From eb74a7a8004e8281cda62525bbc1f3bbe7f5d9da Mon Sep 17 00:00:00 2001 From: hexcoder- Date: Sun, 30 May 2021 12:43:30 +0200 Subject: add documentation for AFL_LLVM_THREADSAFE_INST --- instrumentation/README.neverzero.md | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'instrumentation/README.neverzero.md') 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 -- cgit v1.2.3 From b246de789105750558f3d6f884ba61e54cb98441 Mon Sep 17 00:00:00 2001 From: hexcoder- Date: Sun, 30 May 2021 15:25:10 +0200 Subject: add support for AFL_LLVM_THREADSAFE_INST to other LLVM passes --- instrumentation/README.neverzero.md | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'instrumentation/README.neverzero.md') diff --git a/instrumentation/README.neverzero.md b/instrumentation/README.neverzero.md index 06334eab..9bcae324 100644 --- a/instrumentation/README.neverzero.md +++ b/instrumentation/README.neverzero.md @@ -16,11 +16,12 @@ at a very little cost (one instruction per edge). (The alternative of saturated counters has been tested also and proved to be inferior in terms of path discovery.) -This is implemented in afl-gcc and afl-gcc-fast, however for llvm_mode this is optional if -the llvm version is below 9 - as there is a perfomance bug that is only fixed -in version 9 and onwards. +This is implemented in afl-gcc and afl-gcc-fast, however for llvm_mode this is +optional if multithread safe counters are selected or the llvm version is below +9 - as there are severe performance costs in these cases. -If you want to enable this for llvm versions below 9 then set +If you want to enable this for llvm versions below 9 or thread safe counters +then set ``` export AFL_LLVM_NOT_ZERO=1 -- cgit v1.2.3