179 lines
4.3 KiB
C
179 lines
4.3 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
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* USA; either version 2 of the License, or (at your option) any later
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* version; incorporated herein by reference.
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*
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* ----------------------------------------------------------------------- */
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/*
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* x86 CPUID access device
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*
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* This device is accessed by lseek() to the appropriate CPUID level
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* and then read in chunks of 16 bytes. A larger size means multiple
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* reads of consecutive levels.
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*
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* The lower 32 bits of the file position is used as the incoming %eax,
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* and the upper 32 bits of the file position as the incoming %ecx,
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* the latter intended for "counting" eax levels like eax=4.
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*
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* This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on
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* an SMP box will direct the access to CPU %d.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/fcntl.h>
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#include <linux/init.h>
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#include <linux/poll.h>
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#include <linux/smp.h>
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#include <linux/major.h>
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#include <linux/fs.h>
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#include <linux/device.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/uaccess.h>
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#include <linux/gfp.h>
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#include <asm/processor.h>
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#include <asm/msr.h>
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static struct class *cpuid_class;
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static enum cpuhp_state cpuhp_cpuid_state;
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static void cpuid_smp_cpuid(void *cmd_block)
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{
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struct cpuid_regs *cmd = (struct cpuid_regs *)cmd_block;
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cpuid_count(cmd->eax, cmd->ecx,
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&cmd->eax, &cmd->ebx, &cmd->ecx, &cmd->edx);
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}
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static ssize_t cpuid_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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char __user *tmp = buf;
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struct cpuid_regs cmd;
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int cpu = iminor(file_inode(file));
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u64 pos = *ppos;
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ssize_t bytes = 0;
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int err = 0;
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if (count % 16)
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return -EINVAL; /* Invalid chunk size */
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for (; count; count -= 16) {
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cmd.eax = pos;
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cmd.ecx = pos >> 32;
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err = smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1);
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if (err)
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break;
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if (copy_to_user(tmp, &cmd, 16)) {
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err = -EFAULT;
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break;
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}
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tmp += 16;
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bytes += 16;
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*ppos = ++pos;
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}
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return bytes ? bytes : err;
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}
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static int cpuid_open(struct inode *inode, struct file *file)
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{
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unsigned int cpu;
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struct cpuinfo_x86 *c;
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cpu = iminor(file_inode(file));
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if (cpu >= nr_cpu_ids || !cpu_online(cpu))
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return -ENXIO; /* No such CPU */
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c = &cpu_data(cpu);
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if (c->cpuid_level < 0)
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return -EIO; /* CPUID not supported */
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return 0;
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}
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/*
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* File operations we support
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*/
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static const struct file_operations cpuid_fops = {
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.owner = THIS_MODULE,
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.llseek = no_seek_end_llseek,
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.read = cpuid_read,
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.open = cpuid_open,
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};
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static int cpuid_device_create(unsigned int cpu)
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{
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struct device *dev;
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dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL,
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"cpu%d", cpu);
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return PTR_ERR_OR_ZERO(dev);
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}
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static int cpuid_device_destroy(unsigned int cpu)
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{
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device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
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return 0;
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}
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static char *cpuid_devnode(struct device *dev, umode_t *mode)
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{
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return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt));
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}
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static int __init cpuid_init(void)
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{
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int err;
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if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS,
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"cpu/cpuid", &cpuid_fops)) {
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printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
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CPUID_MAJOR);
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return -EBUSY;
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}
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cpuid_class = class_create(THIS_MODULE, "cpuid");
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if (IS_ERR(cpuid_class)) {
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err = PTR_ERR(cpuid_class);
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goto out_chrdev;
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}
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cpuid_class->devnode = cpuid_devnode;
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err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/cpuid:online",
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cpuid_device_create, cpuid_device_destroy);
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if (err < 0)
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goto out_class;
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cpuhp_cpuid_state = err;
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return 0;
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out_class:
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class_destroy(cpuid_class);
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out_chrdev:
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__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
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return err;
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}
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module_init(cpuid_init);
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static void __exit cpuid_exit(void)
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{
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cpuhp_remove_state(cpuhp_cpuid_state);
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class_destroy(cpuid_class);
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__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
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}
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module_exit(cpuid_exit);
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MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
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MODULE_DESCRIPTION("x86 generic CPUID driver");
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MODULE_LICENSE("GPL");
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