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![Thomas Weißschuh](/assets/img/avatar_default.png)
This can be used by userspace to determine the address size of the running kernel. It frees userspace from having to interpret this information from the UTS machine field. Userspace implementation: https://github.com/util-linux/util-linux/pull/1966 Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://lore.kernel.org/r/20221221-address-bits-v1-1-8446b13244ac@weissschuh.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
300 lines
7 KiB
C
300 lines
7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
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* are not related to any other subsystem
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*
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* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
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*/
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#include <asm/byteorder.h>
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#include <linux/kobject.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/kexec.h>
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#include <linux/profile.h>
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#include <linux/stat.h>
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#include <linux/sched.h>
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#include <linux/capability.h>
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#include <linux/compiler.h>
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#include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */
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#if defined(__LITTLE_ENDIAN)
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#define CPU_BYTEORDER_STRING "little"
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#elif defined(__BIG_ENDIAN)
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#define CPU_BYTEORDER_STRING "big"
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#else
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#error Unknown byteorder
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#endif
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#define KERNEL_ATTR_RO(_name) \
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static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
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#define KERNEL_ATTR_RW(_name) \
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static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
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/* current uevent sequence number */
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static ssize_t uevent_seqnum_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
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}
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KERNEL_ATTR_RO(uevent_seqnum);
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/* cpu byteorder */
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static ssize_t cpu_byteorder_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING);
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}
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KERNEL_ATTR_RO(cpu_byteorder);
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/* address bits */
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static ssize_t address_bits_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sysfs_emit(buf, "%zu\n", sizeof(void *) * 8 /* CHAR_BIT */);
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}
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KERNEL_ATTR_RO(address_bits);
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#ifdef CONFIG_UEVENT_HELPER
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/* uevent helper program, used during early boot */
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static ssize_t uevent_helper_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%s\n", uevent_helper);
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}
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static ssize_t uevent_helper_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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if (count+1 > UEVENT_HELPER_PATH_LEN)
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return -ENOENT;
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memcpy(uevent_helper, buf, count);
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uevent_helper[count] = '\0';
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if (count && uevent_helper[count-1] == '\n')
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uevent_helper[count-1] = '\0';
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return count;
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}
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KERNEL_ATTR_RW(uevent_helper);
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#endif
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#ifdef CONFIG_PROFILING
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static ssize_t profiling_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", prof_on);
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}
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static ssize_t profiling_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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int ret;
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if (prof_on)
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return -EEXIST;
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/*
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* This eventually calls into get_option() which
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* has a ton of callers and is not const. It is
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* easiest to cast it away here.
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*/
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profile_setup((char *)buf);
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ret = profile_init();
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if (ret)
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return ret;
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ret = create_proc_profile();
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if (ret)
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return ret;
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return count;
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}
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KERNEL_ATTR_RW(profiling);
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#endif
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#ifdef CONFIG_KEXEC_CORE
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static ssize_t kexec_loaded_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", !!kexec_image);
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}
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KERNEL_ATTR_RO(kexec_loaded);
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static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", kexec_crash_loaded());
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}
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KERNEL_ATTR_RO(kexec_crash_loaded);
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static ssize_t kexec_crash_size_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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ssize_t size = crash_get_memory_size();
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if (size < 0)
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return size;
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return sprintf(buf, "%zd\n", size);
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}
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static ssize_t kexec_crash_size_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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unsigned long cnt;
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int ret;
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if (kstrtoul(buf, 0, &cnt))
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return -EINVAL;
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ret = crash_shrink_memory(cnt);
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return ret < 0 ? ret : count;
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}
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KERNEL_ATTR_RW(kexec_crash_size);
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#endif /* CONFIG_KEXEC_CORE */
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#ifdef CONFIG_CRASH_CORE
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static ssize_t vmcoreinfo_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
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return sprintf(buf, "%pa %x\n", &vmcore_base,
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(unsigned int)VMCOREINFO_NOTE_SIZE);
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}
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KERNEL_ATTR_RO(vmcoreinfo);
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#endif /* CONFIG_CRASH_CORE */
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/* whether file capabilities are enabled */
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static ssize_t fscaps_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", file_caps_enabled);
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}
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KERNEL_ATTR_RO(fscaps);
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#ifndef CONFIG_TINY_RCU
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int rcu_expedited;
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static ssize_t rcu_expedited_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
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}
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static ssize_t rcu_expedited_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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if (kstrtoint(buf, 0, &rcu_expedited))
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return -EINVAL;
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return count;
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}
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KERNEL_ATTR_RW(rcu_expedited);
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int rcu_normal;
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static ssize_t rcu_normal_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
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}
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static ssize_t rcu_normal_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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if (kstrtoint(buf, 0, &rcu_normal))
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return -EINVAL;
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return count;
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}
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KERNEL_ATTR_RW(rcu_normal);
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#endif /* #ifndef CONFIG_TINY_RCU */
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/*
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* Make /sys/kernel/notes give the raw contents of our kernel .notes section.
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*/
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extern const void __start_notes __weak;
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extern const void __stop_notes __weak;
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#define notes_size (&__stop_notes - &__start_notes)
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static ssize_t notes_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t off, size_t count)
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{
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memcpy(buf, &__start_notes + off, count);
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return count;
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}
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static struct bin_attribute notes_attr __ro_after_init = {
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.attr = {
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.name = "notes",
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.mode = S_IRUGO,
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},
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.read = ¬es_read,
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};
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struct kobject *kernel_kobj;
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EXPORT_SYMBOL_GPL(kernel_kobj);
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static struct attribute * kernel_attrs[] = {
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&fscaps_attr.attr,
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&uevent_seqnum_attr.attr,
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&cpu_byteorder_attr.attr,
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&address_bits_attr.attr,
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#ifdef CONFIG_UEVENT_HELPER
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&uevent_helper_attr.attr,
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#endif
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#ifdef CONFIG_PROFILING
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&profiling_attr.attr,
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#endif
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#ifdef CONFIG_KEXEC_CORE
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&kexec_loaded_attr.attr,
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&kexec_crash_loaded_attr.attr,
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&kexec_crash_size_attr.attr,
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#endif
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#ifdef CONFIG_CRASH_CORE
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&vmcoreinfo_attr.attr,
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#endif
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#ifndef CONFIG_TINY_RCU
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&rcu_expedited_attr.attr,
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&rcu_normal_attr.attr,
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#endif
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NULL
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};
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static const struct attribute_group kernel_attr_group = {
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.attrs = kernel_attrs,
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};
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static int __init ksysfs_init(void)
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{
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int error;
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kernel_kobj = kobject_create_and_add("kernel", NULL);
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if (!kernel_kobj) {
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error = -ENOMEM;
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goto exit;
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}
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error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
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if (error)
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goto kset_exit;
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if (notes_size > 0) {
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notes_attr.size = notes_size;
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error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
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if (error)
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goto group_exit;
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}
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return 0;
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group_exit:
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sysfs_remove_group(kernel_kobj, &kernel_attr_group);
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kset_exit:
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kobject_put(kernel_kobj);
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exit:
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return error;
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}
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core_initcall(ksysfs_init);
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