[PATCH RFC v3 28/36] kmsan: enable KMSAN builds

[glider@google.com]

Make KMSAN usable by adding the necessary Makefile bits and calling
KMSAN initialization routines (kmsan_initialize_shadow() and
kmsan_initialize()) from init/main.c

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org

---
This patch was previously called "kmsan: Changing existing files to
enable KMSAN builds". Logically unrelated parts of it were split away.

Change-Id: I37e0b7f2d2f2b0aeac5753ff9d6b411485fc374e
---
 Makefile             | 3 ++-
 init/main.c          | 3 +++
 mm/Makefile          | 1 +
 scripts/Makefile.lib | 6 ++++++
 4 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 79be70bf2899..181ae2dac415 100644
--- a/Makefile
+++ b/Makefile
@@ -478,7 +478,7 @@ export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE
 
 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
 export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
-export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN
+export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN CFLAGS_KMSAN
 export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
 export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
 export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
@@ -898,6 +898,7 @@ KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
 endif
 
 include scripts/Makefile.kasan
+include scripts/Makefile.kmsan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan
 
diff --git a/init/main.c b/init/main.c
index 91f6ebb30ef0..afcca2a38348 100644
--- a/init/main.c
+++ b/init/main.c
@@ -32,6 +32,7 @@
 #include <linux/nmi.h>
 #include <linux/percpu.h>
 #include <linux/kmod.h>
+#include <linux/kmsan.h>
 #include <linux/vmalloc.h>
 #include <linux/kernel_stat.h>
 #include <linux/start_kernel.h>
@@ -554,6 +555,7 @@ static void __init mm_init(void)
 	 */
 	page_ext_init_flatmem();
 	report_meminit();
+	kmsan_initialize_shadow();
 	mem_init();
 	kmem_cache_init();
 	kmemleak_init();
@@ -625,6 +627,7 @@ asmlinkage __visible void __init start_kernel(void)
 	sort_main_extable();
 	trap_init();
 	mm_init();
+	kmsan_initialize();
 
 	ftrace_init();
 
diff --git a/mm/Makefile b/mm/Makefile
index d996846697ef..419e6e02dfaf 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -71,6 +71,7 @@ obj-$(CONFIG_PAGE_POISONING) += page_poison.o
 obj-$(CONFIG_SLAB) += slab.o
 obj-$(CONFIG_SLUB) += slub.o
 obj-$(CONFIG_KASAN)	+= kasan/
+obj-$(CONFIG_KMSAN)	+= kmsan/
 obj-$(CONFIG_FAILSLAB) += failslab.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_MEMTEST)		+= memtest.o
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 179d55af5852..f9f38f7c1cd4 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -140,6 +140,12 @@ _c_flags += $(if $(patsubst n%,, \
 		$(CFLAGS_KASAN), $(CFLAGS_KASAN_NOSANITIZE))
 endif
 
+ifeq ($(CONFIG_KMSAN),y)
+_c_flags += $(if $(patsubst n%,, \
+		$(KMSAN_SANITIZE_$(basetarget).o)$(KMSAN_SANITIZE)y), \
+		$(CFLAGS_KMSAN))
+endif
+
 ifeq ($(CONFIG_UBSAN),y)
 _c_flags += $(if $(patsubst n%,, \
 		$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_SANITIZE)$(CONFIG_UBSAN_SANITIZE_ALL)), \
-- 
2.24.0.432.g9d3f5f5b63-goog