kmsan: suppress false positives in assembly routines

TODO(glider): handle the assembly in the compiler properly instead

arch/x86/include/asm/bitops.h

@@ -142,7 +142,7 @@ static __always_inline void __clear_bit(long nr, volatile unsigned long *addr)
 
 static __always_inline bool clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr)
 {
-	bool negative;
+	bool negative = false; // TODO(glider): false positive
 	asm volatile(LOCK_PREFIX "andb %2,%1"
 		CC_SET(s)
 		: CC_OUT(s) (negative), ADDR
@@ -245,7 +245,8 @@ test_and_set_bit_lock(long nr, volatile unsigned long *addr)
  */
 static __always_inline bool __test_and_set_bit(long nr, volatile unsigned long *addr)
 {
-	bool oldbit;
+	// TODO(glider): false positive
+	bool oldbit = false;
 
 	asm(__ASM_SIZE(bts) " %2,%1"
 	    CC_SET(c)
@@ -286,7 +287,8 @@ static __always_inline bool test_and_clear_bit(long nr, volatile unsigned long *
  */
 static __always_inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr)
 {
-	bool oldbit;
+	// TODO(glider): false positive
+	bool oldbit = false;
 
 	asm volatile(__ASM_SIZE(btr) " %2,%1"
 		     CC_SET(c)
@@ -298,7 +300,8 @@ static __always_inline bool __test_and_clear_bit(long nr, volatile unsigned long
 /* WARNING: non atomic and it can be reordered! */
 static __always_inline bool __test_and_change_bit(long nr, volatile unsigned long *addr)
 {
-	bool oldbit;
+	// TODO(glider): false positive
+	bool oldbit = false;
 
 	asm volatile(__ASM_SIZE(btc) " %2,%1"
 		     CC_SET(c)
@@ -330,7 +333,9 @@ static __always_inline bool constant_test_bit(long nr, const volatile unsigned l
 
 static __always_inline bool variable_test_bit(long nr, volatile const unsigned long *addr)
 {
-	bool oldbit;
+	/// TODO(glider): instrument the assembly below.
+	///bool oldbit;
+	bool oldbit = false;
 
 	asm volatile(__ASM_SIZE(bt) " %2,%1"
 		     CC_SET(c)

arch/x86/include/asm/cmpxchg.h

@@ -157,7 +157,8 @@ extern void __add_wrong_size(void)
 
 #define __raw_try_cmpxchg(_ptr, _pold, _new, size, lock)		\
 ({									\
-	bool success;							\
+	/* TODO(glider): false positive */				\
+	bool success = false;						\
 	__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold);		\
 	__typeof__(*(_ptr)) __old = *_old;				\
 	__typeof__(*(_ptr)) __new = (_new);				\

arch/x86/include/asm/irqflags.h

@@ -15,7 +15,8 @@
 
 static inline unsigned long native_save_fl(void)
 {
-	unsigned long flags;
+	/// TODO(glider): false positive here.
+	unsigned long flags = 0;
 
 	/*
 	 * "=rm" is safe here, because "pop" adjusts the stack before

arch/x86/include/asm/rmwcc.h

@@ -27,7 +27,8 @@ cc_label:								\
 
 #define __GEN_RMWcc(fullop, var, cc, clobbers, ...)			\
 do {									\
-	bool c;								\
+        /* TODO(glider): false positive */  \
+	bool c = 0;								\
 	asm volatile (fullop CC_SET(cc)					\
 			: [counter] "+m" (var), CC_OUT(cc) (c)		\
 			: __VA_ARGS__ : clobbers);			\