[PATCH RFC v4 20/42] kmsan: x86: increase stack sizes in KMSAN builds

[glider@google.com]

KMSAN instruments the code heavily, increasing register pressure and
preventing functions from being inlined. As a result, the kernel
requires more stack space to run.

Rename KASAN_STACK_ORDER to EXTRA_STACK_ORDER and set EXTRA_STACK_ORDER
to 2 for KMSAN builds, effectively making the stacks 4 times larger.

Signed-off-by: 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: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: linux-mm@kvack.org
---

Change-Id: I1d9df161419a885bf654abff141e247366895b68
---
 arch/x86/include/asm/page_64_types.h | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 288b065955b7..ea9fbf09f43b 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -7,18 +7,20 @@
 #endif
 
 #ifdef CONFIG_KASAN
-#define KASAN_STACK_ORDER 1
+#define EXTRA_STACK_ORDER 1
+#elif defined(CONFIG_KMSAN)
+#define EXTRA_STACK_ORDER 2
 #else
-#define KASAN_STACK_ORDER 0
+#define EXTRA_STACK_ORDER 0
 #endif
 
-#define THREAD_SIZE_ORDER	(2 + KASAN_STACK_ORDER)
+#define THREAD_SIZE_ORDER	(2 + EXTRA_STACK_ORDER)
 #define THREAD_SIZE  (PAGE_SIZE << THREAD_SIZE_ORDER)
 
-#define EXCEPTION_STACK_ORDER (0 + KASAN_STACK_ORDER)
+#define EXCEPTION_STACK_ORDER (0 + EXTRA_STACK_ORDER)
 #define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)
 
-#define IRQ_STACK_ORDER (2 + KASAN_STACK_ORDER)
+#define IRQ_STACK_ORDER (2 + EXTRA_STACK_ORDER)
 #define IRQ_STACK_SIZE (PAGE_SIZE << IRQ_STACK_ORDER)
 
 /*
-- 
2.24.1.735.g03f4e72817-goog