1 // SPDX-License-Identifier: GPL-2.0-only
3 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
4 * are not related to any other subsystem
6 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
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>
22 #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */
24 #if defined(__LITTLE_ENDIAN)
25 #define CPU_BYTEORDER_STRING "little"
26 #elif defined(__BIG_ENDIAN)
27 #define CPU_BYTEORDER_STRING "big"
29 #error Unknown byteorder
32 #define KERNEL_ATTR_RO(_name) \
33 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
35 #define KERNEL_ATTR_RW(_name) \
36 static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
38 /* current uevent sequence number */
39 static ssize_t
uevent_seqnum_show(struct kobject
*kobj
,
40 struct kobj_attribute
*attr
, char *buf
)
42 return sprintf(buf
, "%llu\n", (unsigned long long)uevent_seqnum
);
44 KERNEL_ATTR_RO(uevent_seqnum
);
47 static ssize_t
cpu_byteorder_show(struct kobject
*kobj
,
48 struct kobj_attribute
*attr
, char *buf
)
50 return sysfs_emit(buf
, "%s\n", CPU_BYTEORDER_STRING
);
52 KERNEL_ATTR_RO(cpu_byteorder
);
54 #ifdef CONFIG_UEVENT_HELPER
55 /* uevent helper program, used during early boot */
56 static ssize_t
uevent_helper_show(struct kobject
*kobj
,
57 struct kobj_attribute
*attr
, char *buf
)
59 return sprintf(buf
, "%s\n", uevent_helper
);
61 static ssize_t
uevent_helper_store(struct kobject
*kobj
,
62 struct kobj_attribute
*attr
,
63 const char *buf
, size_t count
)
65 if (count
+1 > UEVENT_HELPER_PATH_LEN
)
67 memcpy(uevent_helper
, buf
, count
);
68 uevent_helper
[count
] = '\0';
69 if (count
&& uevent_helper
[count
-1] == '\n')
70 uevent_helper
[count
-1] = '\0';
73 KERNEL_ATTR_RW(uevent_helper
);
76 #ifdef CONFIG_PROFILING
77 static ssize_t
profiling_show(struct kobject
*kobj
,
78 struct kobj_attribute
*attr
, char *buf
)
80 return sprintf(buf
, "%d\n", prof_on
);
82 static ssize_t
profiling_store(struct kobject
*kobj
,
83 struct kobj_attribute
*attr
,
84 const char *buf
, size_t count
)
91 * This eventually calls into get_option() which
92 * has a ton of callers and is not const. It is
93 * easiest to cast it away here.
95 profile_setup((char *)buf
);
99 ret
= create_proc_profile();
104 KERNEL_ATTR_RW(profiling
);
107 #ifdef CONFIG_KEXEC_CORE
108 static ssize_t
kexec_loaded_show(struct kobject
*kobj
,
109 struct kobj_attribute
*attr
, char *buf
)
111 return sprintf(buf
, "%d\n", !!kexec_image
);
113 KERNEL_ATTR_RO(kexec_loaded
);
115 static ssize_t
kexec_crash_loaded_show(struct kobject
*kobj
,
116 struct kobj_attribute
*attr
, char *buf
)
118 return sprintf(buf
, "%d\n", kexec_crash_loaded());
120 KERNEL_ATTR_RO(kexec_crash_loaded
);
122 static ssize_t
kexec_crash_size_show(struct kobject
*kobj
,
123 struct kobj_attribute
*attr
, char *buf
)
125 ssize_t size
= crash_get_memory_size();
130 return sprintf(buf
, "%zd\n", size
);
132 static ssize_t
kexec_crash_size_store(struct kobject
*kobj
,
133 struct kobj_attribute
*attr
,
134 const char *buf
, size_t count
)
139 if (kstrtoul(buf
, 0, &cnt
))
142 ret
= crash_shrink_memory(cnt
);
143 return ret
< 0 ? ret
: count
;
145 KERNEL_ATTR_RW(kexec_crash_size
);
147 #endif /* CONFIG_KEXEC_CORE */
149 #ifdef CONFIG_CRASH_CORE
151 static ssize_t
vmcoreinfo_show(struct kobject
*kobj
,
152 struct kobj_attribute
*attr
, char *buf
)
154 phys_addr_t vmcore_base
= paddr_vmcoreinfo_note();
155 return sprintf(buf
, "%pa %x\n", &vmcore_base
,
156 (unsigned int)VMCOREINFO_NOTE_SIZE
);
158 KERNEL_ATTR_RO(vmcoreinfo
);
160 #endif /* CONFIG_CRASH_CORE */
162 /* whether file capabilities are enabled */
163 static ssize_t
fscaps_show(struct kobject
*kobj
,
164 struct kobj_attribute
*attr
, char *buf
)
166 return sprintf(buf
, "%d\n", file_caps_enabled
);
168 KERNEL_ATTR_RO(fscaps
);
170 #ifndef CONFIG_TINY_RCU
172 static ssize_t
rcu_expedited_show(struct kobject
*kobj
,
173 struct kobj_attribute
*attr
, char *buf
)
175 return sprintf(buf
, "%d\n", READ_ONCE(rcu_expedited
));
177 static ssize_t
rcu_expedited_store(struct kobject
*kobj
,
178 struct kobj_attribute
*attr
,
179 const char *buf
, size_t count
)
181 if (kstrtoint(buf
, 0, &rcu_expedited
))
186 KERNEL_ATTR_RW(rcu_expedited
);
189 static ssize_t
rcu_normal_show(struct kobject
*kobj
,
190 struct kobj_attribute
*attr
, char *buf
)
192 return sprintf(buf
, "%d\n", READ_ONCE(rcu_normal
));
194 static ssize_t
rcu_normal_store(struct kobject
*kobj
,
195 struct kobj_attribute
*attr
,
196 const char *buf
, size_t count
)
198 if (kstrtoint(buf
, 0, &rcu_normal
))
203 KERNEL_ATTR_RW(rcu_normal
);
204 #endif /* #ifndef CONFIG_TINY_RCU */
207 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
209 extern const void __start_notes __weak
;
210 extern const void __stop_notes __weak
;
211 #define notes_size (&__stop_notes - &__start_notes)
213 static ssize_t
notes_read(struct file
*filp
, struct kobject
*kobj
,
214 struct bin_attribute
*bin_attr
,
215 char *buf
, loff_t off
, size_t count
)
217 memcpy(buf
, &__start_notes
+ off
, count
);
221 static struct bin_attribute notes_attr __ro_after_init
= {
229 struct kobject
*kernel_kobj
;
230 EXPORT_SYMBOL_GPL(kernel_kobj
);
232 static struct attribute
* kernel_attrs
[] = {
234 &uevent_seqnum_attr
.attr
,
235 &cpu_byteorder_attr
.attr
,
236 #ifdef CONFIG_UEVENT_HELPER
237 &uevent_helper_attr
.attr
,
239 #ifdef CONFIG_PROFILING
240 &profiling_attr
.attr
,
242 #ifdef CONFIG_KEXEC_CORE
243 &kexec_loaded_attr
.attr
,
244 &kexec_crash_loaded_attr
.attr
,
245 &kexec_crash_size_attr
.attr
,
247 #ifdef CONFIG_CRASH_CORE
248 &vmcoreinfo_attr
.attr
,
250 #ifndef CONFIG_TINY_RCU
251 &rcu_expedited_attr
.attr
,
252 &rcu_normal_attr
.attr
,
257 static const struct attribute_group kernel_attr_group
= {
258 .attrs
= kernel_attrs
,
261 static int __init
ksysfs_init(void)
265 kernel_kobj
= kobject_create_and_add("kernel", NULL
);
270 error
= sysfs_create_group(kernel_kobj
, &kernel_attr_group
);
274 if (notes_size
> 0) {
275 notes_attr
.size
= notes_size
;
276 error
= sysfs_create_bin_file(kernel_kobj
, ¬es_attr
);
284 sysfs_remove_group(kernel_kobj
, &kernel_attr_group
);
286 kobject_put(kernel_kobj
);
291 core_initcall(ksysfs_init
);