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    Subject[PATCH 4/4] ACPI, APEI, ERST debug support
    Date
    This patch adds debugging/testing support to ERST. A misc device is
    implemented to export raw ERST read/write/clear etc operations to user
    space. With this patch, we can add ERST testing support to
    linuxfirmwarekit ISO (linuxfirmwarekit.org) to verify the kernel
    support and the firmware implementation.

    Signed-off-by: Huang Ying <ying.huang@intel.com>
    Signed-off-by: Andi Kleen <ak@linux.intel.com>
    ---
    drivers/acpi/apei/Kconfig | 9 +
    drivers/acpi/apei/Makefile | 1
    drivers/acpi/apei/erst-dbg.c | 206 +++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 216 insertions(+)
    create mode 100644 drivers/acpi/apei/erst-dbg.c

    --- a/drivers/acpi/apei/Kconfig
    +++ b/drivers/acpi/apei/Kconfig
    @@ -28,3 +28,12 @@ config ACPI_APEI_EINJ
    EINJ provides a hardware error injection mechanism, it is
    mainly used for debugging and testing the other parts of
    APEI and some other RAS features.
    +
    +config ACPI_APEI_ERST_DEBUG
    + tristate "APEI Error Record Serialization Table (ERST) Debug Support"
    + depends on ACPI_APEI
    + help
    + ERST is a way provided by APEI to save and retrieve hardware
    + error infomation to and from a persistent store. Enable this
    + if you want to debugging and testing the ERST kernel support
    + and firmware implementation.
    --- a/drivers/acpi/apei/Makefile
    +++ b/drivers/acpi/apei/Makefile
    @@ -1,5 +1,6 @@
    obj-$(CONFIG_ACPI_APEI) += apei.o
    obj-$(CONFIG_ACPI_APEI_GHES) += ghes.o
    obj-$(CONFIG_ACPI_APEI_EINJ) += einj.o
    +obj-$(CONFIG_ACPI_APEI_ERST_DEBUG) += erst-dbg.o

    apei-y := apei-base.o hest.o cper.o erst.o
    --- /dev/null
    +++ b/drivers/acpi/apei/erst-dbg.c
    @@ -0,0 +1,206 @@
    +/*
    + * APEI Error Record Serialization Table debug support
    + *
    + * ERST is a way provided by APEI to save and retrieve hardware error
    + * infomation 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>
    + *
    + * 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.
    + *
    + * This program is distributed in the hope that it will be useful,
    + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    + * GNU General Public License for more details.
    + *
    + * You should have received a copy of the GNU General Public License
    + * along with this program; if not, write to the Free Software
    + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    + */
    +
    +#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 4096
    +
    +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)
    +{
    + if (erst_disable)
    + return -ENODEV;
    +
    + return nonseekable_open(inode, file);
    +}
    +
    +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 = get_user(record_id, (u64 __user *)arg);
    + if (rc)
    + return rc;
    + 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;
    + ssize_t len = 0;
    + u64 id;
    +
    + if (*off != 0)
    + return -EINVAL;
    +
    + if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
    + return -EINTR;
    +
    +retry_next:
    + rc = erst_get_next_record_id(&id);
    + if (rc)
    + goto out;
    + /* no more record */
    + if (id == APEI_ERST_INVALID_RECORD_ID)
    + goto out;
    +retry:
    + rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
    + /* 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_warning(ERST_DBG_PFX
    + "Record (ID: 0x%llx) length is too long: 0x%lx\n",
    + id, len);
    + rc = -EIO;
    + goto out;
    + }
    + if (len > erst_dbg_buf_len) {
    + kfree(erst_dbg_buf);
    + rc = -ENOMEM;
    + erst_dbg_buf = kmalloc(len, GFP_KERNEL);
    + if (!erst_dbg_buf)
    + goto out;
    + 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) {
    + kfree(erst_dbg_buf);
    + rc = -ENOMEM;
    + erst_dbg_buf = kmalloc(usize, GFP_KERNEL);
    + if (!erst_dbg_buf)
    + goto out;
    + 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,
    + .read = erst_dbg_read,
    + .write = erst_dbg_write,
    + .unlocked_ioctl = erst_dbg_ioctl,
    +};
    +
    +static struct miscdevice erst_dbg_dev = {
    + .minor = MISC_DYNAMIC_MINOR,
    + .name = "erst_dbg",
    + .fops = &erst_dbg_ops,
    +};
    +
    +static __init int erst_dbg_init(void)
    +{
    + 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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