diff options
| -rw-r--r-- | instrumentation/README.lto.md | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/instrumentation/README.lto.md b/instrumentation/README.lto.md index 38252308..3e9d7585 100644 --- a/instrumentation/README.lto.md +++ b/instrumentation/README.lto.md @@ -146,22 +146,22 @@ afl-clang-lto instead of shared libraries! To make instrumented shared libraries work with afl-clang-lto you have to do quite some extra steps. -Every shared library you want to instrument has to be individually compiled- +Every shared library you want to instrument has to be individually compiled. The environment variable `AFL_LLVM_LTO_DONTWRITEID=1` has to be set during compilation. Additionally the environment variable `AFL_LLVM_LTO_STARTID` has to be set to -the combined edge values of all previous compiled instrumented shared +the added edge count values of all previous compiled instrumented shared libraries for that target. E.g. for the first shared library this would be `AFL_LLVM_LTO_STARTID=0` and afl-clang-lto will then report how many edges have been instrumented (let's say it reported 1000 instrumented edges). The second shared library then has to be set to that value -(`AFL_LLVM_LTO_STARTID=1000` in our example), the third to all previous -combined, etc. +(`AFL_LLVM_LTO_STARTID=1000` in our example), for the third to all previous +counts added, etc. The final program compilation step then may *not* have `AFL_LLVM_LTO_DONTWRITEID` -set, and `AFL_LLVM_LTO_STARTID` must be set to all combined edges of all shared -libaries it will be linked to. +set, and `AFL_LLVM_LTO_STARTID` must be set to all edge counts added of all shared +libraries it will be linked to. This is quite some hands-on work, so better stay away from instrumenting shared libraries :-) |