1 /* 2 * Copyright (c) 2019-2022 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 "context_helpers.h" 30 #include <darwintest.h> 31 #include <sys/types.h> 32 #include <sys/sysctl.h> 33 #include <stdbool.h> 34 #include <unistd.h> 35 36 T_GLOBAL_META( 37 T_META_NAMESPACE("xnu.arm"), 38 T_META_RADAR_COMPONENT_NAME("xnu"), 39 T_META_RADAR_COMPONENT_VERSION("arm"), 40 T_META_OWNER("joster"), 41 T_META_REQUIRES_SYSCTL_EQ("hw.optional.arm_kernel_protect", 0), // entitlement will crash on arm_kernel_protect devices 42 T_META_RUN_CONCURRENTLY(true), 43 T_META_TAG_VM_PREFERRED); 44 45 T_DECL(x18_entitled, 46 "Test that x18 is preserved on hardware that supports it, if entitled.") 47 { 48 #ifndef __arm64__ 49 T_SKIP("Running on non-arm64 target, skipping..."); 50 #else 51 bool did_csw = false; 52 uint64_t x18_val; 53 54 for (uint64_t i = 0xFEEDB0B000000000ULL; i < 0xFEEDB0B000000000ULL + 10000; ++i) { 55 asm volatile ("mov x18, %0" : : "r"(i)); 56 int32_t const nr_csw = get_csw_count(); 57 int const rc = usleep(10); 58 int32_t const nr_csw_after = get_csw_count(); 59 60 // There isn't any guarantee usleep() will actually context switch so this is a best effort way 61 // to see if we've switched at least once in all these iterations. 62 did_csw = did_csw || (nr_csw_after > nr_csw); 63 T_QUIET; T_ASSERT_EQ(0, rc, "usleep"); 64 asm volatile ("mov %0, x18" : "=r"(x18_val)); 65 T_QUIET; T_ASSERT_EQ(x18_val, i, "check that x18 reads back correctly after yield"); 66 } 67 68 T_QUIET; T_ASSERT_TRUE(did_csw, "did not context switch, but should have."); 69 #endif 70 } 71