osfmk/i386/x86_hypercall.c

   1 /*
   2  * Copyright (c) 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 <kern/assert.h>
  30 #include <kern/hvg_hypercall.h>
  31 #include <i386/cpuid.h>
  32 #include <os/log.h>
  33
  34
  35 static bool
  36 hvg_live_coredump_enabled(void)
  37 {
  38         return cpuid_vmm_present() && (cpuid_vmm_get_applepv_features() & CPUID_LEAF_FEATURE_COREDUMP) != 0;
  39 }
  40
  41 /*
  42  * This routine issues an Apple hypercall that notifies the hypervisor to
  43  * take a guest kernel coredump. If the vmcore argument is not NULL, the
  44  * name tag of the vmcore file is copied into the caller's vmcore tag array.
  45  * Otherwise the name tag is ignored.
  46  */
  47
  48 hvg_hcall_return_t
  49 hvg_hcall_trigger_dump(hvg_hcall_vmcore_file_t *vmcore,
  50     const hvg_hcall_dump_option_t dump_option)
  51 {
  52         hvg_hcall_return_t ret;
  53         hvg_hcall_output_regs_t output;
  54         const size_t reg_size = sizeof(output.rax);
  55
  56         /* Does the hypervisor support feature: live kernel core dump? */
  57         if (!hvg_live_coredump_enabled()) {
  58                 return HVG_HCALL_FEAT_DISABLED;
  59         }
  60
  61         /* Make sure that we don't overflow vmcore tag array with hypercall output */
  62         if (vmcore && (reg_size != sizeof(uint64_t))) {
  63                 os_log_error(OS_LOG_DEFAULT, "%s: invalid hcall register size, %zu bytes (expect %zu bytes)\n",
  64                     __func__, reg_size, sizeof(uint64_t));
  65                 return HVG_HCALL_INVALID_PARAMETER;
  66         }
  67
  68         switch (dump_option) {
  69         case HVG_HCALL_DUMP_OPTION_REGULAR:
  70                 /* Only regular dump-guest-memory is supported for now */
  71                 break;
  72         default:
  73                 return HVG_HCALL_INVALID_PARAMETER;
  74         }
  75
  76         /* Everything checks out, issue hypercall */
  77         memset(&output, 0, sizeof(hvg_hcall_output_regs_t));
  78         ret = hvg_hypercall1(HVG_HCALL_TRIGGER_DUMP,
  79             dump_option,
  80             &output);
  81
  82         if (ret == HVG_HCALL_SUCCESS) {
  83                 if (vmcore) {
  84                         /* Caller requested vmcore tag to be returned */
  85                         memcpy(&vmcore->tag[0], &output.rax, reg_size);
  86                         memcpy(&vmcore->tag[reg_size], &output.rdi, reg_size);
  87                         memcpy(&vmcore->tag[reg_size * 2], &output.rsi, reg_size);
  88                         memcpy(&vmcore->tag[reg_size * 3], &output.rdx, reg_size);
  89                         memcpy(&vmcore->tag[reg_size * 4], &output.rcx, reg_size);
  90                         memcpy(&vmcore->tag[reg_size * 5], &output.r8, reg_size);
  91                         memcpy(&vmcore->tag[reg_size * 6], &output.r9, reg_size);
  92                         vmcore->tag[reg_size * 7] = '\0';
  93                 }
  94         }
  95         return ret;
  96 }