tests/x18.c

   1 /*
   2  * Copyright (c) 2019 Apple Computer, 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 <darwintest.h>
  30 #include <pthread.h>
  31 #include <sys/types.h>
  32 #include <sys/sysctl.h>
  33
  34 T_GLOBAL_META(
  35         T_META_NAMESPACE("xnu.arm"),
  36         T_META_RUN_CONCURRENTLY(true));
  37
  38 T_DECL(x18_preserved,
  39     "Test that x18 is preserved on hardware that supports it.")
  40 {
  41 #ifndef __arm64__
  42         T_SKIP("Running on non-arm64 target, skipping...");
  43 #else
  44         int arm_kernel_protect = 0;
  45         size_t arm_kernel_protect_size = sizeof(arm_kernel_protect);
  46         bool preserved = true;
  47
  48         int err = sysctlbyname("hw.optional.arm_kernel_protect", &arm_kernel_protect, &arm_kernel_protect_size, NULL, 0);
  49         if (err) {
  50                 T_SKIP("Could not determine state of __ARM_KERNEL_PROTECT__, skipping...");
  51         }
  52         if (arm_kernel_protect) {
  53                 preserved = false;
  54         }
  55
  56         uint64_t x18_val;
  57         for (uint64_t i = 0xFEEDB0B000000000ULL; i < 0xFEEDB0B000000000ULL + 10000; ++i) {
  58                 asm volatile ("mov x18, %0" : : "r"(i));
  59                 sched_yield();
  60                 asm volatile ("mov %0, x18" : "=r"(x18_val));
  61                 if (preserved) {
  62                         T_QUIET; T_ASSERT_EQ(x18_val, i, "check that x18 reads back correctly after yield");
  63                 } else {
  64                         T_QUIET; T_ASSERT_EQ(x18_val, 0ULL, "check that x18 is cleared after yield");
  65                 }
  66         }
  67 #endif
  68 }