/*
   * APEI Generic Hardware Error Source support
   *
   * Generic Hardware Error Source provides a way to report platform
   * hardware errors (such as that from chipset). It works in so called
   * "Firmware First" mode, that is, hardware errors are reported to
   * firmware firstly, then reported to Linux by firmware. This way,
   * some non-standard hardware error registers or non-standard hardware
   * link can be checked by firmware to produce more hardware error
   * information for Linux.
   *
   * For more information about Generic Hardware Error Source, please
   * refer to ACPI Specification version 4.0, section 17.3.2.6
   *
   * Copyright 2010,2011 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/acpi.h>
  #include <linux/io.h>
  #include <linux/interrupt.h>
  #include <linux/timer.h>
  #include <linux/cper.h>
  #include <linux/kdebug.h>
  #include <linux/platform_device.h>
  #include <linux/mutex.h>
  #include <linux/ratelimit.h>
  #include <linux/vmalloc.h>
  #include <linux/irq_work.h>
  #include <linux/llist.h>
  #include <linux/genalloc.h>
  #include <linux/pci.h>
  #include <linux/aer.h>
  
  #include <acpi/ghes.h>
  #include <asm/mce.h>
  #include <asm/tlbflush.h>
  #include <asm/nmi.h>
  
  #include "apei-internal.h"
  
  #define GHES_PFX	"GHES: "
  
  #define GHES_ESTATUS_MAX_SIZE		65536
  #define GHES_ESOURCE_PREALLOC_MAX_SIZE	65536
  
  #define GHES_ESTATUS_POOL_MIN_ALLOC_ORDER 3
  
  /* This is just an estimation for memory pool allocation */
  #define GHES_ESTATUS_CACHE_AVG_SIZE	512
  
  #define GHES_ESTATUS_CACHES_SIZE	4
  
  #define GHES_ESTATUS_IN_CACHE_MAX_NSEC	10000000000ULL
  /* Prevent too many caches are allocated because of RCU */
  #define GHES_ESTATUS_CACHE_ALLOCED_MAX	(GHES_ESTATUS_CACHES_SIZE * 3 / 2)
  
  #define GHES_ESTATUS_CACHE_LEN(estatus_len)			\
  	(sizeof(struct ghes_estatus_cache) + (estatus_len))
  #define GHES_ESTATUS_FROM_CACHE(estatus_cache)			\
  	((struct acpi_generic_status *)				\
  	 ((struct ghes_estatus_cache *)(estatus_cache) + 1))
  
  #define GHES_ESTATUS_NODE_LEN(estatus_len)			\
  	(sizeof(struct ghes_estatus_node) + (estatus_len))
  #define GHES_ESTATUS_FROM_NODE(estatus_node)			\
  	((struct acpi_generic_status *)				\
  	 ((struct ghes_estatus_node *)(estatus_node) + 1))
  
  bool ghes_disable;
  module_param_named(disable, ghes_disable, bool, 0);
  
  static int ghes_panic_timeout	__read_mostly = 30;
  
  /*
   * All error sources notified with SCI shares one notifier function,
   * so they need to be linked and checked one by one.  This is applied
   * to NMI too.
   *
   * RCU is used for these lists, so ghes_list_mutex is only used for
   * list changing, not for traversing.
   */
  static LIST_HEAD(ghes_sci);
  static LIST_HEAD(ghes_nmi);
  static DEFINE_MUTEX(ghes_list_mutex);
  
  /*
   * NMI may be triggered on any CPU, so ghes_nmi_lock is used for
   * mutual exclusion.
   */
  static DEFINE_RAW_SPINLOCK(ghes_nmi_lock);
  
  /*
   * Because the memory area used to transfer hardware error information
   * from BIOS to Linux can be determined only in NMI, IRQ or timer
   * handler, but general ioremap can not be used in atomic context, so
   * a special version of atomic ioremap is implemented for that.
   */
  
  /*
   * Two virtual pages are used, one for NMI context, the other for
   * IRQ/PROCESS context
   */
  #define GHES_IOREMAP_PAGES		2
  #define GHES_IOREMAP_NMI_PAGE(base)	(base)
  #define GHES_IOREMAP_IRQ_PAGE(base)	((base) + PAGE_SIZE)
  
  /* virtual memory area for atomic ioremap */
  static struct vm_struct *ghes_ioremap_area;
  /*
   * These 2 spinlock is used to prevent atomic ioremap virtual memory
   * area from being mapped simultaneously.
   */
  static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi);
  static DEFINE_SPINLOCK(ghes_ioremap_lock_irq);
  
  /*
   * printk is not safe in NMI context.  So in NMI handler, we allocate
   * required memory from lock-less memory allocator
   * (ghes_estatus_pool), save estatus into it, put them into lock-less
   * list (ghes_estatus_llist), then delay printk into IRQ context via
   * irq_work (ghes_proc_irq_work).  ghes_estatus_size_request record
   * required pool size by all NMI error source.
   */
  static struct gen_pool *ghes_estatus_pool;
  static unsigned long ghes_estatus_pool_size_request;
  static struct llist_head ghes_estatus_llist;
  static struct irq_work ghes_proc_irq_work;
  
  struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];
  static atomic_t ghes_estatus_cache_alloced;
  
  static int ghes_ioremap_init(void)
  {
  	ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
  		VM_IOREMAP, VMALLOC_START, VMALLOC_END);
  	if (!ghes_ioremap_area) {
  		pr_err(GHES_PFX "Failed to allocate virtual memory area for atomic ioremap.
  ");
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  static void ghes_ioremap_exit(void)
  {
  	free_vm_area(ghes_ioremap_area);
  }
  
  static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn)
  {
  	unsigned long vaddr;
  
  	vaddr = (unsigned long)GHES_IOREMAP_NMI_PAGE(ghes_ioremap_area->addr);
  	ioremap_page_range(vaddr, vaddr + PAGE_SIZE,
  			   pfn << PAGE_SHIFT, PAGE_KERNEL);
  
  	return (void __iomem *)vaddr;
  }
  
  static void __iomem *ghes_ioremap_pfn_irq(u64 pfn)
  {
  	unsigned long vaddr;
  
  	vaddr = (unsigned long)GHES_IOREMAP_IRQ_PAGE(ghes_ioremap_area->addr);
  	ioremap_page_range(vaddr, vaddr + PAGE_SIZE,
  			   pfn << PAGE_SHIFT, PAGE_KERNEL);
  
  	return (void __iomem *)vaddr;
  }
  
  static void ghes_iounmap_nmi(void __iomem *vaddr_ptr)
  {
  	unsigned long vaddr = (unsigned long __force)vaddr_ptr;
  	void *base = ghes_ioremap_area->addr;
  
  	BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_NMI_PAGE(base));
  	unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
  	__flush_tlb_one(vaddr);
  }
  
  static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
  {
  	unsigned long vaddr = (unsigned long __force)vaddr_ptr;
  	void *base = ghes_ioremap_area->addr;
  
  	BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_IRQ_PAGE(base));
  	unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
  	__flush_tlb_one(vaddr);
  }
  
  static int ghes_estatus_pool_init(void)
  {
  	ghes_estatus_pool = gen_pool_create(GHES_ESTATUS_POOL_MIN_ALLOC_ORDER, -1);
  	if (!ghes_estatus_pool)
  		return -ENOMEM;
  	return 0;
  }
  
  static void ghes_estatus_pool_free_chunk_page(struct gen_pool *pool,
  					      struct gen_pool_chunk *chunk,
  					      void *data)
  {
  	free_page(chunk->start_addr);
  }
  
  static void ghes_estatus_pool_exit(void)
  {
  	gen_pool_for_each_chunk(ghes_estatus_pool,
  				ghes_estatus_pool_free_chunk_page, NULL);
  	gen_pool_destroy(ghes_estatus_pool);
  }
  
  static int ghes_estatus_pool_expand(unsigned long len)
  {
  	unsigned long i, pages, size, addr;
  	int ret;
  
  	ghes_estatus_pool_size_request += PAGE_ALIGN(len);
  	size = gen_pool_size(ghes_estatus_pool);
  	if (size >= ghes_estatus_pool_size_request)
  		return 0;
  	pages = (ghes_estatus_pool_size_request - size) / PAGE_SIZE;
  	for (i = 0; i < pages; i++) {
  		addr = __get_free_page(GFP_KERNEL);
  		if (!addr)
  			return -ENOMEM;
  		ret = gen_pool_add(ghes_estatus_pool, addr, PAGE_SIZE, -1);
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }
  
  static void ghes_estatus_pool_shrink(unsigned long len)
  {
  	ghes_estatus_pool_size_request -= PAGE_ALIGN(len);
  }
  
  static struct ghes *ghes_new(struct acpi_hest_generic *generic)
  {
  	struct ghes *ghes;
  	unsigned int error_block_length;
  	int rc;
  
  	ghes = kzalloc(sizeof(*ghes), GFP_KERNEL);
  	if (!ghes)
  		return ERR_PTR(-ENOMEM);
  	ghes->generic = generic;
  	rc = apei_map_generic_address(&generic->error_status_address);
  	if (rc)
  		goto err_free;
  	error_block_length = generic->error_block_length;
  	if (error_block_length > GHES_ESTATUS_MAX_SIZE) {
  		pr_warning(FW_WARN GHES_PFX
  			   "Error status block length is too long: %u for "
  			   "generic hardware error source: %d.
  ",
  			   error_block_length, generic->header.source_id);
  		error_block_length = GHES_ESTATUS_MAX_SIZE;
  	}
  	ghes->estatus = kmalloc(error_block_length, GFP_KERNEL);
  	if (!ghes->estatus) {
  		rc = -ENOMEM;
  		goto err_unmap;
  	}
  
  	return ghes;
  
  err_unmap:
  	apei_unmap_generic_address(&generic->error_status_address);
  err_free:
  	kfree(ghes);
  	return ERR_PTR(rc);
  }
  
  static void ghes_fini(struct ghes *ghes)
  {
  	kfree(ghes->estatus);
  	apei_unmap_generic_address(&ghes->generic->error_status_address);
  }
  
  static inline int ghes_severity(int severity)
  {
  	switch (severity) {
  	case CPER_SEV_INFORMATIONAL:
  		return GHES_SEV_NO;
  	case CPER_SEV_CORRECTED:
  		return GHES_SEV_CORRECTED;
  	case CPER_SEV_RECOVERABLE:
  		return GHES_SEV_RECOVERABLE;
  	case CPER_SEV_FATAL:
  		return GHES_SEV_PANIC;
  	default:
  		/* Unknown, go panic */
  		return GHES_SEV_PANIC;
  	}
  }
  
  static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len,
  				  int from_phys)
  {
  	void __iomem *vaddr;
  	unsigned long flags = 0;
  	int in_nmi = in_nmi();
  	u64 offset;
  	u32 trunk;
  
  	while (len > 0) {
  		offset = paddr - (paddr & PAGE_MASK);
  		if (in_nmi) {
  			raw_spin_lock(&ghes_ioremap_lock_nmi);
  			vaddr = ghes_ioremap_pfn_nmi(paddr >> PAGE_SHIFT);
  		} else {
  			spin_lock_irqsave(&ghes_ioremap_lock_irq, flags);
  			vaddr = ghes_ioremap_pfn_irq(paddr >> PAGE_SHIFT);
  		}
  		trunk = PAGE_SIZE - offset;
  		trunk = min(trunk, len);
  		if (from_phys)
  			memcpy_fromio(buffer, vaddr + offset, trunk);
  		else
  			memcpy_toio(vaddr + offset, buffer, trunk);
  		len -= trunk;
  		paddr += trunk;
  		buffer += trunk;
  		if (in_nmi) {
  			ghes_iounmap_nmi(vaddr);
  			raw_spin_unlock(&ghes_ioremap_lock_nmi);
  		} else {
  			ghes_iounmap_irq(vaddr);
  			spin_unlock_irqrestore(&ghes_ioremap_lock_irq, flags);
  		}
  	}
  }
  
  static int ghes_read_estatus(struct ghes *ghes, int silent)
  {
  	struct acpi_hest_generic *g = ghes->generic;
  	u64 buf_paddr;
  	u32 len;
  	int rc;
  
  	rc = apei_read(&buf_paddr, &g->error_status_address);
  	if (rc) {
  		if (!silent && printk_ratelimit())
  			pr_warning(FW_WARN GHES_PFX
  "Failed to read error status block address for hardware error source: %d.
  ",
  				   g->header.source_id);
  		return -EIO;
  	}
  	if (!buf_paddr)
  		return -ENOENT;
  
  	ghes_copy_tofrom_phys(ghes->estatus, buf_paddr,
  			      sizeof(*ghes->estatus), 1);
  	if (!ghes->estatus->block_status)
  		return -ENOENT;
  
  	ghes->buffer_paddr = buf_paddr;
  	ghes->flags |= GHES_TO_CLEAR;
  
  	rc = -EIO;
  	len = cper_estatus_len(ghes->estatus);
  	if (len < sizeof(*ghes->estatus))
  		goto err_read_block;
  	if (len > ghes->generic->error_block_length)
  		goto err_read_block;
  	if (cper_estatus_check_header(ghes->estatus))
  		goto err_read_block;
  	ghes_copy_tofrom_phys(ghes->estatus + 1,
  			      buf_paddr + sizeof(*ghes->estatus),
  			      len - sizeof(*ghes->estatus), 1);
  	if (cper_estatus_check(ghes->estatus))
  		goto err_read_block;
  	rc = 0;
  
  err_read_block:
  	if (rc && !silent && printk_ratelimit())
  		pr_warning(FW_WARN GHES_PFX
  			   "Failed to read error status block!
  ");
  	return rc;
  }
  
  static void ghes_clear_estatus(struct ghes *ghes)
  {
  	ghes->estatus->block_status = 0;
  	if (!(ghes->flags & GHES_TO_CLEAR))
  		return;
  	ghes_copy_tofrom_phys(ghes->estatus, ghes->buffer_paddr,
  			      sizeof(ghes->estatus->block_status), 0);
  	ghes->flags &= ~GHES_TO_CLEAR;
  }
  
  static void ghes_handle_memory_failure(struct acpi_generic_data *gdata, int sev)
  {
  #ifdef CONFIG_ACPI_APEI_MEMORY_FAILURE
  	unsigned long pfn;
  	int flags = -1;
  	int sec_sev = ghes_severity(gdata->error_severity);
  	struct cper_sec_mem_err *mem_err;
  	mem_err = (struct cper_sec_mem_err *)(gdata + 1);
  
  	if (!(mem_err->validation_bits & CPER_MEM_VALID_PA))
  		return;
  
  	pfn = mem_err->physical_addr >> PAGE_SHIFT;
  	if (!pfn_valid(pfn)) {
  		pr_warn_ratelimited(FW_WARN GHES_PFX
  		"Invalid address in generic error data: %#llx
  ",
  		mem_err->physical_addr);
  		return;
  	}
  
  	/* iff following two events can be handled properly by now */
  	if (sec_sev == GHES_SEV_CORRECTED &&
  	    (gdata->flags & CPER_SEC_ERROR_THRESHOLD_EXCEEDED))
  		flags = MF_SOFT_OFFLINE;
  	if (sev == GHES_SEV_RECOVERABLE && sec_sev == GHES_SEV_RECOVERABLE)
  		flags = 0;
  
  	if (flags != -1)
  		memory_failure_queue(pfn, 0, flags);
  #endif
  }
  
  static void ghes_do_proc(struct ghes *ghes,
  			 const struct acpi_generic_status *estatus)
  {
  	int sev, sec_sev;
  	struct acpi_generic_data *gdata;
  
  	sev = ghes_severity(estatus->error_severity);
  	apei_estatus_for_each_section(estatus, gdata) {
  		sec_sev = ghes_severity(gdata->error_severity);
  		if (!uuid_le_cmp(*(uuid_le *)gdata->section_type,
  				 CPER_SEC_PLATFORM_MEM)) {
  			struct cper_sec_mem_err *mem_err;
  			mem_err = (struct cper_sec_mem_err *)(gdata+1);
  			ghes_edac_report_mem_error(ghes, sev, mem_err);
  
  #ifdef CONFIG_X86_MCE
  			apei_mce_report_mem_error(sev, mem_err);
  #endif
  			ghes_handle_memory_failure(gdata, sev);
  		}
  #ifdef CONFIG_ACPI_APEI_PCIEAER
  		else if (!uuid_le_cmp(*(uuid_le *)gdata->section_type,
  				      CPER_SEC_PCIE)) {
  			struct cper_sec_pcie *pcie_err;
  			pcie_err = (struct cper_sec_pcie *)(gdata+1);
  			if (sev == GHES_SEV_RECOVERABLE &&
  			    sec_sev == GHES_SEV_RECOVERABLE &&
  			    pcie_err->validation_bits & CPER_PCIE_VALID_DEVICE_ID &&
  			    pcie_err->validation_bits & CPER_PCIE_VALID_AER_INFO) {
  				unsigned int devfn;
  				int aer_severity;
  
  				devfn = PCI_DEVFN(pcie_err->device_id.device,
  						  pcie_err->device_id.function);
  				aer_severity = cper_severity_to_aer(sev);
  
  				/*
  				 * If firmware reset the component to contain
  				 * the error, we must reinitialize it before
  				 * use, so treat it as a fatal AER error.
  				 */
  				if (gdata->flags & CPER_SEC_RESET)
  					aer_severity = AER_FATAL;
  
  				aer_recover_queue(pcie_err->device_id.segment,
  						  pcie_err->device_id.bus,
  						  devfn, aer_severity,
  						  (struct aer_capability_regs *)
  						  pcie_err->aer_info);
  			}
  
  		}
  #endif
  	}
  }
  
  static void __ghes_print_estatus(const char *pfx,
  				 const struct acpi_hest_generic *generic,
  				 const struct acpi_generic_status *estatus)
  {
  	static atomic_t seqno;
  	unsigned int curr_seqno;
  	char pfx_seq[64];
  
  	if (pfx == NULL) {
  		if (ghes_severity(estatus->error_severity) <=
  		    GHES_SEV_CORRECTED)
  			pfx = KERN_WARNING;
  		else
  			pfx = KERN_ERR;
  	}
  	curr_seqno = atomic_inc_return(&seqno);
  	snprintf(pfx_seq, sizeof(pfx_seq), "%s{%u}" HW_ERR, pfx, curr_seqno);
  	printk("%s""Hardware error from APEI Generic Hardware Error Source: %d
  ",
  	       pfx_seq, generic->header.source_id);
  	cper_estatus_print(pfx_seq, estatus);
  }
  
  static int ghes_print_estatus(const char *pfx,
  			      const struct acpi_hest_generic *generic,
  			      const struct acpi_generic_status *estatus)
  {
  	/* Not more than 2 messages every 5 seconds */
  	static DEFINE_RATELIMIT_STATE(ratelimit_corrected, 5*HZ, 2);
  	static DEFINE_RATELIMIT_STATE(ratelimit_uncorrected, 5*HZ, 2);
  	struct ratelimit_state *ratelimit;
  
  	if (ghes_severity(estatus->error_severity) <= GHES_SEV_CORRECTED)
  		ratelimit = &ratelimit_corrected;
  	else
  		ratelimit = &ratelimit_uncorrected;
  	if (__ratelimit(ratelimit)) {
  		__ghes_print_estatus(pfx, generic, estatus);
  		return 1;
  	}
  	return 0;
  }
  
  /*
   * GHES error status reporting throttle, to report more kinds of
   * errors, instead of just most frequently occurred errors.
   */
  static int ghes_estatus_cached(struct acpi_generic_status *estatus)
  {
  	u32 len;
  	int i, cached = 0;
  	unsigned long long now;
  	struct ghes_estatus_cache *cache;
  	struct acpi_generic_status *cache_estatus;
  
  	len = cper_estatus_len(estatus);
  	rcu_read_lock();
  	for (i = 0; i < GHES_ESTATUS_CACHES_SIZE; i++) {
  		cache = rcu_dereference(ghes_estatus_caches[i]);
  		if (cache == NULL)
  			continue;
  		if (len != cache->estatus_len)
  			continue;
  		cache_estatus = GHES_ESTATUS_FROM_CACHE(cache);
  		if (memcmp(estatus, cache_estatus, len))
  			continue;
  		atomic_inc(&cache->count);
  		now = sched_clock();
  		if (now - cache->time_in < GHES_ESTATUS_IN_CACHE_MAX_NSEC)
  			cached = 1;
  		break;
  	}
  	rcu_read_unlock();
  	return cached;
  }
  
  static struct ghes_estatus_cache *ghes_estatus_cache_alloc(
  	struct acpi_hest_generic *generic,
  	struct acpi_generic_status *estatus)
  {
  	int alloced;
  	u32 len, cache_len;
  	struct ghes_estatus_cache *cache;
  	struct acpi_generic_status *cache_estatus;
  
  	alloced = atomic_add_return(1, &ghes_estatus_cache_alloced);
  	if (alloced > GHES_ESTATUS_CACHE_ALLOCED_MAX) {
  		atomic_dec(&ghes_estatus_cache_alloced);
  		return NULL;
  	}
  	len = cper_estatus_len(estatus);
  	cache_len = GHES_ESTATUS_CACHE_LEN(len);
  	cache = (void *)gen_pool_alloc(ghes_estatus_pool, cache_len);
  	if (!cache) {
  		atomic_dec(&ghes_estatus_cache_alloced);
  		return NULL;
  	}
  	cache_estatus = GHES_ESTATUS_FROM_CACHE(cache);
  	memcpy(cache_estatus, estatus, len);
  	cache->estatus_len = len;
  	atomic_set(&cache->count, 0);
  	cache->generic = generic;
  	cache->time_in = sched_clock();
  	return cache;
  }
  
  static void ghes_estatus_cache_free(struct ghes_estatus_cache *cache)
  {
  	u32 len;
  
  	len = cper_estatus_len(GHES_ESTATUS_FROM_CACHE(cache));
  	len = GHES_ESTATUS_CACHE_LEN(len);
  	gen_pool_free(ghes_estatus_pool, (unsigned long)cache, len);
  	atomic_dec(&ghes_estatus_cache_alloced);
  }
  
  static void ghes_estatus_cache_rcu_free(struct rcu_head *head)
  {
  	struct ghes_estatus_cache *cache;
  
  	cache = container_of(head, struct ghes_estatus_cache, rcu);
  	ghes_estatus_cache_free(cache);
  }
  
  static void ghes_estatus_cache_add(
  	struct acpi_hest_generic *generic,
  	struct acpi_generic_status *estatus)
  {
  	int i, slot = -1, count;
  	unsigned long long now, duration, period, max_period = 0;
  	struct ghes_estatus_cache *cache, *slot_cache = NULL, *new_cache;
  
  	new_cache = ghes_estatus_cache_alloc(generic, estatus);
  	if (new_cache == NULL)
  		return;
  	rcu_read_lock();
  	now = sched_clock();
  	for (i = 0; i < GHES_ESTATUS_CACHES_SIZE; i++) {
  		cache = rcu_dereference(ghes_estatus_caches[i]);
  		if (cache == NULL) {
  			slot = i;
  			slot_cache = NULL;
  			break;
  		}
  		duration = now - cache->time_in;
  		if (duration >= GHES_ESTATUS_IN_CACHE_MAX_NSEC) {
  			slot = i;
  			slot_cache = cache;
  			break;
  		}
  		count = atomic_read(&cache->count);
  		period = duration;
  		do_div(period, (count + 1));
  		if (period > max_period) {
  			max_period = period;
  			slot = i;
  			slot_cache = cache;
  		}
  	}
  	/* new_cache must be put into array after its contents are written */
  	smp_wmb();
  	if (slot != -1 && cmpxchg(ghes_estatus_caches + slot,
  				  slot_cache, new_cache) == slot_cache) {
  		if (slot_cache)
  			call_rcu(&slot_cache->rcu, ghes_estatus_cache_rcu_free);
  	} else
  		ghes_estatus_cache_free(new_cache);
  	rcu_read_unlock();
  }
  
  static int ghes_proc(struct ghes *ghes)
  {
  	int rc;
  
  	rc = ghes_read_estatus(ghes, 0);
  	if (rc)
  		goto out;
  	if (!ghes_estatus_cached(ghes->estatus)) {
  		if (ghes_print_estatus(NULL, ghes->generic, ghes->estatus))
  			ghes_estatus_cache_add(ghes->generic, ghes->estatus);
  	}
  	ghes_do_proc(ghes, ghes->estatus);
  out:
  	ghes_clear_estatus(ghes);
  	return 0;
  }
  
  static void ghes_add_timer(struct ghes *ghes)
  {
  	struct acpi_hest_generic *g = ghes->generic;
  	unsigned long expire;
  
  	if (!g->notify.poll_interval) {
  		pr_warning(FW_WARN GHES_PFX "Poll interval is 0 for generic hardware error source: %d, disabled.
  ",
  			   g->header.source_id);
  		return;
  	}
  	expire = jiffies + msecs_to_jiffies(g->notify.poll_interval);
  	ghes->timer.expires = round_jiffies_relative(expire);
  	add_timer(&ghes->timer);
  }
  
  static void ghes_poll_func(unsigned long data)
  {
  	struct ghes *ghes = (void *)data;
  
  	ghes_proc(ghes);
  	if (!(ghes->flags & GHES_EXITING))
  		ghes_add_timer(ghes);
  }
  
  static irqreturn_t ghes_irq_func(int irq, void *data)
  {
  	struct ghes *ghes = data;
  	int rc;
  
  	rc = ghes_proc(ghes);
  	if (rc)
  		return IRQ_NONE;
  
  	return IRQ_HANDLED;
  }
  
  static int ghes_notify_sci(struct notifier_block *this,
  				  unsigned long event, void *data)
  {
  	struct ghes *ghes;
  	int ret = NOTIFY_DONE;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(ghes, &ghes_sci, list) {
  		if (!ghes_proc(ghes))
  			ret = NOTIFY_OK;
  	}
  	rcu_read_unlock();
  
  	return ret;
  }
  
  static struct llist_node *llist_nodes_reverse(struct llist_node *llnode)
  {
  	struct llist_node *next, *tail = NULL;
  
  	while (llnode) {
  		next = llnode->next;
  		llnode->next = tail;
  		tail = llnode;
  		llnode = next;
  	}
  
  	return tail;
  }
  
  static void ghes_proc_in_irq(struct irq_work *irq_work)
  {
  	struct llist_node *llnode, *next;
  	struct ghes_estatus_node *estatus_node;
  	struct acpi_hest_generic *generic;
  	struct acpi_generic_status *estatus;
  	u32 len, node_len;
  
  	llnode = llist_del_all(&ghes_estatus_llist);
  	/*
  	 * Because the time order of estatus in list is reversed,
  	 * revert it back to proper order.
  	 */
  	llnode = llist_nodes_reverse(llnode);
  	while (llnode) {
  		next = llnode->next;
  		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
  					   llnode);
  		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
  		len = cper_estatus_len(estatus);
  		node_len = GHES_ESTATUS_NODE_LEN(len);
  		ghes_do_proc(estatus_node->ghes, estatus);
  		if (!ghes_estatus_cached(estatus)) {
  			generic = estatus_node->generic;
  			if (ghes_print_estatus(NULL, generic, estatus))
  				ghes_estatus_cache_add(generic, estatus);
  		}
  		gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node,
  			      node_len);
  		llnode = next;
  	}
  }
  
  static void ghes_print_queued_estatus(void)
  {
  	struct llist_node *llnode;
  	struct ghes_estatus_node *estatus_node;
  	struct acpi_hest_generic *generic;
  	struct acpi_generic_status *estatus;
  	u32 len, node_len;
  
  	llnode = llist_del_all(&ghes_estatus_llist);
  	/*
  	 * Because the time order of estatus in list is reversed,
  	 * revert it back to proper order.
  	 */
  	llnode = llist_nodes_reverse(llnode);
  	while (llnode) {
  		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
  					   llnode);
  		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
  		len = cper_estatus_len(estatus);
  		node_len = GHES_ESTATUS_NODE_LEN(len);
  		generic = estatus_node->generic;
  		ghes_print_estatus(NULL, generic, estatus);
  		llnode = llnode->next;
  	}
  }
  
  static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
  {
  	struct ghes *ghes, *ghes_global = NULL;
  	int sev, sev_global = -1;
  	int ret = NMI_DONE;
  
  	raw_spin_lock(&ghes_nmi_lock);
  	list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
  		if (ghes_read_estatus(ghes, 1)) {
  			ghes_clear_estatus(ghes);
  			continue;
  		}
  		sev = ghes_severity(ghes->estatus->error_severity);
  		if (sev > sev_global) {
  			sev_global = sev;
  			ghes_global = ghes;
  		}
  		ret = NMI_HANDLED;
  	}
  
  	if (ret == NMI_DONE)
  		goto out;
  
  	if (sev_global >= GHES_SEV_PANIC) {
  		oops_begin();
  		ghes_print_queued_estatus();
  		__ghes_print_estatus(KERN_EMERG, ghes_global->generic,
  				     ghes_global->estatus);
  		/* reboot to log the error! */
  		if (panic_timeout == 0)
  			panic_timeout = ghes_panic_timeout;
  		panic("Fatal hardware error!");
  	}
  
  	list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
  #ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
  		u32 len, node_len;
  		struct ghes_estatus_node *estatus_node;
  		struct acpi_generic_status *estatus;
  #endif
  		if (!(ghes->flags & GHES_TO_CLEAR))
  			continue;
  #ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
  		if (ghes_estatus_cached(ghes->estatus))
  			goto next;
  		/* Save estatus for further processing in IRQ context */
  		len = cper_estatus_len(ghes->estatus);
  		node_len = GHES_ESTATUS_NODE_LEN(len);
  		estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool,
  						      node_len);
  		if (estatus_node) {
  			estatus_node->ghes = ghes;
  			estatus_node->generic = ghes->generic;
  			estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
  			memcpy(estatus, ghes->estatus, len);
  			llist_add(&estatus_node->llnode, &ghes_estatus_llist);
  		}
  next:
  #endif
  		ghes_clear_estatus(ghes);
  	}
  #ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
  	irq_work_queue(&ghes_proc_irq_work);
  #endif
  
  out:
  	raw_spin_unlock(&ghes_nmi_lock);
  	return ret;
  }
  
  static struct notifier_block ghes_notifier_sci = {
  	.notifier_call = ghes_notify_sci,
  };
  
  static unsigned long ghes_esource_prealloc_size(
  	const struct acpi_hest_generic *generic)
  {
  	unsigned long block_length, prealloc_records, prealloc_size;
  
  	block_length = min_t(unsigned long, generic->error_block_length,
  			     GHES_ESTATUS_MAX_SIZE);
  	prealloc_records = max_t(unsigned long,
  				 generic->records_to_preallocate, 1);
  	prealloc_size = min_t(unsigned long, block_length * prealloc_records,
  			      GHES_ESOURCE_PREALLOC_MAX_SIZE);
  
  	return prealloc_size;
  }
  
  static int ghes_probe(struct platform_device *ghes_dev)
  {
  	struct acpi_hest_generic *generic;
  	struct ghes *ghes = NULL;
  	unsigned long len;
  	int rc = -EINVAL;
  
  	generic = *(struct acpi_hest_generic **)ghes_dev->dev.platform_data;
  	if (!generic->enabled)
  		return -ENODEV;
  
  	switch (generic->notify.type) {
  	case ACPI_HEST_NOTIFY_POLLED:
  	case ACPI_HEST_NOTIFY_EXTERNAL:
  	case ACPI_HEST_NOTIFY_SCI:
  	case ACPI_HEST_NOTIFY_NMI:
  		break;
  	case ACPI_HEST_NOTIFY_LOCAL:
  		pr_warning(GHES_PFX "Generic hardware error source: %d notified via local interrupt is not supported!
  ",
  			   generic->header.source_id);
  		goto err;
  	default:
  		pr_warning(FW_WARN GHES_PFX "Unknown notification type: %u for generic hardware error source: %d
  ",
  			   generic->notify.type, generic->header.source_id);
  		goto err;
  	}
  
  	rc = -EIO;
  	if (generic->error_block_length <
  	    sizeof(struct acpi_generic_status)) {
  		pr_warning(FW_BUG GHES_PFX "Invalid error block length: %u for generic hardware error source: %d
  ",
  			   generic->error_block_length,
  			   generic->header.source_id);
  		goto err;
  	}
  	ghes = ghes_new(generic);
  	if (IS_ERR(ghes)) {
  		rc = PTR_ERR(ghes);
  		ghes = NULL;
  		goto err;
  	}
  
  	rc = ghes_edac_register(ghes, &ghes_dev->dev);
  	if (rc < 0)
  		goto err;
  
  	switch (generic->notify.type) {
  	case ACPI_HEST_NOTIFY_POLLED:
  		ghes->timer.function = ghes_poll_func;
  		ghes->timer.data = (unsigned long)ghes;
  		init_timer_deferrable(&ghes->timer);
  		ghes_add_timer(ghes);
  		break;
  	case ACPI_HEST_NOTIFY_EXTERNAL:
  		/* External interrupt vector is GSI */
  		rc = acpi_gsi_to_irq(generic->notify.vector, &ghes->irq);
  		if (rc) {
  			pr_err(GHES_PFX "Failed to map GSI to IRQ for generic hardware error source: %d
  ",
  			       generic->header.source_id);
  			goto err_edac_unreg;
  		}
  		rc = request_irq(ghes->irq, ghes_irq_func, 0, "GHES IRQ", ghes);
  		if (rc) {
  			pr_err(GHES_PFX "Failed to register IRQ for generic hardware error source: %d
  ",
  			       generic->header.source_id);
  			goto err_edac_unreg;
  		}
  		break;
  	case ACPI_HEST_NOTIFY_SCI:
  		mutex_lock(&ghes_list_mutex);
  		if (list_empty(&ghes_sci))
  			register_acpi_hed_notifier(&ghes_notifier_sci);
  		list_add_rcu(&ghes->list, &ghes_sci);
  		mutex_unlock(&ghes_list_mutex);
  		break;
  	case ACPI_HEST_NOTIFY_NMI:
  		len = ghes_esource_prealloc_size(generic);
  		ghes_estatus_pool_expand(len);
  		mutex_lock(&ghes_list_mutex);
  		if (list_empty(&ghes_nmi))
  			register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0,
  						"ghes");
  		list_add_rcu(&ghes->list, &ghes_nmi);
  		mutex_unlock(&ghes_list_mutex);
  		break;
  	default:
  		BUG();
  	}
  	platform_set_drvdata(ghes_dev, ghes);
  
  	return 0;
  err_edac_unreg:
  	ghes_edac_unregister(ghes);
  err:
  	if (ghes) {
  		ghes_fini(ghes);
  		kfree(ghes);
  	}
  	return rc;
  }
  
  static int ghes_remove(struct platform_device *ghes_dev)
  {
  	struct ghes *ghes;
  	struct acpi_hest_generic *generic;
  	unsigned long len;
  
  	ghes = platform_get_drvdata(ghes_dev);
  	generic = ghes->generic;
  
  	ghes->flags |= GHES_EXITING;
  	switch (generic->notify.type) {
  	case ACPI_HEST_NOTIFY_POLLED:
  		del_timer_sync(&ghes->timer);
  		break;
  	case ACPI_HEST_NOTIFY_EXTERNAL:
  		free_irq(ghes->irq, ghes);
  		break;
  	case ACPI_HEST_NOTIFY_SCI:
  		mutex_lock(&ghes_list_mutex);
  		list_del_rcu(&ghes->list);
  		if (list_empty(&ghes_sci))
  			unregister_acpi_hed_notifier(&ghes_notifier_sci);
  		mutex_unlock(&ghes_list_mutex);
  		break;
  	case ACPI_HEST_NOTIFY_NMI:
  		mutex_lock(&ghes_list_mutex);
  		list_del_rcu(&ghes->list);
  		if (list_empty(&ghes_nmi))
  			unregister_nmi_handler(NMI_LOCAL, "ghes");
  		mutex_unlock(&ghes_list_mutex);
  		/*
  		 * To synchronize with NMI handler, ghes can only be
  		 * freed after NMI handler finishes.
  		 */
  		synchronize_rcu();
  		len = ghes_esource_prealloc_size(generic);
  		ghes_estatus_pool_shrink(len);
  		break;
  	default:
  		BUG();
  		break;
  	}
  
  	ghes_fini(ghes);
  
  	ghes_edac_unregister(ghes);
  
  	kfree(ghes);
  
  	platform_set_drvdata(ghes_dev, NULL);
  
  	return 0;
  }
  
  static struct platform_driver ghes_platform_driver = {
  	.driver		= {
  		.name	= "GHES",
  		.owner	= THIS_MODULE,
  	},
  	.probe		= ghes_probe,
  	.remove		= ghes_remove,
  };
  
  static int __init ghes_init(void)
  {
  	int rc;
  
  	if (acpi_disabled)
  		return -ENODEV;
  
  	if (hest_disable) {
  		pr_info(GHES_PFX "HEST is not enabled!
  ");
  		return -EINVAL;
  	}
  
  	if (ghes_disable) {
  		pr_info(GHES_PFX "GHES is not enabled!
  ");
  		return -EINVAL;
  	}
  
  	init_irq_work(&ghes_proc_irq_work, ghes_proc_in_irq);
  
  	rc = ghes_ioremap_init();
  	if (rc)
  		goto err;
  
  	rc = ghes_estatus_pool_init();
  	if (rc)
  		goto err_ioremap_exit;
  
  	rc = ghes_estatus_pool_expand(GHES_ESTATUS_CACHE_AVG_SIZE *
  				      GHES_ESTATUS_CACHE_ALLOCED_MAX);
  	if (rc)
  		goto err_pool_exit;
  
  	rc = platform_driver_register(&ghes_platform_driver);
  	if (rc)
  		goto err_pool_exit;
  
  	rc = apei_osc_setup();
  	if (rc == 0 && osc_sb_apei_support_acked)
  		pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit and WHEA _OSC.
  ");
  	else if (rc == 0 && !osc_sb_apei_support_acked)
  		pr_info(GHES_PFX "APEI firmware first mode is enabled by WHEA _OSC.
  ");
  	else if (rc && osc_sb_apei_support_acked)
  		pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit.
  ");
  	else
  		pr_info(GHES_PFX "Failed to enable APEI firmware first mode.
  ");
  
  	return 0;
  err_pool_exit:
  	ghes_estatus_pool_exit();
  err_ioremap_exit:
  	ghes_ioremap_exit();
  err:
  	return rc;
  }
  
  static void __exit ghes_exit(void)
  {
  	platform_driver_unregister(&ghes_platform_driver);
  	ghes_estatus_pool_exit();
  	ghes_ioremap_exit();
  }
  
  module_init(ghes_init);
  module_exit(ghes_exit);
  
  MODULE_AUTHOR("Huang Ying");
  MODULE_DESCRIPTION("APEI Generic Hardware Error Source support");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:GHES");