acpi/apei/erst-dbg.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * APEI Error Record Serialization Table debug support
0004  *
0005  * ERST is a way provided by APEI to save and retrieve hardware error
0006  * information to and from a persistent store. This file provide the
0007  * debugging/testing support for ERST kernel support and firmware
0008  * implementation.
0009  *
0010  * Copyright 2010 Intel Corp.
0011  *   Author: Huang Ying <ying.huang@intel.com>
0012  */
0013
0014 #include <linux/kernel.h>
0015 #include <linux/module.h>
0016 #include <linux/uaccess.h>
0017 #include <acpi/apei.h>
0018 #include <linux/miscdevice.h>
0019
0020 #include "apei-internal.h"
0021
0022 #define ERST_DBG_PFX            "ERST DBG: "
0023
0024 #define ERST_DBG_RECORD_LEN_MAX     0x4000
0025
0026 static void *erst_dbg_buf;
0027 static unsigned int erst_dbg_buf_len;
0028
0029 /* Prevent erst_dbg_read/write from being invoked concurrently */
0030 static DEFINE_MUTEX(erst_dbg_mutex);
0031
0032 static int erst_dbg_open(struct inode *inode, struct file *file)
0033 {
0034     int rc, *pos;
0035
0036     if (erst_disable)
0037         return -ENODEV;
0038
0039     pos = (int *)&file->private_data;
0040
0041     rc = erst_get_record_id_begin(pos);
0042     if (rc)
0043         return rc;
0044
0045     return nonseekable_open(inode, file);
0046 }
0047
0048 static int erst_dbg_release(struct inode *inode, struct file *file)
0049 {
0050     erst_get_record_id_end();
0051
0052     return 0;
0053 }
0054
0055 static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
0056 {
0057     int rc;
0058     u64 record_id;
0059     u32 record_count;
0060
0061     switch (cmd) {
0062     case APEI_ERST_CLEAR_RECORD:
0063         rc = copy_from_user(&record_id, (void __user *)arg,
0064                     sizeof(record_id));
0065         if (rc)
0066             return -EFAULT;
0067         return erst_clear(record_id);
0068     case APEI_ERST_GET_RECORD_COUNT:
0069         rc = erst_get_record_count();
0070         if (rc < 0)
0071             return rc;
0072         record_count = rc;
0073         rc = put_user(record_count, (u32 __user *)arg);
0074         if (rc)
0075             return rc;
0076         return 0;
0077     default:
0078         return -ENOTTY;
0079     }
0080 }
0081
0082 static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
0083                  size_t usize, loff_t *off)
0084 {
0085     int rc, *pos;
0086     ssize_t len = 0;
0087     u64 id;
0088
0089     if (*off)
0090         return -EINVAL;
0091
0092     if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
0093         return -EINTR;
0094
0095     pos = (int *)&filp->private_data;
0096
0097 retry_next:
0098     rc = erst_get_record_id_next(pos, &id);
0099     if (rc)
0100         goto out;
0101     /* no more record */
0102     if (id == APEI_ERST_INVALID_RECORD_ID) {
0103         /*
0104          * If the persistent store is empty initially, the function
0105          * 'erst_read' below will return "-ENOENT" value. This causes
0106          * 'retry_next' label is entered again. The returned value
0107          * should be zero indicating the read operation is EOF.
0108          */
0109         len = 0;
0110
0111         goto out;
0112     }
0113 retry:
0114     rc = len = erst_read_record(id, erst_dbg_buf, erst_dbg_buf_len,
0115             erst_dbg_buf_len, NULL);
0116     /* The record may be cleared by others, try read next record */
0117     if (rc == -ENOENT)
0118         goto retry_next;
0119     if (rc < 0)
0120         goto out;
0121     if (len > ERST_DBG_RECORD_LEN_MAX) {
0122         pr_warn(ERST_DBG_PFX
0123             "Record (ID: 0x%llx) length is too long: %zd\n", id, len);
0124         rc = -EIO;
0125         goto out;
0126     }
0127     if (len > erst_dbg_buf_len) {
0128         void *p;
0129         rc = -ENOMEM;
0130         p = kmalloc(len, GFP_KERNEL);
0131         if (!p)
0132             goto out;
0133         kfree(erst_dbg_buf);
0134         erst_dbg_buf = p;
0135         erst_dbg_buf_len = len;
0136         goto retry;
0137     }
0138
0139     rc = -EINVAL;
0140     if (len > usize)
0141         goto out;
0142
0143     rc = -EFAULT;
0144     if (copy_to_user(ubuf, erst_dbg_buf, len))
0145         goto out;
0146     rc = 0;
0147 out:
0148     mutex_unlock(&erst_dbg_mutex);
0149     return rc ? rc : len;
0150 }
0151
0152 static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
0153                   size_t usize, loff_t *off)
0154 {
0155     int rc;
0156     struct cper_record_header *rcd;
0157
0158     if (!capable(CAP_SYS_ADMIN))
0159         return -EPERM;
0160
0161     if (usize > ERST_DBG_RECORD_LEN_MAX) {
0162         pr_err(ERST_DBG_PFX "Too long record to be written\n");
0163         return -EINVAL;
0164     }
0165
0166     if (mutex_lock_interruptible(&erst_dbg_mutex))
0167         return -EINTR;
0168     if (usize > erst_dbg_buf_len) {
0169         void *p;
0170         rc = -ENOMEM;
0171         p = kmalloc(usize, GFP_KERNEL);
0172         if (!p)
0173             goto out;
0174         kfree(erst_dbg_buf);
0175         erst_dbg_buf = p;
0176         erst_dbg_buf_len = usize;
0177     }
0178     rc = copy_from_user(erst_dbg_buf, ubuf, usize);
0179     if (rc) {
0180         rc = -EFAULT;
0181         goto out;
0182     }
0183     rcd = erst_dbg_buf;
0184     rc = -EINVAL;
0185     if (rcd->record_length != usize)
0186         goto out;
0187
0188     rc = erst_write(erst_dbg_buf);
0189
0190 out:
0191     mutex_unlock(&erst_dbg_mutex);
0192     return rc < 0 ? rc : usize;
0193 }
0194
0195 static const struct file_operations erst_dbg_ops = {
0196     .owner      = THIS_MODULE,
0197     .open       = erst_dbg_open,
0198     .release    = erst_dbg_release,
0199     .read       = erst_dbg_read,
0200     .write      = erst_dbg_write,
0201     .unlocked_ioctl = erst_dbg_ioctl,
0202     .llseek     = no_llseek,
0203 };
0204
0205 static struct miscdevice erst_dbg_dev = {
0206     .minor  = MISC_DYNAMIC_MINOR,
0207     .name   = "erst_dbg",
0208     .fops   = &erst_dbg_ops,
0209 };
0210
0211 static __init int erst_dbg_init(void)
0212 {
0213     if (erst_disable) {
0214         pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
0215         return -ENODEV;
0216     }
0217     return misc_register(&erst_dbg_dev);
0218 }
0219
0220 static __exit void erst_dbg_exit(void)
0221 {
0222     misc_deregister(&erst_dbg_dev);
0223     kfree(erst_dbg_buf);
0224 }
0225
0226 module_init(erst_dbg_init);
0227 module_exit(erst_dbg_exit);
0228
0229 MODULE_AUTHOR("Huang Ying");
0230 MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
0231 MODULE_LICENSE("GPL");