75 lines
1.9 KiB
C
75 lines
1.9 KiB
C
/*
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* Copyright (c) 2026, Chloe M.
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* Provided under the BSD-3 clause.
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*
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* Description: MD context management
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* Author: Chloe M.
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*/
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#include <hal/context.h>
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#include <hal/kpcr.h>
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#include <hal/thread.h>
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#include <hal/mmu.h>
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#include <ps/process.h>
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#include <string.h>
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VOID
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HalContextSwitch(TRAP_FRAME *Frame)
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{
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THREAD *ThisThread, *NextThread;
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PROCESS *NextParent;
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TCB *ThisTcb, *NextTcb;
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KPCR *Kpcr;
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MCB *Mcb;
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TSS_ENTRY *Tss;
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UPTR KStackTop;
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Kpcr = HalKpcrCurrent();
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Mcb = &Kpcr->Mcb;
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ThisThread = Kpcr->CurrentThread;
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NextThread = NULL;
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/* If there is no thread, get one */
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if (ThisThread == NULL) {
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NextThread = KeSchedDequeue(&Kpcr->SchedQueue);
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if (NextThread == NULL) {
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HalPrimeThreadTimer(SCHED_MIN_QUANTUM);
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return;
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}
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}
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/* Nothing to do if there is no next thread */
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if (NextThread == NULL) {
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NextThread = KeSchedDequeue(&Kpcr->SchedQueue);
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if (NextThread == NULL) {
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HalPrimeThreadTimer(SCHED_MIN_QUANTUM);
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return;
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}
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}
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/* Save the current thread if we have one */
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if (ThisThread != NULL) {
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ThisTcb = &ThisThread->Tcb;
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RtlMemCpy(&ThisTcb->FrameSnapshot, Frame, sizeof(*Frame));
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KeSchedEnqueue(&Kpcr->SchedQueue, ThisThread);
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}
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/* Switch the address space */
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NextParent = NextThread->Parent;
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HalMmuWriteVas(&NextParent->Vas);
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/* Update the task state segment with kstack */
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if (ISSET(NextParent->Flags, PS_USER)) {
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KStackTop = NextTcb->KStackBase + NextTcb->KStackLength;
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Tss = Mcb->Tss;
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Tss->Rsp0Low = KStackTop & 0xFFFFFFFF;
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Tss->Rsp0High = (KStackTop >> 32) & 0xFFFFFFFF;
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}
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/* Context switch here */
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Kpcr->CurrentThread = NextThread;
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NextTcb = &NextThread->Tcb;
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RtlMemCpy(Frame, &NextTcb->FrameSnapshot, sizeof(*Frame));
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HalPrimeThreadTimer(SCHED_MIN_QUANTUM);
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}
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