// SPDX-License-Identifier: GPL-2.0-only /* * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which * are not related to any other subsystem * * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> */ #include <asm/byteorder.h> #include <linux/kobject.h> #include <linux/string.h> #include <linux/sysfs.h> #include <linux/export.h> #include <linux/init.h> #include <linux/kexec.h> #include <linux/profile.h> #include <linux/stat.h> #include <linux/sched.h> #include <linux/capability.h> #include <linux/compiler.h> #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */ #if defined(__LITTLE_ENDIAN) #define CPU_BYTEORDER_STRING "little" #elif defined(__BIG_ENDIAN) #define CPU_BYTEORDER_STRING "big" #else #error Unknown byteorder #endif #define KERNEL_ATTR_RO(_name) \ static struct kobj_attribute _name##_attr = __ATTR_RO(_name) #define KERNEL_ATTR_RW(_name) \ static struct kobj_attribute _name##_attr = __ATTR_RW(_name) /* current uevent sequence number */ static ssize_t uevent_seqnum_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%llu\n", (unsigned long long)uevent_seqnum); } KERNEL_ATTR_RO(uevent_seqnum); /* cpu byteorder */ static ssize_t cpu_byteorder_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING); } KERNEL_ATTR_RO(cpu_byteorder); /* address bits */ static ssize_t address_bits_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%zu\n", sizeof(void *) * 8 /* CHAR_BIT */); } KERNEL_ATTR_RO(address_bits); #ifdef CONFIG_UEVENT_HELPER /* uevent helper program, used during early boot */ static ssize_t uevent_helper_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%s\n", uevent_helper); } static ssize_t uevent_helper_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { if (count+1 > UEVENT_HELPER_PATH_LEN) return -ENOENT; memcpy(uevent_helper, buf, count); uevent_helper[count] = '\0'; if (count && uevent_helper[count-1] == '\n') uevent_helper[count-1] = '\0'; return count; } KERNEL_ATTR_RW(uevent_helper); #endif #ifdef CONFIG_PROFILING static ssize_t profiling_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", prof_on); } static ssize_t profiling_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { int ret; if (prof_on) return -EEXIST; /* * This eventually calls into get_option() which * has a ton of callers and is not const. It is * easiest to cast it away here. */ profile_setup((char *)buf); ret = profile_init(); if (ret) return ret; ret = create_proc_profile(); if (ret) return ret; return count; } KERNEL_ATTR_RW(profiling); #endif #ifdef CONFIG_KEXEC_CORE static ssize_t kexec_loaded_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", !!kexec_image); } KERNEL_ATTR_RO(kexec_loaded); static ssize_t kexec_crash_loaded_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", kexec_crash_loaded()); } KERNEL_ATTR_RO(kexec_crash_loaded); static ssize_t kexec_crash_size_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { ssize_t size = crash_get_memory_size(); if (size < 0) return size; return sysfs_emit(buf, "%zd\n", size); } static ssize_t kexec_crash_size_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { unsigned long cnt; int ret; if (kstrtoul(buf, 0, &cnt)) return -EINVAL; ret = crash_shrink_memory(cnt); return ret < 0 ? ret : count; } KERNEL_ATTR_RW(kexec_crash_size); #endif /* CONFIG_KEXEC_CORE */ #ifdef CONFIG_CRASH_CORE static ssize_t vmcoreinfo_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); return sysfs_emit(buf, "%pa %x\n", &vmcore_base, (unsigned int)VMCOREINFO_NOTE_SIZE); } KERNEL_ATTR_RO(vmcoreinfo); #endif /* CONFIG_CRASH_CORE */ /* whether file capabilities are enabled */ static ssize_t fscaps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", file_caps_enabled); } KERNEL_ATTR_RO(fscaps); #ifndef CONFIG_TINY_RCU int rcu_expedited; static ssize_t rcu_expedited_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited)); } static ssize_t rcu_expedited_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { if (kstrtoint(buf, 0, &rcu_expedited)) return -EINVAL; return count; } KERNEL_ATTR_RW(rcu_expedited); int rcu_normal; static ssize_t rcu_normal_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal)); } static ssize_t rcu_normal_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { if (kstrtoint(buf, 0, &rcu_normal)) return -EINVAL; return count; } KERNEL_ATTR_RW(rcu_normal); #endif /* #ifndef CONFIG_TINY_RCU */ /* * Make /sys/kernel/notes give the raw contents of our kernel .notes section. */ extern const void __start_notes __weak; extern const void __stop_notes __weak; #define notes_size (&__stop_notes - &__start_notes) static ssize_t notes_read(struct file *filp, struct kobject *kobj, struct bin_attribute *bin_attr, char *buf, loff_t off, size_t count) { memcpy(buf, &__start_notes + off, count); return count; } static struct bin_attribute notes_attr __ro_after_init = { .attr = { .name = "notes", .mode = S_IRUGO, }, .read = ¬es_read, }; struct kobject *kernel_kobj; EXPORT_SYMBOL_GPL(kernel_kobj); static struct attribute * kernel_attrs[] = { &fscaps_attr.attr, &uevent_seqnum_attr.attr, &cpu_byteorder_attr.attr, &address_bits_attr.attr, #ifdef CONFIG_UEVENT_HELPER &uevent_helper_attr.attr, #endif #ifdef CONFIG_PROFILING &profiling_attr.attr, #endif #ifdef CONFIG_KEXEC_CORE &kexec_loaded_attr.attr, &kexec_crash_loaded_attr.attr, &kexec_crash_size_attr.attr, #endif #ifdef CONFIG_CRASH_CORE &vmcoreinfo_attr.attr, #endif #ifndef CONFIG_TINY_RCU &rcu_expedited_attr.attr, &rcu_normal_attr.attr, #endif NULL }; static const struct attribute_group kernel_attr_group = { .attrs = kernel_attrs, }; static int __init ksysfs_init(void) { int error; kernel_kobj = kobject_create_and_add("kernel", NULL); if (!kernel_kobj) { error = -ENOMEM; goto exit; } error = sysfs_create_group(kernel_kobj, &kernel_attr_group); if (error) goto kset_exit; if (notes_size > 0) { notes_attr.size = notes_size; error = sysfs_create_bin_file(kernel_kobj, ¬es_attr); if (error) goto group_exit; } return 0; group_exit: sysfs_remove_group(kernel_kobj, &kernel_attr_group); kset_exit: kobject_put(kernel_kobj); exit: return error; } core_initcall(ksysfs_init);