[PATCH] Add EXPORT_UNUSED_SYMBOL and EXPORT_UNUSED_SYMBOL_GPL (f71d20e9) · Commits · 戴 / test

Documentation/feature-removal-schedule.txt

+10 −0

Original line number	Diff line number	Diff line
		@@ -177,6 +177,16 @@ Who: Jean Delvare <khali@linux-fr.org>

		---------------------------

		What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports
		(temporary transition config option provided until then)
		The transition config option will also be removed at the same time.
		When: before 2.6.19
		Why: Unused symbols are both increasing the size of the kernel binary
		and are often a sign of "wrong API"
		Who: Arjan van de Ven <arjan@linux.intel.com>

		---------------------------

		What: remove EXPORT_SYMBOL(tasklist_lock)
		When: August 2006
		Files: kernel/fork.c

include/asm-generic/vmlinux.lds.h

+28 −0

Original line number	Diff line number	Diff line
		@@ -58,6 +58,20 @@
		VMLINUX_SYMBOL(__stop___ksymtab_gpl) = .; \
		} \
		\
		/* Kernel symbol table: Normal unused symbols */ \
		__ksymtab_unused : AT(ADDR(__ksymtab_unused) - LOAD_OFFSET) { \
		VMLINUX_SYMBOL(__start___ksymtab_unused) = .; \
		*(__ksymtab_unused) \
		VMLINUX_SYMBOL(__stop___ksymtab_unused) = .; \
		} \
		\
		/* Kernel symbol table: GPL-only unused symbols */ \
		__ksymtab_unused_gpl : AT(ADDR(__ksymtab_unused_gpl) - LOAD_OFFSET) { \
		VMLINUX_SYMBOL(__start___ksymtab_unused_gpl) = .; \
		*(__ksymtab_unused_gpl) \
		VMLINUX_SYMBOL(__stop___ksymtab_unused_gpl) = .; \
		} \
		\
		/* Kernel symbol table: GPL-future-only symbols */ \
		__ksymtab_gpl_future : AT(ADDR(__ksymtab_gpl_future) - LOAD_OFFSET) { \
		VMLINUX_SYMBOL(__start___ksymtab_gpl_future) = .; \
		@@ -79,6 +93,20 @@
		VMLINUX_SYMBOL(__stop___kcrctab_gpl) = .; \
		} \
		\
		/* Kernel symbol table: Normal unused symbols */ \
		__kcrctab_unused : AT(ADDR(__kcrctab_unused) - LOAD_OFFSET) { \
		VMLINUX_SYMBOL(__start___kcrctab_unused) = .; \
		*(__kcrctab_unused) \
		VMLINUX_SYMBOL(__stop___kcrctab_unused) = .; \
		} \
		\
		/* Kernel symbol table: GPL-only unused symbols */ \
		__kcrctab_unused_gpl : AT(ADDR(__kcrctab_unused_gpl) - LOAD_OFFSET) { \
		VMLINUX_SYMBOL(__start___kcrctab_unused_gpl) = .; \
		*(__kcrctab_unused_gpl) \
		VMLINUX_SYMBOL(__stop___kcrctab_unused_gpl) = .; \
		} \
		\
		/* Kernel symbol table: GPL-future-only symbols */ \
		__kcrctab_gpl_future : AT(ADDR(__kcrctab_gpl_future) - LOAD_OFFSET) { \
		VMLINUX_SYMBOL(__start___kcrctab_gpl_future) = .; \

include/linux/module.h

+20 −0

Original line number	Diff line number	Diff line
		@@ -203,6 +203,15 @@ void __symbol_get_gpl(const char symbol);
		#define EXPORT_SYMBOL_GPL_FUTURE(sym) \
		__EXPORT_SYMBOL(sym, "_gpl_future")


		#ifdef CONFIG_UNUSED_SYMBOLS
		#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
		#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
		#else
		#define EXPORT_UNUSED_SYMBOL(sym)
		#define EXPORT_UNUSED_SYMBOL_GPL(sym)
		#endif

		#endif

		struct module_ref
		@@ -261,6 +270,15 @@ struct module
		unsigned int num_gpl_syms;
		const unsigned long *gpl_crcs;

		/* unused exported symbols. */
		const struct kernel_symbol *unused_syms;
		unsigned int num_unused_syms;
		const unsigned long *unused_crcs;
		/* GPL-only, unused exported symbols. */
		const struct kernel_symbol *unused_gpl_syms;
		unsigned int num_unused_gpl_syms;
		const unsigned long *unused_gpl_crcs;

		/* symbols that will be GPL-only in the near future. */
		const struct kernel_symbol *gpl_future_syms;
		unsigned int num_gpl_future_syms;
		@@ -456,6 +474,8 @@ void module_remove_driver(struct device_driver *);
		#define EXPORT_SYMBOL(sym)
		#define EXPORT_SYMBOL_GPL(sym)
		#define EXPORT_SYMBOL_GPL_FUTURE(sym)
		#define EXPORT_UNUSED_SYMBOL(sym)
		#define EXPORT_UNUSED_SYMBOL_GPL(sym)

		/* Given an address, look for it in the exception tables. */
		static inline const struct exception_table_entry *

kernel/module.c

+76 −2

Original line number	Diff line number	Diff line
		/* Rewritten by Rusty Russell, on the backs of many others...
		/*
		Copyright (C) 2002 Richard Henderson
		Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.

		@@ -122,9 +122,17 @@ extern const struct kernel_symbol __start___ksymtab_gpl[];
		extern const struct kernel_symbol __stop___ksymtab_gpl[];
		extern const struct kernel_symbol __start___ksymtab_gpl_future[];
		extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
		extern const struct kernel_symbol __start___ksymtab_unused[];
		extern const struct kernel_symbol __stop___ksymtab_unused[];
		extern const struct kernel_symbol __start___ksymtab_unused_gpl[];
		extern const struct kernel_symbol __stop___ksymtab_unused_gpl[];
		extern const struct kernel_symbol __start___ksymtab_gpl_future[];
		extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
		extern const unsigned long __start___kcrctab[];
		extern const unsigned long __start___kcrctab_gpl[];
		extern const unsigned long __start___kcrctab_gpl_future[];
		extern const unsigned long __start___kcrctab_unused[];
		extern const unsigned long __start___kcrctab_unused_gpl[];

		#ifndef CONFIG_MODVERSIONS
		#define symversion(base, idx) NULL
		@@ -144,6 +152,17 @@ static const struct kernel_symbol lookup_symbol(const char name,
		return NULL;
		}

		static void printk_unused_warning(const char *name)
		{
		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 "
		"mailinglist together with submitting your code for "
		"inclusion.\n");
		}

		/* Find a symbol, return value, crc and module which owns it */
		static unsigned long __find_symbol(const char *name,
		struct module **owner,
		@@ -186,6 +205,25 @@ static unsigned long __find_symbol(const char *name,
		return ks->value;
		}

		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;
		}

		if (gplok)
		ks = lookup_symbol(name, __start___ksymtab_unused_gpl,
		__stop___ksymtab_unused_gpl);
		if (ks) {
		printk_unused_warning(name);
		*crc = symversion(__start___kcrctab_unused_gpl,
		(ks - __start___ksymtab_unused_gpl));
		return ks->value;
		}

		/* Now try modules. */
		list_for_each_entry(mod, &modules, list) {
		*owner = mod;
		@@ -204,6 +242,23 @@ static unsigned long __find_symbol(const char *name,
		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));
		@@ -1407,6 +1462,8 @@ static struct module load_module(void __user umod,
		exportindex, modindex, obsparmindex, infoindex, gplindex,
		crcindex, gplcrcindex, versindex, pcpuindex, gplfutureindex,
		gplfuturecrcindex, unwindex = 0;
		unsigned int unusedindex, unusedcrcindex, unusedgplindex,
		unusedgplcrcindex;
		struct module *mod;
		long err = 0;
		void percpu = NULL, ptr = NULL; /* Stops spurious gcc warning */
		@@ -1487,9 +1544,13 @@ static struct module load_module(void __user umod,
		exportindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab");
		gplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl");
		gplfutureindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl_future");
		unusedindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused");
		unusedgplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused_gpl");
		crcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab");
		gplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl");
		gplfuturecrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl_future");
		unusedcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused");
		unusedgplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused_gpl");
		setupindex = find_sec(hdr, sechdrs, secstrings, "__param");
		exindex = find_sec(hdr, sechdrs, secstrings, "__ex_table");
		obsparmindex = find_sec(hdr, sechdrs, secstrings, "__obsparm");
		@@ -1638,14 +1699,27 @@ static struct module load_module(void __user umod,
		mod->gpl_crcs = (void *)sechdrs[gplcrcindex].sh_addr;
		mod->num_gpl_future_syms = sechdrs[gplfutureindex].sh_size /
		sizeof(*mod->gpl_future_syms);
		mod->num_unused_syms = sechdrs[unusedindex].sh_size /
		sizeof(*mod->unused_syms);
		mod->num_unused_gpl_syms = sechdrs[unusedgplindex].sh_size /
		sizeof(*mod->unused_gpl_syms);
		mod->gpl_future_syms = (void *)sechdrs[gplfutureindex].sh_addr;
		if (gplfuturecrcindex)
		mod->gpl_future_crcs = (void *)sechdrs[gplfuturecrcindex].sh_addr;

		mod->unused_syms = (void *)sechdrs[unusedindex].sh_addr;
		if (unusedcrcindex)
		mod->unused_crcs = (void *)sechdrs[unusedcrcindex].sh_addr;
		mod->unused_gpl_syms = (void *)sechdrs[unusedgplindex].sh_addr;
		if (unusedgplcrcindex)
		mod->unused_crcs = (void *)sechdrs[unusedgplcrcindex].sh_addr;

		#ifdef CONFIG_MODVERSIONS
		if ((mod->num_syms && !crcindex) \|\|
		(mod->num_gpl_syms && !gplcrcindex) \|\|
		(mod->num_gpl_future_syms && !gplfuturecrcindex)) {
		(mod->num_gpl_future_syms && !gplfuturecrcindex) \|\|
		(mod->num_unused_syms && !unusedcrcindex) \|\|
		(mod->num_unused_gpl_syms && !unusedgplcrcindex)) {
		printk(KERN_WARNING "%s: No versions for exported symbols."
		" Tainting kernel.\n", mod->name);
		add_taint(TAINT_FORCED_MODULE);

lib/Kconfig.debug

+16 −0

Original line number	Diff line number	Diff line
		@@ -23,6 +23,22 @@ config MAGIC_SYSRQ
		keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
		unless you really know what this hack does.

		config UNUSED_SYMBOLS
		bool "Enable unused/obsolete exported symbols"
		default y if X86
		help
		Unused but exported symbols make the kernel needlessly bigger. For
		that reason most of these unused exports will soon be removed. This
		option is provided temporarily to provide a transition period in case
		some external kernel module needs one of these symbols anyway. If you
		encounter such a case in your module, consider if you are actually
		using the right API. (rationale: since nobody in the kernel is using
		this in a module, there is a pretty good chance it's actually the
		wrong interface to use). If you really need the symbol, please send a
		mail to the linux kernel mailing list mentioning the symbol and why
		you really need it, and what the merge plan to the mainline kernel for
		your module is.

		config DEBUG_KERNEL
		bool "Kernel debugging"
		help

Admin message