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Diffstat (limited to 'instrumentation/README.lto.md')
| -rw-r--r-- | instrumentation/README.lto.md | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/instrumentation/README.lto.md b/instrumentation/README.lto.md index abdbd2ac..a2814173 100644 --- a/instrumentation/README.lto.md +++ b/instrumentation/README.lto.md @@ -60,7 +60,12 @@ AUTODICTIONARY: 11 strings found ## Getting llvm 11+ -### Installing llvm from the llvm repository (version 11) +### Installing llvm version 11 + +llvm 11 should be available in all current Linux repositories. +If you use an outdated Linux distribution read the next section. + +### Installing llvm from the llvm repository (version 12) Installing the llvm snapshot builds is easy and mostly painless: @@ -73,11 +78,11 @@ then add the pgp key of llvm and install the packages: ``` wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add - apt-get update && apt-get upgrade -y -apt-get install -y clang-11 clang-tools-11 libc++1-11 libc++-11-dev \ - libc++abi1-11 libc++abi-11-dev libclang1-11 libclang-11-dev \ - libclang-common-11-dev libclang-cpp11 libclang-cpp11-dev liblld-11 \ - liblld-11-dev liblldb-11 liblldb-11-dev libllvm11 libomp-11-dev \ - libomp5-11 lld-11 lldb-11 llvm-11 llvm-11-dev llvm-11-runtime llvm-11-tools +apt-get install -y clang-12 clang-tools-12 libc++1-12 libc++-12-dev \ + libc++abi1-12 libc++abi-12-dev libclang1-12 libclang-12-dev \ + libclang-common-12-dev libclang-cpp12 libclang-cpp12-dev liblld-12 \ + liblld-12-dev liblldb-12 liblldb-12-dev libllvm12 libomp-12-dev \ + libomp5-12 lld-12 lldb-12 llvm-12 llvm-12-dev llvm-12-runtime llvm-12-tools ``` ### Building llvm yourself (version 12) @@ -120,16 +125,22 @@ While compiling, a dictionary based on string comparisons is automatically generated and put into the target binary. This dictionary is transfered to afl-fuzz on start. This improves coverage statistically by 5-10% :) +Note that if for any reason you do not want to use the autodictionary feature +then just set the environment variable `AFL_NO_AUTODICT` when starting afl-fuzz. + ## Fixed memory map -To speed up fuzzing, it is possible to set a fixed shared memory map. +To speed up fuzzing a little bit more, it is possible to set a fixed shared +memory map. Recommended is the value 0x10000. + In most cases this will work without any problems. However if a target uses early constructors, ifuncs or a deferred forkserver this can crash the target. -On unusual operating systems/processors/kernels or weird libraries this might -fail so to change the fixed address at compile time set -AFL_LLVM_MAP_ADDR with a better value (a value of 0 or empty sets the map address -to be dynamic - the original afl way, which is slower). + +Also on unusual operating systems/processors/kernels or weird libraries the +recommended 0x10000 address might not work, so then change the fixed address. + +To enable this feature set AFL_LLVM_MAP_ADDR with the address. ## Document edge IDs |