1 | /* $Id: threadpreempt-r0drv-darwin.cpp 93115 2022-01-01 11:31:46Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - Thread Preemption, Ring-0 Driver, Darwin.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2009-2022 Oracle Corporation
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8 | *
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9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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10 | * available from http://www.virtualbox.org. This file is free software;
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11 | * you can redistribute it and/or modify it under the terms of the GNU
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12 | * General Public License (GPL) as published by the Free Software
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13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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16 | *
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17 | * The contents of this file may alternatively be used under the terms
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18 | * of the Common Development and Distribution License Version 1.0
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19 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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20 | * VirtualBox OSE distribution, in which case the provisions of the
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21 | * CDDL are applicable instead of those of the GPL.
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22 | *
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23 | * You may elect to license modified versions of this file under the
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24 | * terms and conditions of either the GPL or the CDDL or both.
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25 | */
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26 |
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27 |
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28 | /*********************************************************************************************************************************
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29 | * Header Files *
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30 | *********************************************************************************************************************************/
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31 | #include "the-darwin-kernel.h"
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32 | #include "internal/iprt.h"
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33 | #include <iprt/thread.h>
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34 |
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35 | #if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
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36 | # include <iprt/asm-amd64-x86.h>
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37 | #endif
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38 | #include <iprt/assert.h>
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39 | #include <iprt/cpuset.h>
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40 | #include <iprt/errcore.h>
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41 | #include <iprt/mp.h>
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42 |
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43 |
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44 | /*********************************************************************************************************************************
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45 | * Structures and Typedefs *
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46 | *********************************************************************************************************************************/
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47 | typedef struct RTDARWINPREEMPTHACK
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48 | {
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49 | /** The spinlock we exploit for disabling preemption. */
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50 | lck_spin_t *pSpinLock;
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51 | /** The preemption count for this CPU, to guard against nested calls. */
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52 | uint32_t cRecursion;
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53 | } RTDARWINPREEMPTHACK;
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54 | typedef RTDARWINPREEMPTHACK *PRTDARWINPREEMPTHACK;
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55 |
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56 |
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57 | /*********************************************************************************************************************************
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58 | * Global Variables *
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59 | *********************************************************************************************************************************/
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60 | static RTDARWINPREEMPTHACK g_aPreemptHacks[RTCPUSET_MAX_CPUS];
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61 |
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62 |
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63 | /**
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64 | * Allocates the per-cpu spin locks used to disable preemption.
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65 | *
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66 | * Called by rtR0InitNative.
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67 | */
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68 | int rtThreadPreemptDarwinInit(void)
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69 | {
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70 | Assert(g_pDarwinLockGroup);
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71 | IPRT_DARWIN_SAVE_EFL_AC();
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72 |
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73 | for (size_t i = 0; i < RT_ELEMENTS(g_aPreemptHacks); i++)
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74 | {
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75 | g_aPreemptHacks[i].pSpinLock = lck_spin_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
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76 | if (!g_aPreemptHacks[i].pSpinLock)
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77 | return VERR_NO_MEMORY; /* (The caller will invoke rtThreadPreemptDarwinTerm) */
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78 | }
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79 | IPRT_DARWIN_RESTORE_EFL_AC();
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80 | return VINF_SUCCESS;
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81 | }
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82 |
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83 |
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84 | /**
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85 | * Frees the per-cpu spin locks used to disable preemption.
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86 | *
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87 | * Called by rtR0TermNative.
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88 | */
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89 | void rtThreadPreemptDarwinTerm(void)
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90 | {
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91 | IPRT_DARWIN_SAVE_EFL_AC();
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92 |
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93 | for (size_t i = 0; i < RT_ELEMENTS(g_aPreemptHacks); i++)
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94 | if (g_aPreemptHacks[i].pSpinLock)
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95 | {
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96 | lck_spin_free(g_aPreemptHacks[i].pSpinLock, g_pDarwinLockGroup);
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97 | g_aPreemptHacks[i].pSpinLock = NULL;
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98 | }
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99 |
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100 | IPRT_DARWIN_RESTORE_EFL_AC();
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101 | }
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102 |
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103 |
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104 | RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
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105 | {
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106 | RT_NOREF(hThread);
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107 | Assert(hThread == NIL_RTTHREAD);
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108 | return preemption_enabled();
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109 | }
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110 |
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111 |
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112 | RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
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113 | {
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114 | RT_NOREF(hThread);
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115 | if (!g_pfnR0DarwinAstPending)
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116 | return false;
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117 | uint32_t volatile *pfAstPending = g_pfnR0DarwinAstPending(); AssertPtr(pfAstPending);
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118 | uint32_t const fAstPending = *pfAstPending;
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119 |
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120 | AssertMsg(!(fAstPending & UINT32_C(0xfffe0000)), ("%#x\n", fAstPending));
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121 | return (fAstPending & (AST_PREEMPT | AST_QUANTUM | AST_URGENT)) != 0;
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122 | }
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123 |
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124 |
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125 | RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
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126 | {
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127 | /* yes, we think that RTThreadPreemptIsPending is reliable... */
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128 | return g_pfnR0DarwinAstPending != NULL;
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129 | }
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130 |
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131 |
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132 | RTDECL(bool) RTThreadPreemptIsPossible(void)
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133 | {
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134 | /* yes, kernel preemption is possible. */
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135 | return true;
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136 | }
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137 |
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138 |
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139 | RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
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140 | {
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141 | AssertPtr(pState);
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142 | Assert(pState->u32Reserved == 0);
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143 | pState->u32Reserved = 42;
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144 |
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145 | /*
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146 | * Disable to prevent preemption while we grab the per-cpu spin lock.
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147 | * Note! Only take the lock on the first call or we end up spinning for ever.
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148 | */
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149 | RTCCUINTREG fSavedFlags = ASMIntDisableFlags();
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150 | RTCPUID idCpu = RTMpCpuId();
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151 | if (RT_UNLIKELY(idCpu < RT_ELEMENTS(g_aPreemptHacks)))
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152 | {
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153 | Assert(g_aPreemptHacks[idCpu].cRecursion < UINT32_MAX / 2);
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154 | if (++g_aPreemptHacks[idCpu].cRecursion == 1)
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155 | {
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156 | lck_spin_t *pSpinLock = g_aPreemptHacks[idCpu].pSpinLock;
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157 | if (pSpinLock)
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158 | lck_spin_lock(pSpinLock);
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159 | else
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160 | AssertFailed();
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161 | }
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162 | }
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163 | ASMSetFlags(fSavedFlags);
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164 | Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
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165 | RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
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166 | }
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167 |
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168 |
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169 | RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
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170 | {
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171 | AssertPtr(pState);
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172 | Assert(pState->u32Reserved == 42);
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173 | pState->u32Reserved = 0;
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174 | RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
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175 |
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176 | RTCPUID idCpu = RTMpCpuId();
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177 | if (RT_UNLIKELY(idCpu < RT_ELEMENTS(g_aPreemptHacks)))
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178 | {
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179 | Assert(g_aPreemptHacks[idCpu].cRecursion > 0);
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180 | if (--g_aPreemptHacks[idCpu].cRecursion == 0)
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181 | {
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182 | lck_spin_t *pSpinLock = g_aPreemptHacks[idCpu].pSpinLock;
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183 | if (pSpinLock)
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184 | {
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185 | IPRT_DARWIN_SAVE_EFL_AC();
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186 | lck_spin_unlock(pSpinLock);
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187 | IPRT_DARWIN_RESTORE_EFL_AC();
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188 | }
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189 | else
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190 | AssertFailed();
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191 | }
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192 | }
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193 | }
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194 |
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195 |
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196 | RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
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197 | {
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198 | Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
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199 | /** @todo Darwin: Implement RTThreadIsInInterrupt. Required for guest
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200 | * additions! */
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201 | return !ASMIntAreEnabled();
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202 | }
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203 |
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