2 files changed, 12 insertions, 1 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f07842e2d69f..cc02f282d05b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -719,6 +719,17 @@ config KCOV
 
           For more details, see Documentation/kcov.txt.
 
+config KCOV_INSTRUMENT_ALL
+        bool "Instrument all code by default"
+        depends on KCOV
+        default y if KCOV
+        help
+          If you are doing generic system call fuzzing (like e.g. syzkaller),
+          then you will want to instrument the whole kernel and you should
+          say y here. If you are doing more targeted fuzzing (like e.g.
+          filesystem fuzzing with AFL) then you will want to enable coverage
+          for more specific subsets of files, and should say n here.
+
 config DEBUG_SHIRQ
         bool "Debug shared IRQ handlers"
         depends on DEBUG_KERNEL
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index e7df0f5db7ec..76494e15417b 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -138,7 +138,7 @@ endif
 
 ifeq ($(CONFIG_KCOV),y)
 _c_flags += $(if $(patsubst n%,, \
-        $(KCOV_INSTRUMENT_$(basetarget).o)$(KCOV_INSTRUMENT)y), \
+        $(KCOV_INSTRUMENT_$(basetarget).o)$(KCOV_INSTRUMENT)$(CONFIG_KCOV_INSTRUMENT_ALL)), \
         $(CFLAGS_KCOV))
 endif