Save/restore FPU state only on switches from/to userland; move state …

…restoring to end of ISRs
maxdev1 · Feb 12, 2025 · 56f1504 · 56f1504
1 parent 9a873b6
commit 56f1504
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Showing 5 changed files with 16 additions and 15 deletions.
diff --git a/kernel/src/kernel/logger/logger.cpp b/kernel/src/kernel/logger/logger.cpp
@@ -19,12 +19,8 @@
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
 #include "shared/logger/logger.hpp"
-#include "kernel/system/interrupts/interrupts.hpp"
-#include "kernel/system/smp.hpp"
-#include "shared/system/mutex.hpp"
 #include "shared/system/spinlock.hpp"
-#include "shared/utils/string.hpp"
-#include "shared/video/console_video.hpp"
+#include "kernel/system/interrupts/interrupts.hpp"
 
 g_spinlock loggerLock = 0;
 

diff --git a/kernel/src/kernel/system/interrupts/interrupts.cpp b/kernel/src/kernel/system/interrupts/interrupts.cpp
@@ -104,6 +104,8 @@ extern "C" volatile g_processor_state* _interruptHandler(volatile g_processor_st
 	auto newTask = taskingGetCurrentTask();
 	if(!newTask || !newTask->state)
 		panic("%! attempted to switch to null task (%x) or state (%x)", "system", newTask, newTask->state);
+	if(newTask != task)
+		taskingRestoreState(newTask);
 	return newTask->state;
 }
 

diff --git a/kernel/src/kernel/tasking/task.hpp b/kernel/src/kernel/tasking/task.hpp
@@ -74,6 +74,7 @@ struct g_task
     g_task_status status;
     g_task_type type;
     g_mutex lock;
+    int interruptionLevel;
 
     /**
      * Flag that is only relevant when this task is spawned from an executable. After the task has

diff --git a/kernel/src/kernel/tasking/tasking.cpp b/kernel/src/kernel/tasking/tasking.cpp
@@ -280,22 +280,25 @@ void taskingSaveState(g_task* task, g_processor_state* state)
 	// Save latest pointer to interrupt stack top
 	task->state = state;
 
+	// Increase interruption counter
+	task->interruptionLevel++;
+
 	// Save FPU state
-	if(task->fpu.state)
+	if(task->interruptionLevel == 0 && task->fpu.state)
 	{
 		processorSaveFpuState(task->fpu.state);
 		task->fpu.stored = true;
 	}
 }
 
 
-void taskingApplySwitch()
+void taskingRestoreState(g_task* task)
 {
-	g_task* task = taskingGetCurrentTask();
 	if(!task)
-	{
 		panic("%! tried to restore without a current task", "tasking");
-	}
+
+	// Decrease interruption counter
+	task->interruptionLevel--;
 
 	// Switch to process address space
 	if(task->overridePageDirectory)
@@ -314,17 +317,15 @@ void taskingApplySwitch()
 	gdtSetTssEsp0(task->interruptStack.end);
 
 	// Restore FPU state
-	if(task->fpu.stored)
+	if(task->interruptionLevel == 0 && task->fpu.stored)
 	{
 		processorRestoreFpuState(task->fpu.state);
 	}
 }
 
 void taskingSchedule()
 {
-	auto local = taskingGetLocal();
-	schedulerSchedule(local);
-	taskingApplySwitch();
+	schedulerSchedule(taskingGetLocal());
 }
 
 g_process* taskingCreateProcess(g_security_level securityLevel)
@@ -461,6 +462,7 @@ void taskingInitializeTask(g_task* task, g_process* process, g_security_level le
 	task->process = process;
 	task->securityLevel = level;
 	task->status = G_TASK_STATUS_RUNNING;
+	task->interruptionLevel = 1;
 	waitQueueInitialize(&task->waitersJoin);
 	mutexInitializeNonInterruptible(&task->lock, __func__);
 }

diff --git a/kernel/src/kernel/tasking/tasking.hpp b/kernel/src/kernel/tasking/tasking.hpp
@@ -191,7 +191,7 @@ void taskingSaveState(g_task* task, g_processor_state* state);
  * Applies the context switch to the task which is the current one for this core. This sets
  * the correct page directory and TLS variables.
  */
-void taskingApplySwitch();
+void taskingRestoreState(g_task* task);
 
 /**
  * Yields control to the next task. This can only be called while no mutexes