Contributors: 31
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Linus Torvalds (pre-git) |
451 |
33.81% |
21 |
29.58% |
| Borislav Petkov |
253 |
18.97% |
4 |
5.63% |
| H. Peter Anvin |
243 |
18.22% |
3 |
4.23% |
| Hanna V. Linder |
97 |
7.27% |
1 |
1.41% |
| Kay Sievers |
30 |
2.25% |
2 |
2.82% |
| Ivan Orlov |
29 |
2.17% |
1 |
1.41% |
| Sebastian Andrzej Siewior |
27 |
2.02% |
1 |
1.41% |
| Chris Down |
27 |
2.02% |
2 |
2.82% |
| Al Viro |
25 |
1.87% |
5 |
7.04% |
| Matthew Garrett |
22 |
1.65% |
2 |
2.82% |
| Misono, Tomohiro |
15 |
1.12% |
1 |
1.41% |
| Greg Kroah-Hartman |
13 |
0.97% |
6 |
8.45% |
| Akinobu Mita |
13 |
0.97% |
1 |
1.41% |
| Alan Cox |
12 |
0.90% |
1 |
1.41% |
| Rusty Russell |
10 |
0.75% |
1 |
1.41% |
| Fabian Frederick |
10 |
0.75% |
2 |
2.82% |
| Jordan Borgner |
8 |
0.60% |
1 |
1.41% |
| Jonathan Corbet |
8 |
0.60% |
1 |
1.41% |
| Andrew Morton |
7 |
0.52% |
2 |
2.82% |
| Russ Anderson |
5 |
0.37% |
1 |
1.41% |
| Frédéric Weisbecker |
5 |
0.37% |
1 |
1.41% |
| Linus Torvalds |
5 |
0.37% |
1 |
1.41% |
| Avi Kivity |
3 |
0.22% |
1 |
1.41% |
| Dave Jones |
3 |
0.22% |
2 |
2.82% |
| Brian Gerst |
3 |
0.22% |
1 |
1.41% |
| Nicolas Boichat |
2 |
0.15% |
1 |
1.41% |
| Adrian Bunk |
2 |
0.15% |
1 |
1.41% |
| Thomas Gleixner |
2 |
0.15% |
1 |
1.41% |
| Jaswinder Singh Rajput |
2 |
0.15% |
1 |
1.41% |
| Arjan van de Ven |
1 |
0.07% |
1 |
1.41% |
| Mike Travis |
1 |
0.07% |
1 |
1.41% |
| Total |
1334 |
|
71 |
|
// 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 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;
pr_warn("Write to unrecognized MSR 0x%x by %s (pid: %d).\n",
reg, current->comm, current->pid);
pr_warn("See https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/about for details.\n");
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(®s, uregs, sizeof(regs))) {
err = -EFAULT;
break;
}
err = rdmsr_safe_regs_on_cpu(cpu, regs);
if (err)
break;
if (copy_to_user(uregs, ®s, sizeof(regs)))
err = -EFAULT;
break;
case X86_IOC_WRMSR_REGS:
if (!(file->f_mode & FMODE_WRITE)) {
err = -EBADF;
break;
}
if (copy_from_user(®s, 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, ®s, 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 char *msr_devnode(const struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
}
static const struct class msr_class = {
.name = "msr",
.devnode = msr_devnode,
};
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 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;
}
err = class_register(&msr_class);
if (err)
goto out_chrdev;
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_unregister(&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_unregister(&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");