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module.c

/*
   Copyright (C) 2002 Richard Henderson
   Copyright (C) 2001 Rusty Russell, 2002 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/module.h>
#include <linux/moduleloader.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/elf.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/stop_machine.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/mutex.h>
#include <linux/unwind.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>
#include <asm/cacheflush.h>
#include <linux/license.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , a...)
#endif

#ifndef ARCH_SHF_SMALL
#define ARCH_SHF_SMALL 0
#endif

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

/* Protects module list */
static DEFINE_SPINLOCK(modlist_lock);

/* List of modules, protected by module_mutex AND modlist_lock */
static DEFINE_MUTEX(module_mutex);
static LIST_HEAD(modules);

static BLOCKING_NOTIFIER_HEAD(module_notify_list);

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);

/* We require a truly strong try_module_get() */
static inline int strong_try_module_get(struct module *mod)
{
      if (mod && mod->state == MODULE_STATE_COMING)
            return 0;
      return try_module_get(mod);
}

/* A thread that wants to hold a reference to a module only while it
 * is running can call ths 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(Elf_Ehdr *hdr,
                       Elf_Shdr *sechdrs,
                       const char *secstrings,
                       const char *name)
{
      unsigned int i;

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

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

/* lookup symbol in given range of kernel_symbols */
static const struct kernel_symbol *lookup_symbol(const char *name,
      const struct kernel_symbol *start,
      const struct kernel_symbol *stop)
{
      const struct kernel_symbol *ks = start;
      for (; ks < stop; ks++)
            if (strcmp(ks->name, name) == 0)
                  return ks;
      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,
                           const unsigned long **crc,
                           int gplok)
{
      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;
            }
      }
      ks = lookup_symbol(name, __start___ksymtab_gpl_future,
                         __stop___ksymtab_gpl_future);
      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(__start___kcrctab_gpl_future,
                          (ks - __start___ksymtab_gpl_future));
            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;
            ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);
            if (ks) {
                  *crc = symversion(mod->crcs, (ks - mod->syms));
                  return ks->value;
            }

            if (gplok) {
                  ks = lookup_symbol(name, mod->gpl_syms,
                                 mod->gpl_syms + mod->num_gpl_syms);
                  if (ks) {
                        *crc = symversion(mod->gpl_crcs,
                                      (ks - mod->gpl_syms));
                        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 0;
}

/* Search for module by name: must hold module_mutex. */
static struct module *find_module(const char *name)
{
      struct module *mod;

      list_for_each_entry(mod, &modules, list) {
            if (strcmp(mod->name, name) == 0)
                  return mod;
      }
      return NULL;
}

#ifdef CONFIG_SMP
/* Number of blocks used and allocated. */
static unsigned int pcpu_num_used, pcpu_num_allocated;
/* Size of each block.  -ve means used. */
static int *pcpu_size;

static int split_block(unsigned int i, unsigned short size)
{
      /* Reallocation required? */
      if (pcpu_num_used + 1 > pcpu_num_allocated) {
            int *new = kmalloc(sizeof(new[0]) * pcpu_num_allocated*2,
                           GFP_KERNEL);
            if (!new)
                  return 0;

            memcpy(new, pcpu_size, sizeof(new[0])*pcpu_num_allocated);
            pcpu_num_allocated *= 2;
            kfree(pcpu_size);
            pcpu_size = new;
      }

      /* Insert a new subblock */
      memmove(&pcpu_size[i+1], &pcpu_size[i],
            sizeof(pcpu_size[0]) * (pcpu_num_used - i));
      pcpu_num_used++;

      pcpu_size[i+1] -= size;
      pcpu_size[i] = size;
      return 1;
}

static inline unsigned int block_size(int val)
{
      if (val < 0)
            return -val;
      return val;
}

/* Created by linker magic */
extern char __per_cpu_start[], __per_cpu_end[];

static void *percpu_modalloc(unsigned long size, unsigned long align,
                       const char *name)
{
      unsigned long extra;
      unsigned int i;
      void *ptr;

      if (align > SMP_CACHE_BYTES) {
            printk(KERN_WARNING "%s: per-cpu alignment %li > %i\n",
                   name, align, SMP_CACHE_BYTES);
            align = SMP_CACHE_BYTES;
      }

      ptr = __per_cpu_start;
      for (i = 0; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) {
            /* Extra for alignment requirement. */
            extra = ALIGN((unsigned long)ptr, align) - (unsigned long)ptr;
            BUG_ON(i == 0 && extra != 0);

            if (pcpu_size[i] < 0 || pcpu_size[i] < extra + size)
                  continue;

            /* Transfer extra to previous block. */
            if (pcpu_size[i-1] < 0)
                  pcpu_size[i-1] -= extra;
            else
                  pcpu_size[i-1] += extra;
            pcpu_size[i] -= extra;
            ptr += extra;

            /* Split block if warranted */
            if (pcpu_size[i] - size > sizeof(unsigned long))
                  if (!split_block(i, size))
                        return NULL;

            /* Mark allocated */
            pcpu_size[i] = -pcpu_size[i];
            return ptr;
      }

      printk(KERN_WARNING "Could not allocate %lu bytes percpu data\n",
             size);
      return NULL;
}

static void percpu_modfree(void *freeme)
{
      unsigned int i;
      void *ptr = __per_cpu_start + block_size(pcpu_size[0]);

      /* First entry is core kernel percpu data. */
      for (i = 1; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) {
            if (ptr == freeme) {
                  pcpu_size[i] = -pcpu_size[i];
                  goto free;
            }
      }
      BUG();

 free:
      /* Merge with previous? */
      if (pcpu_size[i-1] >= 0) {
            pcpu_size[i-1] += pcpu_size[i];
            pcpu_num_used--;
            memmove(&pcpu_size[i], &pcpu_size[i+1],
                  (pcpu_num_used - i) * sizeof(pcpu_size[0]));
            i--;
      }
      /* Merge with next? */
      if (i+1 < pcpu_num_used && pcpu_size[i+1] >= 0) {
            pcpu_size[i] += pcpu_size[i+1];
            pcpu_num_used--;
            memmove(&pcpu_size[i+1], &pcpu_size[i+2],
                  (pcpu_num_used - (i+1)) * sizeof(pcpu_size[0]));
      }
}

static unsigned int find_pcpusec(Elf_Ehdr *hdr,
                         Elf_Shdr *sechdrs,
                         const char *secstrings)
{
      return find_sec(hdr, sechdrs, secstrings, ".data.percpu");
}

static int percpu_modinit(void)
{
      pcpu_num_used = 2;
      pcpu_num_allocated = 2;
      pcpu_size = kmalloc(sizeof(pcpu_size[0]) * pcpu_num_allocated,
                      GFP_KERNEL);
      /* Static in-kernel percpu data (used). */
      pcpu_size[0] = -ALIGN(__per_cpu_end-__per_cpu_start, SMP_CACHE_BYTES);
      /* Free room. */
      pcpu_size[1] = PERCPU_ENOUGH_ROOM + pcpu_size[0];
      if (pcpu_size[1] < 0) {
            printk(KERN_ERR "No per-cpu room for modules.\n");
            pcpu_num_used = 1;
      }

      return 0;
}     
__initcall(percpu_modinit);
#else /* ... !CONFIG_SMP */
static inline void *percpu_modalloc(unsigned long size, unsigned long align,
                            const char *name)
{
      return NULL;
}
static inline void percpu_modfree(void *pcpuptr)
{
      BUG();
}
static inline unsigned int find_pcpusec(Elf_Ehdr *hdr,
                              Elf_Shdr *sechdrs,
                              const char *secstrings)
{
      return 0;
}
static inline void percpu_modcopy(void *pcpudst, const void *src,
                          unsigned long size)
{
      /* pcpusec should be 0, and size of that section should be 0. */
      BUG_ON(size != 0);
}
#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 *mod, char *buffer)             \
{                                                                     \
      return sprintf(buffer, "%s\n", 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,           \
              .owner = THIS_MODULE },                             \
      .show = show_modinfo_##field,                                 \
      .setup = setup_modinfo_##field,                               \
      .test = modinfo_##field##_exists,                             \
      .free = free_modinfo_##field,                                 \
};

MODINFO_ATTR(version);
MODINFO_ATTR(srcversion);

#ifdef CONFIG_MODULE_UNLOAD
/* Init the unload section of the module. */
static void module_unload_init(struct module *mod)
{
      unsigned int i;

      INIT_LIST_HEAD(&mod->modules_which_use_me);
      for (i = 0; i < NR_CPUS; i++)
            local_set(&mod->ref[i].count, 0);
      /* Hold reference count during initialization. */
      local_set(&mod->ref[raw_smp_processor_id()].count, 1);
      /* Backwards compatibility macros put refcount during init. */
      mod->waiter = current;
}

/* modules using other modules */
struct module_use
{
      struct list_head list;
      struct module *module_which_uses;
};

/* 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->modules_which_use_me, list) {
            if (use->module_which_uses == a) {
                  DEBUGP("%s uses %s!\n", a->name, b->name);
                  return 1;
            }
      }
      DEBUGP("%s does not use %s!\n", a->name, b->name);
      return 0;
}

/* Module a uses b */
static int use_module(struct module *a, struct module *b)
{
      struct module_use *use;
      if (b == NULL || already_uses(a, b)) return 1;

      if (!strong_try_module_get(b))
            return 0;

      DEBUGP("Allocating new usage for %s.\n", a->name);
      use = kmalloc(sizeof(*use), GFP_ATOMIC);
      if (!use) {
            printk("%s: out of memory loading\n", a->name);
            module_put(b);
            return 0;
      }

      use->module_which_uses = a;
      list_add(&use->list, &b->modules_which_use_me);
      return 1;
}

/* Clear the unload stuff of the module. */
static void module_unload_free(struct module *mod)
{
      struct module *i;

      list_for_each_entry(i, &modules, list) {
            struct module_use *use;

            list_for_each_entry(use, &i->modules_which_use_me, list) {
                  if (use->module_which_uses == mod) {
                        DEBUGP("%s unusing %s\n", mod->name, i->name);
                        module_put(i);
                        list_del(&use->list);
                        kfree(use);
                        /* There can be at most one match. */
                        break;
                  }
            }
      }
}

#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);
      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 are told to block. */
      if ((sref->flags & O_NONBLOCK) && 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_run(__try_stop_module, &sref, NR_CPUS);
}

unsigned int module_refcount(struct module *mod)
{
      unsigned int i, total = 0;

      for (i = 0; i < NR_CPUS; i++)
            total += local_read(&mod->ref[i].count);
      return total;
}
EXPORT_SYMBOL(module_refcount);

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

static void wait_for_zero_refcount(struct module *mod)
{
      /* Since we might sleep for some time, drop the semaphore first */
      mutex_unlock(&module_mutex);
      for (;;) {
            DEBUGP("Looking at refcount...\n");
            set_current_state(TASK_UNINTERRUPTIBLE);
            if (module_refcount(mod) == 0)
                  break;
            schedule();
      }
      current->state = TASK_RUNNING;
      mutex_lock(&module_mutex);
}

asmlinkage long
sys_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))
            return -EPERM;

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

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

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

      if (!list_empty(&mod->modules_which_use_me)) {
            /* 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 and wake up
                   waiter --RR */
            DEBUGP("%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 != NULL && mod->exit == NULL)
          || mod->unsafe) {
            forced = try_force_unload(flags);
            if (!forced) {
                  /* This module can't be removed */
                  ret = -EBUSY;
                  goto out;
            }
      }

      /* Set this up before setting mod->state */
      mod->waiter = current;

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

      /* Never wait if forced. */
      if (!forced && module_refcount(mod) != 0)
            wait_for_zero_refcount(mod);

      /* Final destruction now noone is using it. */
      if (mod->exit != NULL) {
            mutex_unlock(&module_mutex);
            mod->exit();
            mutex_lock(&module_mutex);
      }
      free_module(mod);

 out:
      mutex_unlock(&module_mutex);
      return ret;
}

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

      seq_printf(m, " %u ", 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->modules_which_use_me, list) {
            printed_something = 1;
            seq_printf(m, "%s,", use->module_which_uses->name);
      }

      if (mod->unsafe) {
            printed_something = 1;
            seq_printf(m, "[unsafe],");
      }

      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;
      unsigned long flags;
      const unsigned long *crc;

      spin_lock_irqsave(&modlist_lock, flags);
      if (!__find_symbol(symbol, &owner, &crc, 1))
            BUG();
      module_put(owner);
      spin_unlock_irqrestore(&modlist_lock, flags);
}
EXPORT_SYMBOL(__symbol_put);

void symbol_put_addr(void *addr)
{
      struct module *modaddr;

      if (core_kernel_text((unsigned long)addr))
            return;

      if (!(modaddr = module_text_address((unsigned long)addr)))
            BUG();
      module_put(modaddr);
}
EXPORT_SYMBOL_GPL(symbol_put_addr);

static ssize_t show_refcnt(struct module_attribute *mattr,
                     struct module *mod, char *buffer)
{
      /* sysfs holds a reference */
      return sprintf(buffer, "%u\n", module_refcount(mod)-1);
}

static struct module_attribute refcnt = {
      .attr = { .name = "refcnt", .mode = 0444, .owner = THIS_MODULE },
      .show = show_refcnt,
};

#else /* !CONFIG_MODULE_UNLOAD */
static 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)
{
}

static inline int use_module(struct module *a, struct module *b)
{
      return strong_try_module_get(b);
}

static inline void module_unload_init(struct module *mod)
{
}
#endif /* CONFIG_MODULE_UNLOAD */

static struct module_attribute *modinfo_attrs[] = {
      &modinfo_version,
      &modinfo_srcversion,
#ifdef CONFIG_MODULE_UNLOAD
      &refcnt,
#endif
      NULL,
};

static const char vermagic[] = VERMAGIC_STRING;

#ifdef CONFIG_MODVERSIONS
static int check_version(Elf_Shdr *sechdrs,
                   unsigned int versindex,
                   const char *symname,
                   struct module *mod, 
                   const unsigned long *crc)
{
      unsigned int i, num_versions;
      struct modversion_info *versions;

      /* Exporting module didn't supply crcs?  OK, we're already tainted. */
      if (!crc)
            return 1;

      versions = (void *) sechdrs[versindex].sh_addr;
      num_versions = sechdrs[versindex].sh_size
            / sizeof(struct modversion_info);

      for (i = 0; i < num_versions; i++) {
            if (strcmp(versions[i].name, symname) != 0)
                  continue;

            if (versions[i].crc == *crc)
                  return 1;
            printk("%s: disagrees about version of symbol %s\n",
                   mod->name, symname);
            DEBUGP("Found checksum %lX vs module %lX\n",
                   *crc, versions[i].crc);
            return 0;
      }
      /* Not in module's version table.  OK, but that taints the kernel. */
      if (!(tainted & TAINT_FORCED_MODULE)) {
            printk("%s: no version for \"%s\" found: kernel tainted.\n",
                   mod->name, symname);
            add_taint(TAINT_FORCED_MODULE);
      }
      return 1;
}

static inline int check_modstruct_version(Elf_Shdr *sechdrs,
                                unsigned int versindex,
                                struct module *mod)
{
      const unsigned long *crc;
      struct module *owner;

      if (!__find_symbol("struct_module", &owner, &crc, 1))
            BUG();
      return check_version(sechdrs, versindex, "struct_module", mod,
                       crc);
}

/* First part is kernel version, which we ignore. */
static inline int same_magic(const char *amagic, const char *bmagic)
{
      amagic += strcspn(amagic, " ");
      bmagic += strcspn(bmagic, " ");
      return strcmp(amagic, bmagic) == 0;
}
#else
static inline int check_version(Elf_Shdr *sechdrs,
                        unsigned int versindex,
                        const char *symname,
                        struct module *mod, 
                        const unsigned long *crc)
{
      return 1;
}

static inline int check_modstruct_version(Elf_Shdr *sechdrs,
                                unsigned int versindex,
                                struct module *mod)
{
      return 1;
}

static inline int same_magic(const char *amagic, const char *bmagic)
{
      return strcmp(amagic, bmagic) == 0;
}
#endif /* CONFIG_MODVERSIONS */

/* Resolve a symbol for this module.  I.e. if we find one, record usage.
   Must be holding module_mutex. */
static unsigned long resolve_symbol(Elf_Shdr *sechdrs,
                            unsigned int versindex,
                            const char *name,
                            struct module *mod)
{
      struct module *owner;
      unsigned long ret;
      const unsigned long *crc;

      ret = __find_symbol(name, &owner, &crc, mod->license_gplok);
      if (ret) {
            /* use_module can fail due to OOM, or module unloading */
            if (!check_version(sechdrs, versindex, name, mod, crc) ||
                !use_module(mod, owner))
                  ret = 0;
      }
      return ret;
}


/*
 * /sys/module/foo/sections stuff
 * J. Corbet <corbet@lwn.net>
 */
#ifdef CONFIG_KALLSYMS
static ssize_t module_sect_show(struct module_attribute *mattr,
                        struct module *mod, char *buf)
{
      struct module_sect_attr *sattr =
            container_of(mattr, struct module_sect_attr, mattr);
      return sprintf(buf, "0x%lx\n", sattr->address);
}

static void add_sect_attrs(struct module *mod, unsigned int nsect,
            char *secstrings, Elf_Shdr *sechdrs)
{
      unsigned int nloaded = 0, i, size[2];
      struct module_sect_attrs *sect_attrs;
      struct module_sect_attr *sattr;
      struct attribute **gattr;
      
      /* Count loaded sections and allocate structures */
      for (i = 0; i < nsect; i++)
            if (sechdrs[i].sh_flags & SHF_ALLOC)
                  nloaded++;
      size[0] = ALIGN(sizeof(*sect_attrs)
                  + nloaded * sizeof(sect_attrs->attrs[0]),
                  sizeof(sect_attrs->grp.attrs[0]));
      size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.attrs[0]);
      if (! (sect_attrs = kmalloc(size[0] + size[1], GFP_KERNEL)))
            return;

      /* Setup section attributes. */
      sect_attrs->grp.name = "sections";
      sect_attrs->grp.attrs = (void *)sect_attrs + size[0];

      sattr = &sect_attrs->attrs[0];
      gattr = &sect_attrs->grp.attrs[0];
      for (i = 0; i < nsect; i++) {
            if (! (sechdrs[i].sh_flags & SHF_ALLOC))
                  continue;
            sattr->address = sechdrs[i].sh_addr;
            strlcpy(sattr->name, secstrings + sechdrs[i].sh_name,
                  MODULE_SECT_NAME_LEN);
            sattr->mattr.show = module_sect_show;
            sattr->mattr.store = NULL;
            sattr->mattr.attr.name = sattr->name;
            sattr->mattr.attr.owner = mod;
            sattr->mattr.attr.mode = S_IRUGO;
            *(gattr++) = &(sattr++)->mattr.attr;
      }
      *gattr = NULL;

      if (sysfs_create_group(&mod->mkobj.kobj, &sect_attrs->grp))
            goto out;

      mod->sect_attrs = sect_attrs;
      return;
  out:
      kfree(sect_attrs);
}

static void remove_sect_attrs(struct module *mod)
{
      if (mod->sect_attrs) {
            sysfs_remove_group(&mod->mkobj.kobj,
                           &mod->sect_attrs->grp);
            /* We are positive that no one is using any sect attrs
             * at this point.  Deallocate immediately. */
            kfree(mod->sect_attrs);
            mod->sect_attrs = NULL;
      }
}


#else
static inline void add_sect_attrs(struct module *mod, unsigned int nsect,
            char *sectstrings, Elf_Shdr *sechdrs)
{
}

static inline void remove_sect_attrs(struct module *mod)
{
}
#endif /* CONFIG_KALLSYMS */

static int module_add_modinfo_attrs(struct module *mod)
{
      struct module_attribute *attr;
      struct module_attribute *temp_attr;
      int error = 0;
      int i;

      mod->modinfo_attrs = kzalloc((sizeof(struct module_attribute) *
                              (ARRAY_SIZE(modinfo_attrs) + 1)),
                              GFP_KERNEL);
      if (!mod->modinfo_attrs)
            return -ENOMEM;

      temp_attr = mod->modinfo_attrs;
      for (i = 0; (attr = modinfo_attrs[i]) && !error; i++) {
            if (!attr->test ||
                (attr->test && attr->test(mod))) {
                  memcpy(temp_attr, attr, sizeof(*temp_attr));
                  temp_attr->attr.owner = mod;
                  error = sysfs_create_file(&mod->mkobj.kobj,&temp_attr->attr);
                  ++temp_attr;
            }
      }
      return error;
}

static void module_remove_modinfo_attrs(struct module *mod)
{
      struct module_attribute *attr;
      int i;

      for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) {
            /* pick a field to test for end of list */
            if (!attr->attr.name)
                  break;
            sysfs_remove_file(&mod->mkobj.kobj,&attr->attr);
            if (attr->free)
                  attr->free(mod);
      }
      kfree(mod->modinfo_attrs);
}

static int mod_sysfs_setup(struct module *mod,
                     struct kernel_param *kparam,
                     unsigned int num_params)
{
      int err;

      memset(&mod->mkobj.kobj, 0, sizeof(mod->mkobj.kobj));
      err = kobject_set_name(&mod->mkobj.kobj, "%s", mod->name);
      if (err)
            goto out;
      kobj_set_kset_s(&mod->mkobj, module_subsys);
      mod->mkobj.mod = mod;
      err = kobject_register(&mod->mkobj.kobj);
      if (err)
            goto out;

      err = module_param_sysfs_setup(mod, kparam, num_params);
      if (err)
            goto out_unreg;

      err = module_add_modinfo_attrs(mod);
      if (err)
            goto out_unreg;

      return 0;

out_unreg:
      kobject_unregister(&mod->mkobj.kobj);
out:
      return err;
}

static void mod_kobject_remove(struct module *mod)
{
      module_remove_modinfo_attrs(mod);
      module_param_sysfs_remove(mod);

      kobject_unregister(&mod->mkobj.kobj);
}

/*
 * unlink the module with the whole machine is stopped with interrupts off
 * - this defends against kallsyms not taking locks
 */
static int __unlink_module(void *_mod)
{
      struct module *mod = _mod;
      list_del(&mod->list);
      return 0;
}

/* Free a module, remove from lists, etc (must hold module mutex). */
static void free_module(struct module *mod)
{
      /* Delete from various lists */
      stop_machine_run(__unlink_module, mod, NR_CPUS);
      remove_sect_attrs(mod);
      mod_kobject_remove(mod);

      unwind_remove_table(mod->unwind_info, 0);

      /* Arch-specific cleanup. */
      module_arch_cleanup(mod);

      /* Module unload stuff */
      module_unload_free(mod);

      /* This may be NULL, but that's OK */
      module_free(mod, mod->module_init);
      kfree(mod->args);
      if (mod->percpu)
            percpu_modfree(mod->percpu);

      /* Free lock-classes: */
      lockdep_free_key_range(mod->module_core, mod->core_size);

      /* Finally, free the core (containing the module structure) */
      module_free(mod, mod->module_core);
}

void *__symbol_get(const char *symbol)
{
      struct module *owner;
      unsigned long value, flags;
      const unsigned long *crc;

      spin_lock_irqsave(&modlist_lock, flags);
      value = __find_symbol(symbol, &owner, &crc, 1);
      if (value && !strong_try_module_get(owner))
            value = 0;
      spin_unlock_irqrestore(&modlist_lock, flags);

      return (void *)value;
}
EXPORT_SYMBOL_GPL(__symbol_get);

/*
 * Ensure that an exported symbol [global namespace] does not already exist
 * in the Kernel or in some other modules exported symbol table.
 */
static int verify_export_symbols(struct module *mod)
{
      const char *name = NULL;
      unsigned long i, ret = 0;
      struct module *owner;
      const unsigned long *crc;

      for (i = 0; i < mod->num_syms; i++)
              if (__find_symbol(mod->syms[i].name, &owner, &crc, 1)) {
                  name = mod->syms[i].name;
                  ret = -ENOEXEC;
                  goto dup;
            }

      for (i = 0; i < mod->num_gpl_syms; i++)
              if (__find_symbol(mod->gpl_syms[i].name, &owner, &crc, 1)) {
                  name = mod->gpl_syms[i].name;
                  ret = -ENOEXEC;
                  goto dup;
            }

dup:
      if (ret)
            printk(KERN_ERR "%s: exports duplicate symbol %s (owned by %s)\n",
                  mod->name, name, module_name(owner));

      return ret;
}

/* Change all symbols so that sh_value encodes the pointer directly. */
static int simplify_symbols(Elf_Shdr *sechdrs,
                      unsigned int symindex,
                      const char *strtab,
                      unsigned int versindex,
                      unsigned int pcpuindex,
                      struct module *mod)
{
      Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
      unsigned long secbase;
      unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
      int ret = 0;

      for (i = 1; i < n; i++) {
            switch (sym[i].st_shndx) {
            case SHN_COMMON:
                  /* We compiled with -fno-common.  These are not
                     supposed to happen.  */
                  DEBUGP("Common symbol: %s\n", strtab + sym[i].st_name);
                  printk("%s: please compile with -fno-common\n",
                         mod->name);
                  ret = -ENOEXEC;
                  break;

            case SHN_ABS:
                  /* Don't need to do anything */
                  DEBUGP("Absolute symbol: 0x%08lx\n",
                         (long)sym[i].st_value);
                  break;

            case SHN_UNDEF:
                  sym[i].st_value
                    = resolve_symbol(sechdrs, versindex,
                                 strtab + sym[i].st_name, mod);

                  /* Ok if resolved.  */
                  if (sym[i].st_value != 0)
                        break;
                  /* Ok if weak.  */
                  if (ELF_ST_BIND(sym[i].st_info) == STB_WEAK)
                        break;

                  printk(KERN_WARNING "%s: Unknown symbol %s\n",
                         mod->name, strtab + sym[i].st_name);
                  ret = -ENOENT;
                  break;

            default:
                  /* Divert to percpu allocation if a percpu var. */
                  if (sym[i].st_shndx == pcpuindex)
                        secbase = (unsigned long)mod->percpu;
                  else
                        secbase = sechdrs[sym[i].st_shndx].sh_addr;
                  sym[i].st_value += secbase;
                  break;
            }
      }

      return ret;
}

/* Update size with this section: return offset. */
static long get_offset(unsigned long *size, Elf_Shdr *sechdr)
{
      long ret;

      ret = ALIGN(*size, sechdr->sh_addralign ?: 1);
      *size = ret + sechdr->sh_size;
      return ret;
}

/* Lay out the SHF_ALLOC sections in a way not dissimilar to how ld
   might -- code, read-only data, read-write data, small data.  Tally
   sizes, and place the offsets into sh_entsize fields: high bit means it
   belongs in init. */
static void layout_sections(struct module *mod,
                      const Elf_Ehdr *hdr,
                      Elf_Shdr *sechdrs,
                      const char *secstrings)
{
      static unsigned long const masks[][2] = {
            /* NOTE: all executable code must be the first section
             * in this array; otherwise modify the text_size
             * finder in the two loops below */
            { SHF_EXECINSTR | SHF_ALLOC, ARCH_SHF_SMALL },
            { SHF_ALLOC, SHF_WRITE | ARCH_SHF_SMALL },
            { SHF_WRITE | SHF_ALLOC, ARCH_SHF_SMALL },
            { ARCH_SHF_SMALL | SHF_ALLOC, 0 }
      };
      unsigned int m, i;

      for (i = 0; i < hdr->e_shnum; i++)
            sechdrs[i].sh_entsize = ~0UL;

      DEBUGP("Core section allocation order:\n");
      for (m = 0; m < ARRAY_SIZE(masks); ++m) {
            for (i = 0; i < hdr->e_shnum; ++i) {
                  Elf_Shdr *s = &sechdrs[i];

                  if ((s->sh_flags & masks[m][0]) != masks[m][0]
                      || (s->sh_flags & masks[m][1])
                      || s->sh_entsize != ~0UL
                      || strncmp(secstrings + s->sh_name,
                               ".init", 5) == 0)
                        continue;
                  s->sh_entsize = get_offset(&mod->core_size, s);
                  DEBUGP("\t%s\n", secstrings + s->sh_name);
            }
            if (m == 0)
                  mod->core_text_size = mod->core_size;
      }

      DEBUGP("Init section allocation order:\n");
      for (m = 0; m < ARRAY_SIZE(masks); ++m) {
            for (i = 0; i < hdr->e_shnum; ++i) {
                  Elf_Shdr *s = &sechdrs[i];

                  if ((s->sh_flags & masks[m][0]) != masks[m][0]
                      || (s->sh_flags & masks[m][1])
                      || s->sh_entsize != ~0UL
                      || strncmp(secstrings + s->sh_name,
                               ".init", 5) != 0)
                        continue;
                  s->sh_entsize = (get_offset(&mod->init_size, s)
                               | INIT_OFFSET_MASK);
                  DEBUGP("\t%s\n", secstrings + s->sh_name);
            }
            if (m == 0)
                  mod->init_text_size = mod->init_size;
      }
}

static void set_license(struct module *mod, const char *license)
{
      if (!license)
            license = "unspecified";

      mod->license_gplok = license_is_gpl_compatible(license);
      if (!mod->license_gplok && !(tainted & TAINT_PROPRIETARY_MODULE)) {
            printk(KERN_WARNING "%s: module license '%s' taints kernel.\n",
                   mod->name, license);
            add_taint(TAINT_PROPRIETARY_MODULE);
      }
}

/* Parse tag=value strings from .modinfo section */
static char *next_string(char *string, unsigned long *secsize)
{
      /* Skip non-zero chars */
      while (string[0]) {
            string++;
            if ((*secsize)-- <= 1)
                  return NULL;
      }

      /* Skip any zero padding. */
      while (!string[0]) {
            string++;
            if ((*secsize)-- <= 1)
                  return NULL;
      }
      return string;
}

static char *get_modinfo(Elf_Shdr *sechdrs,
                   unsigned int info,
                   const char *tag)
{
      char *p;
      unsigned int taglen = strlen(tag);
      unsigned long size = sechdrs[info].sh_size;

      for (p = (char *)sechdrs[info].sh_addr; p; p = next_string(p, &size)) {
            if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
                  return p + taglen + 1;
      }
      return NULL;
}

static void setup_modinfo(struct module *mod, Elf_Shdr *sechdrs,
                    unsigned int infoindex)
{
      struct module_attribute *attr;
      int i;

      for (i = 0; (attr = modinfo_attrs[i]); i++) {
            if (attr->setup)
                  attr->setup(mod,
                            get_modinfo(sechdrs,
                                    infoindex,
                                    attr->attr.name));
      }
}

#ifdef CONFIG_KALLSYMS
int is_exported(const char *name, const struct module *mod)
{
      if (!mod && lookup_symbol(name, __start___ksymtab, __stop___ksymtab))
            return 1;
      else
            if (mod && lookup_symbol(name, mod->syms, mod->syms + mod->num_syms))
                  return 1;
            else
                  return 0;
}

/* As per nm */
static char elf_type(const Elf_Sym *sym,
                 Elf_Shdr *sechdrs,
                 const char *secstrings,
                 struct module *mod)
{
      if (ELF_ST_BIND(sym->st_info) == STB_WEAK) {
            if (ELF_ST_TYPE(sym->st_info) == STT_OBJECT)
                  return 'v';
            else
                  return 'w';
      }
      if (sym->st_shndx == SHN_UNDEF)
            return 'U';
      if (sym->st_shndx == SHN_ABS)
            return 'a';
      if (sym->st_shndx >= SHN_LORESERVE)
            return '?';
      if (sechdrs[sym->st_shndx].sh_flags & SHF_EXECINSTR)
            return 't';
      if (sechdrs[sym->st_shndx].sh_flags & SHF_ALLOC
          && sechdrs[sym->st_shndx].sh_type != SHT_NOBITS) {
            if (!(sechdrs[sym->st_shndx].sh_flags & SHF_WRITE))
                  return 'r';
            else if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
                  return 'g';
            else
                  return 'd';
      }
      if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
            if (sechdrs[sym->st_shndx].sh_flags & ARCH_SHF_SMALL)
                  return 's';
            else
                  return 'b';
      }
      if (strncmp(secstrings + sechdrs[sym->st_shndx].sh_name,
                ".debug", strlen(".debug")) == 0)
            return 'n';
      return '?';
}

static void add_kallsyms(struct module *mod,
                   Elf_Shdr *sechdrs,
                   unsigned int symindex,
                   unsigned int strindex,
                   const char *secstrings)
{
      unsigned int i;

      mod->symtab = (void *)sechdrs[symindex].sh_addr;
      mod->num_symtab = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
      mod->strtab = (void *)sechdrs[strindex].sh_addr;

      /* Set types up while we still have access to sections. */
      for (i = 0; i < mod->num_symtab; i++)
            mod->symtab[i].st_info
                  = elf_type(&mod->symtab[i], sechdrs, secstrings, mod);
}
#else
static inline void add_kallsyms(struct module *mod,
                        Elf_Shdr *sechdrs,
                        unsigned int symindex,
                        unsigned int strindex,
                        const char *secstrings)
{
}
#endif /* CONFIG_KALLSYMS */

/* Allocate and load the module: note that size of section 0 is always
   zero, and we rely on this for optional sections. */
static struct module *load_module(void __user *umod,
                          unsigned long len,
                          const char __user *uargs)
{
      Elf_Ehdr *hdr;
      Elf_Shdr *sechdrs;
      char *secstrings, *args, *modmagic, *strtab = NULL;
      unsigned int i;
      unsigned int symindex = 0;
      unsigned int strindex = 0;
      unsigned int setupindex;
      unsigned int exindex;
      unsigned int exportindex;
      unsigned int modindex;
      unsigned int obsparmindex;
      unsigned int infoindex;
      unsigned int gplindex;
      unsigned int crcindex;
      unsigned int gplcrcindex;
      unsigned int versindex;
      unsigned int pcpuindex;
      unsigned int gplfutureindex;
      unsigned int gplfuturecrcindex;
      unsigned int unwindex = 0;
      unsigned int unusedindex;
      unsigned int unusedcrcindex;
      unsigned int unusedgplindex;
      unsigned int unusedgplcrcindex;
      struct module *mod;
      long err = 0;
      void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
      struct exception_table_entry *extable;
      mm_segment_t old_fs;

      DEBUGP("load_module: umod=%p, len=%lu, uargs=%p\n",
             umod, len, uargs);
      if (len < sizeof(*hdr))
            return ERR_PTR(-ENOEXEC);

      /* Suck in entire file: we'll want most of it. */
      /* vmalloc barfs on "unusual" numbers.  Check here */
      if (len > 64 * 1024 * 1024 || (hdr = vmalloc(len)) == NULL)
            return ERR_PTR(-ENOMEM);
      if (copy_from_user(hdr, umod, len) != 0) {
            err = -EFAULT;
            goto free_hdr;
      }

      /* Sanity checks against insmoding binaries or wrong arch,
           weird elf version */
      if (memcmp(hdr->e_ident, ELFMAG, 4) != 0
          || hdr->e_type != ET_REL
          || !elf_check_arch(hdr)
          || hdr->e_shentsize != sizeof(*sechdrs)) {
            err = -ENOEXEC;
            goto free_hdr;
      }

      if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr))
            goto truncated;

      /* Convenience variables */
      sechdrs = (void *)hdr + hdr->e_shoff;
      secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
      sechdrs[0].sh_addr = 0;

      for (i = 1; i < hdr->e_shnum; i++) {
            if (sechdrs[i].sh_type != SHT_NOBITS
                && len < sechdrs[i].sh_offset + sechdrs[i].sh_size)
                  goto truncated;

            /* Mark all sections sh_addr with their address in the
               temporary image. */
            sechdrs[i].sh_addr = (size_t)hdr + sechdrs[i].sh_offset;

            /* Internal symbols and strings. */
            if (sechdrs[i].sh_type == SHT_SYMTAB) {
                  symindex = i;
                  strindex = sechdrs[i].sh_link;
                  strtab = (char *)hdr + sechdrs[strindex].sh_offset;
            }
#ifndef CONFIG_MODULE_UNLOAD
            /* Don't load .exit sections */
            if (strncmp(secstrings+sechdrs[i].sh_name, ".exit", 5) == 0)
                  sechdrs[i].sh_flags &= ~(unsigned long)SHF_ALLOC;
#endif
      }

      modindex = find_sec(hdr, sechdrs, secstrings,
                      ".gnu.linkonce.this_module");
      if (!modindex) {
            printk(KERN_WARNING "No module found in object\n");
            err = -ENOEXEC;
            goto free_hdr;
      }
      mod = (void *)sechdrs[modindex].sh_addr;

      if (symindex == 0) {
            printk(KERN_WARNING "%s: module has no symbols (stripped?)\n",
                   mod->name);
            err = -ENOEXEC;
            goto free_hdr;
      }

      /* Optional sections */
      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");
      versindex = find_sec(hdr, sechdrs, secstrings, "__versions");
      infoindex = find_sec(hdr, sechdrs, secstrings, ".modinfo");
      pcpuindex = find_pcpusec(hdr, sechdrs, secstrings);
#ifdef ARCH_UNWIND_SECTION_NAME
      unwindex = find_sec(hdr, sechdrs, secstrings, ARCH_UNWIND_SECTION_NAME);
#endif

      /* Don't keep modinfo section */
      sechdrs[infoindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
#ifdef CONFIG_KALLSYMS
      /* Keep symbol and string tables for decoding later. */
      sechdrs[symindex].sh_flags |= SHF_ALLOC;
      sechdrs[strindex].sh_flags |= SHF_ALLOC;
#endif
      if (unwindex)
            sechdrs[unwindex].sh_flags |= SHF_ALLOC;

      /* Check module struct version now, before we try to use module. */
      if (!check_modstruct_version(sechdrs, versindex, mod)) {
            err = -ENOEXEC;
            goto free_hdr;
      }

      modmagic = get_modinfo(sechdrs, infoindex, "vermagic");
      /* This is allowed: modprobe --force will invalidate it. */
      if (!modmagic) {
            add_taint(TAINT_FORCED_MODULE);
            printk(KERN_WARNING "%s: no version magic, tainting kernel.\n",
                   mod->name);
      } else if (!same_magic(modmagic, vermagic)) {
            printk(KERN_ERR "%s: version magic '%s' should be '%s'\n",
                   mod->name, modmagic, vermagic);
            err = -ENOEXEC;
            goto free_hdr;
      }

      /* Now copy in args */
      args = strndup_user(uargs, ~0UL >> 1);
      if (IS_ERR(args)) {
            err = PTR_ERR(args);
            goto free_hdr;
      }

      if (find_module(mod->name)) {
            err = -EEXIST;
            goto free_mod;
      }

      mod->state = MODULE_STATE_COMING;

      /* Allow arches to frob section contents and sizes.  */
      err = module_frob_arch_sections(hdr, sechdrs, secstrings, mod);
      if (err < 0)
            goto free_mod;

      if (pcpuindex) {
            /* We have a special allocation for this section. */
            percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size,
                               sechdrs[pcpuindex].sh_addralign,
                               mod->name);
            if (!percpu) {
                  err = -ENOMEM;
                  goto free_mod;
            }
            sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
            mod->percpu = percpu;
      }

      /* Determine total sizes, and put offsets in sh_entsize.  For now
         this is done generically; there doesn't appear to be any
         special cases for the architectures. */
      layout_sections(mod, hdr, sechdrs, secstrings);

      /* Do the allocs. */
      ptr = module_alloc(mod->core_size);
      if (!ptr) {
            err = -ENOMEM;
            goto free_percpu;
      }
      memset(ptr, 0, mod->core_size);
      mod->module_core = ptr;

      ptr = module_alloc(mod->init_size);
      if (!ptr && mod->init_size) {
            err = -ENOMEM;
            goto free_core;
      }
      memset(ptr, 0, mod->init_size);
      mod->module_init = ptr;

      /* Transfer each section which specifies SHF_ALLOC */
      DEBUGP("final section addresses:\n");
      for (i = 0; i < hdr->e_shnum; i++) {
            void *dest;

            if (!(sechdrs[i].sh_flags & SHF_ALLOC))
                  continue;

            if (sechdrs[i].sh_entsize & INIT_OFFSET_MASK)
                  dest = mod->module_init
                        + (sechdrs[i].sh_entsize & ~INIT_OFFSET_MASK);
            else
                  dest = mod->module_core + sechdrs[i].sh_entsize;

            if (sechdrs[i].sh_type != SHT_NOBITS)
                  memcpy(dest, (void *)sechdrs[i].sh_addr,
                         sechdrs[i].sh_size);
            /* Update sh_addr to point to copy in image. */
            sechdrs[i].sh_addr = (unsigned long)dest;
            DEBUGP("\t0x%lx %s\n", sechdrs[i].sh_addr, secstrings + sechdrs[i].sh_name);
      }
      /* Module has been moved. */
      mod = (void *)sechdrs[modindex].sh_addr;

      /* Now we've moved module, initialize linked lists, etc. */
      module_unload_init(mod);

      /* Set up license info based on the info section */
      set_license(mod, get_modinfo(sechdrs, infoindex, "license"));

      if (strcmp(mod->name, "ndiswrapper") == 0)
            add_taint(TAINT_PROPRIETARY_MODULE);
      if (strcmp(mod->name, "driverloader") == 0)
            add_taint(TAINT_PROPRIETARY_MODULE);

      /* Set up MODINFO_ATTR fields */
      setup_modinfo(mod, sechdrs, infoindex);

      /* Fix up syms, so that st_value is a pointer to location. */
      err = simplify_symbols(sechdrs, symindex, strtab, versindex, pcpuindex,
                         mod);
      if (err < 0)
            goto cleanup;

      /* Set up EXPORTed & EXPORT_GPLed symbols (section 0 is 0 length) */
      mod->num_syms = sechdrs[exportindex].sh_size / sizeof(*mod->syms);
      mod->syms = (void *)sechdrs[exportindex].sh_addr;
      if (crcindex)
            mod->crcs = (void *)sechdrs[crcindex].sh_addr;
      mod->num_gpl_syms = sechdrs[gplindex].sh_size / sizeof(*mod->gpl_syms);
      mod->gpl_syms = (void *)sechdrs[gplindex].sh_addr;
      if (gplcrcindex)
            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_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);
      }
#endif

      /* Now do relocations. */
      for (i = 1; i < hdr->e_shnum; i++) {
            const char *strtab = (char *)sechdrs[strindex].sh_addr;
            unsigned int info = sechdrs[i].sh_info;

            /* Not a valid relocation section? */
            if (info >= hdr->e_shnum)
                  continue;

            /* Don't bother with non-allocated sections */
            if (!(sechdrs[info].sh_flags & SHF_ALLOC))
                  continue;

            if (sechdrs[i].sh_type == SHT_REL)
                  err = apply_relocate(sechdrs, strtab, symindex, i,mod);
            else if (sechdrs[i].sh_type == SHT_RELA)
                  err = apply_relocate_add(sechdrs, strtab, symindex, i,
                                     mod);
            if (err < 0)
                  goto cleanup;
      }

        /* Find duplicate symbols */
      err = verify_export_symbols(mod);

      if (err < 0)
            goto cleanup;

      /* Set up and sort exception table */
      mod->num_exentries = sechdrs[exindex].sh_size / sizeof(*mod->extable);
      mod->extable = extable = (void *)sechdrs[exindex].sh_addr;
      sort_extable(extable, extable + mod->num_exentries);

      /* Finally, copy percpu area over. */
      percpu_modcopy(mod->percpu, (void *)sechdrs[pcpuindex].sh_addr,
                   sechdrs[pcpuindex].sh_size);

      add_kallsyms(mod, sechdrs, symindex, strindex, secstrings);

      err = module_finalize(hdr, sechdrs, mod);
      if (err < 0)
            goto cleanup;

      /* flush the icache in correct context */
      old_fs = get_fs();
      set_fs(KERNEL_DS);

      /*
       * Flush the instruction cache, since we've played with text.
       * Do it before processing of module parameters, so the module
       * can provide parameter accessor functions of its own.
       */
      if (mod->module_init)
            flush_icache_range((unsigned long)mod->module_init,
                           (unsigned long)mod->module_init
                           + mod->init_size);
      flush_icache_range((unsigned long)mod->module_core,
                     (unsigned long)mod->module_core + mod->core_size);

      set_fs(old_fs);

      mod->args = args;
      if (obsparmindex)
            printk(KERN_WARNING "%s: Ignoring obsolete parameters\n",
                   mod->name);

      /* Size of section 0 is 0, so this works well if no params */
      err = parse_args(mod->name, mod->args,
                   (struct kernel_param *)
                   sechdrs[setupindex].sh_addr,
                   sechdrs[setupindex].sh_size
                   / sizeof(struct kernel_param),
                   NULL);
      if (err < 0)
            goto arch_cleanup;

      err = mod_sysfs_setup(mod, 
                        (struct kernel_param *)
                        sechdrs[setupindex].sh_addr,
                        sechdrs[setupindex].sh_size
                        / sizeof(struct kernel_param));
      if (err < 0)
            goto arch_cleanup;
      add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);

      /* Size of section 0 is 0, so this works well if no unwind info. */
      mod->unwind_info = unwind_add_table(mod,
                                          (void *)sechdrs[unwindex].sh_addr,
                                          sechdrs[unwindex].sh_size);

      /* Get rid of temporary copy */
      vfree(hdr);

      /* Done! */
      return mod;

 arch_cleanup:
      module_arch_cleanup(mod);
 cleanup:
      module_unload_free(mod);
      module_free(mod, mod->module_init);
 free_core:
      module_free(mod, mod->module_core);
 free_percpu:
      if (percpu)
            percpu_modfree(percpu);
 free_mod:
      kfree(args);
 free_hdr:
      vfree(hdr);
      return ERR_PTR(err);

 truncated:
      printk(KERN_ERR "Module len %lu truncated\n", len);
      err = -ENOEXEC;
      goto free_hdr;
}

/*
 * link the module with the whole machine is stopped with interrupts off
 * - this defends against kallsyms not taking locks
 */
static int __link_module(void *_mod)
{
      struct module *mod = _mod;
      list_add(&mod->list, &modules);
      return 0;
}

/* This is where the real work happens */
asmlinkage long
sys_init_module(void __user *umod,
            unsigned long len,
            const char __user *uargs)
{
      struct module *mod;
      int ret = 0;

      /* Must have permission */
      if (!capable(CAP_SYS_MODULE))
            return -EPERM;

      /* Only one module load at a time, please */
      if (mutex_lock_interruptible(&module_mutex) != 0)
            return -EINTR;

      /* Do all the hard work */
      mod = load_module(umod, len, uargs);
      if (IS_ERR(mod)) {
            mutex_unlock(&module_mutex);
            return PTR_ERR(mod);
      }

      /* Now sew it into the lists.  They won't access us, since
           strong_try_module_get() will fail. */
      stop_machine_run(__link_module, mod, NR_CPUS);

      /* Drop lock so they can recurse */
      mutex_unlock(&module_mutex);

      blocking_notifier_call_chain(&module_notify_list,
                  MODULE_STATE_COMING, mod);

      /* Start the module */
      if (mod->init != NULL)
            ret = mod->init();
      if (ret < 0) {
            /* Init routine failed: abort.  Try to protect us from
                   buggy refcounters. */
            mod->state = MODULE_STATE_GOING;
            synchronize_sched();
            if (mod->unsafe)
                  printk(KERN_ERR "%s: module is now stuck!\n",
                         mod->name);
            else {
                  module_put(mod);
                  mutex_lock(&module_mutex);
                  free_module(mod);
                  mutex_unlock(&module_mutex);
            }
            return ret;
      }

      /* Now it's a first class citizen! */
      mutex_lock(&module_mutex);
      mod->state = MODULE_STATE_LIVE;
      /* Drop initial reference. */
      module_put(mod);
      unwind_remove_table(mod->unwind_info, 1);
      module_free(mod, mod->module_init);
      mod->module_init = NULL;
      mod->init_size = 0;
      mod->init_text_size = 0;
      mutex_unlock(&module_mutex);

      return 0;
}

static inline int within(unsigned long addr, void *start, unsigned long size)
{
      return ((void *)addr >= start && (void *)addr < start + size);
}

#ifdef CONFIG_KALLSYMS
/*
 * This ignores the intensely annoying "mapping symbols" found
 * in ARM ELF files: $a, $t and $d.
 */
static inline int is_arm_mapping_symbol(const char *str)
{
      return str[0] == '$' && strchr("atd", str[1]) 
             && (str[2] == '\0' || str[2] == '.');
}

static const char *get_ksymbol(struct module *mod,
                         unsigned long addr,
                         unsigned long *size,
                         unsigned long *offset)
{
      unsigned int i, best = 0;
      unsigned long nextval;

      /* At worse, next value is at end of module */
      if (within(addr, mod->module_init, mod->init_size))
            nextval = (unsigned long)mod->module_init+mod->init_text_size;
      else 
            nextval = (unsigned long)mod->module_core+mod->core_text_size;

      /* Scan for closest preceeding symbol, and next symbol. (ELF
           starts real symbols at 1). */
      for (i = 1; i < mod->num_symtab; i++) {
            if (mod->symtab[i].st_shndx == SHN_UNDEF)
                  continue;

            /* We ignore unnamed symbols: they're uninformative
             * and inserted at a whim. */
            if (mod->symtab[i].st_value <= addr
                && mod->symtab[i].st_value > mod->symtab[best].st_value
                && *(mod->strtab + mod->symtab[i].st_name) != '\0'
                && !is_arm_mapping_symbol(mod->strtab + mod->symtab[i].st_name))
                  best = i;
            if (mod->symtab[i].st_value > addr
                && mod->symtab[i].st_value < nextval
                && *(mod->strtab + mod->symtab[i].st_name) != '\0'
                && !is_arm_mapping_symbol(mod->strtab + mod->symtab[i].st_name))
                  nextval = mod->symtab[i].st_value;
      }

      if (!best)
            return NULL;

      *size = nextval - mod->symtab[best].st_value;
      *offset = addr - mod->symtab[best].st_value;
      return mod->strtab + mod->symtab[best].st_name;
}

/* For kallsyms to ask for address resolution.  NULL means not found.
   We don't lock, as this is used for oops resolution and races are a
   lesser concern. */
const char *module_address_lookup(unsigned long addr,
                          unsigned long *size,
                          unsigned long *offset,
                          char **modname)
{
      struct module *mod;

      list_for_each_entry(mod, &modules, list) {
            if (within(addr, mod->module_init, mod->init_size)
                || within(addr, mod->module_core, mod->core_size)) {
                  *modname = mod->name;
                  return get_ksymbol(mod, addr, size, offset);
            }
      }
      return NULL;
}

struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
                        char *type, char *name, size_t namelen)
{
      struct module *mod;

      mutex_lock(&module_mutex);
      list_for_each_entry(mod, &modules, list) {
            if (symnum < mod->num_symtab) {
                  *value = mod->symtab[symnum].st_value;
                  *type = mod->symtab[symnum].st_info;
                  strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
                        namelen);
                  mutex_unlock(&module_mutex);
                  return mod;
            }
            symnum -= mod->num_symtab;
      }
      mutex_unlock(&module_mutex);
      return NULL;
}

static unsigned long mod_find_symname(struct module *mod, const char *name)
{
      unsigned int i;

      for (i = 0; i < mod->num_symtab; i++)
            if (strcmp(name, mod->strtab+mod->symtab[i].st_name) == 0 &&
                mod->symtab[i].st_info != 'U')
                  return mod->symtab[i].st_value;
      return 0;
}

/* Look for this name: can be of form module:name. */
unsigned long module_kallsyms_lookup_name(const char *name)
{
      struct module *mod;
      char *colon;
      unsigned long ret = 0;

      /* Don't lock: we're in enough trouble already. */
      if ((colon = strchr(name, ':')) != NULL) {
            *colon = '\0';
            if ((mod = find_module(name)) != NULL)
                  ret = mod_find_symname(mod, colon+1);
            *colon = ':';
      } else {
            list_for_each_entry(mod, &modules, list)
                  if ((ret = mod_find_symname(mod, name)) != 0)
                        break;
      }
      return ret;
}
#endif /* CONFIG_KALLSYMS */

/* Called by the /proc file system to return a list of modules. */
static void *m_start(struct seq_file *m, loff_t *pos)
{
      struct list_head *i;
      loff_t n = 0;

      mutex_lock(&module_mutex);
      list_for_each(i, &modules) {
            if (n++ == *pos)
                  break;
      }
      if (i == &modules)
            return NULL;
      return i;
}

static void *m_next(struct seq_file *m, void *p, loff_t *pos)
{
      struct list_head *i = p;
      (*pos)++;
      if (i->next == &modules)
            return NULL;
      return i->next;
}

static void m_stop(struct seq_file *m, void *p)
{
      mutex_unlock(&module_mutex);
}

static int m_show(struct seq_file *m, void *p)
{
      struct module *mod = list_entry(p, struct module, list);
      seq_printf(m, "%s %lu",
               mod->name, mod->init_size + mod->core_size);
      print_unload_info(m, mod);

      /* Informative for users. */
      seq_printf(m, " %s",
               mod->state == MODULE_STATE_GOING ? "Unloading":
               mod->state == MODULE_STATE_COMING ? "Loading":
               "Live");
      /* Used by oprofile and other similar tools. */
      seq_printf(m, " 0x%p", mod->module_core);

      seq_printf(m, "\n");
      return 0;
}

/* Format: modulename size refcount deps address

   Where refcount is a number or -, and deps is a comma-separated list
   of depends or -.
*/
struct seq_operations modules_op = {
      .start      = m_start,
      .next = m_next,
      .stop = m_stop,
      .show = m_show
};

/* Given an address, look for it in the module exception tables. */
const struct exception_table_entry *search_module_extables(unsigned long addr)
{
      unsigned long flags;
      const struct exception_table_entry *e = NULL;
      struct module *mod;

      spin_lock_irqsave(&modlist_lock, flags);
      list_for_each_entry(mod, &modules, list) {
            if (mod->num_exentries == 0)
                  continue;
                        
            e = search_extable(mod->extable,
                           mod->extable + mod->num_exentries - 1,
                           addr);
            if (e)
                  break;
      }
      spin_unlock_irqrestore(&modlist_lock, flags);

      /* Now, if we found one, we are running inside it now, hence
           we cannot unload the module, hence no refcnt needed. */
      return e;
}

/*
 * Is this a valid module address?
 */
int is_module_address(unsigned long addr)
{
      unsigned long flags;
      struct module *mod;

      spin_lock_irqsave(&modlist_lock, flags);

      list_for_each_entry(mod, &modules, list) {
            if (within(addr, mod->module_core, mod->core_size)) {
                  spin_unlock_irqrestore(&modlist_lock, flags);
                  return 1;
            }
      }

      spin_unlock_irqrestore(&modlist_lock, flags);

      return 0;
}


/* Is this a valid kernel address?  We don't grab the lock: we are oopsing. */
struct module *__module_text_address(unsigned long addr)
{
      struct module *mod;

      list_for_each_entry(mod, &modules, list)
            if (within(addr, mod->module_init, mod->init_text_size)
                || within(addr, mod->module_core, mod->core_text_size))
                  return mod;
      return NULL;
}

struct module *module_text_address(unsigned long addr)
{
      struct module *mod;
      unsigned long flags;

      spin_lock_irqsave(&modlist_lock, flags);
      mod = __module_text_address(addr);
      spin_unlock_irqrestore(&modlist_lock, flags);

      return mod;
}

/* Don't grab lock, we're oopsing. */
void print_modules(void)
{
      struct module *mod;

      printk("Modules linked in:");
      list_for_each_entry(mod, &modules, list)
            printk(" %s", mod->name);
      printk("\n");
}

void module_add_driver(struct module *mod, struct device_driver *drv)
{
      if (!mod || !drv)
            return;

      /* Don't check return code; this call is idempotent */
      sysfs_create_link(&drv->kobj, &mod->mkobj.kobj, "module");
}
EXPORT_SYMBOL(module_add_driver);

void module_remove_driver(struct device_driver *drv)
{
      if (!drv)
            return;
      sysfs_remove_link(&drv->kobj, "module");
}
EXPORT_SYMBOL(module_remove_driver);

#ifdef CONFIG_MODVERSIONS
/* Generate the signature for struct module here, too, for modversions. */
void struct_module(struct module *mod) { return; }
EXPORT_SYMBOL(struct_module);
#endif

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