kcov: avoid clang out-of-range warning

The area_size is never larger than the maximum on 64-bit architectutes:

kernel/kcov.c:634:29: error: result of comparison of constant 1152921504606846975 with expression of type '__u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
                if (remote_arg->area_size > LONG_MAX / sizeof(unsigned long))
                    ~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The compiler can correctly optimize the check away and the code appears
correct to me, so just add a cast to avoid the warning.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Justin Stitt <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Bill Wendling <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: arndb

kernel/kcov.c

@@ -627,7 +627,8 @@ static int kcov_ioctl_locked(struct kcov *kcov, unsigned int cmd,
 		mode = kcov_get_mode(remote_arg->trace_mode);
 		if (mode < 0)
 			return mode;
-		if (remote_arg->area_size > LONG_MAX / sizeof(unsigned long))
+		if ((unsigned long)remote_arg->area_size >
+		    LONG_MAX / sizeof(unsigned long))
 			return -EINVAL;
 		kcov->mode = mode;
 		t->kcov = kcov;