kconfig: Update to KConfig to version from kernel 4.17

This updates the KConfig system used in backports to the version from
kernel 4.17. In kernel 4.18 some bigger changes to the KConfig system
were introduced which are harder to backport, so start with using this
older version.

This version now generates the zconf.lex.c and zconf.tab.c files from
the original sources, newer kernel versions will delete these files in
a make clean, after that they are now regenerated. We do not ship them
by default any more, so we need lex and yacc.

The Makefile was not copied from the mainline kernel but this is written
specifically for the backports project.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Anthony Wong <yp@anthonywong.net>

1 files changed, 146 insertions, 47 deletions

diff --git a/backport/kconf/expr.c b/backport/kconf/expr.c
index cbf4996d..e1a39e90 100644
--- a/backport/kconf/expr.c
+++ b/backport/kconf/expr.c
@@ -94,7 +94,7 @@ struct expr *expr_copy(const struct expr *org)
 		e->right.expr = expr_copy(org->right.expr);
 		break;
 	default:
-		printf("can't copy type %d\n", e->type);
+		fprintf(stderr, "can't copy type %d\n", e->type);
 		free(e);
 		e = NULL;
 		break;
@@ -113,7 +113,7 @@ void expr_free(struct expr *e)
 		break;
 	case E_NOT:
 		expr_free(e->left.expr);
-		return;
+		break;
 	case E_EQUAL:
 	case E_GEQ:
 	case E_GTH:
@@ -127,7 +127,7 @@ void expr_free(struct expr *e)
 		expr_free(e->right.expr);
 		break;
 	default:
-		printf("how to free type %d?\n", e->type);
+		fprintf(stderr, "how to free type %d?\n", e->type);
 		break;
 	}
 	free(e);
@@ -138,8 +138,18 @@ static int trans_count;
 #define e1 (*ep1)
 #define e2 (*ep2)
 
+/*
+ * expr_eliminate_eq() helper.
+ *
+ * Walks the two expression trees given in 'ep1' and 'ep2'. Any node that does
+ * not have type 'type' (E_OR/E_AND) is considered a leaf, and is compared
+ * against all other leaves. Two equal leaves are both replaced with either 'y'
+ * or 'n' as appropriate for 'type', to be eliminated later.
+ */
 static void __expr_eliminate_eq(enum expr_type type, struct expr **ep1, struct expr **ep2)
 {
+	/* Recurse down to leaves */
+
 	if (e1->type == type) {
 		__expr_eliminate_eq(type, &e1->left.expr, &e2);
 		__expr_eliminate_eq(type, &e1->right.expr, &e2);
@@ -150,12 +160,18 @@ static void __expr_eliminate_eq(enum expr_type type, struct expr **ep1, struct e
 		__expr_eliminate_eq(type, &e1, &e2->right.expr);
 		return;
 	}
+
+	/* e1 and e2 are leaves. Compare them. */
+
 	if (e1->type == E_SYMBOL && e2->type == E_SYMBOL &&
 	    e1->left.sym == e2->left.sym &&
 	    (e1->left.sym == &symbol_yes || e1->left.sym == &symbol_no))
 		return;
 	if (!expr_eq(e1, e2))
 		return;
+
+	/* e1 and e2 are equal leaves. Prepare them for elimination. */
+
 	trans_count++;
 	expr_free(e1); expr_free(e2);
 	switch (type) {
@@ -172,6 +188,35 @@ static void __expr_eliminate_eq(enum expr_type type, struct expr **ep1, struct e
 	}
 }
 
+/*
+ * Rewrites the expressions 'ep1' and 'ep2' to remove operands common to both.
+ * Example reductions:
+ *
+ *	ep1: A && B           ->  ep1: y
+ *	ep2: A && B && C      ->  ep2: C
+ *
+ *	ep1: A || B           ->  ep1: n
+ *	ep2: A || B || C      ->  ep2: C
+ *
+ *	ep1: A && (B && FOO)  ->  ep1: FOO
+ *	ep2: (BAR && B) && A  ->  ep2: BAR
+ *
+ *	ep1: A && (B || C)    ->  ep1: y
+ *	ep2: (C || B) && A    ->  ep2: y
+ *
+ * Comparisons are done between all operands at the same "level" of && or ||.
+ * For example, in the expression 'e1 && (e2 || e3) && (e4 || e5)', the
+ * following operands will be compared:
+ *
+ *	- 'e1', 'e2 || e3', and 'e4 || e5', against each other
+ *	- e2 against e3
+ *	- e4 against e5
+ *
+ * Parentheses are irrelevant within a single level. 'e1 && (e2 && e3)' and
+ * '(e1 && e2) && e3' are both a single level.
+ *
+ * See __expr_eliminate_eq() as well.
+ */
 void expr_eliminate_eq(struct expr **ep1, struct expr **ep2)
 {
 	if (!e1 || !e2)
@@ -197,6 +242,12 @@ void expr_eliminate_eq(struct expr **ep1, struct expr **ep2)
 #undef e1
 #undef e2
 
+/*
+ * Returns true if 'e1' and 'e2' are equal, after minor simplification. Two
+ * &&/|| expressions are considered equal if every operand in one expression
+ * equals some operand in the other (operands do not need to appear in the same
+ * order), recursively.
+ */
 static int expr_eq(struct expr *e1, struct expr *e2)
 {
 	int res, old_count;
@@ -243,6 +294,17 @@ static int expr_eq(struct expr *e1, struct expr *e2)
 	return 0;
 }
 
+/*
+ * Recursively performs the following simplifications in-place (as well as the
+ * corresponding simplifications with swapped operands):
+ *
+ *	expr && n  ->  n
+ *	expr && y  ->  expr
+ *	expr || n  ->  expr
+ *	expr || y  ->  y
+ *
+ * Returns the optimized expression.
+ */
 static struct expr *expr_eliminate_yn(struct expr *e)
 {
 	struct expr *tmp;
@@ -516,12 +578,21 @@ static struct expr *expr_join_and(struct expr *e1, struct expr *e2)
 	return NULL;
 }
 
+/*
+ * expr_eliminate_dups() helper.
+ *
+ * Walks the two expression trees given in 'ep1' and 'ep2'. Any node that does
+ * not have type 'type' (E_OR/E_AND) is considered a leaf, and is compared
+ * against all other leaves to look for simplifications.
+ */
 static void expr_eliminate_dups1(enum expr_type type, struct expr **ep1, struct expr **ep2)
 {
 #define e1 (*ep1)
 #define e2 (*ep2)
 	struct expr *tmp;
 
+	/* Recurse down to leaves */
+
 	if (e1->type == type) {
 		expr_eliminate_dups1(type, &e1->left.expr, &e2);
 		expr_eliminate_dups1(type, &e1->right.expr, &e2);
@@ -532,6 +603,9 @@ static void expr_eliminate_dups1(enum expr_type type, struct expr **ep1, struct
 		expr_eliminate_dups1(type, &e1, &e2->right.expr);
 		return;
 	}
+
+	/* e1 and e2 are leaves. Compare and process them. */
+
 	if (e1 == e2)
 		return;
 
@@ -568,6 +642,17 @@ static void expr_eliminate_dups1(enum expr_type type, struct expr **ep1, struct
 #undef e2
 }
 
+/*
+ * Rewrites 'e' in-place to remove ("join") duplicate and other redundant
+ * operands.
+ *
+ * Example simplifications:
+ *
+ *	A || B || A    ->  A || B
+ *	A && B && A=y  ->  A=y && B
+ *
+ * Returns the deduplicated expression.
+ */
 struct expr *expr_eliminate_dups(struct expr *e)
 {
 	int oldcount;
@@ -584,6 +669,7 @@ struct expr *expr_eliminate_dups(struct expr *e)
 			;
 		}
 		if (!trans_count)
+			/* No simplifications done in this pass. We're done */
 			break;
 		e = expr_eliminate_yn(e);
 	}
@@ -591,6 +677,12 @@ struct expr *expr_eliminate_dups(struct expr *e)
 	return e;
 }
 
+/*
+ * Performs various simplifications involving logical operators and
+ * comparisons.
+ *
+ * Allocates and returns a new expression.
+ */
 struct expr *expr_transform(struct expr *e)
 {
 	struct expr *tmp;
@@ -805,6 +897,20 @@ bool expr_depends_symbol(struct expr *dep, struct symbol *sym)
  	return false;
 }
 
+/*
+ * Inserts explicit comparisons of type 'type' to symbol 'sym' into the
+ * expression 'e'.
+ *
+ * Examples transformations for type == E_UNEQUAL, sym == &symbol_no:
+ *
+ *	A              ->  A!=n
+ *	!A             ->  A=n
+ *	A && B         ->  !(A=n || B=n)
+ *	A || B         ->  !(A=n && B=n)
+ *	A && (B || C)  ->  !(A=n || (B=n && C=n))
+ *
+ * Allocates and returns a new expression.
+ */
 struct expr *expr_trans_compare(struct expr *e, enum expr_type type, struct symbol *sym)
 {
 	struct expr *e1, *e2;
@@ -893,7 +999,10 @@ static enum string_value_kind expr_parse_string(const char *str,
 	switch (type) {
 	case S_BOOLEAN:
 	case S_TRISTATE:
-		return k_string;
+		val->s = !strcmp(str, "n") ? 0 :
+			 !strcmp(str, "m") ? 1 :
+			 !strcmp(str, "y") ? 2 : -1;
+		return k_signed;
 	case S_INT:
 		val->s = strtoll(str, &tail, 10);
 		kind = k_signed;
@@ -1028,49 +1137,9 @@ static int expr_compare_type(enum expr_type t1, enum expr_type t2)
 	return 0;
 }
 
-static inline struct expr *
-expr_get_leftmost_symbol(const struct expr *e)
-{
-
-	if (e == NULL)
-		return NULL;
-
-	while (e->type != E_SYMBOL)
-		e = e->left.expr;
-
-	return expr_copy(e);
-}
-
-/*
- * Given expression `e1' and `e2', returns the leaf of the longest
- * sub-expression of `e1' not containing 'e2.
- */
-struct expr *expr_simplify_unmet_dep(struct expr *e1, struct expr *e2)
-{
-	struct expr *ret;
-
-	switch (e1->type) {
-	case E_OR:
-		return expr_alloc_and(
-		    expr_simplify_unmet_dep(e1->left.expr, e2),
-		    expr_simplify_unmet_dep(e1->right.expr, e2));
-	case E_AND: {
-		struct expr *e;
-		e = expr_alloc_and(expr_copy(e1), expr_copy(e2));
-		e = expr_eliminate_dups(e);
-		ret = (!expr_eq(e, e1)) ? e1 : NULL;
-		expr_free(e);
-		break;
-		}
-	default:
-		ret = e1;
-		break;
-	}
-
-	return expr_get_leftmost_symbol(ret);
-}
-
-void expr_print(struct expr *e, void (*fn)(void *, struct symbol *, const char *), void *data, int prevtoken)
+void expr_print(struct expr *e,
+		void (*fn)(void *, struct symbol *, const char *),
+		void *data, int prevtoken)
 {
 	if (!e) {
 		fn(data, NULL, "y");
@@ -1204,3 +1273,33 @@ void expr_gstr_print(struct expr *e, struct gstr *gs)
 {
 	expr_print(e, expr_print_gstr_helper, gs, E_NONE);
 }
+
+/*
+ * Transform the top level "||" tokens into newlines and prepend each
+ * line with a minus. This makes expressions much easier to read.
+ * Suitable for reverse dependency expressions.
+ */
+static void expr_print_revdep(struct expr *e,
+			      void (*fn)(void *, struct symbol *, const char *),
+			      void *data, tristate pr_type, const char **title)
+{
+	if (e->type == E_OR) {
+		expr_print_revdep(e->left.expr, fn, data, pr_type, title);
+		expr_print_revdep(e->right.expr, fn, data, pr_type, title);
+	} else if (expr_calc_value(e) == pr_type) {
+		if (*title) {
+			fn(data, NULL, *title);
+			*title = NULL;
+		}
+
+		fn(data, NULL, "  - ");
+		expr_print(e, fn, data, E_NONE);
+		fn(data, NULL, "\n");
+	}
+}
+
+void expr_gstr_print_revdep(struct expr *e, struct gstr *gs,
+			    tristate pr_type, const char *title)
+{
+	expr_print_revdep(e, expr_print_gstr_helper, gs, pr_type, &title);
+}