[PATCH] kasan: remove redundant config option

[Walter Wu]

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

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

Signed-off-by: Walter Wu <walter-zh.wu at mediatek.com>
Suggested-by: Dmitry Vyukov <dvyukov at google.com>
Cc: Andrey Ryabinin <aryabinin at virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov at google.com>
Cc: Andrey Konovalov <andreyknvl at google.com>
Cc: Alexander Potapenko <glider at google.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
---
 arch/arm64/kernel/sleep.S        |  2 +-
 arch/x86/kernel/acpi/wakeup_64.S |  2 +-
 include/linux/kasan.h            |  2 +-
 lib/Kconfig.kasan                | 11 ++++-------
 mm/kasan/common.c                |  2 +-
 mm/kasan/kasan.h                 |  2 +-
 mm/kasan/report_generic.c        |  2 +-
 scripts/Makefile.kasan           | 10 ++++++++--
 8 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index 6bdef7362c0e..7c44ede122a9 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -133,7 +133,7 @@ SYM_FUNC_START(_cpu_resume)
 	 */
 	bl	cpu_do_resume
 
-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
 	mov	x0, sp
 	bl	kasan_unpoison_task_stack_below
 #endif
diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index 5d3a0b8fd379..c7f412f4e07d 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/arch/x86/kernel/acpi/wakeup_64.S
@@ -112,7 +112,7 @@ SYM_FUNC_START(do_suspend_lowlevel)
 	movq	pt_regs_r14(%rax), %r14
 	movq	pt_regs_r15(%rax), %r15
 
-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
 	/*
 	 * The suspend path may have poisoned some areas deeper in the stack,
 	 * which we now need to unpoison.
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 5e0655fb2a6f..35d1e9b2cbfa 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -302,7 +302,7 @@ static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
 
 #endif /* CONFIG_KASAN */
 
-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
 void kasan_unpoison_task_stack(struct task_struct *task);
 #else
 static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index f5fa4ba126bf..59de74293454 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -138,9 +138,11 @@ config KASAN_INLINE
 
 endchoice
 
-config KASAN_STACK_ENABLE
-	bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
+config KASAN_STACK
+	bool "Enable stack instrumentation (unsafe)"
 	depends on KASAN_GENERIC || KASAN_SW_TAGS
+	default y if CC_IS_GCC
+	default n if CC_IS_CLANG
 	help
 	  The LLVM stack address sanitizer has a know problem that
 	  causes excessive stack usage in a lot of functions, see
@@ -154,11 +156,6 @@ config KASAN_STACK_ENABLE
 	  CONFIG_COMPILE_TEST.	On gcc it is assumed to always be safe
 	  to use and enabled by default.
 
-config KASAN_STACK
-	int
-	default 1 if KASAN_STACK_ENABLE || CC_IS_GCC
-	default 0
-
 config KASAN_SW_TAGS_IDENTIFY
 	bool "Enable memory corruption identification"
 	depends on KASAN_SW_TAGS
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 38ba2aecd8f4..02ec7f81dc16 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -63,7 +63,7 @@ void __kasan_unpoison_range(const void *address, size_t size)
 	unpoison_range(address, size);
 }
 
-#if CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN_STACK)
 /* Unpoison the entire stack for a task. */
 void kasan_unpoison_task_stack(struct task_struct *task)
 {
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index cc4d9e1d49b1..bdfdb1cff653 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -224,7 +224,7 @@ void *find_first_bad_addr(void *addr, size_t size);
 const char *get_bug_type(struct kasan_access_info *info);
 void metadata_fetch_row(char *buffer, void *row);
 
-#if defined(CONFIG_KASAN_GENERIC) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN_GENERIC) && defined(CONFIG_KASAN_STACK)
 void print_address_stack_frame(const void *addr);
 #else
 static inline void print_address_stack_frame(const void *addr) { }
diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c
index 8a9c889872da..137a1dba1978 100644
--- a/mm/kasan/report_generic.c
+++ b/mm/kasan/report_generic.c
@@ -128,7 +128,7 @@ void metadata_fetch_row(char *buffer, void *row)
 	memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW);
 }
 
-#if CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN_STACK)
 static bool __must_check tokenize_frame_descr(const char **frame_descr,
 					      char *token, size_t max_tok_len,
 					      unsigned long *value)
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 1e000cc2e7b4..abf231d209b1 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 @@ else
 	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 @@ else
 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)
 
-- 
2.18.0