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| author | hexcoder- <heiko@hexco.de> | 2021-05-30 12:43:30 +0200 |
|---|---|---|
| committer | hexcoder- <heiko@hexco.de> | 2021-05-30 12:43:30 +0200 |
| commit | eb74a7a8004e8281cda62525bbc1f3bbe7f5d9da (patch) | |
| tree | a951b63f4f038805fdf39eb6d8f4c70dc8e82f28 /instrumentation | |
| parent | c9539aa6b7fb4b9d2dae6c65446c525375388c2f (diff) | |
| download | afl++-eb74a7a8004e8281cda62525bbc1f3bbe7f5d9da.tar.gz | |
add documentation for AFL_LLVM_THREADSAFE_INST
Diffstat (limited to 'instrumentation')
| -rw-r--r-- | instrumentation/README.llvm.md | 4 | ||||
| -rw-r--r-- | instrumentation/README.neverzero.md | 5 |
2 files changed, 9 insertions, 0 deletions
diff --git a/instrumentation/README.llvm.md b/instrumentation/README.llvm.md index adce6c1d..a9d51829 100644 --- a/instrumentation/README.llvm.md +++ b/instrumentation/README.llvm.md @@ -144,6 +144,10 @@ is not optimal and was only fixed in llvm 9. You can set this with AFL_LLVM_NOT_ZERO=1 See [README.neverzero.md](README.neverzero.md) +Support for thread safe counters has been added for mode LLVM CLASSIC. +Activate it with `AFL_LLVM_THREADSAFE_INST=1`. The tradeoff is better precision in +multi threaded apps for a slightly higher instrumentation overhead. + ## 4) Snapshot feature To speed up fuzzing you can use a linux loadable kernel module which enables diff --git a/instrumentation/README.neverzero.md b/instrumentation/README.neverzero.md index 49104e00..06334eab 100644 --- a/instrumentation/README.neverzero.md +++ b/instrumentation/README.neverzero.md @@ -33,3 +33,8 @@ AFL_LLVM_SKIP_NEVERZERO=1 ``` If the target does not have extensive loops or functions that are called a lot then this can give a small performance boost. + +Please note that the default counter implementations are not thread safe! + +Support for thread safe counters in mode LLVM CLASSIC can be activated with setting +`AFL_LLVM_THREADSAFE_INST=1`. \ No newline at end of file |