BACKPORT: kasan: remove redundant config option

CONFIG_KASAN_STACK and CONFIG_KASAN_STACK_ENABLE both enable KASAN stack
instrumentation, but we should only need one config, so that we remove
CONFIG_KASAN_STACK_ENABLE and make CONFIG_KASAN_STACK workable.  see [1].

When enable KASAN stack instrumentation, then for gcc we could do no
prompt and default value y, and for clang prompt and default value n.

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=210221

Link: https://lkml.kernel.org/r/20210226012531.29231-1-walter-zh.wu@mediatek.com
Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

(cherry picked from commit 3bc29a8e251a9469ce69e62118d70eaf0caa5acb
 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm)
(cherry picked from commit 0d9e60b66271414a18a1d4f1fe2c923245f1e3a8
 https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm)
[glider: resolved a minor merge conflict, squashed two patches together]

Bug: 182930667
Signed-off-by: Alexander Potapenko <glider@google.com>
Change-Id: I1b3d2cdcf45727a25d36ac7f417a4f026152d6a8
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 1e000cc..abf231d 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -2,6 +2,12 @@
 CFLAGS_KASAN_NOSANITIZE := -fno-builtin
 KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
 
+ifdef CONFIG_KASAN_STACK
+	stack_enable := 1
+else
+	stack_enable := 0
+endif
+
 ifdef CONFIG_KASAN_GENERIC
 
 ifdef CONFIG_KASAN_INLINE
@@ -27,7 +33,7 @@
 	CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \
 	 $(call cc-param,asan-globals=1) \
 	 $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \
-	 $(call cc-param,asan-stack=$(CONFIG_KASAN_STACK)) \
+	 $(call cc-param,asan-stack=$(stack_enable)) \
 	 $(call cc-param,asan-instrument-allocas=1)
 endif
 
@@ -42,7 +48,7 @@
 endif
 
 CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
-		-mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
+		-mllvm -hwasan-instrument-stack=$(stack_enable) \
 		-mllvm -hwasan-use-short-granules=0 \
 		$(instrumentation_flags)