mm/kmemleak.c: use address-of operator on section symbols

[ Upstream commit b0d14fc4 ]

Clang warns:

  mm/kmemleak.c:1955:28: warning: array comparison always evaluates to a constant [-Wtautological-compare]
        if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
                                  ^
  mm/kmemleak.c:1955:60: warning: array comparison always evaluates to a constant [-Wtautological-compare]
        if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)

These are not true arrays, they are linker defined symbols, which are just
addresses.  Using the address of operator silences the warning and does
not change the resulting assembly with either clang/ld.lld or gcc/ld
(tested with diff + objdump -Dr).
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/895
Link: http://lkml.kernel.org/r/20200220051551.44000-1-natechancellor@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

mm/kmemleak.c

@@ -2039,7 +2039,7 @@ void __init kmemleak_init(void)
 	create_object((unsigned long)__bss_start, __bss_stop - __bss_start,
 		      KMEMLEAK_GREY, GFP_ATOMIC);
 	/* only register .data..ro_after_init if not within .data */
-	if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
+	if (&__start_ro_after_init < &_sdata || &__end_ro_after_init > &_edata)
 		create_object((unsigned long)__start_ro_after_init,
 			      __end_ro_after_init - __start_ro_after_init,
 			      KMEMLEAK_GREY, GFP_ATOMIC);