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// SPDX-License-Identifier: GPL-2.0-only
/*
* APEI Error Record Serialization Table debug support
*
* ERST is a way provided by APEI to save and retrieve hardware error
* information to and from a persistent store. This file provide the
* debugging/testing support for ERST kernel support and firmware
* implementation.
*
* Copyright 2010 Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <acpi/apei.h>
#include <linux/miscdevice.h>
#include "apei-internal.h"
#define ERST_DBG_PFX "ERST DBG: "
#define ERST_DBG_RECORD_LEN_MAX 0x4000
static void *erst_dbg_buf;
static unsigned int erst_dbg_buf_len;
/* Prevent erst_dbg_read/write from being invoked concurrently */
static DEFINE_MUTEX(erst_dbg_mutex);
static int erst_dbg_open(struct inode *inode, struct file *file)
{
int rc, *pos;
if (erst_disable)
return -ENODEV;
pos = (int *)&file->private_data;
rc = erst_get_record_id_begin(pos);
if (rc)
return rc;
return nonseekable_open(inode, file);
}
static int erst_dbg_release(struct inode *inode, struct file *file)
{
erst_get_record_id_end();
return 0;
}
static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
int rc;
u64 record_id;
u32 record_count;
switch (cmd) {
case APEI_ERST_CLEAR_RECORD:
rc = copy_from_user(&record_id, (void __user *)arg,
sizeof(record_id));
if (rc)
return -EFAULT;
return erst_clear(record_id);
case APEI_ERST_GET_RECORD_COUNT:
rc = erst_get_record_count();
if (rc < 0)
return rc;
record_count = rc;
rc = put_user(record_count, (u32 __user *)arg);
if (rc)
return rc;
return 0;
default:
return -ENOTTY;
}
}
static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
size_t usize, loff_t *off)
{
int rc, *pos;
ssize_t len = 0;
u64 id;
if (*off)
return -EINVAL;
if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
return -EINTR;
pos = (int *)&filp->private_data;
retry_next:
rc = erst_get_record_id_next(pos, &id);
if (rc)
goto out;
/* no more record */
if (id == APEI_ERST_INVALID_RECORD_ID) {
/*
* If the persistent store is empty initially, the function
* 'erst_read' below will return "-ENOENT" value. This causes
* 'retry_next' label is entered again. The returned value
* should be zero indicating the read operation is EOF.
*/
len = 0;
goto out;
}
retry:
rc = len = erst_read_record(id, erst_dbg_buf, erst_dbg_buf_len,
erst_dbg_buf_len, NULL);
/* The record may be cleared by others, try read next record */
if (rc == -ENOENT)
goto retry_next;
if (rc < 0)
goto out;
if (len > ERST_DBG_RECORD_LEN_MAX) {
pr_warn(ERST_DBG_PFX
"Record (ID: 0x%llx) length is too long: %zd\n", id, len);
rc = -EIO;
goto out;
}
if (len > erst_dbg_buf_len) {
void *p;
rc = -ENOMEM;
p = kmalloc(len, GFP_KERNEL);
if (!p)
goto out;
kfree(erst_dbg_buf);
erst_dbg_buf = p;
erst_dbg_buf_len = len;
goto retry;
}
rc = -EINVAL;
if (len > usize)
goto out;
rc = -EFAULT;
if (copy_to_user(ubuf, erst_dbg_buf, len))
goto out;
rc = 0;
out:
mutex_unlock(&erst_dbg_mutex);
return rc ? rc : len;
}
static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
size_t usize, loff_t *off)
{
int rc;
struct cper_record_header *rcd;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (usize > ERST_DBG_RECORD_LEN_MAX) {
pr_err(ERST_DBG_PFX "Too long record to be written\n");
return -EINVAL;
}
if (mutex_lock_interruptible(&erst_dbg_mutex))
return -EINTR;
if (usize > erst_dbg_buf_len) {
void *p;
rc = -ENOMEM;
p = kmalloc(usize, GFP_KERNEL);
if (!p)
goto out;
kfree(erst_dbg_buf);
erst_dbg_buf = p;
erst_dbg_buf_len = usize;
}
rc = copy_from_user(erst_dbg_buf, ubuf, usize);
if (rc) {
rc = -EFAULT;
goto out;
}
rcd = erst_dbg_buf;
rc = -EINVAL;
if (rcd->record_length != usize)
goto out;
rc = erst_write(erst_dbg_buf);
out:
mutex_unlock(&erst_dbg_mutex);
return rc < 0 ? rc : usize;
}
static const struct file_operations erst_dbg_ops = {
.owner = THIS_MODULE,
.open = erst_dbg_open,
.release = erst_dbg_release,
.read = erst_dbg_read,
.write = erst_dbg_write,
.unlocked_ioctl = erst_dbg_ioctl,
.llseek = no_llseek,
};
static struct miscdevice erst_dbg_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "erst_dbg",
.fops = &erst_dbg_ops,
};
static __init int erst_dbg_init(void)
{
if (erst_disable) {
pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
return -ENODEV;
}
return misc_register(&erst_dbg_dev);
}
static __exit void erst_dbg_exit(void)
{
misc_deregister(&erst_dbg_dev);
kfree(erst_dbg_buf);
}
module_init(erst_dbg_init);
module_exit(erst_dbg_exit);
MODULE_AUTHOR("Huang Ying");
MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
MODULE_LICENSE("GPL");
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