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>

1 files changed, 30 insertions, 4 deletions

diff --git a/scripts/genksyms/parse.y b/scripts/genksyms/parse.y
index 09a265cd719..ba5c242866c 100644
--- a/scripts/genksyms/parse.y
+++ b/scripts/genksyms/parse.y
@@ -25,6 +25,7 @@
 
 #include <assert.h>
 #include <stdlib.h>
+#include <string.h>
 #include "genksyms.h"
 
 static int is_typedef;
@@ -227,16 +228,19 @@ type_specifier:
                   add_symbol(i->string, SYM_UNION, s, is_extern);
                   $$ = $3;
                 }
-        | ENUM_KEYW IDENT BRACE_PHRASE
+        | ENUM_KEYW IDENT enum_body
                 { struct string_list *s = *$3, *i = *$2, *r;
                   r = copy_node(i); r->tag = SYM_ENUM;
                   r->next = (*$1)->next; *$3 = r; (*$1)->next = NULL;
                   add_symbol(i->string, SYM_ENUM, s, is_extern);
                   $$ = $3;
                 }
-
-        /* Anonymous s/u/e definitions.  Nothing needs doing.  */
-        | ENUM_KEYW BRACE_PHRASE                        { $$ = $2; }
+        /*
+         * Anonymous enum definition. Tell add_symbol() to restart its counter.
+         */
+        | ENUM_KEYW enum_body
+                { add_symbol(NULL, SYM_ENUM, NULL, 0); $$ = $2; }
+        /* Anonymous s/u definitions.  Nothing needs doing.  */
         | STRUCT_KEYW class_body                        { $$ = $2; }
         | UNION_KEYW class_body                         { $$ = $2; }
         ;
@@ -449,6 +453,28 @@ attribute_opt:
         | attribute_opt ATTRIBUTE_PHRASE
         ;
 
+enum_body:
+        '{' enumerator_list '}'                         { $$ = $3; }
+        | '{' enumerator_list ',' '}'                   { $$ = $4; }
+         ;
+
+enumerator_list:
+        enumerator
+        | enumerator_list ',' enumerator
+
+enumerator:
+        IDENT
+                {
+                        const char *name = strdup((*$1)->string);
+                        add_symbol(name, SYM_ENUM_CONST, NULL, 0);
+                }
+        | IDENT '=' EXPRESSION_PHRASE
+                {
+                        const char *name = strdup((*$1)->string);
+                        struct string_list *expr = copy_list_range(*$3, *$2);
+                        add_symbol(name, SYM_ENUM_CONST, expr, 0);
+                }
+
 asm_definition:
         ASM_PHRASE ';'                                  { $$ = $2; }
         ;