1  /*
  2   * Copyright (c) 2013 Apple Inc. All rights reserved.
  3   *
  4   * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  5   *
  6   * This file contains Original Code and/or Modifications of Original Code
  7   * as defined in and that are subject to the Apple Public Source License
  8   * Version 2.0 (the 'License'). You may not use this file except in
  9   * compliance with the License. The rights granted to you under the License
 10   * may not be used to create, or enable the creation or redistribution of,
 11   * unlawful or unlicensed copies of an Apple operating system, or to
 12   * circumvent, violate, or enable the circumvention or violation of, any
 13   * terms of an Apple operating system software license agreement.
 14   *
 15   * Please obtain a copy of the License at
 16   * http://www.opensource.apple.com/apsl/ and read it before using this file.
 17   *
 18   * The Original Code and all software distributed under the License are
 19   * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 20   * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 21   * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 22   * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 23   * Please see the License for the specific language governing rights and
 24   * limitations under the License.
 25   *
 26   * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 27   */
 28  #include <mach/mach_types.h>
 29  #include <mach/host_info.h>
 30  #include <kern/locks.h>
 31  #include <kern/ecc.h>
 32  #include <kern/spl.h>
 33  #include <pexpert/pexpert.h>
 34  #include <libkern/OSAtomic.h>
 35  
 36  /*
 37   * ECC data.  Not really KPCs, but this still seems like the
 38   * best home for this code.
 39   *
 40   * Circular buffer of events.  When we fill up, drop data.
 41   */
 42  #define ECC_EVENT_BUFFER_COUNT  5
 43  struct ecc_event                ecc_data[ECC_EVENT_BUFFER_COUNT];
 44  static uint32_t                 ecc_data_next_read;
 45  static uint32_t                 ecc_data_next_write;
 46  static boolean_t                ecc_data_empty = TRUE; // next read == next write : empty or full?
 47  static LCK_GRP_DECLARE(ecc_data_lock_group, "ecc-data");
 48  static LCK_SPIN_DECLARE(ecc_data_lock, &ecc_data_lock_group);
 49  static uint32_t                 ecc_correction_count;
 50  
 51  uint32_t
 52  ecc_log_get_correction_count()
 53  {
 54  	return ecc_correction_count;
 55  }
 56  
 57  kern_return_t
 58  ecc_log_record_event(const struct ecc_event *ev)
 59  {
 60  	spl_t x;
 61  
 62  	if (ev->count > ECC_EVENT_INFO_DATA_ENTRIES) {
 63  		panic("Count of %u on ecc event is too large.", (unsigned)ev->count);
 64  	}
 65  
 66  	x = splhigh();
 67  	lck_spin_lock(&ecc_data_lock);
 68  
 69  	ecc_correction_count++;
 70  
 71  	if (ecc_data_next_read == ecc_data_next_write && !ecc_data_empty) {
 72  		lck_spin_unlock(&ecc_data_lock);
 73  		splx(x);
 74  		return KERN_FAILURE;
 75  	}
 76  
 77  	bcopy(ev, &ecc_data[ecc_data_next_write], sizeof(*ev));
 78  	ecc_data_next_write++;
 79  	ecc_data_next_write %= ECC_EVENT_BUFFER_COUNT;
 80  	ecc_data_empty = FALSE;
 81  
 82  	lck_spin_unlock(&ecc_data_lock);
 83  	splx(x);
 84  
 85  	return KERN_SUCCESS;
 86  }
 87  
 88  
 89  kern_return_t
 90  ecc_log_get_next_event(struct ecc_event *ev)
 91  {
 92  	spl_t x;
 93  
 94  	x = splhigh();
 95  	lck_spin_lock(&ecc_data_lock);
 96  
 97  	if (ecc_data_empty) {
 98  		assert(ecc_data_next_write == ecc_data_next_read);
 99  
100  		lck_spin_unlock(&ecc_data_lock);
101  		splx(x);
102  		return KERN_FAILURE;
103  	}
104  
105  	bcopy(&ecc_data[ecc_data_next_read], ev, sizeof(*ev));
106  	ecc_data_next_read++;
107  	ecc_data_next_read %= ECC_EVENT_BUFFER_COUNT;
108  
109  	if (ecc_data_next_read == ecc_data_next_write) {
110  		ecc_data_empty = TRUE;
111  	}
112  
113  	lck_spin_unlock(&ecc_data_lock);
114  	splx(x);
115  
116  	return KERN_SUCCESS;
117  }