cregit-Linux how code gets into the kernel

Release 4.10 drivers/xen/mcelog.c

Directory: drivers/xen
/******************************************************************************
 * mcelog.c
 * Driver for receiving and transferring machine check error infomation
 *
 * Copyright (c) 2012 Intel Corporation
 * Author: Liu, Jinsong <jinsong.liu@intel.com>
 * Author: Jiang, Yunhong <yunhong.jiang@intel.com>
 * Author: Ke, Liping <liping.ke@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */


#define pr_fmt(fmt) "xen_mcelog: " fmt

#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/uaccess.h>
#include <linux/capability.h>
#include <linux/poll.h>
#include <linux/sched.h>

#include <xen/interface/xen.h>
#include <xen/events.h>
#include <xen/interface/vcpu.h>
#include <xen/xen.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>


static struct mc_info g_mi;

static struct mcinfo_logical_cpu *g_physinfo;

static uint32_t ncpus;

static DEFINE_MUTEX(mcelog_lock);


static struct xen_mce_log xen_mcelog = {
	.signature	= XEN_MCE_LOG_SIGNATURE,
	.len		= XEN_MCE_LOG_LEN,
	.recordlen	= sizeof(struct xen_mce),
};

static DEFINE_SPINLOCK(xen_mce_chrdev_state_lock);

static int xen_mce_chrdev_open_count;	
/* #times opened */

static int xen_mce_chrdev_open_exclu;	
/* already open exclusive? */

static DECLARE_WAIT_QUEUE_HEAD(xen_mce_chrdev_wait);


static int xen_mce_chrdev_open(struct inode *inode, struct file *file) { spin_lock(&xen_mce_chrdev_state_lock); if (xen_mce_chrdev_open_exclu || (xen_mce_chrdev_open_count && (file->f_flags & O_EXCL))) { spin_unlock(&xen_mce_chrdev_state_lock); return -EBUSY; } if (file->f_flags & O_EXCL) xen_mce_chrdev_open_exclu = 1; xen_mce_chrdev_open_count++; spin_unlock(&xen_mce_chrdev_state_lock); return nonseekable_open(inode, file); }

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static int xen_mce_chrdev_release(struct inode *inode, struct file *file) { spin_lock(&xen_mce_chrdev_state_lock); xen_mce_chrdev_open_count--; xen_mce_chrdev_open_exclu = 0; spin_unlock(&xen_mce_chrdev_state_lock); return 0; }

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static ssize_t xen_mce_chrdev_read(struct file *filp, char __user *ubuf, size_t usize, loff_t *off) { char __user *buf = ubuf; unsigned num; int i, err; mutex_lock(&mcelog_lock); num = xen_mcelog.next; /* Only supports full reads right now */ err = -EINVAL; if (*off != 0 || usize < XEN_MCE_LOG_LEN*sizeof(struct xen_mce)) goto out; err = 0; for (i = 0; i < num; i++) { struct xen_mce *m = &xen_mcelog.entry[i]; err |= copy_to_user(buf, m, sizeof(*m)); buf += sizeof(*m); } memset(xen_mcelog.entry, 0, num * sizeof(struct xen_mce)); xen_mcelog.next = 0; if (err) err = -EFAULT; out: mutex_unlock(&mcelog_lock); return err ? err : buf - ubuf; }

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static unsigned int xen_mce_chrdev_poll(struct file *file, poll_table *wait) { poll_wait(file, &xen_mce_chrdev_wait, wait); if (xen_mcelog.next) return POLLIN | POLLRDNORM; return 0; }

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static long xen_mce_chrdev_ioctl(struct file *f, unsigned int cmd, unsigned long arg) { int __user *p = (int __user *)arg; if (!capable(CAP_SYS_ADMIN)) return -EPERM; switch (cmd) { case MCE_GET_RECORD_LEN: return put_user(sizeof(struct xen_mce), p); case MCE_GET_LOG_LEN: return put_user(XEN_MCE_LOG_LEN, p); case MCE_GETCLEAR_FLAGS: { unsigned flags; do { flags = xen_mcelog.flags; } while (cmpxchg(&xen_mcelog.flags, flags, 0) != flags); return put_user(flags, p); } default: return -ENOTTY; } }

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static const struct file_operations xen_mce_chrdev_ops = { .open = xen_mce_chrdev_open, .release = xen_mce_chrdev_release, .read = xen_mce_chrdev_read, .poll = xen_mce_chrdev_poll, .unlocked_ioctl = xen_mce_chrdev_ioctl, .llseek = no_llseek, }; static struct miscdevice xen_mce_chrdev_device = { MISC_MCELOG_MINOR, "mcelog", &xen_mce_chrdev_ops, }; /* * Caller should hold the mcelog_lock */
static void xen_mce_log(struct xen_mce *mce) { unsigned entry; entry = xen_mcelog.next; /* * When the buffer fills up discard new entries. * Assume that the earlier errors are the more * interesting ones: */ if (entry >= XEN_MCE_LOG_LEN) { set_bit(XEN_MCE_OVERFLOW, (unsigned long *)&xen_mcelog.flags); return; } memcpy(xen_mcelog.entry + entry, mce, sizeof(struct xen_mce)); xen_mcelog.next++; }

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static int convert_log(struct mc_info *mi) { struct mcinfo_common *mic; struct mcinfo_global *mc_global; struct mcinfo_bank *mc_bank; struct xen_mce m; uint32_t i; mic = NULL; x86_mcinfo_lookup(&mic, mi, MC_TYPE_GLOBAL); if (unlikely(!mic)) { pr_warn("Failed to find global error info\n"); return -ENODEV; } memset(&m, 0, sizeof(struct xen_mce)); mc_global = (struct mcinfo_global *)mic; m.mcgstatus = mc_global->mc_gstatus; m.apicid = mc_global->mc_apicid; for (i = 0; i < ncpus; i++) if (g_physinfo[i].mc_apicid == m.apicid) break; if (unlikely(i == ncpus)) { pr_warn("Failed to match cpu with apicid %d\n", m.apicid); return -ENODEV; } m.socketid = g_physinfo[i].mc_chipid; m.cpu = m.extcpu = g_physinfo[i].mc_cpunr; m.cpuvendor = (__u8)g_physinfo[i].mc_vendor; m.mcgcap = g_physinfo[i].mc_msrvalues[__MC_MSR_MCGCAP].value; mic = NULL; x86_mcinfo_lookup(&mic, mi, MC_TYPE_BANK); if (unlikely(!mic)) { pr_warn("Fail to find bank error info\n"); return -ENODEV; } do { if ((!mic) || (mic->size == 0) || (mic->type != MC_TYPE_GLOBAL && mic->type != MC_TYPE_BANK && mic->type != MC_TYPE_EXTENDED && mic->type != MC_TYPE_RECOVERY)) break; if (mic->type == MC_TYPE_BANK) { mc_bank = (struct mcinfo_bank *)mic; m.misc = mc_bank->mc_misc; m.status = mc_bank->mc_status; m.addr = mc_bank->mc_addr; m.tsc = mc_bank->mc_tsc; m.bank = mc_bank->mc_bank; m.finished = 1; /*log this record*/ xen_mce_log(&m); } mic = x86_mcinfo_next(mic); } while (1); return 0; }

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static int mc_queue_handle(uint32_t flags) { struct xen_mc mc_op; int ret = 0; mc_op.cmd = XEN_MC_fetch; mc_op.interface_version = XEN_MCA_INTERFACE_VERSION; set_xen_guest_handle(mc_op.u.mc_fetch.data, &g_mi); do { mc_op.u.mc_fetch.flags = flags; ret = HYPERVISOR_mca(&mc_op); if (ret) { pr_err("Failed to fetch %surgent error log\n", flags == XEN_MC_URGENT ? "" : "non"); break; } if (mc_op.u.mc_fetch.flags & XEN_MC_NODATA || mc_op.u.mc_fetch.flags & XEN_MC_FETCHFAILED) break; else { ret = convert_log(&g_mi); if (ret) pr_warn("Failed to convert this error log, continue acking it anyway\n"); mc_op.u.mc_fetch.flags = flags | XEN_MC_ACK; ret = HYPERVISOR_mca(&mc_op); if (ret) { pr_err("Failed to ack previous error log\n"); break; } } } while (1); return ret; }

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/* virq handler for machine check error info*/
static void xen_mce_work_fn(struct work_struct *work) { int err; mutex_lock(&mcelog_lock); /* urgent mc_info */ err = mc_queue_handle(XEN_MC_URGENT); if (err) pr_err("Failed to handle urgent mc_info queue, continue handling nonurgent mc_info queue anyway\n"); /* nonurgent mc_info */ err = mc_queue_handle(XEN_MC_NONURGENT); if (err) pr_err("Failed to handle nonurgent mc_info queue\n"); /* wake processes polling /dev/mcelog */ wake_up_interruptible(&xen_mce_chrdev_wait); mutex_unlock(&mcelog_lock); }

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static DECLARE_WORK(xen_mce_work, xen_mce_work_fn);
static irqreturn_t xen_mce_interrupt(int irq, void *dev_id) { schedule_work(&xen_mce_work); return IRQ_HANDLED; }

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static int bind_virq_for_mce(void) { int ret; struct xen_mc mc_op; memset(&mc_op, 0, sizeof(struct xen_mc)); /* Fetch physical CPU Numbers */ mc_op.cmd = XEN_MC_physcpuinfo; mc_op.interface_version = XEN_MCA_INTERFACE_VERSION; set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo); ret = HYPERVISOR_mca(&mc_op); if (ret) { pr_err("Failed to get CPU numbers\n"); return ret; } /* Fetch each CPU Physical Info for later reference*/ ncpus = mc_op.u.mc_physcpuinfo.ncpus; g_physinfo = kcalloc(ncpus, sizeof(struct mcinfo_logical_cpu), GFP_KERNEL); if (!g_physinfo) return -ENOMEM; set_xen_guest_handle(mc_op.u.mc_physcpuinfo.info, g_physinfo); ret = HYPERVISOR_mca(&mc_op); if (ret) { pr_err("Failed to get CPU info\n"); kfree(g_physinfo); return ret; } ret = bind_virq_to_irqhandler(VIRQ_MCA, 0, xen_mce_interrupt, 0, "mce", NULL); if (ret < 0) { pr_err("Failed to bind virq\n"); kfree(g_physinfo); return ret; } return 0; }

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static int __init xen_late_init_mcelog(void) { int ret; /* Only DOM0 is responsible for MCE logging */ if (!xen_initial_domain()) return -ENODEV; /* register character device /dev/mcelog for xen mcelog */ ret = misc_register(&xen_mce_chrdev_device); if (ret) return ret; ret = bind_virq_for_mce(); if (ret) goto deregister; return 0; deregister: misc_deregister(&xen_mce_chrdev_device); return ret; }

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device_initcall(xen_late_init_mcelog);

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Directory: drivers/xen
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