Commit eedc9d83 authored by Russell King's avatar Russell King Committed by Sam Ravnborg
Browse files

kbuild: fix headers_exports with boolean expression 



When we had code like this in a header unifdef failed to
deduct that the expression was always false - and we had code exported
that was not intended for userspace.

#if defined(__KERNEL__) && !defined(__ASSEMBLY__)
  int a;
#endif

This commit implment support in unidef which allows it to work out if
an #if expression always evaluates true or false for symbols which
are being undefined/always defined.

The patch is slightly more complicated than I'd hoped because unifdef
needs to see lines fully evaluated - doing otherwise causes it to
mark the line as "dirty" and copy it over no matter what.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
parent 67b7ebe0

scripts/unifdef.c

+37 −11
Original line number Diff line number Diff line
@@ -678,8 +678,10 @@ eval_unary(const struct ops *ops, int *valp, const char **cpp) 
	if (*cp == '!') {

		debug("eval%d !", ops - eval_ops);

		cp++;

		if (eval_unary(ops, valp, &cp) == LT_IF)

		if (eval_unary(ops, valp, &cp) == LT_IF) {

			*cpp = cp;

			return (LT_IF);

		}

		*valp = !*valp;

	} else if (*cp == '(') {

		cp++;
@@ -700,13 +702,16 @@ eval_unary(const struct ops *ops, int *valp, const char **cpp) 
			return (LT_IF);

		cp = skipcomment(cp);

		sym = findsym(cp);

		if (sym < 0)

			return (LT_IF);

		*valp = (value[sym] != NULL);

		cp = skipsym(cp);

		cp = skipcomment(cp);

		if (*cp++ != ')')

			return (LT_IF);

		if (sym >= 0)

			*valp = (value[sym] != NULL);

		else {

			*cpp = cp;

			return (LT_IF);

		}

		keepthis = false;

	} else if (!endsym(*cp)) {

		debug("eval%d symbol", ops - eval_ops);
@@ -741,11 +746,11 @@ eval_table(const struct ops *ops, int *valp, const char **cpp) 
	const struct op *op;

	const char *cp;

	int val;

	Linetype lhs, rhs;



	debug("eval%d", ops - eval_ops);

	cp = *cpp;

	if (ops->inner(ops+1, valp, &cp) == LT_IF)

		return (LT_IF);

	lhs = ops->inner(ops+1, valp, &cp);

	for (;;) {

		cp = skipcomment(cp);

		for (op = ops->op; op->str != NULL; op++)
@@ -755,14 +760,32 @@ eval_table(const struct ops *ops, int *valp, const char **cpp) 
			break;

		cp += strlen(op->str);

		debug("eval%d %s", ops - eval_ops, op->str);

		if (ops->inner(ops+1, &val, &cp) == LT_IF)

			return (LT_IF);

		rhs = ops->inner(ops+1, &val, &cp);

		if (op->fn == op_and && (lhs == LT_FALSE || rhs == LT_FALSE)) {

			debug("eval%d: and always false", ops - eval_ops);

			if (lhs == LT_IF)

				*valp = val;

			lhs = LT_FALSE;

			continue;

		}

		if (op->fn == op_or && (lhs == LT_TRUE || rhs == LT_TRUE)) {

			debug("eval%d: or always true", ops - eval_ops);

			if (lhs == LT_IF)

				*valp = val;

			lhs = LT_TRUE;

			continue;

		}

		if (rhs == LT_IF)

			lhs = LT_IF;

		if (lhs != LT_IF)

			*valp = op->fn(*valp, val);

	}



	*cpp = cp;

	debug("eval%d = %d", ops - eval_ops, *valp);

	return (*valp ? LT_TRUE : LT_FALSE);

	if (lhs != LT_IF)

		lhs = (*valp ? LT_TRUE : LT_FALSE);

	return lhs;

}



/*
@@ -773,12 +796,15 @@ eval_table(const struct ops *ops, int *valp, const char **cpp) 
static Linetype

ifeval(const char **cpp)

{

	const char *cp = *cpp;

	int ret;

	int val;



	debug("eval %s", *cpp);

	keepthis = killconsts ? false : true;

	ret = eval_table(eval_ops, &val, cpp);

	ret = eval_table(eval_ops, &val, &cp);

	if (ret != LT_IF)

		*cpp = cp;

	debug("eval = %d", val);

	return (keepthis ? LT_IF : ret);

}

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