erst.c

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/*
 * APEI Error Record Serialization Table support
 *
 * ERST is a way provided by APEI to save and retrieve hardware error
 * information to and from a persistent store.
 *
 * For more information about ERST, please refer to ACPI Specification
 * version 4.0, section 17.4.
 *
 * Copyright 2010 Intel Corp.
 *   Author: Huang Ying <[email protected]>
 *
 * 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/init.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/acpi.h>
#include <linux/uaccess.h>
#include <linux/cper.h>
#include <linux/nmi.h>
#include <linux/hardirq.h>
#include <linux/pstore.h>
#include <acpi/apei.h>

#include "apei-internal.h"

#define ERST_PFX "ERST: "

/* ERST command status */
#define ERST_STATUS_SUCCESS         0x0
#define ERST_STATUS_NOT_ENOUGH_SPACE        0x1
#define ERST_STATUS_HARDWARE_NOT_AVAILABLE  0x2
#define ERST_STATUS_FAILED          0x3
#define ERST_STATUS_RECORD_STORE_EMPTY      0x4
#define ERST_STATUS_RECORD_NOT_FOUND        0x5

#define ERST_TAB_ENTRY(tab)                     \
    ((struct acpi_whea_header *)((char *)(tab) +            \
                     sizeof(struct acpi_table_erst)))

#define SPIN_UNIT       100         /* 100ns */
/* Firmware should respond within 1 milliseconds */
#define FIRMWARE_TIMEOUT    (1 * NSEC_PER_MSEC)
#define FIRMWARE_MAX_STALL  50          /* 50us */

int erst_disable;
EXPORT_SYMBOL_GPL(erst_disable);

static struct acpi_table_erst *erst_tab;

/* ERST Error Log Address Range atrributes */
#define ERST_RANGE_RESERVED 0x0001
#define ERST_RANGE_NVRAM    0x0002
#define ERST_RANGE_SLOW     0x0004

/*
 * ERST Error Log Address Range, used as buffer for reading/writing
 * error records.
 */
static struct erst_erange {
    u64 base;
    u64 size;
    void __iomem *vaddr;
    u32 attr;
} erst_erange;

/*
 * Prevent ERST interpreter to run simultaneously, because the
 * corresponding firmware implementation may not work properly when
 * invoked simultaneously.
 *
 * It is used to provide exclusive accessing for ERST Error Log
 * Address Range too.
 */
static DEFINE_RAW_SPINLOCK(erst_lock);

static inline int erst_errno(int command_status)
{
    switch (command_status) {
    case ERST_STATUS_SUCCESS:
        return 0;
    case ERST_STATUS_HARDWARE_NOT_AVAILABLE:
        return -ENODEV;
    case ERST_STATUS_NOT_ENOUGH_SPACE:
        return -ENOSPC;
    case ERST_STATUS_RECORD_STORE_EMPTY:
    case ERST_STATUS_RECORD_NOT_FOUND:
        return -ENOENT;
    default:
        return -EINVAL;
    }
}

static int erst_timedout(u64 *t, u64 spin_unit)
{
    if ((s64)*t < spin_unit) {
        pr_warning(FW_WARN ERST_PFX
               "Firmware does not respond in time\n");
        return 1;
    }
    *t -= spin_unit;
    ndelay(spin_unit);
    touch_nmi_watchdog();
    return 0;
}

static int erst_exec_load_var1(struct apei_exec_context *ctx,
                   struct acpi_whea_header *entry)
{
    return __apei_exec_read_register(entry, &ctx->var1);
}

static int erst_exec_load_var2(struct apei_exec_context *ctx,
                   struct acpi_whea_header *entry)
{
    return __apei_exec_read_register(entry, &ctx->var2);
}

static int erst_exec_store_var1(struct apei_exec_context *ctx,
                struct acpi_whea_header *entry)
{
    return __apei_exec_write_register(entry, ctx->var1);
}

static int erst_exec_add(struct apei_exec_context *ctx,
             struct acpi_whea_header *entry)
{
    ctx->var1 += ctx->var2;
    return 0;
}

static int erst_exec_subtract(struct apei_exec_context *ctx,
                  struct acpi_whea_header *entry)
{
    ctx->var1 -= ctx->var2;
    return 0;
}

static int erst_exec_add_value(struct apei_exec_context *ctx,
                   struct acpi_whea_header *entry)
{
    int rc;
    u64 val;

    rc = __apei_exec_read_register(entry, &val);
    if (rc)
        return rc;
    val += ctx->value;
    rc = __apei_exec_write_register(entry, val);
    return rc;
}

static int erst_exec_subtract_value(struct apei_exec_context *ctx,
                    struct acpi_whea_header *entry)
{
    int rc;
    u64 val;

    rc = __apei_exec_read_register(entry, &val);
    if (rc)
        return rc;
    val -= ctx->value;
    rc = __apei_exec_write_register(entry, val);
    return rc;
}

static int erst_exec_stall(struct apei_exec_context *ctx,
               struct acpi_whea_header *entry)
{
    u64 stall_time;

    if (ctx->value > FIRMWARE_MAX_STALL) {
        if (!in_nmi())
            pr_warning(FW_WARN ERST_PFX
            "Too long stall time for stall instruction: %llx.\n",
                   ctx->value);
        stall_time = FIRMWARE_MAX_STALL;
    } else
        stall_time = ctx->value;
    udelay(stall_time);
    return 0;
}

static int erst_exec_stall_while_true(struct apei_exec_context *ctx,
                      struct acpi_whea_header *entry)
{
    int rc;
    u64 val;
    u64 timeout = FIRMWARE_TIMEOUT;
    u64 stall_time;

    if (ctx->var1 > FIRMWARE_MAX_STALL) {
        if (!in_nmi())
            pr_warning(FW_WARN ERST_PFX
        "Too long stall time for stall while true instruction: %llx.\n",
                   ctx->var1);
        stall_time = FIRMWARE_MAX_STALL;
    } else
        stall_time = ctx->var1;

    for (;;) {
        rc = __apei_exec_read_register(entry, &val);
        if (rc)
            return rc;
        if (val != ctx->value)
            break;
        if (erst_timedout(&timeout, stall_time * NSEC_PER_USEC))
            return -EIO;
    }
    return 0;
}

static int erst_exec_skip_next_instruction_if_true(
    struct apei_exec_context *ctx,
    struct acpi_whea_header *entry)
{
    int rc;
    u64 val;

    rc = __apei_exec_read_register(entry, &val);
    if (rc)
        return rc;
    if (val == ctx->value) {
        ctx->ip += 2;
        return APEI_EXEC_SET_IP;
    }

    return 0;
}

static int erst_exec_goto(struct apei_exec_context *ctx,
              struct acpi_whea_header *entry)
{
    ctx->ip = ctx->value;
    return APEI_EXEC_SET_IP;
}

static int erst_exec_set_src_address_base(struct apei_exec_context *ctx,
                      struct acpi_whea_header *entry)
{
    return __apei_exec_read_register(entry, &ctx->src_base);
}

static int erst_exec_set_dst_address_base(struct apei_exec_context *ctx,
                      struct acpi_whea_header *entry)
{
    return __apei_exec_read_register(entry, &ctx->dst_base);
}

static int erst_exec_move_data(struct apei_exec_context *ctx,
                   struct acpi_whea_header *entry)
{
    int rc;
    u64 offset;
    void *src, *dst;

    /* ioremap does not work in interrupt context */
    if (in_interrupt()) {
        pr_warning(ERST_PFX
               "MOVE_DATA can not be used in interrupt context");
        return -EBUSY;
    }

    rc = __apei_exec_read_register(entry, &offset);
    if (rc)
        return rc;

    src = ioremap(ctx->src_base + offset, ctx->var2);
    if (!src)
        return -ENOMEM;
    dst = ioremap(ctx->dst_base + offset, ctx->var2);
    if (!dst)
        return -ENOMEM;

    memmove(dst, src, ctx->var2);

    iounmap(src);
    iounmap(dst);

    return 0;
}

static struct apei_exec_ins_type erst_ins_type[] = {
    [ACPI_ERST_READ_REGISTER] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = apei_exec_read_register,
    },
    [ACPI_ERST_READ_REGISTER_VALUE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = apei_exec_read_register_value,
    },
    [ACPI_ERST_WRITE_REGISTER] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = apei_exec_write_register,
    },
    [ACPI_ERST_WRITE_REGISTER_VALUE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = apei_exec_write_register_value,
    },
    [ACPI_ERST_NOOP] = {
        .flags = 0,
        .run = apei_exec_noop,
    },
    [ACPI_ERST_LOAD_VAR1] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_load_var1,
    },
    [ACPI_ERST_LOAD_VAR2] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_load_var2,
    },
    [ACPI_ERST_STORE_VAR1] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_store_var1,
    },
    [ACPI_ERST_ADD] = {
        .flags = 0,
        .run = erst_exec_add,
    },
    [ACPI_ERST_SUBTRACT] = {
        .flags = 0,
        .run = erst_exec_subtract,
    },
    [ACPI_ERST_ADD_VALUE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_add_value,
    },
    [ACPI_ERST_SUBTRACT_VALUE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_subtract_value,
    },
    [ACPI_ERST_STALL] = {
        .flags = 0,
        .run = erst_exec_stall,
    },
    [ACPI_ERST_STALL_WHILE_TRUE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_stall_while_true,
    },
    [ACPI_ERST_SKIP_NEXT_IF_TRUE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_skip_next_instruction_if_true,
    },
    [ACPI_ERST_GOTO] = {
        .flags = 0,
        .run = erst_exec_goto,
    },
    [ACPI_ERST_SET_SRC_ADDRESS_BASE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_set_src_address_base,
    },
    [ACPI_ERST_SET_DST_ADDRESS_BASE] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_set_dst_address_base,
    },
    [ACPI_ERST_MOVE_DATA] = {
        .flags = APEI_EXEC_INS_ACCESS_REGISTER,
        .run = erst_exec_move_data,
    },
};

static inline void erst_exec_ctx_init(struct apei_exec_context *ctx)
{
    apei_exec_ctx_init(ctx, erst_ins_type, ARRAY_SIZE(erst_ins_type),
               ERST_TAB_ENTRY(erst_tab), erst_tab->entries);
}

static int erst_get_erange(struct erst_erange *range)
{
    struct apei_exec_context ctx;
    int rc;

    erst_exec_ctx_init(&ctx);
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_RANGE);
    if (rc)
        return rc;
    range->base = apei_exec_ctx_get_output(&ctx);
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_LENGTH);
    if (rc)
        return rc;
    range->size = apei_exec_ctx_get_output(&ctx);
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_ATTRIBUTES);
    if (rc)
        return rc;
    range->attr = apei_exec_ctx_get_output(&ctx);

    return 0;
}

static ssize_t __erst_get_record_count(void)
{
    struct apei_exec_context ctx;
    int rc;

    erst_exec_ctx_init(&ctx);
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_RECORD_COUNT);
    if (rc)
        return rc;
    return apei_exec_ctx_get_output(&ctx);
}

ssize_t erst_get_record_count(void)
{
    ssize_t count;
    unsigned long flags;

    if (erst_disable)
        return -ENODEV;

    raw_spin_lock_irqsave(&erst_lock, flags);
    count = __erst_get_record_count();
    raw_spin_unlock_irqrestore(&erst_lock, flags);

    return count;
}
EXPORT_SYMBOL_GPL(erst_get_record_count);

#define ERST_RECORD_ID_CACHE_SIZE_MIN   16
#define ERST_RECORD_ID_CACHE_SIZE_MAX   1024

struct erst_record_id_cache {
    struct mutex lock;
    u64 *entries;
    int len;
    int size;
    int refcount;
};

static struct erst_record_id_cache erst_record_id_cache = {
    .lock = __MUTEX_INITIALIZER(erst_record_id_cache.lock),
    .refcount = 0,
};

static int __erst_get_next_record_id(u64 *record_id)
{
    struct apei_exec_context ctx;
    int rc;

    erst_exec_ctx_init(&ctx);
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_RECORD_ID);
    if (rc)
        return rc;
    *record_id = apei_exec_ctx_get_output(&ctx);

    return 0;
}

int erst_get_record_id_begin(int *pos)
{
    int rc;

    if (erst_disable)
        return -ENODEV;

    rc = mutex_lock_interruptible(&erst_record_id_cache.lock);
    if (rc)
        return rc;
    erst_record_id_cache.refcount++;
    mutex_unlock(&erst_record_id_cache.lock);

    *pos = 0;

    return 0;
}
EXPORT_SYMBOL_GPL(erst_get_record_id_begin);

/* erst_record_id_cache.lock must be held by caller */
static int __erst_record_id_cache_add_one(void)
{
    u64 id, prev_id, first_id;
    int i, rc;
    u64 *entries;
    unsigned long flags;

    id = prev_id = first_id = APEI_ERST_INVALID_RECORD_ID;
retry:
    raw_spin_lock_irqsave(&erst_lock, flags);
    rc = __erst_get_next_record_id(&id);
    raw_spin_unlock_irqrestore(&erst_lock, flags);
    if (rc == -ENOENT)
        return 0;
    if (rc)
        return rc;
    if (id == APEI_ERST_INVALID_RECORD_ID)
        return 0;
    /* can not skip current ID, or loop back to first ID */
    if (id == prev_id || id == first_id)
        return 0;
    if (first_id == APEI_ERST_INVALID_RECORD_ID)
        first_id = id;
    prev_id = id;

    entries = erst_record_id_cache.entries;
    for (i = 0; i < erst_record_id_cache.len; i++) {
        if (entries[i] == id)
            break;
    }
    /* record id already in cache, try next */
    if (i < erst_record_id_cache.len)
        goto retry;
    if (erst_record_id_cache.len >= erst_record_id_cache.size) {
        int new_size, alloc_size;
        u64 *new_entries;

        new_size = erst_record_id_cache.size * 2;
        new_size = clamp_val(new_size, ERST_RECORD_ID_CACHE_SIZE_MIN,
                     ERST_RECORD_ID_CACHE_SIZE_MAX);
        if (new_size <= erst_record_id_cache.size) {
            if (printk_ratelimit())
                pr_warning(FW_WARN ERST_PFX
                       "too many record ID!\n");
            return 0;
        }
        alloc_size = new_size * sizeof(entries[0]);
        if (alloc_size < PAGE_SIZE)
            new_entries = kmalloc(alloc_size, GFP_KERNEL);
        else
            new_entries = vmalloc(alloc_size);
        if (!new_entries)
            return -ENOMEM;
        memcpy(new_entries, entries,
               erst_record_id_cache.len * sizeof(entries[0]));
        if (erst_record_id_cache.size < PAGE_SIZE)
            kfree(entries);
        else
            vfree(entries);
        erst_record_id_cache.entries = entries = new_entries;
        erst_record_id_cache.size = new_size;
    }
    entries[i] = id;
    erst_record_id_cache.len++;

    return 1;
}

/*
 * Get the record ID of an existing error record on the persistent
 * storage. If there is no error record on the persistent storage, the
 * returned record_id is APEI_ERST_INVALID_RECORD_ID.
 */
int erst_get_record_id_next(int *pos, u64 *record_id)
{
    int rc = 0;
    u64 *entries;

    if (erst_disable)
        return -ENODEV;

    /* must be enclosed by erst_get_record_id_begin/end */
    BUG_ON(!erst_record_id_cache.refcount);
    BUG_ON(*pos < 0 || *pos > erst_record_id_cache.len);

    mutex_lock(&erst_record_id_cache.lock);
    entries = erst_record_id_cache.entries;
    for (; *pos < erst_record_id_cache.len; (*pos)++)
        if (entries[*pos] != APEI_ERST_INVALID_RECORD_ID)
            break;
    /* found next record id in cache */
    if (*pos < erst_record_id_cache.len) {
        *record_id = entries[*pos];
        (*pos)++;
        goto out_unlock;
    }

    /* Try to add one more record ID to cache */
    rc = __erst_record_id_cache_add_one();
    if (rc < 0)
        goto out_unlock;
    /* successfully add one new ID */
    if (rc == 1) {
        *record_id = erst_record_id_cache.entries[*pos];
        (*pos)++;
        rc = 0;
    } else {
        *pos = -1;
        *record_id = APEI_ERST_INVALID_RECORD_ID;
    }
out_unlock:
    mutex_unlock(&erst_record_id_cache.lock);

    return rc;
}
EXPORT_SYMBOL_GPL(erst_get_record_id_next);

/* erst_record_id_cache.lock must be held by caller */
static void __erst_record_id_cache_compact(void)
{
    int i, wpos = 0;
    u64 *entries;

    if (erst_record_id_cache.refcount)
        return;

    entries = erst_record_id_cache.entries;
    for (i = 0; i < erst_record_id_cache.len; i++) {
        if (entries[i] == APEI_ERST_INVALID_RECORD_ID)
            continue;
        if (wpos != i)
            memcpy(&entries[wpos], &entries[i], sizeof(entries[i]));
        wpos++;
    }
    erst_record_id_cache.len = wpos;
}

void erst_get_record_id_end(void)
{
    /*
     * erst_disable != 0 should be detected by invoker via the
     * return value of erst_get_record_id_begin/next, so this
     * function should not be called for erst_disable != 0.
     */
    BUG_ON(erst_disable);

    mutex_lock(&erst_record_id_cache.lock);
    erst_record_id_cache.refcount--;
    BUG_ON(erst_record_id_cache.refcount < 0);
    __erst_record_id_cache_compact();
    mutex_unlock(&erst_record_id_cache.lock);
}
EXPORT_SYMBOL_GPL(erst_get_record_id_end);

static int __erst_write_to_storage(u64 offset)
{
    struct apei_exec_context ctx;
    u64 timeout = FIRMWARE_TIMEOUT;
    u64 val;
    int rc;

    erst_exec_ctx_init(&ctx);
    rc = apei_exec_run_optional(&ctx, ACPI_ERST_BEGIN_WRITE);
    if (rc)
        return rc;
    apei_exec_ctx_set_input(&ctx, offset);
    rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_OFFSET);
    if (rc)
        return rc;
    rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
    if (rc)
        return rc;
    for (;;) {
        rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
        if (rc)
            return rc;
        val = apei_exec_ctx_get_output(&ctx);
        if (!val)
            break;
        if (erst_timedout(&timeout, SPIN_UNIT))
            return -EIO;
    }
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
    if (rc)
        return rc;
    val = apei_exec_ctx_get_output(&ctx);
    rc = apei_exec_run_optional(&ctx, ACPI_ERST_END);
    if (rc)
        return rc;

    return erst_errno(val);
}

static int __erst_read_from_storage(u64 record_id, u64 offset)
{
    struct apei_exec_context ctx;
    u64 timeout = FIRMWARE_TIMEOUT;
    u64 val;
    int rc;

    erst_exec_ctx_init(&ctx);
    rc = apei_exec_run_optional(&ctx, ACPI_ERST_BEGIN_READ);
    if (rc)
        return rc;
    apei_exec_ctx_set_input(&ctx, offset);
    rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_OFFSET);
    if (rc)
        return rc;
    apei_exec_ctx_set_input(&ctx, record_id);
    rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_ID);
    if (rc)
        return rc;
    rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
    if (rc)
        return rc;
    for (;;) {
        rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
        if (rc)
            return rc;
        val = apei_exec_ctx_get_output(&ctx);
        if (!val)
            break;
        if (erst_timedout(&timeout, SPIN_UNIT))
            return -EIO;
    };
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
    if (rc)
        return rc;
    val = apei_exec_ctx_get_output(&ctx);
    rc = apei_exec_run_optional(&ctx, ACPI_ERST_END);
    if (rc)
        return rc;

    return erst_errno(val);
}

static int __erst_clear_from_storage(u64 record_id)
{
    struct apei_exec_context ctx;
    u64 timeout = FIRMWARE_TIMEOUT;
    u64 val;
    int rc;

    erst_exec_ctx_init(&ctx);
    rc = apei_exec_run_optional(&ctx, ACPI_ERST_BEGIN_CLEAR);
    if (rc)
        return rc;
    apei_exec_ctx_set_input(&ctx, record_id);
    rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_ID);
    if (rc)
        return rc;
    rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
    if (rc)
        return rc;
    for (;;) {
        rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
        if (rc)
            return rc;
        val = apei_exec_ctx_get_output(&ctx);
        if (!val)
            break;
        if (erst_timedout(&timeout, SPIN_UNIT))
            return -EIO;
    }
    rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
    if (rc)
        return rc;
    val = apei_exec_ctx_get_output(&ctx);
    rc = apei_exec_run_optional(&ctx, ACPI_ERST_END);
    if (rc)
        return rc;

    return erst_errno(val);
}

/* NVRAM ERST Error Log Address Range is not supported yet */
static void pr_unimpl_nvram(void)
{
    if (printk_ratelimit())
        pr_warning(ERST_PFX
        "NVRAM ERST Log Address Range is not implemented yet\n");
}

static int __erst_write_to_nvram(const struct cper_record_header *record)
{
    /* do not print message, because printk is not safe for NMI */
    return -ENOSYS;
}

static int __erst_read_to_erange_from_nvram(u64 record_id, u64 *offset)
{
    pr_unimpl_nvram();
    return -ENOSYS;
}

static int __erst_clear_from_nvram(u64 record_id)
{
    pr_unimpl_nvram();
    return -ENOSYS;
}

int erst_write(const struct cper_record_header *record)
{
    int rc;
    unsigned long flags;
    struct cper_record_header *rcd_erange;

    if (erst_disable)
        return -ENODEV;

    if (memcmp(record->signature, CPER_SIG_RECORD, CPER_SIG_SIZE))
        return -EINVAL;

    if (erst_erange.attr & ERST_RANGE_NVRAM) {
        if (!raw_spin_trylock_irqsave(&erst_lock, flags))
            return -EBUSY;
        rc = __erst_write_to_nvram(record);
        raw_spin_unlock_irqrestore(&erst_lock, flags);
        return rc;
    }

    if (record->record_length > erst_erange.size)
        return -EINVAL;

    if (!raw_spin_trylock_irqsave(&erst_lock, flags))
        return -EBUSY;
    memcpy(erst_erange.vaddr, record, record->record_length);
    rcd_erange = erst_erange.vaddr;
    /* signature for serialization system */
    memcpy(&rcd_erange->persistence_information, "ER", 2);

    rc = __erst_write_to_storage(0);
    raw_spin_unlock_irqrestore(&erst_lock, flags);

    return rc;
}
EXPORT_SYMBOL_GPL(erst_write);

static int __erst_read_to_erange(u64 record_id, u64 *offset)
{
    int rc;

    if (erst_erange.attr & ERST_RANGE_NVRAM)
        return __erst_read_to_erange_from_nvram(
            record_id, offset);

    rc = __erst_read_from_storage(record_id, 0);
    if (rc)
        return rc;
    *offset = 0;

    return 0;
}

static ssize_t __erst_read(u64 record_id, struct cper_record_header *record,
               size_t buflen)
{
    int rc;
    u64 offset, len = 0;
    struct cper_record_header *rcd_tmp;

    rc = __erst_read_to_erange(record_id, &offset);
    if (rc)
        return rc;
    rcd_tmp = erst_erange.vaddr + offset;
    len = rcd_tmp->record_length;
    if (len <= buflen)
        memcpy(record, rcd_tmp, len);

    return len;
}

/*
 * If return value > buflen, the buffer size is not big enough,
 * else if return value < 0, something goes wrong,
 * else everything is OK, and return value is record length
 */
ssize_t erst_read(u64 record_id, struct cper_record_header *record,
          size_t buflen)
{
    ssize_t len;
    unsigned long flags;

    if (erst_disable)
        return -ENODEV;

    raw_spin_lock_irqsave(&erst_lock, flags);
    len = __erst_read(record_id, record, buflen);
    raw_spin_unlock_irqrestore(&erst_lock, flags);
    return len;
}
EXPORT_SYMBOL_GPL(erst_read);

int erst_clear(u64 record_id)
{
    int rc, i;
    unsigned long flags;
    u64 *entries;

    if (erst_disable)
        return -ENODEV;

    rc = mutex_lock_interruptible(&erst_record_id_cache.lock);
    if (rc)
        return rc;
    raw_spin_lock_irqsave(&erst_lock, flags);
    if (erst_erange.attr & ERST_RANGE_NVRAM)
        rc = __erst_clear_from_nvram(record_id);
    else
        rc = __erst_clear_from_storage(record_id);
    raw_spin_unlock_irqrestore(&erst_lock, flags);
    if (rc)
        goto out;
    entries = erst_record_id_cache.entries;
    for (i = 0; i < erst_record_id_cache.len; i++) {
        if (entries[i] == record_id)
            entries[i] = APEI_ERST_INVALID_RECORD_ID;
    }
    __erst_record_id_cache_compact();
out:
    mutex_unlock(&erst_record_id_cache.lock);
    return rc;
}
EXPORT_SYMBOL_GPL(erst_clear);

static int __init setup_erst_disable(char *str)
{
    erst_disable = 1;
    return 0;
}

__setup("erst_disable", setup_erst_disable);

static int erst_check_table(struct acpi_table_erst *erst_tab)
{
    if ((erst_tab->header_length !=
         (sizeof(struct acpi_table_erst) - sizeof(erst_tab->header)))
        && (erst_tab->header_length != sizeof(struct acpi_table_erst)))
        return -EINVAL;
    if (erst_tab->header.length < sizeof(struct acpi_table_erst))
        return -EINVAL;
    if (erst_tab->entries !=
        (erst_tab->header.length - sizeof(struct acpi_table_erst)) /
        sizeof(struct acpi_erst_entry))
        return -EINVAL;

    return 0;
}

static int erst_open_pstore(struct pstore_info *psi);
static int erst_close_pstore(struct pstore_info *psi);
static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
               struct timespec *time, char **buf,
               struct pstore_info *psi);
static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
               u64 *id, unsigned int part,
               size_t size, struct pstore_info *psi);
static int erst_clearer(enum pstore_type_id type, u64 id,
            struct pstore_info *psi);

static struct pstore_info erst_info = {
    .owner      = THIS_MODULE,
    .name       = "erst",
    .open       = erst_open_pstore,
    .close      = erst_close_pstore,
    .read       = erst_reader,
    .write      = erst_writer,
    .erase      = erst_clearer
};

#define CPER_CREATOR_PSTORE                     \
    UUID_LE(0x75a574e3, 0x5052, 0x4b29, 0x8a, 0x8e, 0xbe, 0x2c, \
        0x64, 0x90, 0xb8, 0x9d)
#define CPER_SECTION_TYPE_DMESG                     \
    UUID_LE(0xc197e04e, 0xd545, 0x4a70, 0x9c, 0x17, 0xa5, 0x54, \
        0x94, 0x19, 0xeb, 0x12)
#define CPER_SECTION_TYPE_MCE                       \
    UUID_LE(0xfe08ffbe, 0x95e4, 0x4be7, 0xbc, 0x73, 0x40, 0x96, \
        0x04, 0x4a, 0x38, 0xfc)

struct cper_pstore_record {
    struct cper_record_header hdr;
    struct cper_section_descriptor sec_hdr;
    char data[];
} __packed;

static int reader_pos;

static int erst_open_pstore(struct pstore_info *psi)
{
    int rc;

    if (erst_disable)
        return -ENODEV;

    rc = erst_get_record_id_begin(&reader_pos);

    return rc;
}

static int erst_close_pstore(struct pstore_info *psi)
{
    erst_get_record_id_end();

    return 0;
}

static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
               struct timespec *time, char **buf,
               struct pstore_info *psi)
{
    int rc;
    ssize_t len = 0;
    u64 record_id;
    struct cper_pstore_record *rcd;
    size_t rcd_len = sizeof(*rcd) + erst_info.bufsize;

    if (erst_disable)
        return -ENODEV;

    rcd = kmalloc(rcd_len, GFP_KERNEL);
    if (!rcd) {
        rc = -ENOMEM;
        goto out;
    }
skip:
    rc = erst_get_record_id_next(&reader_pos, &record_id);
    if (rc)
        goto out;

    /* no more record */
    if (record_id == APEI_ERST_INVALID_RECORD_ID) {
        rc = -EINVAL;
        goto out;
    }

    len = erst_read(record_id, &rcd->hdr, rcd_len);
    /* The record may be cleared by others, try read next record */
    if (len == -ENOENT)
        goto skip;
    else if (len < sizeof(*rcd)) {
        rc = -EIO;
        goto out;
    }
    if (uuid_le_cmp(rcd->hdr.creator_id, CPER_CREATOR_PSTORE) != 0)
        goto skip;

    *buf = kmalloc(len, GFP_KERNEL);
    if (*buf == NULL) {
        rc = -ENOMEM;
        goto out;
    }
    memcpy(*buf, rcd->data, len - sizeof(*rcd));
    *id = record_id;
    if (uuid_le_cmp(rcd->sec_hdr.section_type,
            CPER_SECTION_TYPE_DMESG) == 0)
        *type = PSTORE_TYPE_DMESG;
    else if (uuid_le_cmp(rcd->sec_hdr.section_type,
                 CPER_SECTION_TYPE_MCE) == 0)
        *type = PSTORE_TYPE_MCE;
    else
        *type = PSTORE_TYPE_UNKNOWN;

    if (rcd->hdr.validation_bits & CPER_VALID_TIMESTAMP)
        time->tv_sec = rcd->hdr.timestamp;
    else
        time->tv_sec = 0;
    time->tv_nsec = 0;

out:
    kfree(rcd);
    return (rc < 0) ? rc : (len - sizeof(*rcd));
}

static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
               u64 *id, unsigned int part,
               size_t size, struct pstore_info *psi)
{
    struct cper_pstore_record *rcd = (struct cper_pstore_record *)
                    (erst_info.buf - sizeof(*rcd));
    int ret;

    memset(rcd, 0, sizeof(*rcd));
    memcpy(rcd->hdr.signature, CPER_SIG_RECORD, CPER_SIG_SIZE);
    rcd->hdr.revision = CPER_RECORD_REV;
    rcd->hdr.signature_end = CPER_SIG_END;
    rcd->hdr.section_count = 1;
    rcd->hdr.error_severity = CPER_SEV_FATAL;
    /* timestamp valid. platform_id, partition_id are invalid */
    rcd->hdr.validation_bits = CPER_VALID_TIMESTAMP;
    rcd->hdr.timestamp = get_seconds();
    rcd->hdr.record_length = sizeof(*rcd) + size;
    rcd->hdr.creator_id = CPER_CREATOR_PSTORE;
    rcd->hdr.notification_type = CPER_NOTIFY_MCE;
    rcd->hdr.record_id = cper_next_record_id();
    rcd->hdr.flags = CPER_HW_ERROR_FLAGS_PREVERR;

    rcd->sec_hdr.section_offset = sizeof(*rcd);
    rcd->sec_hdr.section_length = size;
    rcd->sec_hdr.revision = CPER_SEC_REV;
    /* fru_id and fru_text is invalid */
    rcd->sec_hdr.validation_bits = 0;
    rcd->sec_hdr.flags = CPER_SEC_PRIMARY;
    switch (type) {
    case PSTORE_TYPE_DMESG:
        rcd->sec_hdr.section_type = CPER_SECTION_TYPE_DMESG;
        break;
    case PSTORE_TYPE_MCE:
        rcd->sec_hdr.section_type = CPER_SECTION_TYPE_MCE;
        break;
    default:
        return -EINVAL;
    }
    rcd->sec_hdr.section_severity = CPER_SEV_FATAL;

    ret = erst_write(&rcd->hdr);
    *id = rcd->hdr.record_id;

    return ret;
}

static int erst_clearer(enum pstore_type_id type, u64 id,
            struct pstore_info *psi)
{
    return erst_clear(id);
}

static int __init erst_init(void)
{
    int rc = 0;
    acpi_status status;
    struct apei_exec_context ctx;
    struct apei_resources erst_resources;
    struct resource *r;
    char *buf;

    if (acpi_disabled)
        goto err;

    if (erst_disable) {
        pr_info(ERST_PFX
    "Error Record Serialization Table (ERST) support is disabled.\n");
        goto err;
    }

    status = acpi_get_table(ACPI_SIG_ERST, 0,
                (struct acpi_table_header **)&erst_tab);
    if (status == AE_NOT_FOUND)
        goto err;
    else if (ACPI_FAILURE(status)) {
        const char *msg = acpi_format_exception(status);
        pr_err(ERST_PFX "Failed to get table, %s\n", msg);
        rc = -EINVAL;
        goto err;
    }

    rc = erst_check_table(erst_tab);
    if (rc) {
        pr_err(FW_BUG ERST_PFX "ERST table is invalid\n");
        goto err;
    }

    apei_resources_init(&erst_resources);
    erst_exec_ctx_init(&ctx);
    rc = apei_exec_collect_resources(&ctx, &erst_resources);
    if (rc)
        goto err_fini;
    rc = apei_resources_request(&erst_resources, "APEI ERST");
    if (rc)
        goto err_fini;
    rc = apei_exec_pre_map_gars(&ctx);
    if (rc)
        goto err_release;
    rc = erst_get_erange(&erst_erange);
    if (rc) {
        if (rc == -ENODEV)
            pr_info(ERST_PFX
    "The corresponding hardware device or firmware implementation "
    "is not available.\n");
        else
            pr_err(ERST_PFX
                   "Failed to get Error Log Address Range.\n");
        goto err_unmap_reg;
    }

    r = request_mem_region(erst_erange.base, erst_erange.size, "APEI ERST");
    if (!r) {
        pr_err(ERST_PFX
        "Can not request iomem region <0x%16llx-0x%16llx> for ERST.\n",
        (unsigned long long)erst_erange.base,
        (unsigned long long)erst_erange.base + erst_erange.size);
        rc = -EIO;
        goto err_unmap_reg;
    }
    rc = -ENOMEM;
    erst_erange.vaddr = ioremap_cache(erst_erange.base,
                      erst_erange.size);
    if (!erst_erange.vaddr)
        goto err_release_erange;

    buf = kmalloc(erst_erange.size, GFP_KERNEL);
    spin_lock_init(&erst_info.buf_lock);
    if (buf) {
        erst_info.buf = buf + sizeof(struct cper_pstore_record);
        erst_info.bufsize = erst_erange.size -
                    sizeof(struct cper_pstore_record);
        if (pstore_register(&erst_info)) {
            pr_info(ERST_PFX "Could not register with persistent store\n");
            kfree(buf);
        }
    }

    pr_info(ERST_PFX
    "Error Record Serialization Table (ERST) support is initialized.\n");

    return 0;

err_release_erange:
    release_mem_region(erst_erange.base, erst_erange.size);
err_unmap_reg:
    apei_exec_post_unmap_gars(&ctx);
err_release:
    apei_resources_release(&erst_resources);
err_fini:
    apei_resources_fini(&erst_resources);
err:
    erst_disable = 1;
    return rc;
}

device_initcall(erst_init);