genksyms: Track changes to enum constants
Enum constants can be used as array sizes; if the enum itself does not
appear in the symbol expansion, a change in the enum constant will go
unnoticed. Example patch that changes the ABI but does not change the
checksum with current genksyms:
| enum e {
| E1,
| E2,
|+ E3,
| E_MAX
| };
|
| struct s {
| int a[E_MAX];
| }
|
| int f(struct s *s) { ... }
| EXPORT_SYMBOL(f)
Therefore, remember the value of each enum constant and
expand each occurence to <constant> <value>. The value is not actually
computed, but instead an expression in the form
(last explicitly assigned value) + N
is used. This avoids having to parse and semantically understand whole
of C.
Note: The changes won't take effect until the lexer and parser are
rebuilt by the next patch.
Signed-off-by: Michal Marek <mmarek@suse.cz>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c
index 4a35081..f9e7553 100644
--- a/scripts/genksyms/genksyms.c
+++ b/scripts/genksyms/genksyms.c
@@ -62,6 +62,7 @@
[SYM_ENUM] = {'e', "enum"},
[SYM_STRUCT] = {'s', "struct"},
[SYM_UNION] = {'u', "union"},
+ [SYM_ENUM_CONST] = {'E', "enum constant"},
};
static int equal_list(struct string_list *a, struct string_list *b);
@@ -149,10 +150,16 @@
static enum symbol_type map_to_ns(enum symbol_type t)
{
- if (t == SYM_TYPEDEF)
- t = SYM_NORMAL;
- else if (t == SYM_UNION)
- t = SYM_STRUCT;
+ switch (t) {
+ case SYM_ENUM_CONST:
+ case SYM_NORMAL:
+ case SYM_TYPEDEF:
+ return SYM_NORMAL;
+ case SYM_ENUM:
+ case SYM_STRUCT:
+ case SYM_UNION:
+ return SYM_STRUCT;
+ }
return t;
}
@@ -191,10 +198,47 @@
struct string_list *defn, int is_extern,
int is_reference)
{
- unsigned long h = crc32(name) % HASH_BUCKETS;
+ unsigned long h;
struct symbol *sym;
enum symbol_status status = STATUS_UNCHANGED;
+ /* The parser adds symbols in the order their declaration completes,
+ * so it is safe to store the value of the previous enum constant in
+ * a static variable.
+ */
+ static int enum_counter;
+ static struct string_list *last_enum_expr;
+ if (type == SYM_ENUM_CONST) {
+ if (defn) {
+ free_list(last_enum_expr, NULL);
+ last_enum_expr = copy_list_range(defn, NULL);
+ enum_counter = 1;
+ } else {
+ struct string_list *expr;
+ char buf[20];
+
+ snprintf(buf, sizeof(buf), "%d", enum_counter++);
+ if (last_enum_expr) {
+ expr = copy_list_range(last_enum_expr, NULL);
+ defn = concat_list(mk_node("("),
+ expr,
+ mk_node(")"),
+ mk_node("+"),
+ mk_node(buf), NULL);
+ } else {
+ defn = mk_node(buf);
+ }
+ }
+ } else if (type == SYM_ENUM) {
+ free_list(last_enum_expr, NULL);
+ last_enum_expr = NULL;
+ enum_counter = 0;
+ if (!name)
+ /* Anonymous enum definition, nothing more to do */
+ return NULL;
+ }
+
+ h = crc32(name) % HASH_BUCKETS;
for (sym = symtab[h]; sym; sym = sym->hash_next) {
if (map_to_ns(sym->type) == map_to_ns(type) &&
strcmp(name, sym->name) == 0) {
@@ -343,6 +387,22 @@
return newnode;
}
+struct string_list *copy_list_range(struct string_list *start,
+ struct string_list *end)
+{
+ struct string_list *res, *n;
+
+ if (start == end)
+ return NULL;
+ n = res = copy_node(start);
+ for (start = start->next; start != end; start = start->next) {
+ n->next = copy_node(start);
+ n = n->next;
+ }
+ n->next = NULL;
+ return res;
+}
+
static int equal_list(struct string_list *a, struct string_list *b)
{
while (a && b) {
@@ -512,6 +572,7 @@
crc = partial_crc32_one(' ', crc);
break;
+ case SYM_ENUM_CONST:
case SYM_TYPEDEF:
subsym = find_symbol(cur->string, cur->tag, 0);
/* FIXME: Bad reference files can segfault here. */