Introduced V86 mode. It really fits in nicely :)

3 files changed, 270 insertions, 0 deletions

diff --git a/Source/Kernel/TaskManager/V86/V86Thread.class.cpp b/Source/Kernel/TaskManager/V86/V86Thread.class.cpp
new file mode 100644
index 0000000..babf5b6
--- /dev/null
+++ b/Source/Kernel/TaskManager/V86/V86Thread.class.cpp
@@ -0,0 +1,200 @@
+#include "V86Thread.class.h"
+#include <TaskManager/Task.ns.h>
+
+u16int V86Thread::allocSeg = V86_ALLOC_START;
+
+u16int V86Thread::alloc(u16int length) {
+	if (length & 0xF) length = (length & 0xFFFF0) + 0x10;
+	u16int segments = length / 16;
+	if (allocSeg < V86_ALLOC_START) allocSeg = V86_ALLOC_START;
+	if (allocSeg + segments > V86_ALLOC_END) allocSeg = V86_ALLOC_START;
+	u16int ret = allocSeg;
+	allocSeg += segments;
+	return ret;
+}
+
+void V86Thread::runV86(V86Thread* thread, u32int data, u32int ss, u32int cs) {
+	thread->m_process->getPagedir()->switchTo();
+	//Setup values on user stack
+	u32int *stack = (u32int*)(FP_TO_LINEAR(ss, V86_STACKSIZE));
+	stack--; *stack = data;
+
+	u32int sp = V86_STACKSIZE - 4;
+
+	//Setup a false iret structure on the kernel stack, containing (first pushed first) :
+	// - gs = cs
+	// - fs = cs
+	// - ds = cs
+	// - es = cs
+	// - stack segment = ss (temporarily in ecx)
+	// - stack pointer = sp (temp in ebx)
+	// - flags (OR'ed with EFLAGS.VM)
+	// - code segment = cs (temp in eax)
+	// - instruction pointer = ip (is 0)
+	asm volatile("			\
+			pushl %%eax;	\
+			pushl %%eax;	\
+			pushl %%eax;	\
+			pushl %%eax;	\
+			pushl %%ecx;	\
+			pushl %%ebx;	\
+			pushf;			\
+			pop %%ebx;		\
+			or $0x200, %%ebx;	\
+			or $0x20000, %%ebx;	\
+			push %%ebx;		\
+			pushl %%eax;	\
+			pushl $0;		\
+			iret;			\
+			" : : "a"(cs), "c"(ss), "b"(sp));
+}
+
+/*
+ *	Set up a V86 task :
+ *	Allocate space for the kernel stack
+ *	Map frames in lower 1MB : IVT (first page), BDA (0xA0000 to 0xFFFFF)
+ *  Find somewhere to put the stack and the code, still in lower 1MB
+ *  Map that space, and copy the 16bit code to that place
+ *  Setup values on the kernel stack for starting the thread (V86Thread::runV86),
+ *  giving it entry point and stack location
+ */
+
+V86Thread::V86Thread(v86_function_t* entry, v86_retval_t* ret, u32int data) : Thread() {
+	m_ret = ret; m_ret->finished = false;
+	m_xchgspace = 0;
+	m_isKernel = true;
+	m_if = true;
+	m_process = Task::currProcess();
+	m_kernelStack.addr = Mem::alloc(STACKSIZE);
+	m_kernelStack.size = STACKSIZE;	
+
+	m_process->getPagedir()->switchTo();
+
+	m_process->getPagedir()->allocFrame(0, true, true);	//Map IVT frame
+	for (u32int i = 0xA0000; i < 0xFFFFF; i += 0x1000) {		//Map BDA frames
+		m_process->getPagedir()->allocFrame(i, true, true);
+	}
+
+	u16int cs = alloc(entry->size);	//Alocate segments for the code to run in
+	u8int* codeptr = (u8int*)(FP_TO_LINEAR(cs, 0));
+	for (u32int i = ((u32int)(codeptr) & 0xFFFFF000); i < (u32int)(codeptr) + entry->size; i += 0x1000) {
+		m_process->getPagedir()->allocFrame(i, true, true);
+	}
+	memcpy(codeptr, entry->data, entry->size);	//Copy the code there
+
+	u16int ss = alloc(V86_STACKSIZE);
+	u8int* stackptr = (u8int*)(FP_TO_LINEAR(ss, 0));
+	for (u32int i = ((u32int)stackptr & 0xFFFFF000); i < (u32int)stackptr + V86_STACKSIZE; i += 0x1000) {
+		m_process->getPagedir()->allocFrame(i, true, true);
+	}
+
+	u32int* stack = (u32int*)((u32int)m_kernelStack.addr + m_kernelStack.size);
+	stack--; *stack = cs;	//Pass code segment (ip = 0)
+	stack--; *stack = ss;	//Pass stack segment (sp = V86_STACKSIZE)
+	stack--; *stack = data;	//Pass data for thread
+	stack--; *stack = (u32int)this;	//Pass thread pointer
+	stack--; *stack = 0;
+	m_esp = (u32int)stack;
+	m_ebp = m_esp + 8;
+	m_eip = (u32int)runV86;
+
+	m_state = T_RUNNING;
+	m_process->registerThread(this);
+	Task::registerThread(this);
+}
+
+bool V86Thread::handleV86GPF(registers_t *regs) {
+	u8int* ip = (u8int*)FP_TO_LINEAR(regs->cs, regs->eip);
+	u16int *ivt = 0;
+	u16int *stack = (u16int*)FP_TO_LINEAR(regs->ss, regs->useresp);
+	u32int *stack32 = (u32int*)stack;
+	bool is_operand32 = false, is_address32 = false;
+
+	while (true) {
+		switch (ip[0]) {
+			case 0x66:		// O32
+				is_operand32 = true;
+				ip++; regs->eip = (u16int)(regs->eip + 1);
+				break;
+			case 0x67:		// A32
+				is_address32 = true;
+				ip++; regs->eip = (u16int)(regs->eip + 1);
+				break;
+			case 0x9C:		// PUSHF
+				if (is_operand32) {
+					regs->esp = ((regs->esp & 0xFFFF) - 4) & 0xFFFF;
+					stack32--;
+					*stack32 = regs->eflags & VALID_FLAGS;
+					if (m_if)
+						*stack32 |= EFLAGS_IF;
+					else
+						*stack32 &= ~EFLAGS_IF;
+				} else {
+					regs->esp = ((regs->esp & 0xFFFF) - 2) & 0xFFFF;
+					stack--;
+					*stack = regs->eflags;
+					if (m_if)
+						*stack |= EFLAGS_IF;
+					else
+						*stack &= ~EFLAGS_IF;
+				}
+				regs->eip = (u16int)(regs->eip + 1);
+				return true;
+			case 0x9D:		// POPF
+				if (is_operand32) {
+					regs->eflags = EFLAGS_IF | EFLAGS_VM | (stack32[0] & VALID_FLAGS);
+					m_if = (stack32[0] & EFLAGS_IF) != 0;
+					regs->esp = ((regs->esp & 0xFFFF) + 4) & 0xFFFF;
+				} else {
+					regs->eflags = EFLAGS_IF | EFLAGS_VM | stack[0];
+					m_if = (stack[0] & EFLAGS_IF) != 0;
+					regs->esp = ((regs->esp & 0xFFFF) + 2) & 0xFFFF;
+				}
+				regs->eip = (u16int)(regs->eip + 1);
+				return true;
+			case 0xCD:		// INT N
+				if (ip[1] == 3) return false;	//Breakpoint exception, here used for telling that thread has ended
+
+				stack -= 3;
+				regs->useresp = ((regs->useresp & 0xFFFF) - 6) & 0xFFFF;
+
+				stack[0] = (u16int)(regs->eip + 2);
+				stack[1] = regs->cs;
+				stack[2] = (u16int)regs->eflags;
+
+				regs->cs = ivt[ip[1] * 2 + 1];
+				regs->eip = ivt[ip[1] * 2];
+				return true;
+			case 0xCF:		// IRET
+				regs->eip = stack[0];
+				regs->cs = stack[1];
+				regs->eflags = EFLAGS_IF | EFLAGS_VM | stack[2];
+				m_if = (stack[2] & EFLAGS_IF) != 0;
+				regs->esp = (u16int)(regs->esp + 6);
+				return true;
+			case 0xFA:		// CLI
+				m_if = false;
+				regs->eip = (u16int)(regs->eip + 1);
+				return true;
+			case 0xFB:		// STI
+				m_if = true;
+				regs->eip = (u16int)(regs->eip + 1);
+				return true;
+			default:
+				return false;
+		}
+	}
+}
+
+void V86Thread::handleException(registers_t *regs, int no) {
+	if (no == 13) {			//General protection fault
+		if (!handleV86GPF(regs)) {
+			m_ret->finished = true;
+			m_ret->regs = *regs;
+			Task::currentThreadExits(0);
+			return;
+		}
+	} else {
+		Thread::handleException(regs, no);
+	}
+}
diff --git a/Source/Kernel/TaskManager/V86/V86Thread.class.h b/Source/Kernel/TaskManager/V86/V86Thread.class.h
new file mode 100644
index 0000000..b14670b
--- /dev/null
+++ b/Source/Kernel/TaskManager/V86/V86Thread.class.h
@@ -0,0 +1,59 @@
+#ifndef DEF_V86THREAD_CLASS_H
+#define DEF_V86THREAD_CLASS_H
+
+#include <TaskManager/Thread.class.h>
+
+typedef u32int FARPTR;
+#define MK_FP(seg, off) ((FARPTR)(((u32int)(seg) << 16) | (u16int) (off)))
+#define FP_SEG(fp) (((FARPTR)fp) >> 16)
+#define FP_OFF(fp) (((FARPTR)fp) & 0xFFFF)
+#define FP_TO_LINEAR(seg, off) ((void*)((((u16int)(seg)) << 4) + ((u16int)(off))))
+inline FARPTR LINEAR_TO_FP(void* ptr) {
+	u32int seg, off;
+	off = ((size_t) ptr) & 0xF;
+	seg = ((size_t) ptr - ((size_t) ptr & 0xF)) / 16;
+	return MK_FP(seg, off);
+}
+
+struct v86_retval_t {
+	registers_t regs;
+	bool finished;
+};
+
+struct v86_function_t {
+	u16int size;
+	u8int data[];
+};
+
+#define V86_STACKSIZE 1024
+
+// (in segments)
+#define V86_ALLOC_START 0x1000
+#define V86_ALLOC_END 0x9000
+
+#define EFLAGS_IF 0x200
+#define EFLAGS_VM 0x20000
+#define VALID_FLAGS 0xDFF
+
+class V86Thread : public Thread {
+	private:
+	V86Thread();
+	V86Thread(V86Thread&);
+
+	v86_retval_t* m_ret;
+
+	bool m_if;	//V86 IF flag
+
+	static u16int allocSeg;
+	static u16int alloc(u16int length);	//Returns a segment number
+
+	static void runV86(V86Thread* t, u32int data, u32int ss, u32int cs);
+	
+	public:
+	V86Thread(v86_function_t* entry, v86_retval_t* ret, u32int data);
+
+	bool handleV86GPF(registers_t *regs);
+	void handleException(registers_t *regs, int no);	
+};
+
+#endif
diff --git a/Source/Kernel/TaskManager/V86/v86.wtf.asm b/Source/Kernel/TaskManager/V86/v86.wtf.asm
new file mode 100644
index 0000000..15e3969
--- /dev/null
+++ b/Source/Kernel/TaskManager/V86/v86.wtf.asm
@@ -0,0 +1,11 @@
+[BITS 16]
+
+[GLOBAL v86test]
+v86test:
+	dw v86test_end - v86test_start	
+v86test_start:
+	mov ax, 0013h
+	int 10h
+	int 3
+v86test_end:
+	db 0