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![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation inc 675 mass ave cambridge ma 02139 usa either version 2 of the license or at your option any later version incorporated herein by reference extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 4 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190524100844.465381181@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
191 lines
4.3 KiB
C
191 lines
4.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* ----------------------------------------------------------------------- *
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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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* ----------------------------------------------------------------------- */
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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 <linux/completion.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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struct cpuid_regs_done {
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struct cpuid_regs regs;
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struct completion done;
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};
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static void cpuid_smp_cpuid(void *cmd_block)
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{
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struct cpuid_regs_done *cmd = cmd_block;
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cpuid_count(cmd->regs.eax, cmd->regs.ecx,
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&cmd->regs.eax, &cmd->regs.ebx,
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&cmd->regs.ecx, &cmd->regs.edx);
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complete(&cmd->done);
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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_done 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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init_completion(&cmd.done);
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for (; count; count -= 16) {
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call_single_data_t csd = {
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.func = cpuid_smp_cpuid,
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.info = &cmd,
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};
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cmd.regs.eax = pos;
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cmd.regs.ecx = pos >> 32;
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err = smp_call_function_single_async(cpu, &csd);
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if (err)
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break;
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wait_for_completion(&cmd.done);
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if (copy_to_user(tmp, &cmd.regs, 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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reinit_completion(&cmd.done);
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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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