Root/kernel/ksysfs.c

1/*
2 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
3 * are not related to any other subsystem
4 *
5 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
6 *
7 * This file is release under the GPLv2
8 *
9 */
10
11#include <linux/kobject.h>
12#include <linux/string.h>
13#include <linux/sysfs.h>
14#include <linux/export.h>
15#include <linux/init.h>
16#include <linux/kexec.h>
17#include <linux/profile.h>
18#include <linux/stat.h>
19#include <linux/sched.h>
20#include <linux/capability.h>
21
22#define KERNEL_ATTR_RO(_name) \
23static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
24
25#define KERNEL_ATTR_RW(_name) \
26static struct kobj_attribute _name##_attr = \
27    __ATTR(_name, 0644, _name##_show, _name##_store)
28
29/* current uevent sequence number */
30static ssize_t uevent_seqnum_show(struct kobject *kobj,
31                  struct kobj_attribute *attr, char *buf)
32{
33    return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
34}
35KERNEL_ATTR_RO(uevent_seqnum);
36
37/* uevent helper program, used during early boot */
38static ssize_t uevent_helper_show(struct kobject *kobj,
39                  struct kobj_attribute *attr, char *buf)
40{
41    return sprintf(buf, "%s\n", uevent_helper);
42}
43static ssize_t uevent_helper_store(struct kobject *kobj,
44                   struct kobj_attribute *attr,
45                   const char *buf, size_t count)
46{
47    if (count+1 > UEVENT_HELPER_PATH_LEN)
48        return -ENOENT;
49    memcpy(uevent_helper, buf, count);
50    uevent_helper[count] = '\0';
51    if (count && uevent_helper[count-1] == '\n')
52        uevent_helper[count-1] = '\0';
53    return count;
54}
55KERNEL_ATTR_RW(uevent_helper);
56
57
58#ifdef CONFIG_PROFILING
59static ssize_t profiling_show(struct kobject *kobj,
60                  struct kobj_attribute *attr, char *buf)
61{
62    return sprintf(buf, "%d\n", prof_on);
63}
64static ssize_t profiling_store(struct kobject *kobj,
65                   struct kobj_attribute *attr,
66                   const char *buf, size_t count)
67{
68    int ret;
69
70    if (prof_on)
71        return -EEXIST;
72    /*
73     * This eventually calls into get_option() which
74     * has a ton of callers and is not const. It is
75     * easiest to cast it away here.
76     */
77    profile_setup((char *)buf);
78    ret = profile_init();
79    if (ret)
80        return ret;
81    ret = create_proc_profile();
82    if (ret)
83        return ret;
84    return count;
85}
86KERNEL_ATTR_RW(profiling);
87#endif
88
89#ifdef CONFIG_KEXEC
90static ssize_t kexec_loaded_show(struct kobject *kobj,
91                 struct kobj_attribute *attr, char *buf)
92{
93    return sprintf(buf, "%d\n", !!kexec_image);
94}
95KERNEL_ATTR_RO(kexec_loaded);
96
97static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
98                       struct kobj_attribute *attr, char *buf)
99{
100    return sprintf(buf, "%d\n", !!kexec_crash_image);
101}
102KERNEL_ATTR_RO(kexec_crash_loaded);
103
104static ssize_t kexec_crash_size_show(struct kobject *kobj,
105                       struct kobj_attribute *attr, char *buf)
106{
107    return sprintf(buf, "%zu\n", crash_get_memory_size());
108}
109static ssize_t kexec_crash_size_store(struct kobject *kobj,
110                   struct kobj_attribute *attr,
111                   const char *buf, size_t count)
112{
113    unsigned long cnt;
114    int ret;
115
116    if (kstrtoul(buf, 0, &cnt))
117        return -EINVAL;
118
119    ret = crash_shrink_memory(cnt);
120    return ret < 0 ? ret : count;
121}
122KERNEL_ATTR_RW(kexec_crash_size);
123
124static ssize_t vmcoreinfo_show(struct kobject *kobj,
125                   struct kobj_attribute *attr, char *buf)
126{
127    return sprintf(buf, "%lx %x\n",
128               paddr_vmcoreinfo_note(),
129               (unsigned int)vmcoreinfo_max_size);
130}
131KERNEL_ATTR_RO(vmcoreinfo);
132
133#endif /* CONFIG_KEXEC */
134
135/* whether file capabilities are enabled */
136static ssize_t fscaps_show(struct kobject *kobj,
137                  struct kobj_attribute *attr, char *buf)
138{
139    return sprintf(buf, "%d\n", file_caps_enabled);
140}
141KERNEL_ATTR_RO(fscaps);
142
143int rcu_expedited;
144static ssize_t rcu_expedited_show(struct kobject *kobj,
145                  struct kobj_attribute *attr, char *buf)
146{
147    return sprintf(buf, "%d\n", rcu_expedited);
148}
149static ssize_t rcu_expedited_store(struct kobject *kobj,
150                   struct kobj_attribute *attr,
151                   const char *buf, size_t count)
152{
153    if (kstrtoint(buf, 0, &rcu_expedited))
154        return -EINVAL;
155
156    return count;
157}
158KERNEL_ATTR_RW(rcu_expedited);
159
160/*
161 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
162 */
163extern const void __start_notes __attribute__((weak));
164extern const void __stop_notes __attribute__((weak));
165#define notes_size (&__stop_notes - &__start_notes)
166
167static ssize_t notes_read(struct file *filp, struct kobject *kobj,
168              struct bin_attribute *bin_attr,
169              char *buf, loff_t off, size_t count)
170{
171    memcpy(buf, &__start_notes + off, count);
172    return count;
173}
174
175static struct bin_attribute notes_attr = {
176    .attr = {
177        .name = "notes",
178        .mode = S_IRUGO,
179    },
180    .read = &notes_read,
181};
182
183struct kobject *kernel_kobj;
184EXPORT_SYMBOL_GPL(kernel_kobj);
185
186static struct attribute * kernel_attrs[] = {
187    &fscaps_attr.attr,
188    &uevent_seqnum_attr.attr,
189    &uevent_helper_attr.attr,
190#ifdef CONFIG_PROFILING
191    &profiling_attr.attr,
192#endif
193#ifdef CONFIG_KEXEC
194    &kexec_loaded_attr.attr,
195    &kexec_crash_loaded_attr.attr,
196    &kexec_crash_size_attr.attr,
197    &vmcoreinfo_attr.attr,
198#endif
199    &rcu_expedited_attr.attr,
200    NULL
201};
202
203static struct attribute_group kernel_attr_group = {
204    .attrs = kernel_attrs,
205};
206
207static int __init ksysfs_init(void)
208{
209    int error;
210
211    kernel_kobj = kobject_create_and_add("kernel", NULL);
212    if (!kernel_kobj) {
213        error = -ENOMEM;
214        goto exit;
215    }
216    error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
217    if (error)
218        goto kset_exit;
219
220    if (notes_size > 0) {
221        notes_attr.size = notes_size;
222        error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
223        if (error)
224            goto group_exit;
225    }
226
227    return 0;
228
229group_exit:
230    sysfs_remove_group(kernel_kobj, &kernel_attr_group);
231kset_exit:
232    kobject_put(kernel_kobj);
233exit:
234    return error;
235}
236
237core_initcall(ksysfs_init);
238

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