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#include <linux/compiler.h>
22
23#include <linux/rcupdate.h> /* rcu_expedited */
24
25#define KERNEL_ATTR_RO(_name) \
26static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
27
28#define KERNEL_ATTR_RW(_name) \
29static struct kobj_attribute _name##_attr = \
30    __ATTR(_name, 0644, _name##_show, _name##_store)
31
32/* current uevent sequence number */
33static ssize_t uevent_seqnum_show(struct kobject *kobj,
34                  struct kobj_attribute *attr, char *buf)
35{
36    return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
37}
38KERNEL_ATTR_RO(uevent_seqnum);
39
40/* uevent helper program, used during early boot */
41static ssize_t uevent_helper_show(struct kobject *kobj,
42                  struct kobj_attribute *attr, char *buf)
43{
44    return sprintf(buf, "%s\n", uevent_helper);
45}
46static ssize_t uevent_helper_store(struct kobject *kobj,
47                   struct kobj_attribute *attr,
48                   const char *buf, size_t count)
49{
50    if (count+1 > UEVENT_HELPER_PATH_LEN)
51        return -ENOENT;
52    memcpy(uevent_helper, buf, count);
53    uevent_helper[count] = '\0';
54    if (count && uevent_helper[count-1] == '\n')
55        uevent_helper[count-1] = '\0';
56    return count;
57}
58KERNEL_ATTR_RW(uevent_helper);
59
60
61#ifdef CONFIG_PROFILING
62static ssize_t profiling_show(struct kobject *kobj,
63                  struct kobj_attribute *attr, char *buf)
64{
65    return sprintf(buf, "%d\n", prof_on);
66}
67static ssize_t profiling_store(struct kobject *kobj,
68                   struct kobj_attribute *attr,
69                   const char *buf, size_t count)
70{
71    int ret;
72
73    if (prof_on)
74        return -EEXIST;
75    /*
76     * This eventually calls into get_option() which
77     * has a ton of callers and is not const. It is
78     * easiest to cast it away here.
79     */
80    profile_setup((char *)buf);
81    ret = profile_init();
82    if (ret)
83        return ret;
84    ret = create_proc_profile();
85    if (ret)
86        return ret;
87    return count;
88}
89KERNEL_ATTR_RW(profiling);
90#endif
91
92#ifdef CONFIG_KEXEC
93static ssize_t kexec_loaded_show(struct kobject *kobj,
94                 struct kobj_attribute *attr, char *buf)
95{
96    return sprintf(buf, "%d\n", !!kexec_image);
97}
98KERNEL_ATTR_RO(kexec_loaded);
99
100static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
101                       struct kobj_attribute *attr, char *buf)
102{
103    return sprintf(buf, "%d\n", !!kexec_crash_image);
104}
105KERNEL_ATTR_RO(kexec_crash_loaded);
106
107static ssize_t kexec_crash_size_show(struct kobject *kobj,
108                       struct kobj_attribute *attr, char *buf)
109{
110    return sprintf(buf, "%zu\n", crash_get_memory_size());
111}
112static ssize_t kexec_crash_size_store(struct kobject *kobj,
113                   struct kobj_attribute *attr,
114                   const char *buf, size_t count)
115{
116    unsigned long cnt;
117    int ret;
118
119    if (kstrtoul(buf, 0, &cnt))
120        return -EINVAL;
121
122    ret = crash_shrink_memory(cnt);
123    return ret < 0 ? ret : count;
124}
125KERNEL_ATTR_RW(kexec_crash_size);
126
127static ssize_t vmcoreinfo_show(struct kobject *kobj,
128                   struct kobj_attribute *attr, char *buf)
129{
130    return sprintf(buf, "%lx %x\n",
131               paddr_vmcoreinfo_note(),
132               (unsigned int)sizeof(vmcoreinfo_note));
133}
134KERNEL_ATTR_RO(vmcoreinfo);
135
136#endif /* CONFIG_KEXEC */
137
138/* whether file capabilities are enabled */
139static ssize_t fscaps_show(struct kobject *kobj,
140                  struct kobj_attribute *attr, char *buf)
141{
142    return sprintf(buf, "%d\n", file_caps_enabled);
143}
144KERNEL_ATTR_RO(fscaps);
145
146int rcu_expedited;
147static ssize_t rcu_expedited_show(struct kobject *kobj,
148                  struct kobj_attribute *attr, char *buf)
149{
150    return sprintf(buf, "%d\n", rcu_expedited);
151}
152static ssize_t rcu_expedited_store(struct kobject *kobj,
153                   struct kobj_attribute *attr,
154                   const char *buf, size_t count)
155{
156    if (kstrtoint(buf, 0, &rcu_expedited))
157        return -EINVAL;
158
159    return count;
160}
161KERNEL_ATTR_RW(rcu_expedited);
162
163/*
164 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
165 */
166extern const void __start_notes __weak;
167extern const void __stop_notes __weak;
168#define notes_size (&__stop_notes - &__start_notes)
169
170static ssize_t notes_read(struct file *filp, struct kobject *kobj,
171              struct bin_attribute *bin_attr,
172              char *buf, loff_t off, size_t count)
173{
174    memcpy(buf, &__start_notes + off, count);
175    return count;
176}
177
178static struct bin_attribute notes_attr = {
179    .attr = {
180        .name = "notes",
181        .mode = S_IRUGO,
182    },
183    .read = &notes_read,
184};
185
186struct kobject *kernel_kobj;
187EXPORT_SYMBOL_GPL(kernel_kobj);
188
189static struct attribute * kernel_attrs[] = {
190    &fscaps_attr.attr,
191    &uevent_seqnum_attr.attr,
192    &uevent_helper_attr.attr,
193#ifdef CONFIG_PROFILING
194    &profiling_attr.attr,
195#endif
196#ifdef CONFIG_KEXEC
197    &kexec_loaded_attr.attr,
198    &kexec_crash_loaded_attr.attr,
199    &kexec_crash_size_attr.attr,
200    &vmcoreinfo_attr.attr,
201#endif
202    &rcu_expedited_attr.attr,
203    NULL
204};
205
206static struct attribute_group kernel_attr_group = {
207    .attrs = kernel_attrs,
208};
209
210static int __init ksysfs_init(void)
211{
212    int error;
213
214    kernel_kobj = kobject_create_and_add("kernel", NULL);
215    if (!kernel_kobj) {
216        error = -ENOMEM;
217        goto exit;
218    }
219    error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
220    if (error)
221        goto kset_exit;
222
223    if (notes_size > 0) {
224        notes_attr.size = notes_size;
225        error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
226        if (error)
227            goto group_exit;
228    }
229
230    return 0;
231
232group_exit:
233    sysfs_remove_group(kernel_kobj, &kernel_attr_group);
234kset_exit:
235    kobject_put(kernel_kobj);
236exit:
237    return error;
238}
239
240core_initcall(ksysfs_init);
241

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