/*
   * 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 <linux/pstore.h>
  #include <acpi/apei.h>
  
  #include "apei-internal.h"
  
  #undef pr_fmt
  #define pr_fmt(fmt) "ERST: " fmt
  
  /* 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_warn(FW_WARN "Firmware does not respond in time.
  ");
  		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_warn(FW_WARN
  			"Too long stall time for stall instruction: 0x%llx.
  ",
  				   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_warn(FW_WARN
  		"Too long stall time for stall while true instruction: 0x%llx.
  ",
  				   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_warn("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) {
  		iounmap(src);
  		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_warn(FW_WARN "too many record IDs!
  ");
  			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)
  			entries[wpos] = 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_warn("NVRAM ERST Log Address Range not implemented yet.
  ");
  }
  
  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, int *count,
  			   struct timespec *time, char **buf,
  			   bool *compressed, struct pstore_info *psi);
  static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
  		       u64 *id, unsigned int part, int count, bool compressed,
  		       size_t size, struct pstore_info *psi);
  static int erst_clearer(enum pstore_type_id type, u64 id, int count,
  			struct timespec time, struct pstore_info *psi);
  
  static struct pstore_info erst_info = {
  	.owner		= THIS_MODULE,
  	.name		= "erst",
  	.flags		= PSTORE_FLAGS_FRAGILE,
  	.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_DMESG_Z					\
  	UUID_LE(0x4f118707, 0x04dd, 0x4055, 0xb5, 0xdd, 0x95, 0x6d,	\
  		0x34, 0xdd, 0xfa, 0xc6)
  #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, int *count,
  			   struct timespec *time, char **buf,
  			   bool *compressed, 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;
  	*compressed = false;
  	if (uuid_le_cmp(rcd->sec_hdr.section_type,
  			CPER_SECTION_TYPE_DMESG_Z) == 0) {
  		*type = PSTORE_TYPE_DMESG;
  		*compressed = true;
  	} else 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, int count, bool compressed,
  		       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:
  		if (compressed)
  			rcd->sec_hdr.section_type = CPER_SECTION_TYPE_DMESG_Z;
  		else
  			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, int count,
  			struct timespec time, 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(
  	"Error Record Serialization Table (ERST) support is disabled.
  ");
  		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("Failed to get table, %s
  ", msg);
  		rc = -EINVAL;
  		goto err;
  	}
  
  	rc = erst_check_table(erst_tab);
  	if (rc) {
  		pr_err(FW_BUG "ERST table is invalid.
  ");
  		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(
  	"The corresponding hardware device or firmware implementation "
  	"is not available.
  ");
  		else
  			pr_err("Failed to get Error Log Address Range.
  ");
  		goto err_unmap_reg;
  	}
  
  	r = request_mem_region(erst_erange.base, erst_erange.size, "APEI ERST");
  	if (!r) {
  		pr_err("Can not request [mem %#010llx-%#010llx] for ERST.
  ",
  		       (unsigned long long)erst_erange.base,
  		       (unsigned long long)erst_erange.base + erst_erange.size - 1);
  		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(
  	"Error Record Serialization Table (ERST) support is initialized.
  ");
  
  	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);
  		rc = pstore_register(&erst_info);
  		if (rc) {
  			if (rc != -EPERM)
  				pr_info(
  				"Could not register with persistent store.
  ");
  			erst_info.buf = NULL;
  			erst_info.bufsize = 0;
  			kfree(buf);
  		}
  	} else
  		pr_err(
  		"Failed to allocate %lld bytes for persistent store error log.
  ",
  		erst_erange.size);
  
  	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);