From 2af9a634d6585709a01edde5ee6aa08b7b3fa9f4 Mon Sep 17 00:00:00 2001 From: vanhauser-thc Date: Wed, 26 May 2021 22:51:37 +0200 Subject: [PATCH] fix cmpcov doc for qemu --- qemu_mode/README.md | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/qemu_mode/README.md b/qemu_mode/README.md index 38cb5ba6..d28479d9 100644 --- a/qemu_mode/README.md +++ b/qemu_mode/README.md @@ -110,22 +110,23 @@ takes priority over any included ranges or AFL_INST_LIBS. CompareCoverage is a sub-instrumentation with effects similar to laf-intel. -The environment variable that enables QEMU CompareCoverage is AFL_COMPCOV_LEVEL. -There is also ./libcompcov/ which implements CompareCoverage for *cmp functions -(splitting memcmp, strncmp, etc. to make these conditions easier solvable by -afl-fuzz). +You have to set `AFL_PRELOAD=/path/to/libcompcov.so` together with +setting the AFL_COMPCOV_LEVEL you want to enable it. AFL_COMPCOV_LEVEL=1 is to instrument comparisons with only immediate -values / read-only memory. AFL_COMPCOV_LEVEL=2 instruments all -comparison instructions and memory comparison functions when libcompcov -is preloaded. -AFL_COMPCOV_LEVEL=3 has the same effects of AFL_COMPCOV_LEVEL=2 but enables also -the instrumentation of the floating-point comparisons on x86 and x86_64 (experimental). +values / read-only memory. + +AFL_COMPCOV_LEVEL=2 instruments all comparison instructions and memory +comparison functions when libcompcov is preloaded. + +AFL_COMPCOV_LEVEL=3 has the same effects of AFL_COMPCOV_LEVEL=2 but enables +also the instrumentation of the floating-point comparisons on x86 and x86_64 +(experimental). Integer comparison instructions are currently instrumented only on the x86, x86_64, arm and aarch64 targets. -Highly recommended. +Recommended, but not as good as CMPLOG mode (see below). ## 8) CMPLOG mode