On Thu, May 07, 2020 at 06:25:31PM +0200, Arnd Bergmann wrote:
> Clang does not allow -fsanitize-coverage=trace-{pc,cmp} together
> with -fsanitize=bounds or with ubsan:
>
> clang: error: argument unused during compilation:
> '-fsanitize-coverage=trace-pc' [-Werror,-Wunused-command-line-argument]
> clang: error: argument unused during compilation:
> '-fsanitize-coverage=trace-cmp' [-Werror,-Wunused-command-line-argument]
>
> To avoid the warning, check whether clang can handle this correctly
> or disallow ubsan and kcsan when kcov is enabled.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=45831
> Link: https://lore.kernel.org/lkml/[email protected]
> Signed-off-by: Arnd Bergmann <[email protected]>
Applied for v5.9 and pushed, thank you!
Thanx, Paul
> ---
> v2: this implements Marco's suggestion to check what the compiler
> actually supports, and references the bug report I now opened.
>
> Let's wait for replies on that bug report before this gets applied,
> in case the feedback there changes the conclusion.
> ---
> lib/Kconfig.kcsan | 11 +++++++++++
> lib/Kconfig.ubsan | 11 +++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
> index ea28245c6c1d..a7276035ca0d 100644
> --- a/lib/Kconfig.kcsan
> +++ b/lib/Kconfig.kcsan
> @@ -3,9 +3,20 @@
> config HAVE_ARCH_KCSAN
> bool
>
> +config KCSAN_KCOV_BROKEN
> + def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
> + depends on CC_IS_CLANG
> + depends on !$(cc-option,-Werror=unused-command-line-argument
> -fsanitize=thread -fsanitize-coverage=trace-pc)
> + help
> + Some versions of clang support either KCSAN and KCOV but not the
> + combination of the two.
> + See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
> + in newer releases.
> +
> menuconfig KCSAN
> bool "KCSAN: dynamic data race detector"
> depends on HAVE_ARCH_KCSAN && DEBUG_KERNEL && !KASAN
> + depends on !KCSAN_KCOV_BROKEN
> select STACKTRACE
> help
> The Kernel Concurrency Sanitizer (KCSAN) is a dynamic
> diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
> index 929211039bac..a5ba2fd51823 100644
> --- a/lib/Kconfig.ubsan
> +++ b/lib/Kconfig.ubsan
> @@ -26,9 +26,20 @@ config UBSAN_TRAP
> the system. For some system builders this is an acceptable
> trade-off.
>
> +config UBSAN_KCOV_BROKEN
> + def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
> + depends on CC_IS_CLANG
> + depends on !$(cc-option,-Werror=unused-command-line-argument
> -fsanitize=bounds -fsanitize-coverage=trace-pc)
> + help
> + Some versions of clang support either UBSAN or KCOV but not the
> + combination of the two.
> + See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
> + in newer releases.
> +
> config UBSAN_BOUNDS
> bool "Perform array index bounds checking"
> default UBSAN
> + depends on !UBSAN_KCOV_BROKEN
> help
> This option enables detection of directly indexed out of bounds
> array accesses, where the array size is known at compile time.
> --
> 2.26.0
>
