletoIR
```
<LLFI_BUILD_ROOT>/tools/compiletoIR --readable -o factorial.ll factorial.c
```
Alternatively, you can build your own IR file with clang.
Instrument factorial with calls to LLFI libraries and create executables under llfi directory
```
<LLFI_BUILD_ROOT>/bin/instrument --readable factorial.ll
```
Run factorial executable with profiling functions instrumented
```
<LLFI_BUILD_ROOT>/bin/profile llfi/factorial-profiling.exe 6
```
In file llfi/baseline/golden_std_output, you should be able to see 720

Run factorial executable with fault injection functions instrumented

<LLFI_BUILD_ROOT>/bin/injectfault llfi/factorial-faultinjection.exe 6

Results

After fault injection, output from LLFI and the tested application can be found in the llfi directory.

Directory	Contents
std_output	Piped STDOUT from the tested application
llfi_stat_output	Fault injection statistics
error_output	Failure reports (program crashes, hangs, etc.)

References