| Message ID | 1527499328-13213-28-git-send-email-yamada.masahiro@socionext.com |
|---|---|
| State | New |
| Headers | show |
| Series | kconfig: move compiler capability tests to Kconfig | expand |
2018-05-28 18:22 GMT+09:00 Masahiro Yamada <yamada.masahiro@socionext.com>: > As Documentation/kbuild/kconfig-language.txt notes, 'select' should be > be used with care - it forces a lower limit of another symbol, ignoring > the dependency. Currently, KCOV can select GCC_PLUGINS even if arch > does not select HAVE_GCC_PLUGINS. This could cause the unmet direct > dependency. > > Now that Kconfig can test compiler capability, let's handle this in a > more sophisticated way. > > There are two ways to enable KCOV; use the compiler that natively > supports -fsanitize-coverage=trace-pc, or build the SANCOV plugin if > the compiler has ability to build GCC plugins. Hence, the correct > dependency for KCOV is: > > depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS > > You do not need to build the SANCOV plugin if the compiler already > supports -fsanitize-coverage=trace-pc. Hence, the select should be: > > select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC > > With this, GCC_PLUGIN_SANCOV is selected only when necessary, so > scripts/Makefile.gcc-plugins can be cleaner. > > I also cleaned up Kconfig and scripts/Makefile.kcov as well. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > Reviewed-by: Kees Cook <keescook@chromium.org> > --- > > Changes in v5: None > Changes in v4: None > Changes in v3: > - Replace the previous 'select -> imply' patch with > a new approach > > Changes in v2: > - Drop depends on GCC_VERSION > > Makefile | 2 +- > lib/Kconfig.debug | 11 +++++++---- > scripts/Makefile.gcc-plugins | 6 +----- > scripts/Makefile.kcov | 10 ++++++---- > 4 files changed, 15 insertions(+), 14 deletions(-) > > diff --git a/Makefile b/Makefile > index 80e0800..4b5a17a 100644 > --- a/Makefile > +++ b/Makefile > @@ -626,7 +626,7 @@ all: vmlinux > CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \ > $(call cc-option,-fno-tree-loop-im) \ > $(call cc-disable-warning,maybe-uninitialized,) > -export CFLAGS_GCOV CFLAGS_KCOV > +export CFLAGS_GCOV > > # The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default > # values of the respective KBUILD_* variables > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index c40c7b7..b76cab2 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -736,12 +736,15 @@ config ARCH_HAS_KCOV > only for x86_64. KCOV requires testing on other archs, and most likely > disabling of instrumentation for some early boot code. > > +config CC_HAS_SANCOV_TRACE_PC > + def_bool $(cc-option,-fsanitize-coverage=trace-pc) > + > config KCOV > bool "Code coverage for fuzzing" > depends on ARCH_HAS_KCOV > + depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS > select DEBUG_FS > - select GCC_PLUGINS if !COMPILE_TEST > - select GCC_PLUGIN_SANCOV if !COMPILE_TEST > + select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC > help > KCOV exposes kernel code coverage information in a form suitable > for coverage-guided fuzzing (randomized testing). > @@ -755,7 +758,7 @@ config KCOV > config KCOV_ENABLE_COMPARISONS > bool "Enable comparison operands collection by KCOV" > depends on KCOV > - default n > + depends on $(cc-option,-fsanitize-coverage=trace-cmp) > help > KCOV also exposes operands of every comparison in the instrumented > code along with operand sizes and PCs of the comparison instructions. > @@ -765,7 +768,7 @@ config KCOV_ENABLE_COMPARISONS > config KCOV_INSTRUMENT_ALL > bool "Instrument all code by default" > depends on KCOV > - default y if KCOV > + default y > help > If you are doing generic system call fuzzing (like e.g. syzkaller), > then you will want to instrument the whole kernel and you should > diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins > index 7f5c862..0ce3802 100644 > --- a/scripts/Makefile.gcc-plugins > +++ b/scripts/Makefile.gcc-plugins > @@ -14,16 +14,12 @@ ifdef CONFIG_GCC_PLUGINS > endif > > ifdef CONFIG_GCC_PLUGIN_SANCOV > - ifeq ($(strip $(CFLAGS_KCOV)),) > # It is needed because of the gcc-plugin.sh and gcc version checks. > gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so > > - ifneq ($(PLUGINCC),) > - CFLAGS_KCOV := $(SANCOV_PLUGIN) > - else > + ifeq ($(PLUGINCC),) > $(warning warning: cannot use CONFIG_KCOV: -fsanitize-coverage=trace-pc is not supported by compiler) > endif > - endif > endif > > gcc-plugin-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += structleak_plugin.so > diff --git a/scripts/Makefile.kcov b/scripts/Makefile.kcov > index 5cc7203..d71ba73 100644 > --- a/scripts/Makefile.kcov > +++ b/scripts/Makefile.kcov > @@ -1,7 +1,9 @@ > ifdef CONFIG_KCOV > -CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) > -ifeq ($(CONFIG_KCOV_ENABLE_COMPARISONS),y) > -CFLAGS_KCOV += $(call cc-option,-fsanitize-coverage=trace-cmp,) > -endif > + > +kcov-flags-$(CONFIG_CC_HAS_SANCOV_TRACE_PC) += -fsanitize-coverage=trace-pc > +kcov-flags-$(CONFIG_KCOV_ENABLE_COMPARISONS) += -fsanitize-coverage=trace-cmp > +kcov-flags-$(CONFIG_GCC_PLUGIN_SANKOV) += -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so > + This is my mistake. SANKOV -> SANCOV I fixed it locally. > +export CFLAGS_KCOV := $(kcov-flags-y) > > endif > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Best Regards Masahiro Yamada
diff --git a/Makefile b/Makefile index 80e0800..4b5a17a 100644 --- a/Makefile +++ b/Makefile @@ -626,7 +626,7 @@ all: vmlinux CFLAGS_GCOV := -fprofile-arcs -ftest-coverage \ $(call cc-option,-fno-tree-loop-im) \ $(call cc-disable-warning,maybe-uninitialized,) -export CFLAGS_GCOV CFLAGS_KCOV +export CFLAGS_GCOV # The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default # values of the respective KBUILD_* variables diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c40c7b7..b76cab2 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -736,12 +736,15 @@ config ARCH_HAS_KCOV only for x86_64. KCOV requires testing on other archs, and most likely disabling of instrumentation for some early boot code. +config CC_HAS_SANCOV_TRACE_PC + def_bool $(cc-option,-fsanitize-coverage=trace-pc) + config KCOV bool "Code coverage for fuzzing" depends on ARCH_HAS_KCOV + depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS select DEBUG_FS - select GCC_PLUGINS if !COMPILE_TEST - select GCC_PLUGIN_SANCOV if !COMPILE_TEST + select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC help KCOV exposes kernel code coverage information in a form suitable for coverage-guided fuzzing (randomized testing). @@ -755,7 +758,7 @@ config KCOV config KCOV_ENABLE_COMPARISONS bool "Enable comparison operands collection by KCOV" depends on KCOV - default n + depends on $(cc-option,-fsanitize-coverage=trace-cmp) help KCOV also exposes operands of every comparison in the instrumented code along with operand sizes and PCs of the comparison instructions. @@ -765,7 +768,7 @@ config KCOV_ENABLE_COMPARISONS config KCOV_INSTRUMENT_ALL bool "Instrument all code by default" depends on KCOV - default y if KCOV + default y help If you are doing generic system call fuzzing (like e.g. syzkaller), then you will want to instrument the whole kernel and you should diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index 7f5c862..0ce3802 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -14,16 +14,12 @@ ifdef CONFIG_GCC_PLUGINS endif ifdef CONFIG_GCC_PLUGIN_SANCOV - ifeq ($(strip $(CFLAGS_KCOV)),) # It is needed because of the gcc-plugin.sh and gcc version checks. gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so - ifneq ($(PLUGINCC),) - CFLAGS_KCOV := $(SANCOV_PLUGIN) - else + ifeq ($(PLUGINCC),) $(warning warning: cannot use CONFIG_KCOV: -fsanitize-coverage=trace-pc is not supported by compiler) endif - endif endif gcc-plugin-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += structleak_plugin.so diff --git a/scripts/Makefile.kcov b/scripts/Makefile.kcov index 5cc7203..d71ba73 100644 --- a/scripts/Makefile.kcov +++ b/scripts/Makefile.kcov @@ -1,7 +1,9 @@ ifdef CONFIG_KCOV -CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) -ifeq ($(CONFIG_KCOV_ENABLE_COMPARISONS),y) -CFLAGS_KCOV += $(call cc-option,-fsanitize-coverage=trace-cmp,) -endif + +kcov-flags-$(CONFIG_CC_HAS_SANCOV_TRACE_PC) += -fsanitize-coverage=trace-pc +kcov-flags-$(CONFIG_KCOV_ENABLE_COMPARISONS) += -fsanitize-coverage=trace-cmp +kcov-flags-$(CONFIG_GCC_PLUGIN_SANKOV) += -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so + +export CFLAGS_KCOV := $(kcov-flags-y) endif