drivers/acpi/apei/erst.c - kernel/msm-4.19 - Gitiles

 /*
  * 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 <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/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 <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 miliseconds */
 #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);

 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;
 }

 /*
  * 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_next_record_id(u64 *record_id)
 {
 	int rc;
 	unsigned long flags;

 	if (erst_disable)
 		return -ENODEV;

 	raw_spin_lock_irqsave(&erst_lock, flags);
 	rc = __erst_get_next_record_id(record_id);
 	raw_spin_unlock_irqrestore(&erst_lock, flags);

 	return rc;
 }
 EXPORT_SYMBOL_GPL(erst_get_next_record_id);

 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(&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(&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(&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(&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(&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(&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);

 /*
  * If return value > buflen, the buffer size is not big enough,
  * else if return value = 0, there is no more record to read,
  * else if return value < 0, something goes wrong,
  * else everything is OK, and return value is record length
  */
 ssize_t erst_read_next(struct cper_record_header *record, size_t buflen)
 {
 	int rc;
 	ssize_t len;
 	unsigned long flags;
 	u64 record_id;

 	if (erst_disable)
 		return -ENODEV;

 	raw_spin_lock_irqsave(&erst_lock, flags);
 	rc = __erst_get_next_record_id(&record_id);
 	if (rc) {
 		raw_spin_unlock_irqrestore(&erst_lock, flags);
 		return rc;
 	}
 	/* no more record */
 	if (record_id == APEI_ERST_INVALID_RECORD_ID) {
 		raw_spin_unlock_irqrestore(&erst_lock, flags);
 		return 0;
 	}

 	len = __erst_read(record_id, record, buflen);
 	raw_spin_unlock_irqrestore(&erst_lock, flags);

 	return len;
 }
 EXPORT_SYMBOL_GPL(erst_read_next);

 int erst_clear(u64 record_id)
 {
 	int rc;
 	unsigned long flags;

 	if (erst_disable)
 		return -ENODEV;

 	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);

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

 	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) {
 		pr_info(ERST_PFX "Table is not found!\n");
 		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;

 	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);
	/*
	* 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 <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/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 <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 miliseconds */
	#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);

	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;
	}

	/*
	* 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_next_record_id(u64 *record_id)
	{
	int rc;
	unsigned long flags;

	if (erst_disable)
	return -ENODEV;

	raw_spin_lock_irqsave(&erst_lock, flags);
	rc = __erst_get_next_record_id(record_id);
	raw_spin_unlock_irqrestore(&erst_lock, flags);

	return rc;
	}
	EXPORT_SYMBOL_GPL(erst_get_next_record_id);

	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(&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(&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(&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(&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(&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(&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);

	/*
	* If return value > buflen, the buffer size is not big enough,
	* else if return value = 0, there is no more record to read,
	* else if return value < 0, something goes wrong,
	* else everything is OK, and return value is record length
	*/
	ssize_t erst_read_next(struct cper_record_header *record, size_t buflen)
	{
	int rc;
	ssize_t len;
	unsigned long flags;
	u64 record_id;

	if (erst_disable)
	return -ENODEV;

	raw_spin_lock_irqsave(&erst_lock, flags);
	rc = __erst_get_next_record_id(&record_id);
	if (rc) {
	raw_spin_unlock_irqrestore(&erst_lock, flags);
	return rc;
	}
	/* no more record */
	if (record_id == APEI_ERST_INVALID_RECORD_ID) {
	raw_spin_unlock_irqrestore(&erst_lock, flags);
	return 0;
	}

	len = __erst_read(record_id, record, buflen);
	raw_spin_unlock_irqrestore(&erst_lock, flags);

	return len;
	}
	EXPORT_SYMBOL_GPL(erst_read_next);

	int erst_clear(u64 record_id)
	{
	int rc;
	unsigned long flags;

	if (erst_disable)
	return -ENODEV;

	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);

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

	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) {
	pr_info(ERST_PFX "Table is not found!\n");
	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;

	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);