ubsan, kcsan: Don't combine sanitizer with kcov on clang

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.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marco Elver <elver@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://bugs.llvm.org/show_bug.cgi?id=45831
Link: https://lore.kernel.org/lkml/20200505142341.1096942-1-arnd@arndb.de
Link: https://lkml.kernel.org/r/20200521142047.169334-2-elver@google.com

diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index 689b6b8..b5d88ac 100644 (file)
--- 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 27bcc25..774315d 100644 (file)
--- 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.