From e37ddb82500393cb417c3ab0fe0726d9a8652372 Mon Sep 17 00:00:00 2001 From: Michal Marek Date: Thu, 3 Feb 2011 23:57:09 +0100 Subject: 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 . 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 Acked-by: Sam Ravnborg --- scripts/genksyms/lex.l | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) (limited to 'scripts/genksyms/lex.l') diff --git a/scripts/genksyms/lex.l b/scripts/genksyms/lex.l index c125d06fbd36..e4ddd493fec3 100644 --- a/scripts/genksyms/lex.l +++ b/scripts/genksyms/lex.l @@ -99,12 +99,23 @@ MC_TOKEN ([~%^&*+=|<>/-]=)|(&&)|("||")|(->)|(<<)|(>>) /* Macros to append to our phrase collection list. */ +/* + * We mark any token, that that equals to a known enumerator, as + * SYM_ENUM_CONST. The parser will change this for struct and union tags later, + * the only problem is struct and union members: + * enum e { a, b }; struct s { int a, b; } + * but in this case, the only effect will be, that the ABI checksums become + * more volatile, which is acceptable. Also, such collisions are quite rare, + * so far it was only observed in include/linux/telephony.h. + */ #define _APP(T,L) do { \ cur_node = next_node; \ next_node = xmalloc(sizeof(*next_node)); \ next_node->next = cur_node; \ cur_node->string = memcpy(xmalloc(L+1), T, L+1); \ - cur_node->tag = SYM_NORMAL; \ + cur_node->tag = \ + find_symbol(cur_node->string, SYM_ENUM_CONST, 1)?\ + SYM_ENUM_CONST : SYM_NORMAL ; \ } while (0) #define APP _APP(yytext, yyleng) @@ -182,8 +193,8 @@ repeat: case STRUCT_KEYW: case UNION_KEYW: - dont_want_brace_phrase = 3; case ENUM_KEYW: + dont_want_brace_phrase = 3; suppress_type_lookup = 2; goto fini; @@ -312,7 +323,20 @@ repeat: ++count; APP; goto repeat; - case ')': case ']': case '}': + case '}': + /* is this the last line of an enum declaration? */ + if (count == 0) + { + /* Put back the token we just read so's we can find it again + after registering the expression. */ + unput(token); + + lexstate = ST_NORMAL; + token = EXPRESSION_PHRASE; + break; + } + /* FALLTHRU */ + case ')': case ']': --count; APP; goto repeat; -- cgit