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

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