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

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