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![Petr Tesarik](/assets/img/avatar_default.png)
Provide a wrapper function to be used by kernel code to check whether a crash kernel is loaded. It returns the same value that can be seen in /sys/kernel/kexec_crash_loaded by userspace programs. I'm exporting the function, because it will be used by Xen, and it is possible to compile Xen modules separately to enable the use of PV drivers with unmodified bare-metal kernels. Link: http://lkml.kernel.org/r/20160713121955.14969.69080.stgit@hananiah.suse.cz Signed-off-by: Petr Tesarik <ptesarik@suse.com> Cc: Juergen Gross <jgross@suse.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Eric Biederman <ebiederm@xmission.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Dave Young <dyoung@redhat.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
265 lines
6.2 KiB
C
265 lines
6.2 KiB
C
/*
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* kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
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* are not related to any other subsystem
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*
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* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
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*
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* This file is release under the GPLv2
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*
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*/
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#include <linux/kobject.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/kexec.h>
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#include <linux/profile.h>
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#include <linux/stat.h>
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#include <linux/sched.h>
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#include <linux/capability.h>
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#include <linux/compiler.h>
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#include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */
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#define KERNEL_ATTR_RO(_name) \
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static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
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#define KERNEL_ATTR_RW(_name) \
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static struct kobj_attribute _name##_attr = \
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__ATTR(_name, 0644, _name##_show, _name##_store)
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/* current uevent sequence number */
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static ssize_t uevent_seqnum_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
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}
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KERNEL_ATTR_RO(uevent_seqnum);
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#ifdef CONFIG_UEVENT_HELPER
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/* uevent helper program, used during early boot */
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static ssize_t uevent_helper_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%s\n", uevent_helper);
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}
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static ssize_t uevent_helper_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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if (count+1 > UEVENT_HELPER_PATH_LEN)
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return -ENOENT;
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memcpy(uevent_helper, buf, count);
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uevent_helper[count] = '\0';
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if (count && uevent_helper[count-1] == '\n')
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uevent_helper[count-1] = '\0';
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return count;
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}
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KERNEL_ATTR_RW(uevent_helper);
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#endif
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#ifdef CONFIG_PROFILING
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static ssize_t profiling_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", prof_on);
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}
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static ssize_t profiling_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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int ret;
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if (prof_on)
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return -EEXIST;
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/*
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* This eventually calls into get_option() which
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* has a ton of callers and is not const. It is
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* easiest to cast it away here.
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*/
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profile_setup((char *)buf);
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ret = profile_init();
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if (ret)
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return ret;
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ret = create_proc_profile();
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if (ret)
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return ret;
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return count;
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}
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KERNEL_ATTR_RW(profiling);
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#endif
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#ifdef CONFIG_KEXEC_CORE
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static ssize_t kexec_loaded_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", !!kexec_image);
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}
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KERNEL_ATTR_RO(kexec_loaded);
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static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", kexec_crash_loaded());
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}
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KERNEL_ATTR_RO(kexec_crash_loaded);
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static ssize_t kexec_crash_size_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%zu\n", crash_get_memory_size());
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}
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static ssize_t kexec_crash_size_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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unsigned long cnt;
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int ret;
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if (kstrtoul(buf, 0, &cnt))
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return -EINVAL;
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ret = crash_shrink_memory(cnt);
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return ret < 0 ? ret : count;
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}
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KERNEL_ATTR_RW(kexec_crash_size);
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static ssize_t vmcoreinfo_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
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return sprintf(buf, "%pa %x\n", &vmcore_base,
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(unsigned int)sizeof(vmcoreinfo_note));
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}
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KERNEL_ATTR_RO(vmcoreinfo);
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#endif /* CONFIG_KEXEC_CORE */
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/* whether file capabilities are enabled */
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static ssize_t fscaps_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", file_caps_enabled);
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}
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KERNEL_ATTR_RO(fscaps);
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#ifndef CONFIG_TINY_RCU
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int rcu_expedited;
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static ssize_t rcu_expedited_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
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}
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static ssize_t rcu_expedited_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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if (kstrtoint(buf, 0, &rcu_expedited))
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return -EINVAL;
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return count;
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}
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KERNEL_ATTR_RW(rcu_expedited);
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int rcu_normal;
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static ssize_t rcu_normal_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
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}
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static ssize_t rcu_normal_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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if (kstrtoint(buf, 0, &rcu_normal))
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return -EINVAL;
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return count;
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}
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KERNEL_ATTR_RW(rcu_normal);
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#endif /* #ifndef CONFIG_TINY_RCU */
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/*
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* Make /sys/kernel/notes give the raw contents of our kernel .notes section.
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*/
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extern const void __start_notes __weak;
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extern const void __stop_notes __weak;
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#define notes_size (&__stop_notes - &__start_notes)
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static ssize_t notes_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t off, size_t count)
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{
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memcpy(buf, &__start_notes + off, count);
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return count;
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}
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static struct bin_attribute notes_attr = {
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.attr = {
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.name = "notes",
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.mode = S_IRUGO,
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},
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.read = ¬es_read,
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};
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struct kobject *kernel_kobj;
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EXPORT_SYMBOL_GPL(kernel_kobj);
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static struct attribute * kernel_attrs[] = {
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&fscaps_attr.attr,
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&uevent_seqnum_attr.attr,
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#ifdef CONFIG_UEVENT_HELPER
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&uevent_helper_attr.attr,
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#endif
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#ifdef CONFIG_PROFILING
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&profiling_attr.attr,
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#endif
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#ifdef CONFIG_KEXEC_CORE
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&kexec_loaded_attr.attr,
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&kexec_crash_loaded_attr.attr,
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&kexec_crash_size_attr.attr,
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&vmcoreinfo_attr.attr,
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#endif
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#ifndef CONFIG_TINY_RCU
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&rcu_expedited_attr.attr,
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&rcu_normal_attr.attr,
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#endif
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NULL
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};
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static struct attribute_group kernel_attr_group = {
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.attrs = kernel_attrs,
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};
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static int __init ksysfs_init(void)
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{
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int error;
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kernel_kobj = kobject_create_and_add("kernel", NULL);
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if (!kernel_kobj) {
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error = -ENOMEM;
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goto exit;
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}
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error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
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if (error)
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goto kset_exit;
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if (notes_size > 0) {
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notes_attr.size = notes_size;
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error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
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if (error)
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goto group_exit;
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}
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return 0;
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group_exit:
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sysfs_remove_group(kernel_kobj, &kernel_attr_group);
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kset_exit:
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kobject_put(kernel_kobj);
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exit:
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return error;
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}
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core_initcall(ksysfs_init);
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