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Commit ad9546c9 authored by Rusty Russell's avatar Rusty Russell
Browse files

module: neaten __find_symbol, rename to find_symbol 



__find_symbol() has grown over time: there are now 5 different arrays
of symbols it traverses.  It also shouldn't print out a warning on
some calls (ie. verify_symbol which simply checks for name clashes,
and __symbol_put which checks for bugs).

1) Rename to find_symbol: no need for underscores.
2) Use bool and add "warn" parameter to suppress warnings.
3) Make table-driven rather than open coded.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent ea01e798

kernel/module.c

+125 −121
Original line number Diff line number Diff line
@@ -164,131 +164,140 @@ static const struct kernel_symbol *lookup_symbol(const char *name, 
	return NULL;

}



static void printk_unused_warning(const char *name)

static bool always_ok(bool gplok, bool warn, const char *name)

{

	return true;

}



static bool printk_unused_warning(bool gplok, bool warn, const char *name)

{

	if (warn) {

		printk(KERN_WARNING "Symbol %s is marked as UNUSED, "

		       "however this module is using it.\n", name);

	printk(KERN_WARNING "This symbol will go away in the future.\n");

	printk(KERN_WARNING "Please evalute if this is the right api to use, "

		"and if it really is, submit a report the linux kernel "

		printk(KERN_WARNING

		       "This symbol will go away in the future.\n");

		printk(KERN_WARNING

		       "Please evalute if this is the right api to use and if "

		       "it really is, submit a report the linux kernel "

		       "mailinglist together with submitting your code for "

		       "inclusion.\n");

	}

	return true;

}



/* Find a symbol, return value, crc and module which owns it */

static unsigned long __find_symbol(const char *name,

				   struct module **owner,

				   const unsigned long **crc,

				   int gplok)

static bool gpl_only_unused_warning(bool gplok, bool warn, const char *name)

{

	struct module *mod;

	const struct kernel_symbol *ks;



	/* Core kernel first. */

	*owner = NULL;

	ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab);

	if (ks) {

		*crc = symversion(__start___kcrctab, (ks - __start___ksymtab));

		return ks->value;

	}

	if (gplok) {

		ks = lookup_symbol(name, __start___ksymtab_gpl,

					 __stop___ksymtab_gpl);

		if (ks) {

			*crc = symversion(__start___kcrctab_gpl,

					  (ks - __start___ksymtab_gpl));

			return ks->value;

	if (!gplok)

		return false;

	return printk_unused_warning(gplok, warn, name);

}



static bool gpl_only(bool gplok, bool warn, const char *name)

{

	return gplok;

}

	ks = lookup_symbol(name, __start___ksymtab_gpl_future,

				 __stop___ksymtab_gpl_future);

	if (ks) {

		if (!gplok) {



static bool warn_if_not_gpl(bool gplok, bool warn, const char *name)

{

	if (!gplok && warn) {

		printk(KERN_WARNING "Symbol %s is being used "

		       "by a non-GPL module, which will not "

		       "be allowed in the future\n", name);

		printk(KERN_WARNING "Please see the file "

		       "Documentation/feature-removal-schedule.txt "

			       "in the kernel source tree for more "

			       "details.\n");

		       "in the kernel source tree for more details.\n");

	}

		*crc = symversion(__start___kcrctab_gpl_future,

				  (ks - __start___ksymtab_gpl_future));

		return ks->value;

	return true;

}



	ks = lookup_symbol(name, __start___ksymtab_unused,

				 __stop___ksymtab_unused);

	if (ks) {

		printk_unused_warning(name);

		*crc = symversion(__start___kcrctab_unused,

				  (ks - __start___ksymtab_unused));

		return ks->value;

struct symsearch {

	const struct kernel_symbol *start, *stop;

	const unsigned long *crcs;

	bool (*check)(bool gplok, bool warn, const char *name);

};



/* Look through this array of symbol tables for a symbol match which

 * passes the check function. */

static const struct kernel_symbol *search_symarrays(const struct symsearch *arr,

						    unsigned int num,

						    const char *name,

						    bool gplok,

						    bool warn,

						    const unsigned long **crc)

{

	unsigned int i;

	const struct kernel_symbol *ks;



	for (i = 0; i < num; i++) {

		ks = lookup_symbol(name, arr[i].start, arr[i].stop);

		if (!ks || !arr[i].check(gplok, warn, name))

			continue;



		if (crc)

			*crc = symversion(arr[i].crcs, ks - arr[i].start);

		return ks;

	}

	return NULL;

}



	if (gplok)

		ks = lookup_symbol(name, __start___ksymtab_unused_gpl,

				 __stop___ksymtab_unused_gpl);

/* Find a symbol, return value, (optional) crc and (optional) module

 * which owns it */

static unsigned long find_symbol(const char *name,

				 struct module **owner,

				 const unsigned long **crc,

				 bool gplok,

				 bool warn)

{

	struct module *mod;

	const struct kernel_symbol *ks;

	const struct symsearch arr[] = {

		{ __start___ksymtab, __stop___ksymtab, __start___kcrctab,

		  always_ok },

		{ __start___ksymtab_gpl, __stop___ksymtab_gpl,

		  __start___kcrctab_gpl, gpl_only },

		{ __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future,

		  __start___kcrctab_gpl_future, warn_if_not_gpl },

		{ __start___ksymtab_unused, __stop___ksymtab_unused,

		  __start___kcrctab_unused, printk_unused_warning },

		{ __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl,

		  __start___kcrctab_unused_gpl, gpl_only_unused_warning },

	};



	/* Core kernel first. */

	ks = search_symarrays(arr, ARRAY_SIZE(arr), name, gplok, warn, crc);

	if (ks) {

		printk_unused_warning(name);

		*crc = symversion(__start___kcrctab_unused_gpl,

				  (ks - __start___ksymtab_unused_gpl));

		if (owner)

			*owner = NULL;

		return ks->value;

	}



	/* Now try modules. */

	list_for_each_entry(mod, &modules, list) {

		*owner = mod;

		ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);

		if (ks) {

			*crc = symversion(mod->crcs, (ks - mod->syms));

			return ks->value;

		}

		struct symsearch arr[] = {

			{ mod->syms, mod->syms + mod->num_syms, mod->crcs,

			  always_ok },

			{ mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,

			  mod->gpl_crcs, gpl_only },

			{ mod->gpl_future_syms,

			  mod->gpl_future_syms + mod->num_gpl_future_syms,

			  mod->gpl_future_crcs, warn_if_not_gpl },

			{ mod->unused_syms,

			  mod->unused_syms + mod->num_unused_syms,

			  mod->unused_crcs, printk_unused_warning },

			{ mod->unused_gpl_syms,

			  mod->unused_gpl_syms + mod->num_unused_gpl_syms,

			  mod->unused_gpl_crcs, gpl_only_unused_warning },

		};



		if (gplok) {

			ks = lookup_symbol(name, mod->gpl_syms,

					   mod->gpl_syms + mod->num_gpl_syms);

		ks = search_symarrays(arr, ARRAY_SIZE(arr),

				      name, gplok, warn, crc);

		if (ks) {

				*crc = symversion(mod->gpl_crcs,

						  (ks - mod->gpl_syms));

			if (owner)

				*owner = mod;

			return ks->value;

		}

	}

		ks = lookup_symbol(name, mod->unused_syms, mod->unused_syms + mod->num_unused_syms);

		if (ks) {

			printk_unused_warning(name);

			*crc = symversion(mod->unused_crcs, (ks - mod->unused_syms));

			return ks->value;

		}



		if (gplok) {

			ks = lookup_symbol(name, mod->unused_gpl_syms,

					   mod->unused_gpl_syms + mod->num_unused_gpl_syms);

			if (ks) {

				printk_unused_warning(name);

				*crc = symversion(mod->unused_gpl_crcs,

						  (ks - mod->unused_gpl_syms));

				return ks->value;

			}

		}

		ks = lookup_symbol(name, mod->gpl_future_syms,

				   (mod->gpl_future_syms +

				    mod->num_gpl_future_syms));

		if (ks) {

			if (!gplok) {

				printk(KERN_WARNING "Symbol %s is being used "

				       "by a non-GPL module, which will not "

				       "be allowed in the future\n", name);

				printk(KERN_WARNING "Please see the file "

				       "Documentation/feature-removal-schedule.txt "

				       "in the kernel source tree for more "

				       "details.\n");

			}

			*crc = symversion(mod->gpl_future_crcs,

					  (ks - mod->gpl_future_syms));

			return ks->value;

		}

	}

	DEBUGP("Failed to find symbol %s\n", name);

	return -ENOENT;

}
@@ -777,10 +786,9 @@ static void print_unload_info(struct seq_file *m, struct module *mod) 
void __symbol_put(const char *symbol)

{

	struct module *owner;

	const unsigned long *crc;



	preempt_disable();

	if (IS_ERR_VALUE(__find_symbol(symbol, &owner, &crc, 1)))

	if (IS_ERR_VALUE(find_symbol(symbol, &owner, NULL, true, false)))

		BUG();

	module_put(owner);

	preempt_enable();
@@ -924,13 +932,10 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs, 
					  struct module *mod)

{

	const unsigned long *crc;

	struct module *owner;



	if (IS_ERR_VALUE(__find_symbol("struct_module",

						&owner, &crc, 1)))

	if (IS_ERR_VALUE(find_symbol("struct_module", NULL, &crc, true, false)))

		BUG();

	return check_version(sechdrs, versindex, "struct_module", mod,

			     crc);

	return check_version(sechdrs, versindex, "struct_module", mod, crc);

}



/* First part is kernel version, which we ignore. */
@@ -974,8 +979,8 @@ static unsigned long resolve_symbol(Elf_Shdr *sechdrs, 
	unsigned long ret;

	const unsigned long *crc;



	ret = __find_symbol(name, &owner, &crc,

			!(mod->taints & TAINT_PROPRIETARY_MODULE));

	ret = find_symbol(name, &owner, &crc,

			  !(mod->taints & TAINT_PROPRIETARY_MODULE), true);

	if (!IS_ERR_VALUE(ret)) {

		/* use_module can fail due to OOM,

		   or module initialization or unloading */
@@ -1376,10 +1381,9 @@ void *__symbol_get(const char *symbol) 
{

	struct module *owner;

	unsigned long value;

	const unsigned long *crc;



	preempt_disable();

	value = __find_symbol(symbol, &owner, &crc, 1);

	value = find_symbol(symbol, &owner, NULL, true, true);

	if (IS_ERR_VALUE(value))

		value = 0;

	else if (strong_try_module_get(owner))
@@ -1402,16 +1406,16 @@ static int verify_export_symbols(struct module *mod) 
	const unsigned long *crc;



	for (i = 0; i < mod->num_syms; i++)

		if (!IS_ERR_VALUE(__find_symbol(mod->syms[i].name,

							&owner, &crc, 1))) {

		if (!IS_ERR_VALUE(find_symbol(mod->syms[i].name,

					      &owner, &crc, true, false))) {

			name = mod->syms[i].name;

			ret = -ENOEXEC;

			goto dup;

		}



	for (i = 0; i < mod->num_gpl_syms; i++)

		if (!IS_ERR_VALUE(__find_symbol(mod->gpl_syms[i].name,

							&owner, &crc, 1))) {

		if (!IS_ERR_VALUE(find_symbol(mod->gpl_syms[i].name,

					      &owner, &crc, true, false))) {

			name = mod->gpl_syms[i].name;

			ret = -ENOEXEC;

			goto dup;