From: Victor Chibotaru <tch...@google.com> 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 <tch...@google.com> Signed-off-by: Alexander Potapenko <gli...@google.com> Cc: Dmitry Vyukov <dvyu...@google.com> Cc: Andrey Konovalov <andreyk...@google.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Mark Rutland <mark.rutl...@arm.com> Cc: Alexander Popov <alex.po...@linux.com> Cc: Andrey Ryabinin <aryabi...@virtuozzo.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Vegard Nossum <vegard.nos...@oracle.com> Cc: Quentin Casasnovas <quentin.casasno...@oracle.com> Cc: syzkal...@googlegroups.com Cc: linux...@kvack.org Cc: linux-kernel@vger.kernel.org --- Clang instrumentation: https://clang.llvm.org/docs/SanitizerCoverage.html#tracing-data-flow v3: - Andrey Ryabinin's comments: reinstated scripts/Makefile.kcov and moved CFLAGS_KCOV there, dropped CFLAGS_KCOV_COMPS - allow building with GCC v2: - updated KCOV_ENABLE_COMPARISONS description --- Makefile | 3 +-- lib/Kconfig.debug | 10 ++++++++++ scripts/Makefile.kcov | 7 +++++++ scripts/Makefile.lib | 6 ++++++ 4 files changed, 24 insertions(+), 2 deletions(-) create mode 100644 scripts/Makefile.kcov diff --git a/Makefile b/Makefile index 2835863bdd5a..43f642167d68 100644 --- a/Makefile +++ b/Makefile @@ -373,8 +373,6 @@ CFLAGS_KERNEL = AFLAGS_KERNEL = LDFLAGS_vmlinux = CFLAGS_GCOV := -fprofile-arcs -ftest-coverage -fno-tree-loop-im $(call cc-disable-warning,maybe-uninitialized,) -CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) - # Use USERINCLUDE when you must reference the UAPI directories only. USERINCLUDE := \ @@ -657,6 +655,7 @@ ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLA KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO endif +include scripts/Makefile.kcov include scripts/Makefile.gcc-plugins ifdef CONFIG_READABLE_ASM 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.kcov b/scripts/Makefile.kcov new file mode 100644 index 000000000000..5cc72037e423 --- /dev/null +++ b/scripts/Makefile.kcov @@ -0,0 +1,7 @@ +ifdef CONFIG_KCOV +CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) +ifeq ($(CONFIG_KCOV_ENABLE_COMPARISONS),y) +CFLAGS_KCOV += $(call cc-option,-fsanitize-coverage=trace-cmp,) +endif + +endif 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
