From: Victor Chibotaru <[email protected]> The flag enables Clang instrumentation of comparison operations (currently not supported by GCC). This instrumentation is needed by the new KCOV device to collect comparison operands.
Signed-off-by: Victor Chibotaru <[email protected]> Signed-off-by: Alexander Potapenko <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Andrey Konovalov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Alexander Popov <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Kees Cook <[email protected]> Cc: Vegard Nossum <[email protected]> Cc: Quentin Casasnovas <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] --- Clang instrumentation: https://clang.llvm.org/docs/SanitizerCoverage.html#tracing-data-flow v2: - updated KCOV_ENABLE_COMPARISONS description --- Makefile | 5 +++-- lib/Kconfig.debug | 10 ++++++++++ scripts/Makefile.lib | 6 ++++++ 3 files changed, 19 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 2835863bdd5a..c2a8e56df748 100644 --- a/Makefile +++ b/Makefile @@ -374,7 +374,7 @@ AFLAGS_KERNEL = LDFLAGS_vmlinux = CFLAGS_GCOV := -fprofile-arcs -ftest-coverage -fno-tree-loop-im $(call cc-disable-warning,maybe-uninitialized,) CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) - +CFLAGS_KCOV_COMPS := $(call cc-option,-fsanitize-coverage=trace-cmp,) # Use USERINCLUDE when you must reference the UAPI directories only. USERINCLUDE := \ @@ -420,7 +420,7 @@ export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS -export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KCOV CFLAGS_KASAN CFLAGS_UBSAN +export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KCOV CFLAGS_KCOV_COMPS CFLAGS_KASAN CFLAGS_UBSAN export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL @@ -822,6 +822,7 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init) KBUILD_ARFLAGS := $(call ar-option,D) include scripts/Makefile.kasan +include scripts/Makefile.kcov include scripts/Makefile.extrawarn include scripts/Makefile.ubsan diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 2689b7c50c52..a10eb4e34719 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -759,6 +759,16 @@ config KCOV For more details, see Documentation/dev-tools/kcov.rst. +config KCOV_ENABLE_COMPARISONS + bool "Enable comparison operands collection by KCOV" + depends on KCOV + default n + help + KCOV also exposes operands of every comparison in the instrumented + code along with operand sizes and PCs of the comparison instructions. + These operands can be used by fuzzing engines to improve the quality + of fuzzing coverage. + config KCOV_INSTRUMENT_ALL bool "Instrument all code by default" depends on KCOV diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 5e975fee0f5b..7ddd5932c832 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -142,6 +142,12 @@ _c_flags += $(if $(patsubst n%,, \ $(CFLAGS_KCOV)) endif +ifeq ($(CONFIG_KCOV_ENABLE_COMPARISONS),y) +_c_flags += $(if $(patsubst n%,, \ + $(KCOV_INSTRUMENT_$(basetarget).o)$(KCOV_INSTRUMENT)$(CONFIG_KCOV_INSTRUMENT_ALL)), \ + $(CFLAGS_KCOV_COMPS)) +endif + # If building the kernel in a separate objtree expand all occurrences # of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/'). -- 2.14.2.920.gcf0c67979c-goog
