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| author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2018-05-28 18:22:04 +0900 |
|---|---|---|
| committer | Masahiro Yamada <yamada.masahiro@socionext.com> | 2018-06-11 09:14:08 +0900 |
| commit | 5aadfdeb8de001ca04d500586e3b033404c28617 (patch) | |
| tree | a430e73a414b972a4a4cb71ba98fad5af960254d /lib/Kconfig.debug | |
| parent | 6a61b70b43c9c4cbc7314bf6c8b5ba8b0d6e1e7b (diff) | |
| download | lwn-5aadfdeb8de001ca04d500586e3b033404c28617.tar.gz lwn-5aadfdeb8de001ca04d500586e3b033404c28617.zip | |
kcov: test compiler capability in Kconfig and correct dependency
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>
Diffstat (limited to 'lib/Kconfig.debug')
| -rw-r--r-- | lib/Kconfig.debug | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index eb885942eb0f..d543c65ce0eb 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 |