[PATCH -tip v2 01/11] ubsan, kcsan: don't combine sanitizer with kcov on clang

Marco Elver
2020-05-21T11:09:56Z

From: Arnd Bergmann <arnd@arndb.de>

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/20200505142341.1096942-1-arnd@arndb.de
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marco Elver <elver@google.com>
---
This patch is already in -rcu tree, but since since the series is based
on -tip, to avoid conflict it is required for the subsequent patches.
---
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 48469c95d78e..3baea77bf37f 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.
--
2.26.2.761.g0e0b3e54be-goog