User mode code can now run !

We have a sample process (hardcoded in ASM in Task.wtf.asm) that
displays a's and sleeps 20ms, but it's on a hidden virtual terminal so
it's useless :D

4 files changed, 73 insertions, 7 deletions

diff --git a/Source/Kernel/TaskManager/Task.ns.cpp b/Source/Kernel/TaskManager/Task.ns.cpp
index a34f14f..1d1676e 100644
--- a/Source/Kernel/TaskManager/Task.ns.cpp
+++ b/Source/Kernel/TaskManager/Task.ns.cpp
@@ -94,8 +94,11 @@ void doSwitch() {
 	eip = t->getEip();
 	cr3 = currentProcess->getPagedir()->physicalAddr;
 
+	asm volatile("cli");
+
+	t->setKernelStack();
+
 	asm volatile("			\
-			cli;			\
 			mov %0, %%ebp;	\
 			mov %1, %%esp;	\
 			mov %2, %%ecx;	\
diff --git a/Source/Kernel/TaskManager/Task.wtf.asm b/Source/Kernel/TaskManager/Task.wtf.asm
index 77db18e..2e5b9f8 100644
--- a/Source/Kernel/TaskManager/Task.wtf.asm
+++ b/Source/Kernel/TaskManager/Task.wtf.asm
@@ -47,3 +47,18 @@ copy_page_physical:
    popf                  ; Pop EFLAGS back.
    pop ebx               ; Get the original value of EBX back.
    ret
+
+
+[GLOBAL sample_task]
+sample_task:
+	mov eax, 0x00000001	;temporarily defined as syscall id for writing one char to screen
+	mov ebx, 'a'		;loopingly write a's to screen
+	int 64
+	mov eax, 0x00000002	;temporary syscall for sleeping
+	mov ebx, 20			;20ms
+	int 64
+	jmp sample_task
+	int 66				;finish task - will never happen since we have an infinite loop
+[GLOBAL sample_task_size]
+sample_task_size:
+	dd sample_task_size - sample_task
diff --git a/Source/Kernel/TaskManager/Thread.class.cpp b/Source/Kernel/TaskManager/Thread.class.cpp
index 6d62474..63d8160 100644
--- a/Source/Kernel/TaskManager/Thread.class.cpp
+++ b/Source/Kernel/TaskManager/Thread.class.cpp
@@ -2,11 +2,51 @@
 #include <TaskManager/Task.ns.h>
 #include <MemoryManager/PageAlloc.ns.h>
 #include <DeviceManager/Time.ns.h>
+#include <MemoryManager/GDT.ns.h>
 
 void runThread(Thread* thread, void* data, thread_entry_t entry_point) {
-	asm volatile("sti");
-	u32int ret = entry_point(data);	//Run !
-	asm volatile("mov %0, %%eax; int $66;" : : "r"(ret));	//Syscall for thread ending
+	if (thread->m_isKernel) {
+		asm volatile("sti");
+		u32int ret = entry_point(data);	//Run !
+		asm volatile("mov %0, %%eax; int $66;" : : "r"(ret));	//Syscall for thread ending
+	} else {
+		//Setup values on user stack
+		u32int *stack = (u32int*)((u32int)thread->m_userStack.addr + thread->m_userStack.size);
+		stack--;
+		*stack = (u32int)data;
+		stack--;
+		*stack = 0;
+		u32int esp = (u32int)stack, eip = (u32int)entry_point;
+		//Setup a false structure for returning from an interrupt :
+		//- update data segments to 0x23 = user data segment with RPL=3
+		//- mov esp in ebx and eip in ecx
+		//- push value for ss : 0x23 (user data seg rpl3)
+		//- push value for esp
+		//- push flags
+		//- update flags, set IF = 1 (interrupts flag)
+		//- push value for cs : 0x1B = user code segment with RPL=3
+		//- push eip
+		//- return from fake interrupt
+		asm volatile("				\
+				mov $0x23, %%ax;	\
+				mov %%ax, %%ds;		\
+				mov %%ax, %%es;		\
+				mov %%ax, %%fs;		\
+				mov %%ax, %%gs;		\
+									\
+				mov %0, %%ebx;		\
+				mov %1, %%ecx;		\
+				pushl $0x23;		\
+				pushl %%ebx;		\
+				pushf;				\
+				pop %%eax;			\
+				or $0x200, %%eax;	\
+				push %%eax;			\
+				pushl $0x1B;		\
+				push %%ecx;			\
+				iret;				\
+				" : : "r"(esp), "r"(eip));
+	}
 }
 
 Thread::Thread() {	//Private constructor, does nothing
@@ -27,7 +67,10 @@ Thread::Thread(Process* process, thread_entry_t entry_point, void* data) {
 Thread::~Thread() {
 	Task::unregisterThread(this);
 	Mem::kfree(m_kernelStack.addr);
-	if (!m_isKernel) m_process->heap().free(m_userStack.addr);
+	if (m_userStack.addr != 0) {
+		m_process->getPagedir()->switchTo();
+		m_process->heap().free(m_userStack.addr);
+	}
 	//Don't unregister thread in process, it has probably already been done
 }
 
@@ -111,11 +154,11 @@ void Thread::handleException(registers_t regs, int no) {
 		*(m_process->m_vt) << "At:" << (u32int)faddr;
 
 		*(m_process->m_vt) << "\nThread finishing.\n";
-		finish(E_PAGEFAULT);
+		Task::currentThreadExits(E_PAGEFAULT);	//Calling this will setup a new stack
 		return;
 	}
 	*(m_process->m_vt) << "\nThread finishing.\n";
-	finish(E_UNHANDLED_EXCEPTION);
+	Task::currentThreadExits(E_UNHANDLED_EXCEPTION);
 }
 
 void Thread::setState(u32int esp, u32int ebp, u32int eip) {
@@ -124,6 +167,10 @@ void Thread::setState(u32int esp, u32int ebp, u32int eip) {
 	m_eip = eip;
 }
 
+void Thread::setKernelStack() {
+	GDT::tss_entry.esp0 = (u32int)(m_kernelStack.addr) + m_kernelStack.size;
+}
+
 u32int Thread::getEsp() { return m_esp; }
 u32int Thread::getEbp() { return m_ebp; }
 u32int Thread::getEip() { return m_eip; }
diff --git a/Source/Kernel/TaskManager/Thread.class.h b/Source/Kernel/TaskManager/Thread.class.h
index 9c8fa26..aeb1f93 100644
--- a/Source/Kernel/TaskManager/Thread.class.h
+++ b/Source/Kernel/TaskManager/Thread.class.h
@@ -43,6 +43,7 @@ class Thread {
 	void handleException(registers_t regs, int no);
 
 	void setState(u32int esp, u32int ebp, u32int eip);
+	void setKernelStack();
 	u32int getEsp();
 	u32int getEbp();
 	u32int getEip();