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/* $Id: threadpreempt-r0drv-darwin.cpp $ */
/** @file
* IPRT - Thread Preemption, Ring-0 Driver, Darwin.
*/
/*
* Copyright (C) 2009-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include "the-darwin-kernel.h"
#include "internal/iprt.h"
#include <iprt/thread.h>
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
# include <iprt/asm-amd64-x86.h>
#endif
#include <iprt/assert.h>
#include <iprt/cpuset.h>
#include <iprt/errcore.h>
#include <iprt/mp.h>
/*********************************************************************************************************************************
* Structures and Typedefs *
*********************************************************************************************************************************/
typedef struct RTDARWINPREEMPTHACK
{
/** The spinlock we exploit for disabling preemption. */
lck_spin_t *pSpinLock;
/** The preemption count for this CPU, to guard against nested calls. */
uint32_t cRecursion;
} RTDARWINPREEMPTHACK;
typedef RTDARWINPREEMPTHACK *PRTDARWINPREEMPTHACK;
/*********************************************************************************************************************************
* Global Variables *
*********************************************************************************************************************************/
static RTDARWINPREEMPTHACK g_aPreemptHacks[RTCPUSET_MAX_CPUS];
/**
* Allocates the per-cpu spin locks used to disable preemption.
*
* Called by rtR0InitNative.
*/
int rtThreadPreemptDarwinInit(void)
{
Assert(g_pDarwinLockGroup);
IPRT_DARWIN_SAVE_EFL_AC();
for (size_t i = 0; i < RT_ELEMENTS(g_aPreemptHacks); i++)
{
g_aPreemptHacks[i].pSpinLock = lck_spin_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
if (!g_aPreemptHacks[i].pSpinLock)
return VERR_NO_MEMORY; /* (The caller will invoke rtThreadPreemptDarwinTerm) */
}
IPRT_DARWIN_RESTORE_EFL_AC();
return VINF_SUCCESS;
}
/**
* Frees the per-cpu spin locks used to disable preemption.
*
* Called by rtR0TermNative.
*/
void rtThreadPreemptDarwinTerm(void)
{
IPRT_DARWIN_SAVE_EFL_AC();
for (size_t i = 0; i < RT_ELEMENTS(g_aPreemptHacks); i++)
if (g_aPreemptHacks[i].pSpinLock)
{
lck_spin_free(g_aPreemptHacks[i].pSpinLock, g_pDarwinLockGroup);
g_aPreemptHacks[i].pSpinLock = NULL;
}
IPRT_DARWIN_RESTORE_EFL_AC();
}
RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
{
RT_NOREF(hThread);
Assert(hThread == NIL_RTTHREAD);
return preemption_enabled();
}
RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
{
RT_NOREF(hThread);
if (!g_pfnR0DarwinAstPending)
return false;
uint32_t volatile *pfAstPending = g_pfnR0DarwinAstPending(); AssertPtr(pfAstPending);
uint32_t const fAstPending = *pfAstPending;
AssertMsg(!(fAstPending & UINT32_C(0xfffe0000)), ("%#x\n", fAstPending));
return (fAstPending & (AST_PREEMPT | AST_QUANTUM | AST_URGENT)) != 0;
}
RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
{
/* yes, we think that RTThreadPreemptIsPending is reliable... */
return g_pfnR0DarwinAstPending != NULL;
}
RTDECL(bool) RTThreadPreemptIsPossible(void)
{
/* yes, kernel preemption is possible. */
return true;
}
RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
{
AssertPtr(pState);
Assert(pState->u32Reserved == 0);
pState->u32Reserved = 42;
/*
* Disable to prevent preemption while we grab the per-cpu spin lock.
* Note! Only take the lock on the first call or we end up spinning for ever.
*/
RTCCUINTREG fSavedFlags = ASMIntDisableFlags();
RTCPUID idCpu = RTMpCpuId();
if (RT_UNLIKELY(idCpu < RT_ELEMENTS(g_aPreemptHacks)))
{
Assert(g_aPreemptHacks[idCpu].cRecursion < UINT32_MAX / 2);
if (++g_aPreemptHacks[idCpu].cRecursion == 1)
{
lck_spin_t *pSpinLock = g_aPreemptHacks[idCpu].pSpinLock;
if (pSpinLock)
lck_spin_lock(pSpinLock);
else
AssertFailed();
}
}
ASMSetFlags(fSavedFlags);
Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
}
RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
{
AssertPtr(pState);
Assert(pState->u32Reserved == 42);
pState->u32Reserved = 0;
RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
RTCPUID idCpu = RTMpCpuId();
if (RT_UNLIKELY(idCpu < RT_ELEMENTS(g_aPreemptHacks)))
{
Assert(g_aPreemptHacks[idCpu].cRecursion > 0);
if (--g_aPreemptHacks[idCpu].cRecursion == 0)
{
lck_spin_t *pSpinLock = g_aPreemptHacks[idCpu].pSpinLock;
if (pSpinLock)
{
IPRT_DARWIN_SAVE_EFL_AC();
lck_spin_unlock(pSpinLock);
IPRT_DARWIN_RESTORE_EFL_AC();
}
else
AssertFailed();
}
}
}
RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
{
Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
/** @todo Darwin: Implement RTThreadIsInInterrupt. Required for guest
* additions! */
return !ASMIntAreEnabled();
}
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