osfmk/i386/panic_notify.c

   1 /*
   2  * Copyright (c) 2000-2020 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
  29 #include <architecture/i386/pio.h>
  30 #include <i386/panic_notify.h>
  31 #include <kern/assert.h>
  32 #include <pexpert/pexpert.h>
  33 #include <stdint.h>
  34
  35 /*
  36  * An I/O port to issue a read from, in the event of a panic.
  37  * Useful for triggering logic analyzers.
  38  */
  39 static uint16_t panic_io_port = 0;
  40
  41 /*
  42  * Similar to the panic_io_port, the pvpanic_io_port is used to notify
  43  * interested parties (in this case the host/hypervisor), that a panic
  44  * has occurred.
  45  * Where it differs from panic_io_port is that it is written and read
  46  * according to the pvpanic specification:
  47  * https://raw.githubusercontent.com/qemu/qemu/master/docs/specs/pvpanic.txt
  48  */
  49 static uint16_t pvpanic_io_port = 0;
  50
  51 void
  52 panic_notify_init(void)
  53 {
  54         (void) PE_parse_boot_argn("panic_io_port", &panic_io_port, sizeof(panic_io_port));
  55
  56         /*
  57          * XXX
  58          * Defer reading the notifcation bit until panic time. This maintains
  59          * backwards compatibility with Apple's QEMU. Once backwards
  60          * compatibilty is no longer needed the check should be performed here
  61          * before setting pvpanic_io_port.
  62          */
  63         (void) PE_parse_boot_argn("pvpanic_io_port", &pvpanic_io_port, sizeof(pvpanic_io_port));
  64 }
  65
  66 void
  67 panic_notify(void)
  68 {
  69         if (panic_io_port != 0) {
  70                 (void) inb(panic_io_port);
  71         }
  72
  73         if (pvpanic_io_port != 0 &&
  74             (inb(pvpanic_io_port) & PVPANIC_NOTIFICATION_BIT) != 0) {
  75                 outb(pvpanic_io_port, PVPANIC_NOTIFICATION_BIT);
  76         }
  77 }