Merge tag 'sh-for-v6.6-tag1' of git://git.kernel.org/pub/scm/linux/kernel/git/glaubit...
[platform/kernel/linux-rpi.git] / kernel / ksysfs.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
4  *                   are not related to any other subsystem
5  *
6  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
7  */
8
9 #include <asm/byteorder.h>
10 #include <linux/kobject.h>
11 #include <linux/string.h>
12 #include <linux/sysfs.h>
13 #include <linux/export.h>
14 #include <linux/init.h>
15 #include <linux/kexec.h>
16 #include <linux/profile.h>
17 #include <linux/stat.h>
18 #include <linux/sched.h>
19 #include <linux/capability.h>
20 #include <linux/compiler.h>
21
22 #include <linux/rcupdate.h>     /* rcu_expedited and rcu_normal */
23
24 #if defined(__LITTLE_ENDIAN)
25 #define CPU_BYTEORDER_STRING    "little"
26 #elif defined(__BIG_ENDIAN)
27 #define CPU_BYTEORDER_STRING    "big"
28 #else
29 #error Unknown byteorder
30 #endif
31
32 #define KERNEL_ATTR_RO(_name) \
33 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
34
35 #define KERNEL_ATTR_RW(_name) \
36 static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
37
38 /* current uevent sequence number */
39 static ssize_t uevent_seqnum_show(struct kobject *kobj,
40                                   struct kobj_attribute *attr, char *buf)
41 {
42         return sysfs_emit(buf, "%llu\n", (unsigned long long)uevent_seqnum);
43 }
44 KERNEL_ATTR_RO(uevent_seqnum);
45
46 /* cpu byteorder */
47 static ssize_t cpu_byteorder_show(struct kobject *kobj,
48                                   struct kobj_attribute *attr, char *buf)
49 {
50         return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING);
51 }
52 KERNEL_ATTR_RO(cpu_byteorder);
53
54 /* address bits */
55 static ssize_t address_bits_show(struct kobject *kobj,
56                                  struct kobj_attribute *attr, char *buf)
57 {
58         return sysfs_emit(buf, "%zu\n", sizeof(void *) * 8 /* CHAR_BIT */);
59 }
60 KERNEL_ATTR_RO(address_bits);
61
62 #ifdef CONFIG_UEVENT_HELPER
63 /* uevent helper program, used during early boot */
64 static ssize_t uevent_helper_show(struct kobject *kobj,
65                                   struct kobj_attribute *attr, char *buf)
66 {
67         return sysfs_emit(buf, "%s\n", uevent_helper);
68 }
69 static ssize_t uevent_helper_store(struct kobject *kobj,
70                                    struct kobj_attribute *attr,
71                                    const char *buf, size_t count)
72 {
73         if (count+1 > UEVENT_HELPER_PATH_LEN)
74                 return -ENOENT;
75         memcpy(uevent_helper, buf, count);
76         uevent_helper[count] = '\0';
77         if (count && uevent_helper[count-1] == '\n')
78                 uevent_helper[count-1] = '\0';
79         return count;
80 }
81 KERNEL_ATTR_RW(uevent_helper);
82 #endif
83
84 #ifdef CONFIG_PROFILING
85 static ssize_t profiling_show(struct kobject *kobj,
86                                   struct kobj_attribute *attr, char *buf)
87 {
88         return sysfs_emit(buf, "%d\n", prof_on);
89 }
90 static ssize_t profiling_store(struct kobject *kobj,
91                                    struct kobj_attribute *attr,
92                                    const char *buf, size_t count)
93 {
94         int ret;
95
96         if (prof_on)
97                 return -EEXIST;
98         /*
99          * This eventually calls into get_option() which
100          * has a ton of callers and is not const.  It is
101          * easiest to cast it away here.
102          */
103         profile_setup((char *)buf);
104         ret = profile_init();
105         if (ret)
106                 return ret;
107         ret = create_proc_profile();
108         if (ret)
109                 return ret;
110         return count;
111 }
112 KERNEL_ATTR_RW(profiling);
113 #endif
114
115 #ifdef CONFIG_KEXEC_CORE
116 static ssize_t kexec_loaded_show(struct kobject *kobj,
117                                  struct kobj_attribute *attr, char *buf)
118 {
119         return sysfs_emit(buf, "%d\n", !!kexec_image);
120 }
121 KERNEL_ATTR_RO(kexec_loaded);
122
123 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
124                                        struct kobj_attribute *attr, char *buf)
125 {
126         return sysfs_emit(buf, "%d\n", kexec_crash_loaded());
127 }
128 KERNEL_ATTR_RO(kexec_crash_loaded);
129
130 static ssize_t kexec_crash_size_show(struct kobject *kobj,
131                                        struct kobj_attribute *attr, char *buf)
132 {
133         ssize_t size = crash_get_memory_size();
134
135         if (size < 0)
136                 return size;
137
138         return sysfs_emit(buf, "%zd\n", size);
139 }
140 static ssize_t kexec_crash_size_store(struct kobject *kobj,
141                                    struct kobj_attribute *attr,
142                                    const char *buf, size_t count)
143 {
144         unsigned long cnt;
145         int ret;
146
147         if (kstrtoul(buf, 0, &cnt))
148                 return -EINVAL;
149
150         ret = crash_shrink_memory(cnt);
151         return ret < 0 ? ret : count;
152 }
153 KERNEL_ATTR_RW(kexec_crash_size);
154
155 #endif /* CONFIG_KEXEC_CORE */
156
157 #ifdef CONFIG_CRASH_CORE
158
159 static ssize_t vmcoreinfo_show(struct kobject *kobj,
160                                struct kobj_attribute *attr, char *buf)
161 {
162         phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
163         return sysfs_emit(buf, "%pa %x\n", &vmcore_base,
164                           (unsigned int)VMCOREINFO_NOTE_SIZE);
165 }
166 KERNEL_ATTR_RO(vmcoreinfo);
167
168 #ifdef CONFIG_CRASH_HOTPLUG
169 static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj,
170                                struct kobj_attribute *attr, char *buf)
171 {
172         unsigned int sz = crash_get_elfcorehdr_size();
173
174         return sysfs_emit(buf, "%u\n", sz);
175 }
176 KERNEL_ATTR_RO(crash_elfcorehdr_size);
177
178 #endif
179
180 #endif /* CONFIG_CRASH_CORE */
181
182 /* whether file capabilities are enabled */
183 static ssize_t fscaps_show(struct kobject *kobj,
184                                   struct kobj_attribute *attr, char *buf)
185 {
186         return sysfs_emit(buf, "%d\n", file_caps_enabled);
187 }
188 KERNEL_ATTR_RO(fscaps);
189
190 #ifndef CONFIG_TINY_RCU
191 int rcu_expedited;
192 static ssize_t rcu_expedited_show(struct kobject *kobj,
193                                   struct kobj_attribute *attr, char *buf)
194 {
195         return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited));
196 }
197 static ssize_t rcu_expedited_store(struct kobject *kobj,
198                                    struct kobj_attribute *attr,
199                                    const char *buf, size_t count)
200 {
201         if (kstrtoint(buf, 0, &rcu_expedited))
202                 return -EINVAL;
203
204         return count;
205 }
206 KERNEL_ATTR_RW(rcu_expedited);
207
208 int rcu_normal;
209 static ssize_t rcu_normal_show(struct kobject *kobj,
210                                struct kobj_attribute *attr, char *buf)
211 {
212         return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal));
213 }
214 static ssize_t rcu_normal_store(struct kobject *kobj,
215                                 struct kobj_attribute *attr,
216                                 const char *buf, size_t count)
217 {
218         if (kstrtoint(buf, 0, &rcu_normal))
219                 return -EINVAL;
220
221         return count;
222 }
223 KERNEL_ATTR_RW(rcu_normal);
224 #endif /* #ifndef CONFIG_TINY_RCU */
225
226 /*
227  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
228  */
229 extern const void __start_notes __weak;
230 extern const void __stop_notes __weak;
231 #define notes_size (&__stop_notes - &__start_notes)
232
233 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
234                           struct bin_attribute *bin_attr,
235                           char *buf, loff_t off, size_t count)
236 {
237         memcpy(buf, &__start_notes + off, count);
238         return count;
239 }
240
241 static struct bin_attribute notes_attr __ro_after_init  = {
242         .attr = {
243                 .name = "notes",
244                 .mode = S_IRUGO,
245         },
246         .read = &notes_read,
247 };
248
249 struct kobject *kernel_kobj;
250 EXPORT_SYMBOL_GPL(kernel_kobj);
251
252 static struct attribute * kernel_attrs[] = {
253         &fscaps_attr.attr,
254         &uevent_seqnum_attr.attr,
255         &cpu_byteorder_attr.attr,
256         &address_bits_attr.attr,
257 #ifdef CONFIG_UEVENT_HELPER
258         &uevent_helper_attr.attr,
259 #endif
260 #ifdef CONFIG_PROFILING
261         &profiling_attr.attr,
262 #endif
263 #ifdef CONFIG_KEXEC_CORE
264         &kexec_loaded_attr.attr,
265         &kexec_crash_loaded_attr.attr,
266         &kexec_crash_size_attr.attr,
267 #endif
268 #ifdef CONFIG_CRASH_CORE
269         &vmcoreinfo_attr.attr,
270 #ifdef CONFIG_CRASH_HOTPLUG
271         &crash_elfcorehdr_size_attr.attr,
272 #endif
273 #endif
274 #ifndef CONFIG_TINY_RCU
275         &rcu_expedited_attr.attr,
276         &rcu_normal_attr.attr,
277 #endif
278         NULL
279 };
280
281 static const struct attribute_group kernel_attr_group = {
282         .attrs = kernel_attrs,
283 };
284
285 static int __init ksysfs_init(void)
286 {
287         int error;
288
289         kernel_kobj = kobject_create_and_add("kernel", NULL);
290         if (!kernel_kobj) {
291                 error = -ENOMEM;
292                 goto exit;
293         }
294         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
295         if (error)
296                 goto kset_exit;
297
298         if (notes_size > 0) {
299                 notes_attr.size = notes_size;
300                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
301                 if (error)
302                         goto group_exit;
303         }
304
305         return 0;
306
307 group_exit:
308         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
309 kset_exit:
310         kobject_put(kernel_kobj);
311 exit:
312         return error;
313 }
314
315 core_initcall(ksysfs_init);