module.c

/*
   Copyright (C) 2002 Richard Henderson
   Copyright (C) 2001 Rusty Russell, 2002, 2010 Rusty Russell IBM.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <linux/export.h>
#include <linux/moduleloader.h>
#include <linux/ftrace_event.h>
#include <linux/init.h>
#include <linux/kallsyms.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/elf.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/fcntl.h>
#include <linux/rcupdate.h>
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/vermagic.h>
#include <linux/notifier.h>
#include <linux/sched.h>
#include <linux/stop_machine.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/mutex.h>
#include <linux/rculist.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <linux/license.h>
#include <asm/sections.h>
#include <linux/tracepoint.h>
#include <linux/ftrace.h>
#include <linux/async.h>
#include <linux/percpu.h>
#include <linux/kmemleak.h>
#include <linux/jump_label.h>
#include <linux/pfn.h>
#include <linux/bsearch.h>
#include <linux/fips.h>
#include <uapi/linux/module.h>
#include "module-internal.h"

#define CREATE_TRACE_POINTS
#include <trace/events/module.h>

#ifndef ARCH_SHF_SMALL
#define ARCH_SHF_SMALL 0
#endif

/*
 * Modules' sections will be aligned on page boundaries
 * to ensure complete separation of code and data, but
 * only when CONFIG_DEBUG_SET_MODULE_RONX=y
 */
#ifdef CONFIG_DEBUG_SET_MODULE_RONX
# define debug_align(X) ALIGN(X, PAGE_SIZE)
#else
# define debug_align(X) (X)
#endif

/*
 * Given BASE and SIZE this macro calculates the number of pages the
 * memory regions occupies
 */
#define MOD_NUMBER_OF_PAGES(BASE, SIZE) (((SIZE) > 0) ?		\
		(PFN_DOWN((unsigned long)(BASE) + (SIZE) - 1) -	\
			 PFN_DOWN((unsigned long)BASE) + 1)	\
		: (0UL))

/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))

/*
 * Mutex protects:
 * 1) List of modules (also safely readable with preempt_disable),
 * 2) module_use links,
 * 3) module_addr_min/module_addr_max.
 * (delete uses stop_machine/add uses RCU list operations). */
DEFINE_MUTEX(module_mutex);
EXPORT_SYMBOL_GPL(module_mutex);
static LIST_HEAD(modules);
#ifdef CONFIG_KGDB_KDB
struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */
#endif /* CONFIG_KGDB_KDB */

#ifdef CONFIG_MODULE_SIG
#ifdef CONFIG_MODULE_SIG_FORCE
static bool sig_enforce = true;
#else
static bool sig_enforce = false;

static int param_set_bool_enable_only(const char *val,
				      const struct kernel_param *kp)
{
	int err;
	bool test;
	struct kernel_param dummy_kp = *kp;

	dummy_kp.arg = &test;

	err = param_set_bool(val, &dummy_kp);
	if (err)
		return err;

	/* Don't let them unset it once it's set! */
	if (!test && sig_enforce)
		return -EROFS;

	if (test)
		sig_enforce = true;
	return 0;
}

static const struct kernel_param_ops param_ops_bool_enable_only = {
	.flags = KERNEL_PARAM_FL_NOARG,
	.set = param_set_bool_enable_only,
	.get = param_get_bool,
};
#define param_check_bool_enable_only param_check_bool

module_param(sig_enforce, bool_enable_only, 0644);
#endif /* !CONFIG_MODULE_SIG_FORCE */
#endif /* CONFIG_MODULE_SIG */

/* Block module loading/unloading? */
int modules_disabled = 0;
core_param(nomodule, modules_disabled, bint, 0);

/* Waiting for a module to finish initializing? */
static DECLARE_WAIT_QUEUE_HEAD(module_wq);

static BLOCKING_NOTIFIER_HEAD(module_notify_list);

/* Bounds of module allocation, for speeding __module_address.
 * Protected by module_mutex. */
static unsigned long module_addr_min = -1UL, module_addr_max = 0;

int register_module_notifier(struct notifier_block * nb)
{
	return blocking_notifier_chain_register(&module_notify_list, nb);
}
EXPORT_SYMBOL(register_module_notifier);

int unregister_module_notifier(struct notifier_block * nb)
{
	return blocking_notifier_chain_unregister(&module_notify_list, nb);
}
EXPORT_SYMBOL(unregister_module_notifier);

struct load_info {
	Elf_Ehdr *hdr;
	unsigned long len;
	Elf_Shdr *sechdrs;
	char *secstrings, *strtab;
	unsigned long symoffs, stroffs;
	struct _ddebug *debug;
	unsigned int num_debug;
	bool sig_ok;
	struct {
		unsigned int sym, str, mod, vers, info, pcpu;
	} index;
};

/* We require a truly strong try_module_get(): 0 means failure due to
   ongoing or failed initialization etc. */
static inline int strong_try_module_get(struct module *mod)
{
	BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED);
	if (mod && mod->state == MODULE_STATE_COMING)
		return -EBUSY;
	if (try_module_get(mod))
		return 0;
	else
		return -ENOENT;
}

static inline void add_taint_module(struct module *mod, unsigned flag,
				    enum lockdep_ok lockdep_ok)
{
	add_taint(flag, lockdep_ok);
	mod->taints |= (1U << flag);
}

/*
 * A thread that wants to hold a reference to a module only while it
 * is running can call this to safely exit.  nfsd and lockd use this.
 */
void __module_put_and_exit(struct module *mod, long code)
{
	module_put(mod);
	do_exit(code);
}
EXPORT_SYMBOL(__module_put_and_exit);

/* Find a module section: 0 means not found. */
static unsigned int find_sec(const struct load_info *info, const char *name)
{
	unsigned int i;

	for (i = 1; i < info->hdr->e_shnum; i++) {
		Elf_Shdr *shdr = &info->sechdrs[i];
		/* Alloc bit cleared means "ignore it." */
		if ((shdr->sh_flags & SHF_ALLOC)
		    && strcmp(info->secstrings + shdr->sh_name, name) == 0)
			return i;
	}
	return 0;
}

/* Find a module section, or NULL. */
static void *section_addr(const struct load_info *info, const char *name)
{
	/* Section 0 has sh_addr 0. */
	return (void *)info->sechdrs[find_sec(info, name)].sh_addr;
}

/* Find a module section, or NULL.  Fill in number of "objects" in section. */
static void *section_objs(const struct load_info *info,
			  const char *name,
			  size_t object_size,
			  unsigned int *num)
{
	unsigned int sec = find_sec(info, name);

	/* Section 0 has sh_addr 0 and sh_size 0. */
	*num = info->sechdrs[sec].sh_size / object_size;
	return (void *)info->sechdrs[sec].sh_addr;
}

/* Provided by the linker */
extern const struct kernel_symbol __start___ksymtab[];
extern const struct kernel_symbol __stop___ksymtab[];
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 unsigned long __start___kcrctab[];
extern const unsigned long __start___kcrctab_gpl[];
extern const unsigned long __start___kcrctab_gpl_future[];
#ifdef CONFIG_UNUSED_SYMBOLS
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 unsigned long __start___kcrctab_unused[];
extern const unsigned long __start___kcrctab_unused_gpl[];
#endif

#ifndef CONFIG_MODVERSIONS
#define symversion(base, idx) NULL
#else
#define symversion(base, idx) ((base != NULL) ? ((base) + (idx)) : NULL)
#endif

static bool each_symbol_in_section(const struct symsearch *arr,
				   unsigned int arrsize,
				   struct module *owner,
				   bool (*fn)(const struct symsearch *syms,
					      struct module *owner,
					      void *data),
				   void *data)
{
	unsigned int j;

	for (j = 0; j < arrsize; j++) {
		if (fn(&arr[j], owner, data))
			return true;
	}

	return false;
}

/* Returns true as soon as fn returns true, otherwise false. */
bool each_symbol_section(bool (*fn)(const struct symsearch *arr,
				    struct module *owner,
				    void *data),
			 void *data)
{
	struct module *mod;
	static const struct symsearch arr[] = {
		{ __start___ksymtab, __stop___ksymtab, __start___kcrctab,
		  NOT_GPL_ONLY, false },
		{ __start___ksymtab_gpl, __stop___ksymtab_gpl,
		  __start___kcrctab_gpl,
		  GPL_ONLY, false },
		{ __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future,
		  __start___kcrctab_gpl_future,
		  WILL_BE_GPL_ONLY, false },
#ifdef CONFIG_UNUSED_SYMBOLS
		{ __start___ksymtab_unused, __stop___ksymtab_unused,
		  __start___kcrctab_unused,
		  NOT_GPL_ONLY, true },
		{ __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl,
		  __start___kcrctab_unused_gpl,
		  GPL_ONLY, true },
#endif
	};

	if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))
		return true;

	list_for_each_entry_rcu(mod, &modules, list) {
		struct symsearch arr[] = {
			{ mod->syms, mod->syms + mod->num_syms, mod->crcs,
			  NOT_GPL_ONLY, false },
			{ mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,
			  mod->gpl_crcs,
			  GPL_ONLY, false },
			{ mod->gpl_future_syms,
			  mod->gpl_future_syms + mod->num_gpl_future_syms,
			  mod->gpl_future_crcs,
			  WILL_BE_GPL_ONLY, false },
#ifdef CONFIG_UNUSED_SYMBOLS
			{ mod->unused_syms,
			  mod->unused_syms + mod->num_unused_syms,
			  mod->unused_crcs,
			  NOT_GPL_ONLY, true },
			{ mod->unused_gpl_syms,
			  mod->unused_gpl_syms + mod->num_unused_gpl_syms,
			  mod->unused_gpl_crcs,
			  GPL_ONLY, true },
#endif
		};

		if (mod->state == MODULE_STATE_UNFORMED)
			continue;

		if (each_symbol_in_section(arr, ARRAY_SIZE(arr), mod, fn, data))
			return true;
	}
	return false;
}
EXPORT_SYMBOL_GPL(each_symbol_section);

struct find_symbol_arg {
	/* Input */
	const char *name;
	bool gplok;
	bool warn;

	/* Output */
	struct module *owner;
	const unsigned long *crc;
	const struct kernel_symbol *sym;
};

static bool check_symbol(const struct symsearch *syms,
				 struct module *owner,
				 unsigned int symnum, void *data)
{
	struct find_symbol_arg *fsa = data;

	if (!fsa->gplok) {
		if (syms->licence == GPL_ONLY)
			return false;
		if (syms->licence == WILL_BE_GPL_ONLY && fsa->warn) {
			pr_warn("Symbol %s is being used by a non-GPL module, "
				"which will not be allowed in the future\n",
				fsa->name);
		}
	}

#ifdef CONFIG_UNUSED_SYMBOLS
	if (syms->unused && fsa->warn) {
		pr_warn("Symbol %s is marked as UNUSED, however this module is "
			"using it.\n", fsa->name);
		pr_warn("This symbol will go away in the future.\n");
		pr_warn("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");
	}
#endif

	fsa->owner = owner;
	fsa->crc = symversion(syms->crcs, symnum);
	fsa->sym = &syms->start[symnum];
	return true;
}

static int cmp_name(const void *va, const void *vb)
{
	const char *a;
	const struct kernel_symbol *b;
	a = va; b = vb;
	return strcmp(a, b->name);
}

static bool find_symbol_in_section(const struct symsearch *syms,
				   struct module *owner,
				   void *data)
{
	struct find_symbol_arg *fsa = data;
	struct kernel_symbol *sym;

	sym = bsearch(fsa->name, syms->start, syms->stop - syms->start,
			sizeof(struct kernel_symbol), cmp_name);

	if (sym != NULL && check_symbol(syms, owner, sym - syms->start, data))
		return true;

	return false;
}

/* Find a symbol and return it, along with, (optional) crc and
 * (optional) module which owns it.  Needs preempt disabled or module_mutex. */
const struct kernel_symbol *find_symbol(const char *name,
					struct module **owner,
					const unsigned long **crc,
					bool gplok,
					bool warn)
{
	struct find_symbol_arg fsa;

	fsa.name = name;
	fsa.gplok = gplok;
	fsa.warn = warn;

	if (each_symbol_section(find_symbol_in_section, &fsa)) {
		if (owner)
			*owner = fsa.owner;
		if (crc)
			*crc = fsa.crc;
		return fsa.sym;
	}

	pr_debug("Failed to find symbol %s\n", name);
	return NULL;
}
EXPORT_SYMBOL_GPL(find_symbol);

/* Search for module by name: must hold module_mutex. */
static struct module *find_module_all(const char *name, size_t len,
				      bool even_unformed)
{
	struct module *mod;

	list_for_each_entry(mod, &modules, list) {
		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
			continue;
		if (strlen(mod->name) == len && !memcmp(mod->name, name, len))
			return mod;
	}
	return NULL;
}

struct module *find_module(const char *name)
{
	return find_module_all(name, strlen(name), false);
}
EXPORT_SYMBOL_GPL(find_module);

#ifdef CONFIG_SMP

static inline void __percpu *mod_percpu(struct module *mod)
{
	return mod->percpu;
}

static int percpu_modalloc(struct module *mod, struct load_info *info)
{
	Elf_Shdr *pcpusec = &info->sechdrs[info->index.pcpu];
	unsigned long align = pcpusec->sh_addralign;

	if (!pcpusec->sh_size)
		return 0;

	if (align > PAGE_SIZE) {
		pr_warn("%s: per-cpu alignment %li > %li\n",
			mod->name, align, PAGE_SIZE);
		align = PAGE_SIZE;
	}

	mod->percpu = __alloc_reserved_percpu(pcpusec->sh_size, align);
	if (!mod->percpu) {
		pr_warn("%s: Could not allocate %lu bytes percpu data\n",
			mod->name, (unsigned long)pcpusec->sh_size);
		return -ENOMEM;
	}
	mod->percpu_size = pcpusec->sh_size;
	return 0;
}

static void percpu_modfree(struct module *mod)
{
	free_percpu(mod->percpu);
}

static unsigned int find_pcpusec(struct load_info *info)
{
	return find_sec(info, ".data..percpu");
}

static void percpu_modcopy(struct module *mod,
			   const void *from, unsigned long size)
{
	int cpu;

	for_each_possible_cpu(cpu)
		memcpy(per_cpu_ptr(mod->percpu, cpu), from, size);
}

/**
 * is_module_percpu_address - test whether address is from module static percpu
 * @addr: address to test
 *
 * Test whether @addr belongs to module static percpu area.
 *
 * RETURNS:
 * %true if @addr is from module static percpu area
 */
bool is_module_percpu_address(unsigned long addr)
{
	struct module *mod;
	unsigned int cpu;

	preempt_disable();

	list_for_each_entry_rcu(mod, &modules, list) {
		if (mod->state == MODULE_STATE_UNFORMED)
			continue;
		if (!mod->percpu_size)
			continue;
		for_each_possible_cpu(cpu) {
			void *start = per_cpu_ptr(mod->percpu, cpu);

			if ((void *)addr >= start &&
			    (void *)addr < start + mod->percpu_size) {
				preempt_enable();
				return true;
			}
		}
	}

	preempt_enable();
	return false;
}

#else /* ... !CONFIG_SMP */

static inline void __percpu *mod_percpu(struct module *mod)
{
	return NULL;
}
static int percpu_modalloc(struct module *mod, struct load_info *info)
{
	/* UP modules shouldn't have this section: ENOMEM isn't quite right */
	if (info->sechdrs[info->index.pcpu].sh_size != 0)
		return -ENOMEM;
	return 0;
}
static inline void percpu_modfree(struct module *mod)
{
}
static unsigned int find_pcpusec(struct load_info *info)
{
	return 0;
}
static inline void percpu_modcopy(struct module *mod,
				  const void *from, unsigned long size)
{
	/* pcpusec should be 0, and size of that section should be 0. */
	BUG_ON(size != 0);
}
bool is_module_percpu_address(unsigned long addr)
{
	return false;
}

#endif /* CONFIG_SMP */

#define MODINFO_ATTR(field)	\
static void setup_modinfo_##field(struct module *mod, const char *s)  \
{                                                                     \
	mod->field = kstrdup(s, GFP_KERNEL);                          \
}                                                                     \
static ssize_t show_modinfo_##field(struct module_attribute *mattr,   \
			struct module_kobject *mk, char *buffer)      \
{                                                                     \
	return scnprintf(buffer, PAGE_SIZE, "%s\n", mk->mod->field);  \
}                                                                     \
static int modinfo_##field##_exists(struct module *mod)               \
{                                                                     \
	return mod->field != NULL;                                    \
}                                                                     \
static void free_modinfo_##field(struct module *mod)                  \
{                                                                     \
	kfree(mod->field);                                            \
	mod->field = NULL;                                            \
}                                                                     \
static struct module_attribute modinfo_##field = {                    \
	.attr = { .name = __stringify(field), .mode = 0444 },         \
	.show = show_modinfo_##field,                                 \
	.setup = setup_modinfo_##field,                               \
	.test = modinfo_##field##_exists,                             \
	.free = free_modinfo_##field,                                 \
};

MODINFO_ATTR(version);
MODINFO_ATTR(srcversion);

static char last_unloaded_module[MODULE_NAME_LEN+1];

#ifdef CONFIG_MODULE_UNLOAD

EXPORT_TRACEPOINT_SYMBOL(module_get);

/* Init the unload section of the module. */
static int module_unload_init(struct module *mod)
{
	mod->refptr = alloc_percpu(struct module_ref);
	if (!mod->refptr)
		return -ENOMEM;

	INIT_LIST_HEAD(&mod->source_list);
	INIT_LIST_HEAD(&mod->target_list);

	/* Hold reference count during initialization. */
	raw_cpu_write(mod->refptr->incs, 1);

	return 0;
}

/* Does a already use b? */
static int already_uses(struct module *a, struct module *b)
{
	struct module_use *use;

	list_for_each_entry(use, &b->source_list, source_list) {
		if (use->source == a) {
			pr_debug("%s uses %s!\n", a->name, b->name);
			return 1;
		}
	}
	pr_debug("%s does not use %s!\n", a->name, b->name);
	return 0;
}

/*
 * Module a uses b
 *  - we add 'a' as a "source", 'b' as a "target" of module use
 *  - the module_use is added to the list of 'b' sources (so
 *    'b' can walk the list to see who sourced them), and of 'a'
 *    targets (so 'a' can see what modules it targets).
 */
static int add_module_usage(struct module *a, struct module *b)
{
	struct module_use *use;

	pr_debug("Allocating new usage for %s.\n", a->name);
	use = kmalloc(sizeof(*use), GFP_ATOMIC);
	if (!use) {
		pr_warn("%s: out of memory loading\n", a->name);
		return -ENOMEM;
	}

	use->source = a;
	use->target = b;
	list_add(&use->source_list, &b->source_list);
	list_add(&use->target_list, &a->target_list);
	return 0;
}

/* Module a uses b: caller needs module_mutex() */
int ref_module(struct module *a, struct module *b)
{
	int err;

	if (b == NULL || already_uses(a, b))
		return 0;

	/* If module isn't available, we fail. */
	err = strong_try_module_get(b);
	if (err)
		return err;

	err = add_module_usage(a, b);
	if (err) {
		module_put(b);
		return err;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(ref_module);

/* Clear the unload stuff of the module. */
static void module_unload_free(struct module *mod)
{
	struct module_use *use, *tmp;

	mutex_lock(&module_mutex);
	list_for_each_entry_safe(use, tmp, &mod->target_list, target_list) {
		struct module *i = use->target;
		pr_debug("%s unusing %s\n", mod->name, i->name);
		module_put(i);
		list_del(&use->source_list);
		list_del(&use->target_list);
		kfree(use);
	}
	mutex_unlock(&module_mutex);

	free_percpu(mod->refptr);
}

#ifdef CONFIG_MODULE_FORCE_UNLOAD
static inline int try_force_unload(unsigned int flags)
{
	int ret = (flags & O_TRUNC);
	if (ret)
		add_taint(TAINT_FORCED_RMMOD, LOCKDEP_NOW_UNRELIABLE);
	return ret;
}
#else
static inline int try_force_unload(unsigned int flags)
{
	return 0;
}
#endif /* CONFIG_MODULE_FORCE_UNLOAD */

struct stopref
{
	struct module *mod;
	int flags;
	int *forced;
};

/* Whole machine is stopped with interrupts off when this runs. */
static int __try_stop_module(void *_sref)
{
	struct stopref *sref = _sref;

	/* If it's not unused, quit unless we're forcing. */
	if (module_refcount(sref->mod) != 0) {
		if (!(*sref->forced = try_force_unload(sref->flags)))
			return -EWOULDBLOCK;
	}

	/* Mark it as dying. */
	sref->mod->state = MODULE_STATE_GOING;
	return 0;
}

static int try_stop_module(struct module *mod, int flags, int *forced)
{
	struct stopref sref = { mod, flags, forced };

	return stop_machine(__try_stop_module, &sref, NULL);
}

unsigned long module_refcount(struct module *mod)
{
	unsigned long incs = 0, decs = 0;
	int cpu;

	for_each_possible_cpu(cpu)
		decs += per_cpu_ptr(mod->refptr, cpu)->decs;
	/*
	 * ensure the incs are added up after the decs.
	 * module_put ensures incs are visible before decs with smp_wmb.
	 *
	 * This 2-count scheme avoids the situation where the refcount
	 * for CPU0 is read, then CPU0 increments the module refcount,
	 * then CPU1 drops that refcount, then the refcount for CPU1 is
	 * read. We would record a decrement but not its corresponding
	 * increment so we would see a low count (disaster).
	 *
	 * Rare situation? But module_refcount can be preempted, and we
	 * might be tallying up 4096+ CPUs. So it is not impossible.
	 */
	smp_rmb();
	for_each_possible_cpu(cpu)
		incs += per_cpu_ptr(mod->refptr, cpu)->incs;
	return incs - decs;
}
EXPORT_SYMBOL(module_refcount);

/* This exists whether we can unload or not */
static void free_module(struct module *mod);

SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
		unsigned int, flags)
{
	struct module *mod;
	char name[MODULE_NAME_LEN];
	int ret, forced = 0;

	if (!capable(CAP_SYS_MODULE) || modules_disabled)
		return -EPERM;

	if (strncpy_from_user(name, name_user, MODULE_NAME_LEN-1) < 0)
		return -EFAULT;
	name[MODULE_NAME_LEN-1] = '\0';

	if (!(flags & O_NONBLOCK))
		pr_warn("waiting module removal not supported: please upgrade\n");

	if (mutex_lock_interruptible(&module_mutex) != 0)
		return -EINTR;

	mod = find_module(name);
	if (!mod) {
		ret = -ENOENT;
		goto out;
	}

	if (!list_empty(&mod->source_list)) {
		/* Other modules depend on us: get rid of them first. */
		ret = -EWOULDBLOCK;
		goto out;
	}

	/* Doing init or already dying? */
	if (mod->state != MODULE_STATE_LIVE) {
		/* FIXME: if (force), slam module count damn the torpedoes */
		pr_debug("%s already dying\n", mod->name);
		ret = -EBUSY;
		goto out;
	}

	/* If it has an init func, it must have an exit func to unload */
	if (mod->init && !mod->exit) {
		forced = try_force_unload(flags);
		if (!forced) {
			/* This module can't be removed */
			ret = -EBUSY;
			goto out;
		}
	}

	/* Stop the machine so refcounts can't move and disable module. */
	ret = try_stop_module(mod, flags, &forced);
	if (ret != 0)
		goto out;

	mutex_unlock(&module_mutex);
	/* Final destruction now no one is using it. */
	if (mod->exit != NULL)
		mod->exit();
	blocking_notifier_call_chain(&module_notify_list,
				     MODULE_STATE_GOING, mod);
	async_synchronize_full();

	/* Store the name of the last unloaded module for diagnostic purposes */
	strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));

	free_module(mod);
	return 0;
out:
	mutex_unlock(&module_mutex);
	return ret;
}

static inline void print_unload_info(struct seq_file *m, struct module *mod)
{
	struct module_use *use;
	int printed_something = 0;

	seq_printf(m, " %lu ", module_refcount(mod));

	/* Always include a trailing , so userspace can differentiate
           between this and the old multi-field proc format. */
	list_for_each_entry(use, &mod->source_list, source_list) {
		printed_something = 1;
		seq_printf(m, "%s,", use->source->name);
	}

	if (mod->init != NULL && mod->exit == NULL) {
		printed_something = 1;
		seq_printf(m, "[permanent],");
	}

	if (!printed_something)
		seq_printf(m, "-");
}

void __symbol_put(const char *symbol)
{
	struct module *owner;

	preempt_disable();
	if (!find_symbol(symbol, &owner, NULL, true, false))
		BUG();
	module_put(owner);
	preempt_enable();
}
EXPORT_SYMBOL(__symbol_put);

/* Note this assumes addr is a function, which it currently always is. */
void symbol_put_addr(void *addr)
{
	struct module *modaddr;
	unsigned long a = (unsigned long)dereference_function_descriptor(addr);

	if (core_kernel_text(a))
		return;

	/* module_text_address is safe here: we're supposed to have reference
	 * to module from symbol_get, so it can't go away. */
	modaddr = __module_text_address(a);
	BUG_ON(!modaddr);
	module_put(modaddr);
}
EXPORT_SYMBOL_GPL(symbol_put_addr);

static ssize_t show_refcnt(struct module_attribute *mattr,
			   struct module_kobject *mk, char *buffer)
{
	return sprintf(buffer, "%lu\n", module_refcount(mk->mod));
}

static struct module_attribute modinfo_refcnt =
	__ATTR(refcnt, 0444, show_refcnt, NULL);

void __module_get(struct module *module)
{
	if (module) {
		preempt_disable();
		__this_cpu_inc(module->refptr->incs);
		trace_module_get(module, _RET_IP_);
		preempt_enable();
	}
}
EXPORT_SYMBOL(__module_get);

bool try_module_get(struct module *module)
{
	bool ret = true;

	if (module) {
		preempt_disable();

		if (likely(module_is_live(module))) {
			__this_cpu_inc(module->refptr->incs);
			trace_module_get(module, _RET_IP_);
		} else
			ret = false;

		preempt_enable();
	}
	return ret;
}
EXPORT_SYMBOL(try_module_get);

void module_put(struct module *module)
{
	if (module) {
		preempt_disable();
		smp_wmb(); /* see comment in module_refcount */
		__this_cpu_inc(module->refptr->decs);

		trace_module_put(module, _RET_IP_);
		preempt_enable();
	}
}
EXPORT_SYMBOL(module_put);

#else /* !CONFIG_MODULE_UNLOAD */
static inline void print_unload_info(struct seq_file *m, struct module *mod)
{
	/* We don't know the usage count, or what modules are using. */
	seq_printf(m, " - -");
}

static inline void module_unload_free(struct module *mod)
{
}

int ref_module(struct module *a, struct module *b)
{
	return strong_try_module_get(b);
}
EXPORT_SYMBOL_GPL(ref_module);

static inline int module_unload_init(struct module *mod)
{
	return 0;