text: /*
   * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
   * 		     are not related to any other subsystem
   *
   * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
   * 
   * This file is release under the GPLv2
   *
   */
  
  #include <linux/kobject.h>
  #include <linux/string.h>
  #include <linux/sysfs.h>
  #include <linux/export.h>
  #include <linux/init.h>
  #include <linux/kexec.h>
  #include <linux/profile.h>
  #include <linux/stat.h>
  #include <linux/sched.h>
  #include <linux/capability.h>
  #include <linux/compiler.h>
  
  #include <linux/rcupdate.h>	/* rcu_expedited */
  
  #define KERNEL_ATTR_RO(_name) \
  static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
  
  #define KERNEL_ATTR_RW(_name) \
  static struct kobj_attribute _name##_attr = \
  	__ATTR(_name, 0644, _name##_show, _name##_store)
  
  /* current uevent sequence number */
  static ssize_t uevent_seqnum_show(struct kobject *kobj,
  				  struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
  }
  KERNEL_ATTR_RO(uevent_seqnum);
  
  #ifdef CONFIG_UEVENT_HELPER
  /* uevent helper program, used during early boot */
  static ssize_t uevent_helper_show(struct kobject *kobj,
  				  struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%s\n", uevent_helper);
  }
  static ssize_t uevent_helper_store(struct kobject *kobj,
  				   struct kobj_attribute *attr,
  				   const char *buf, size_t count)
  {
  	if (count+1 > UEVENT_HELPER_PATH_LEN)
  		return -ENOENT;
  	memcpy(uevent_helper, buf, count);
  	uevent_helper[count] = '\0';
  	if (count && uevent_helper[count-1] == '\n')
  		uevent_helper[count-1] = '\0';
  	return count;
  }
  KERNEL_ATTR_RW(uevent_helper);
  #endif
  
  #ifdef CONFIG_PROFILING
  static ssize_t profiling_show(struct kobject *kobj,
  				  struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d\n", prof_on);
  }
  static ssize_t profiling_store(struct kobject *kobj,
  				   struct kobj_attribute *attr,
  				   const char *buf, size_t count)
  {
  	int ret;
  
  	if (prof_on)
  		return -EEXIST;
  	/*
  	 * This eventually calls into get_option() which
  	 * has a ton of callers and is not const.  It is
  	 * easiest to cast it away here.
  	 */
  	profile_setup((char *)buf);
  	ret = profile_init();
  	if (ret)
  		return ret;
  	ret = create_proc_profile();
  	if (ret)
  		return ret;
  	return count;
  }
  KERNEL_ATTR_RW(profiling);
  #endif
  
  #ifdef CONFIG_KEXEC
  static ssize_t kexec_loaded_show(struct kobject *kobj,
  				 struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d\n", !!kexec_image);
  }
  KERNEL_ATTR_RO(kexec_loaded);
  
  static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
  				       struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d\n", !!kexec_crash_image);
  }
  KERNEL_ATTR_RO(kexec_crash_loaded);
  
  static ssize_t kexec_crash_size_show(struct kobject *kobj,
  				       struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%zu\n", crash_get_memory_size());
  }
  static ssize_t kexec_crash_size_store(struct kobject *kobj,
  				   struct kobj_attribute *attr,
  				   const char *buf, size_t count)
  {
  	unsigned long cnt;
  	int ret;
  
  	if (kstrtoul(buf, 0, &cnt))
  		return -EINVAL;
  
  	ret = crash_shrink_memory(cnt);
  	return ret < 0 ? ret : count;
  }
  KERNEL_ATTR_RW(kexec_crash_size);
  
  static ssize_t vmcoreinfo_show(struct kobject *kobj,
  			       struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%lx %x\n",
  		       paddr_vmcoreinfo_note(),
  		       (unsigned int)sizeof(vmcoreinfo_note));
  }
  KERNEL_ATTR_RO(vmcoreinfo);
  
  #endif /* CONFIG_KEXEC */
  
  /* whether file capabilities are enabled */
  static ssize_t fscaps_show(struct kobject *kobj,
  				  struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d\n", file_caps_enabled);
  }
  KERNEL_ATTR_RO(fscaps);
  
  int rcu_expedited;
  static ssize_t rcu_expedited_show(struct kobject *kobj,
  				  struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d\n", rcu_expedited);
  }
  static ssize_t rcu_expedited_store(struct kobject *kobj,
  				   struct kobj_attribute *attr,
  				   const char *buf, size_t count)
  {
  	if (kstrtoint(buf, 0, &rcu_expedited))
  		return -EINVAL;
  
  	return count;
  }
  KERNEL_ATTR_RW(rcu_expedited);
  
  /*
   * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
   */
  extern const void __start_notes __weak;
  extern const void __stop_notes __weak;
  #define	notes_size (&__stop_notes - &__start_notes)
  
  static ssize_t notes_read(struct file *filp, struct kobject *kobj,
  			  struct bin_attribute *bin_attr,
  			  char *buf, loff_t off, size_t count)
  {
  	memcpy(buf, &__start_notes + off, count);
  	return count;
  }
  
  static struct bin_attribute notes_attr = {
  	.attr = {
  		.name = "notes",
  		.mode = S_IRUGO,
  	},
  	.read = &notes_read,
  };
  
  struct kobject *kernel_kobj;
  EXPORT_SYMBOL_GPL(kernel_kobj);
  
  static struct attribute * kernel_attrs[] = {
  	&fscaps_attr.attr,
  	&uevent_seqnum_attr.attr,
  #ifdef CONFIG_UEVENT_HELPER
  	&uevent_helper_attr.attr,
  #endif
  #ifdef CONFIG_PROFILING
  	&profiling_attr.attr,
  #endif
  #ifdef CONFIG_KEXEC
  	&kexec_loaded_attr.attr,
  	&kexec_crash_loaded_attr.attr,
  	&kexec_crash_size_attr.attr,
  	&vmcoreinfo_attr.attr,
  #endif
  	&rcu_expedited_attr.attr,
  	NULL
  };
  
  static struct attribute_group kernel_attr_group = {
  	.attrs = kernel_attrs,
  };
  
  static int __init ksysfs_init(void)
  {
  	int error;
  
  	kernel_kobj = kobject_create_and_add("kernel", NULL);
  	if (!kernel_kobj) {
  		error = -ENOMEM;
  		goto exit;
  	}
  	error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
  	if (error)
  		goto kset_exit;
  
  	if (notes_size > 0) {
  		notes_attr.size = notes_size;
  		error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
  		if (error)
  			goto group_exit;
  	}
  
  	return 0;
  
  group_exit:
  	sysfs_remove_group(kernel_kobj, &kernel_attr_group);
  kset_exit:
  	kobject_put(kernel_kobj);
  exit:
  	return error;
  }
  
  core_initcall(ksysfs_init);
  