Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/kcsan

Pull the KCSAN subsystem from Paul E. McKenney:

   "This pull request contains base kernel concurrency sanitizer
    (KCSAN) enablement for x86, courtesy of Marco Elver.  KCSAN is a
    sampling watchpoint-based data-race detector, and is documented in
    Documentation/dev-tools/kcsan.rst.  KCSAN was announced in September,
    and much feedback has since been incorporated:

      http://lkml.kernel.org/r/CANpmjNPJ_bHjfLZCAPV23AXFfiPiyXXqqu72n6TgWzb2Gnu1eA@mail.gmail.com

    The data races located thus far have resulted in a number of fixes:

      https://github.com/google/ktsan/wiki/KCSAN#upstream-fixes-of-data-races-found-by-kcsan

    Additional information may be found here:

      https://lore.kernel.org/lkml/20191114180303.66955-1-elver@google.com/
   "

Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 31 insertions, 2 deletions

diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
new file mode 100644
index 000000000000..caf1111a28ae
--- /dev/null
+++ b/scripts/Makefile.kcsan
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+ifdef CONFIG_KCSAN
+
+CFLAGS_KCSAN := -fsanitize=thread
+
+endif # CONFIG_KCSAN
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 179d55af5852..8952f909f7c9 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -152,6 +152,16 @@ _c_flags += $(if $(patsubst n%,, \
 	$(CFLAGS_KCOV))
 endif
 
+#
+# Enable KCSAN flags except some files or directories we don't want to check
+# (depends on variables KCSAN_SANITIZE_obj.o, KCSAN_SANITIZE)
+#
+ifeq ($(CONFIG_KCSAN),y)
+_c_flags += $(if $(patsubst n%,, \
+	$(KCSAN_SANITIZE_$(basetarget).o)$(KCSAN_SANITIZE)y), \
+	$(CFLAGS_KCSAN))
+endif
+
 # $(srctree)/$(src) for including checkin headers from generated source files
 # $(objtree)/$(obj) for including generated headers from checkin source files
 ifeq ($(KBUILD_EXTMOD),)
diff --git a/scripts/atomic/gen-atomic-instrumented.sh b/scripts/atomic/gen-atomic-instrumented.sh
index e09812372b17..8b8b2a6f8d68 100755
--- a/scripts/atomic/gen-atomic-instrumented.sh
+++ b/scripts/atomic/gen-atomic-instrumented.sh
@@ -20,7 +20,7 @@ gen_param_check()
 	# We don't write to constant parameters
 	[ ${type#c} != ${type} ] && rw="read"
 
-	printf "\tkasan_check_${rw}(${name}, sizeof(*${name}));\n"
+	printf "\t__atomic_check_${rw}(${name}, sizeof(*${name}));\n"
 }
 
 #gen_param_check(arg...)
@@ -107,7 +107,7 @@ cat <<EOF
 #define ${xchg}(ptr, ...)						\\
 ({									\\
 	typeof(ptr) __ai_ptr = (ptr);					\\
-	kasan_check_write(__ai_ptr, ${mult}sizeof(*__ai_ptr));		\\
+	__atomic_check_write(__ai_ptr, ${mult}sizeof(*__ai_ptr));		\\
 	arch_${xchg}(__ai_ptr, __VA_ARGS__);				\\
 })
 EOF
@@ -148,6 +148,19 @@ cat << EOF
 
 #include <linux/build_bug.h>
 #include <linux/kasan-checks.h>
+#include <linux/kcsan-checks.h>
+
+static inline void __atomic_check_read(const volatile void *v, size_t size)
+{
+	kasan_check_read(v, size);
+	kcsan_check_atomic_read(v, size);
+}
+
+static inline void __atomic_check_write(const volatile void *v, size_t size)
+{
+	kasan_check_write(v, size);
+	kcsan_check_atomic_write(v, size);
+}
 
 EOF