Commit 64e6c1e1 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Sam Ravnborg
Browse files

genksyms: track symbol checksum changes 



Sometimes it is preferable to avoid changes of exported symbol checksums
(to avoid breaking externally provided modules).  When a checksum change
occurs, it can be hard to figure out what caused this change: underlying
types may have changed, or additional type information may simply have
become available at the point where a symbol is exported.

Add a new --reference option to genksyms which allows it to report why
checksums change, based on the type information dumps it creates with the
--dump-types flag.  Genksyms will read in such a dump from a previous run,
and report which symbols have changed (and why).

The behavior can be controlled for an entire build as follows: If
KBUILD_SYMTYPES is set, genksyms uses --dump-types to produce *.symtypes
dump files.  If any *.symref files exist, those will be used as the
reference to check against.  If KBUILD_PRESERVE is set, checksum changes
will fail the build.

Signed-off-by: default avatarAndreas Gruenbacher <agruen@suse.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
parent a680eedc

scripts/Makefile.build

+13 −3
Original line number Diff line number Diff line
@@ -153,12 +153,18 @@ $(obj)/%.i: $(src)/%.c FORCE 


quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@

cmd_cc_symtypes_c	   = \

		set -e;							\

		$(CPP) -D__GENKSYMS__ $(c_flags) $<			\

		| $(GENKSYMS) -T $@ >/dev/null;				\

		| $(GENKSYMS) -T $@					\

			      -r $(firstword $(wildcard			\

				     $(@:.symtypes=.symref) /dev/null))	\

			      $(if $(KBUILD_PRESERVE),-p)		\

			      -a $(ARCH)				\

		  >/dev/null;						\

		test -s $@ || rm -f $@



$(obj)/%.symtypes : $(src)/%.c FORCE

	$(call if_changed_dep,cc_symtypes_c)

	$(call cmd,cc_symtypes_c)



# C (.c) files

# The C file is compiled and updated dependency information is generated.
@@ -187,7 +193,11 @@ cmd_modversions = \ 
	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then	\

		$(CPP) -D__GENKSYMS__ $(c_flags) $<			\

		| $(GENKSYMS) $(if $(KBUILD_SYMTYPES),			\

			      -T $(@D)/$(@F:.o=.symtypes)) -a $(ARCH)	\

			           -T $(@:.o=.symtypes))		\

			      -r $(firstword $(wildcard			\

				     $(@:.o=.symref) /dev/null))	\

			      $(if $(KBUILD_PRESERVE),-p)		\

			      -a $(ARCH)				\

		> $(@D)/.tmp_$(@F:.o=.ver);				\

									\

		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 		\

scripts/genksyms/genksyms.c

+220 −16
Original line number Diff line number Diff line
@@ -42,7 +42,8 @@ static FILE *debugfile; 
int cur_line = 1;

char *cur_filename;



static int flag_debug, flag_dump_defs, flag_dump_types, flag_warnings;

static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,

	   flag_preserve, flag_warnings;

static const char *arch = "";

static const char *mod_prefix = "";
@@ -58,6 +59,8 @@ static const char *const symbol_type_name[] = { 


static int equal_list(struct string_list *a, struct string_list *b);

static void print_list(FILE * f, struct string_list *list);

static void print_location(void);

static void print_type_name(enum symbol_type type, const char *name);



/*----------------------------------------------------------------------*/
@@ -151,25 +154,66 @@ struct symbol *find_symbol(const char *name, enum symbol_type ns) 


	for (sym = symtab[h]; sym; sym = sym->hash_next)

		if (map_to_ns(sym->type) == map_to_ns(ns) &&

		    strcmp(name, sym->name) == 0)

		    strcmp(name, sym->name) == 0 &&

		    sym->is_declared)

			break;



	return sym;

}



struct symbol *add_symbol(const char *name, enum symbol_type type,

			  struct string_list *defn, int is_extern)

static int is_unknown_symbol(struct symbol *sym)

{

	struct string_list *defn;



	return ((sym->type == SYM_STRUCT ||

		 sym->type == SYM_UNION ||

		 sym->type == SYM_ENUM) &&

		(defn = sym->defn)  && defn->tag == SYM_NORMAL &&

			strcmp(defn->string, "}") == 0 &&

		(defn = defn->next) && defn->tag == SYM_NORMAL &&

			strcmp(defn->string, "UNKNOWN") == 0 &&

		(defn = defn->next) && defn->tag == SYM_NORMAL &&

			strcmp(defn->string, "{") == 0);

}



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;

	struct symbol *sym;

	enum symbol_status status = STATUS_UNCHANGED;



	for (sym = symtab[h]; sym; sym = sym->hash_next) {

		if (map_to_ns(sym->type) == map_to_ns(type)

		    && strcmp(name, sym->name) == 0) {

			if (!equal_list(sym->defn, defn))

		if (map_to_ns(sym->type) == map_to_ns(type) &&

		    strcmp(name, sym->name) == 0) {

			if (is_reference)

				/* fall through */ ;

			else if (sym->type == type &&

				 equal_list(sym->defn, defn)) {

				sym->is_declared = 1;

				return sym;

			} else if (!sym->is_declared) {

				status = is_unknown_symbol(sym) ?

					STATUS_DEFINED : STATUS_MODIFIED;

			} else {

				error_with_pos("redefinition of %s", name);

				return sym;

			}

			break;

		}

	}



	if (sym) {

		struct symbol **psym;



		for (psym = &symtab[h]; *psym; psym = &(*psym)->hash_next) {

			if (*psym == sym) {

				*psym = sym->hash_next;

				break;

			}

		}

		--nsyms;

	}



	sym = xmalloc(sizeof(*sym));
@@ -183,6 +227,9 @@ struct symbol *add_symbol(const char *name, enum symbol_type type, 
	sym->hash_next = symtab[h];

	symtab[h] = sym;



	sym->is_declared = !is_reference;

	sym->status = status;



	if (flag_debug) {

		fprintf(debugfile, "Defn for %s %s == <",

			symbol_type_name[type], name);
@@ -196,6 +243,18 @@ struct symbol *add_symbol(const char *name, enum symbol_type type, 
	return sym;

}



struct symbol *add_symbol(const char *name, enum symbol_type type,

			  struct string_list *defn, int is_extern)

{

	return __add_symbol(name, type, defn, is_extern, 0);

}



struct symbol *add_reference_symbol(const char *name, enum symbol_type type,

				    struct string_list *defn, int is_extern)

{

	return __add_symbol(name, type, defn, is_extern, 1);

}



/*----------------------------------------------------------------------*/



void free_node(struct string_list *node)
@@ -236,6 +295,82 @@ static int equal_list(struct string_list *a, struct string_list *b) 
	return !a && !b;

}



#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))



struct string_list *read_node(FILE *f)

{

	char buffer[256];

	struct string_list node = {

		.string = buffer,

		.tag = SYM_NORMAL };

	int c;



	while ((c = fgetc(f)) != EOF) {

		if (c == ' ') {

			if (node.string == buffer)

				continue;

			break;

		} else if (c == '\n') {

			if (node.string == buffer)

				return NULL;

			ungetc(c, f);

			break;

		}

		if (node.string >= buffer + sizeof(buffer) - 1) {

			fprintf(stderr, "Token too long\n");

			exit(1);

		}

		*node.string++ = c;

	}

	if (node.string == buffer)

		return NULL;

	*node.string = 0;

	node.string = buffer;



	if (node.string[1] == '#') {

		int n;



		for (n = 0; n < ARRAY_SIZE(symbol_type_name); n++) {

			if (node.string[0] == symbol_type_name[n][0]) {

				node.tag = n;

				node.string += 2;

				return copy_node(&node);

			}

		}

		fprintf(stderr, "Unknown type %c\n", node.string[0]);

		exit(1);

	}

	return copy_node(&node);

}



static void read_reference(FILE *f)

{

	while (!feof(f)) {

		struct string_list *defn = NULL;

		struct string_list *sym, *def;

		int is_extern = 0;



		sym = read_node(f);

		if (!sym)

			continue;

		def = read_node(f);

		if (def && def->tag == SYM_NORMAL &&

		    !strcmp(def->string, "extern")) {

			is_extern = 1;

			free_node(def);

			def = read_node(f);

		}

		while (def) {

			def->next = defn;

			defn = def;

			def = read_node(f);

		}

		add_reference_symbol(xstrdup(sym->string), sym->tag,

					      defn, is_extern);

		free_node(sym);

	}

}



static void print_node(FILE * f, struct string_list *list)

{

	if (list->tag != SYM_NORMAL) {
@@ -311,6 +446,7 @@ static unsigned long expand_and_crc_sym(struct symbol *sym, unsigned long crc) 


		case SYM_TYPEDEF:

			subsym = find_symbol(cur->string, cur->tag);

			/* FIXME: Bad reference files can segfault here. */

			if (subsym->expansion_trail) {

				if (flag_dump_defs)

					fprintf(debugfile, "%s ", cur->string);
@@ -347,9 +483,22 @@ static unsigned long expand_and_crc_sym(struct symbol *sym, unsigned long crc) 
				t = n;



				n = xmalloc(sizeof(*n));

				n->string = xstrdup("{ UNKNOWN }");

				n->string = xstrdup("{");

				n->tag = SYM_NORMAL;

				n->next = t;

				t = n;



				n = xmalloc(sizeof(*n));

				n->string = xstrdup("UNKNOWN");

				n->tag = SYM_NORMAL;

				n->next = t;

				t = n;



				n = xmalloc(sizeof(*n));

				n->string = xstrdup("}");

				n->tag = SYM_NORMAL;

				n->next = t;

				t = n;



				subsym =

				    add_symbol(cur->string, cur->tag, n, 0);
@@ -397,20 +546,42 @@ void export_symbol(const char *name) 
		error_with_pos("export undefined symbol %s", name);

	else {

		unsigned long crc;

		int has_changed = 0;



		if (flag_dump_defs)

			fprintf(debugfile, "Export %s == <", name);



		expansion_trail = (struct symbol *)-1L;



		sym->expansion_trail = expansion_trail;

		expansion_trail = sym;

		crc = expand_and_crc_sym(sym, 0xffffffff) ^ 0xffffffff;



		sym = expansion_trail;

		while (sym != (struct symbol *)-1L) {

			struct symbol *n = sym->expansion_trail;



			if (sym->status != STATUS_UNCHANGED) {

				if (!has_changed) {

					print_location();

					fprintf(stderr, "%s: %s: modversion "

						"changed because of changes "

						"in ", flag_preserve ? "error" :

						       "warning", name);

				} else

					fprintf(stderr, ", ");

				print_type_name(sym->type, sym->name);

				if (sym->status == STATUS_DEFINED)

					fprintf(stderr, " (became defined)");

				has_changed = 1;

				if (flag_preserve)

					errors++;

			}

			sym->expansion_trail = 0;

			sym = n;

		}

		if (has_changed)

			fprintf(stderr, "\n");



		if (flag_dump_defs)

			fputs(">\n", debugfile);
@@ -421,13 +592,26 @@ void export_symbol(const char *name) 
}



/*----------------------------------------------------------------------*/



static void print_location(void)

{

	fprintf(stderr, "%s:%d: ", cur_filename ? : "<stdin>", cur_line);

}



static void print_type_name(enum symbol_type type, const char *name)

{

	if (type != SYM_NORMAL)

		fprintf(stderr, "%s %s", symbol_type_name[type], name);

	else

		fprintf(stderr, "%s", name);

}



void error_with_pos(const char *fmt, ...)

{

	va_list args;



	if (flag_warnings) {

		fprintf(stderr, "%s:%d: ", cur_filename ? : "<stdin>",

			cur_line);

		print_location();



		va_start(args, fmt);

		vfprintf(stderr, fmt, args);
@@ -445,7 +629,9 @@ static void genksyms_usage(void) 
	      "  -a, --arch            Select architecture\n"

	      "  -d, --debug           Increment the debug level (repeatable)\n"

	      "  -D, --dump            Dump expanded symbol defs (for debugging only)\n"

	      "  -T, --dump-types file Dump expanded types into file (for debugging only)\n"

	      "  -r, --reference file  Read reference symbols from a file\n"

	      "  -T, --dump-types file Dump expanded types into file\n"

	      "  -p, --preserve        Preserve reference modversions or fail\n"

	      "  -w, --warnings        Enable warnings\n"

	      "  -q, --quiet           Disable warnings (default)\n"

	      "  -h, --help            Print this message\n"
@@ -454,7 +640,9 @@ static void genksyms_usage(void) 
	      "  -a                    Select architecture\n"

	      "  -d                    Increment the debug level (repeatable)\n"

	      "  -D                    Dump expanded symbol defs (for debugging only)\n"

	      "  -T file               Dump expanded types into file (for debugging only)\n"

	      "  -r file               Read reference symbols from a file\n"

	      "  -T file               Dump expanded types into file\n"

	      "  -p                    Preserve reference modversions or fail\n"

	      "  -w                    Enable warnings\n"

	      "  -q                    Disable warnings (default)\n"

	      "  -h                    Print this message\n"
@@ -465,7 +653,7 @@ static void genksyms_usage(void) 


int main(int argc, char **argv)

{

	FILE *dumpfile = NULL;

	FILE *dumpfile = NULL, *ref_file = NULL;

	int o;



#ifdef __GNU_LIBRARY__
@@ -475,16 +663,18 @@ int main(int argc, char **argv) 
		{"warnings", 0, 0, 'w'},

		{"quiet", 0, 0, 'q'},

		{"dump", 0, 0, 'D'},

		{"reference", 1, 0, 'r'},

		{"dump-types", 1, 0, 'T'},

		{"preserve", 0, 0, 'p'},

		{"version", 0, 0, 'V'},

		{"help", 0, 0, 'h'},

		{0, 0, 0, 0}

	};



	while ((o = getopt_long(argc, argv, "a:dwqVDT:h",

	while ((o = getopt_long(argc, argv, "a:dwqVDr:T:ph",

				&long_opts[0], NULL)) != EOF)

#else				/* __GNU_LIBRARY__ */

	while ((o = getopt(argc, argv, "a:dwqVDT:h")) != EOF)

	while ((o = getopt(argc, argv, "a:dwqVDr:T:ph")) != EOF)

#endif				/* __GNU_LIBRARY__ */

		switch (o) {

		case 'a':
@@ -505,6 +695,14 @@ int main(int argc, char **argv) 
		case 'D':

			flag_dump_defs = 1;

			break;

		case 'r':

			flag_reference = 1;

			ref_file = fopen(optarg, "r");

			if (!ref_file) {

				perror(optarg);

				return 1;

			}

			break;

		case 'T':

			flag_dump_types = 1;

			dumpfile = fopen(optarg, "w");
@@ -513,6 +711,9 @@ int main(int argc, char **argv) 
				return 1;

			}

			break;

		case 'p':

			flag_preserve = 1;

			break;

		case 'h':

			genksyms_usage();

			return 0;
@@ -533,6 +734,9 @@ int main(int argc, char **argv) 
		/* setlinebuf(debugfile); */

	}



	if (flag_reference)

		read_reference(ref_file);



	yyparse();



	if (flag_dump_types && visited_symbols) {

scripts/genksyms/genksyms.h

+6 −0
Original line number Diff line number Diff line
@@ -29,6 +29,10 @@ enum symbol_type { 
	SYM_NORMAL, SYM_TYPEDEF, SYM_ENUM, SYM_STRUCT, SYM_UNION

};



enum symbol_status {

	STATUS_UNCHANGED, STATUS_DEFINED, STATUS_MODIFIED

};



struct string_list {

	struct string_list *next;

	enum symbol_type tag;
@@ -43,6 +47,8 @@ struct symbol { 
	struct symbol *expansion_trail;

	struct symbol *visited;

	int is_extern;

	int is_declared;

	enum symbol_status status;

};



typedef struct string_list **yystype;

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