4e328c2f7a
Previously we only set it on thread init which caused interrupts to stomp on the stack of the most recently started thread, potentially overwriting their cr3 and other variables and causing a crash.
91 lines
2.1 KiB
C++
91 lines
2.1 KiB
C++
#include "scheduler/scheduler.h"
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#include "common/gdt.h"
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#include "debug/debug.h"
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#include "lib/linked_list.h"
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#include "scheduler/process_manager.h"
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namespace {
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extern "C" void context_switch(uint64_t* current_esp, uint64_t* next_esp);
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} // namespace
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Scheduler* gScheduler = nullptr;
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void Scheduler::Init() { gScheduler = new Scheduler(); }
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Scheduler::Scheduler() {
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Process& root = gProcMan->FromId(0);
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sleep_thread_ = root.GetThread(0);
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// TODO: Implement a separate sleep thread?
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current_thread_ = sleep_thread_;
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}
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void Scheduler::SwapToCurrent(Thread& prev) {
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if (current_thread_->GetState() != Thread::RUNNABLE) {
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panic("Swapping to non-runnable thread.");
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}
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current_thread_->SetState(Thread::RUNNING);
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SetRsp0(current_thread_->Rsp0Start());
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context_switch(prev.Rsp0Ptr(), current_thread_->Rsp0Ptr());
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asm volatile("sti");
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}
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void Scheduler::Preempt() {
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if (!enabled_) {
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return;
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}
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asm volatile("cli");
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if (current_thread_ == sleep_thread_) {
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// Sleep should never be preempted. (We should yield it if another thread
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// becomes scheduleable).
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asm volatile("sti");
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return;
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}
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if (runnable_threads_.size() == 0) {
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// Continue.
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asm volatile("sti");
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return;
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}
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RefPtr<Thread> prev = current_thread_;
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prev->SetState(Thread::RUNNABLE);
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current_thread_ = runnable_threads_.CycleFront(prev);
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SwapToCurrent(*prev);
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}
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void Scheduler::Yield() {
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if (!enabled_) {
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dbgln("WARN Scheduler skipped yield.");
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return;
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}
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asm volatile("cli");
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RefPtr<Thread> prev = current_thread_;
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if (prev == sleep_thread_) {
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if (runnable_threads_.size() == 0) {
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panic("Sleep thread yielded without next.");
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return;
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} else {
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// FIXME: Memory operation.
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current_thread_ = runnable_threads_.PopFront();
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prev->SetState(Thread::RUNNABLE);
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}
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} else {
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if (runnable_threads_.size() == 0) {
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current_thread_ = sleep_thread_;
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dbgln("Sleeping");
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gProcMan->DumpProcessStates();
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} else {
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// FIXME: Memory operation.
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current_thread_ = runnable_threads_.PopFront();
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}
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}
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SwapToCurrent(*prev);
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}
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