Commit e37ddb82 authored by Michal Marek's avatar Michal Marek
Browse files

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: default avatarMichal Marek <mmarek@suse.cz>
Acked-by: default avatarSam Ravnborg <sam@ravnborg.org>
parent 01762c4e

scripts/genksyms/genksyms.c

+66 −5
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ static const struct { 
	[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 unsigned long crc32(const char *s) 


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 @@ static struct symbol *__add_symbol(const char *name, enum symbol_type type, 
			    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 @@ struct string_list *copy_node(struct string_list *node) 
	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 @@ static unsigned long expand_and_crc_sym(struct symbol *sym, unsigned long crc) 
			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. */

scripts/genksyms/genksyms.h

+4 −1
Original line number Diff line number Diff line
@@ -26,7 +26,8 @@ 
#include <stdio.h>



enum symbol_type {

	SYM_NORMAL, SYM_TYPEDEF, SYM_ENUM, SYM_STRUCT, SYM_UNION

	SYM_NORMAL, SYM_TYPEDEF, SYM_ENUM, SYM_STRUCT, SYM_UNION,

	SYM_ENUM_CONST

};



enum symbol_status {
@@ -66,6 +67,8 @@ void export_symbol(const char *); 
void free_node(struct string_list *list);

void free_list(struct string_list *s, struct string_list *e);

struct string_list *copy_node(struct string_list *);

struct string_list *copy_list_range(struct string_list *start,

				    struct string_list *end);



int yylex(void);

int yyparse(void);

scripts/genksyms/lex.l

+27 −3
Original line number Diff line number Diff line
@@ -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;

scripts/genksyms/parse.y

+30 −4
Original line number Diff line number Diff line
@@ -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; }

	;

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