Orange Pi5 kernel

Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards

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orangepi/linux-orangepi-5.10.y.git/trunk/arch/x86/kernel/msr.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
 *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
 *
 * ----------------------------------------------------------------------- */
 
/*
 * x86 MSR access device
 *
 * This device is accessed by lseek() to the appropriate register number
 * and then read/write in chunks of 8 bytes.  A larger size means multiple
 * reads or writes of the same register.
 *
 * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
 * an SMP box will direct the access to CPU %d.
 */
 
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
#include <linux/module.h>
 
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/smp.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
#include <linux/security.h>
 
#include <asm/cpufeature.h>
#include <asm/msr.h>
 
static struct class *msr_class;
static enum cpuhp_state cpuhp_msr_state;
 
enum allow_write_msrs {
<------>MSR_WRITES_ON,
<------>MSR_WRITES_OFF,
<------>MSR_WRITES_DEFAULT,
};
 
static enum allow_write_msrs allow_writes = MSR_WRITES_DEFAULT;
 
static ssize_t msr_read(struct file *file, char __user *buf,
<------><------><------>size_t count, loff_t *ppos)
{
<------>u32 __user *tmp = (u32 __user *) buf;
<------>u32 data[2];
<------>u32 reg = *ppos;
<------>int cpu = iminor(file_inode(file));
<------>int err = 0;
<------>ssize_t bytes = 0;
 
<------>if (count % 8)
<------><------>return -EINVAL;	/* Invalid chunk size */
 
<------>for (; count; count -= 8) {
<------><------>err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
<------><------>if (err)
<------><------><------>break;
<------><------>if (copy_to_user(tmp, &data, 8)) {
<------><------><------>err = -EFAULT;
<------><------><------>break;
<------><------>}
<------><------>tmp += 2;
<------><------>bytes += 8;
<------>}
 
<------>return bytes ? bytes : err;
}
 
static int filter_write(u32 reg)
{
<------>/*
<------> * MSRs writes usually happen all at once, and can easily saturate kmsg.
<------> * Only allow one message every 30 seconds.
<------> *
<------> * It's possible to be smarter here and do it (for example) per-MSR, but
<------> * it would certainly be more complex, and this is enough at least to
<------> * avoid saturating the ring buffer.
<------> */
<------>static DEFINE_RATELIMIT_STATE(fw_rs, 30 * HZ, 1);
 
<------>switch (allow_writes) {
<------>case MSR_WRITES_ON:  return 0;
<------>case MSR_WRITES_OFF: return -EPERM;
<------>default: break;
<------>}
 
<------>if (!__ratelimit(&fw_rs))
<------><------>return 0;
 
<------>if (reg == MSR_IA32_ENERGY_PERF_BIAS)
<------><------>return 0;
 
<------>pr_err("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@kernel.org.\n",
<------>       reg, current->comm, current->pid);
 
<------>return 0;
}
 
static ssize_t msr_write(struct file *file, const char __user *buf,
<------><------><------> size_t count, loff_t *ppos)
{
<------>const u32 __user *tmp = (const u32 __user *)buf;
<------>u32 data[2];
<------>u32 reg = *ppos;
<------>int cpu = iminor(file_inode(file));
<------>int err = 0;
<------>ssize_t bytes = 0;
 
<------>err = security_locked_down(LOCKDOWN_MSR);
<------>if (err)
<------><------>return err;
 
<------>err = filter_write(reg);
<------>if (err)
<------><------>return err;
 
<------>if (count % 8)
<------><------>return -EINVAL;	/* Invalid chunk size */
 
<------>for (; count; count -= 8) {
<------><------>if (copy_from_user(&data, tmp, 8)) {
<------><------><------>err = -EFAULT;
<------><------><------>break;
<------><------>}
 
<------><------>add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
 
<------><------>err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
<------><------>if (err)
<------><------><------>break;
 
<------><------>tmp += 2;
<------><------>bytes += 8;
<------>}
 
<------>return bytes ? bytes : err;
}
 
static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
{
<------>u32 __user *uregs = (u32 __user *)arg;
<------>u32 regs[8];
<------>int cpu = iminor(file_inode(file));
<------>int err;
 
<------>switch (ioc) {
<------>case X86_IOC_RDMSR_REGS:
<------><------>if (!(file->f_mode & FMODE_READ)) {
<------><------><------>err = -EBADF;
<------><------><------>break;
<------><------>}
<------><------>if (copy_from_user(&regs, uregs, sizeof(regs))) {
<------><------><------>err = -EFAULT;
<------><------><------>break;
<------><------>}
<------><------>err = rdmsr_safe_regs_on_cpu(cpu, regs);
<------><------>if (err)
<------><------><------>break;
<------><------>if (copy_to_user(uregs, &regs, sizeof(regs)))
<------><------><------>err = -EFAULT;
<------><------>break;
 
<------>case X86_IOC_WRMSR_REGS:
<------><------>if (!(file->f_mode & FMODE_WRITE)) {
<------><------><------>err = -EBADF;
<------><------><------>break;
<------><------>}
<------><------>if (copy_from_user(&regs, uregs, sizeof(regs))) {
<------><------><------>err = -EFAULT;
<------><------><------>break;
<------><------>}
<------><------>err = security_locked_down(LOCKDOWN_MSR);
<------><------>if (err)
<------><------><------>break;
 
<------><------>err = filter_write(regs[1]);
<------><------>if (err)
<------><------><------>return err;
 
<------><------>add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
 
<------><------>err = wrmsr_safe_regs_on_cpu(cpu, regs);
<------><------>if (err)
<------><------><------>break;
<------><------>if (copy_to_user(uregs, &regs, sizeof(regs)))
<------><------><------>err = -EFAULT;
<------><------>break;
 
<------>default:
<------><------>err = -ENOTTY;
<------><------>break;
<------>}
 
<------>return err;
}
 
static int msr_open(struct inode *inode, struct file *file)
{
<------>unsigned int cpu = iminor(file_inode(file));
<------>struct cpuinfo_x86 *c;
 
<------>if (!capable(CAP_SYS_RAWIO))
<------><------>return -EPERM;
 
<------>if (cpu >= nr_cpu_ids || !cpu_online(cpu))
<------><------>return -ENXIO;	/* No such CPU */
 
<------>c = &cpu_data(cpu);
<------>if (!cpu_has(c, X86_FEATURE_MSR))
<------><------>return -EIO;	/* MSR not supported */
 
<------>return 0;
}
 
/*
 * File operations we support
 */
static const struct file_operations msr_fops = {
<------>.owner = THIS_MODULE,
<------>.llseek = no_seek_end_llseek,
<------>.read = msr_read,
<------>.write = msr_write,
<------>.open = msr_open,
<------>.unlocked_ioctl = msr_ioctl,
<------>.compat_ioctl = msr_ioctl,
};
 
static int msr_device_create(unsigned int cpu)
{
<------>struct device *dev;
 
<------>dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL,
<------><------><------>    "msr%d", cpu);
<------>return PTR_ERR_OR_ZERO(dev);
}
 
static int msr_device_destroy(unsigned int cpu)
{
<------>device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
<------>return 0;
}
 
static char *msr_devnode(struct device *dev, umode_t *mode)
{
<------>return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
}
 
static int __init msr_init(void)
{
<------>int err;
 
<------>if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
<------><------>pr_err("unable to get major %d for msr\n", MSR_MAJOR);
<------><------>return -EBUSY;
<------>}
<------>msr_class = class_create(THIS_MODULE, "msr");
<------>if (IS_ERR(msr_class)) {
<------><------>err = PTR_ERR(msr_class);
<------><------>goto out_chrdev;
<------>}
<------>msr_class->devnode = msr_devnode;
 
<------>err  = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/msr:online",
<------><------><------><------> msr_device_create, msr_device_destroy);
<------>if (err < 0)
<------><------>goto out_class;
<------>cpuhp_msr_state = err;
<------>return 0;
 
out_class:
<------>class_destroy(msr_class);
out_chrdev:
<------>__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
<------>return err;
}
module_init(msr_init);
 
static void __exit msr_exit(void)
{
<------>cpuhp_remove_state(cpuhp_msr_state);
<------>class_destroy(msr_class);
<------>__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
}
module_exit(msr_exit)
 
static int set_allow_writes(const char *val, const struct kernel_param *cp)
{
<------>/* val is NUL-terminated, see kernfs_fop_write() */
<------>char *s = strstrip((char *)val);
 
<------>if (!strcmp(s, "on"))
<------><------>allow_writes = MSR_WRITES_ON;
<------>else if (!strcmp(s, "off"))
<------><------>allow_writes = MSR_WRITES_OFF;
<------>else
<------><------>allow_writes = MSR_WRITES_DEFAULT;
 
<------>return 0;
}
 
static int get_allow_writes(char *buf, const struct kernel_param *kp)
{
<------>const char *res;
 
<------>switch (allow_writes) {
<------>case MSR_WRITES_ON:  res = "on"; break;
<------>case MSR_WRITES_OFF: res = "off"; break;
<------>default: res = "default"; break;
<------>}
 
<------>return sprintf(buf, "%s\n", res);
}
 
static const struct kernel_param_ops allow_writes_ops = {
<------>.set = set_allow_writes,
<------>.get = get_allow_writes
};
 
module_param_cb(allow_writes, &allow_writes_ops, NULL, 0600);
 
MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
MODULE_DESCRIPTION("x86 generic MSR driver");
MODULE_LICENSE("GPL");
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