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#include "V86Thread.class.h"
#include <TaskManager/Task.ns.h>
#include <TaskManager/V86/V86.ns.h>
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();
//Map all lower memory
V86::map();
u16int cs = V86::allocSeg(entry->size); //Alocate segments for the code to run in
u8int* codeptr = (u8int*)(FP_TO_LINEAR(cs, 0));
memcpy(codeptr, entry->data, entry->size); //Copy the code there
u16int ss = V86::allocSeg(V86_STACKSIZE);
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 & 0xFFFF));
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->useresp = ((regs->useresp & 0xFFFF) - 4) & 0xFFFF;
stack32--;
*stack32 = regs->eflags & VALID_FLAGS;
if (m_if)
*stack32 |= EFLAGS_IF;
else
*stack32 &= ~EFLAGS_IF;
} else {
regs->useresp = ((regs->useresp & 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->useresp = ((regs->useresp & 0xFFFF) + 4) & 0xFFFF;
} else {
regs->eflags = EFLAGS_IF | EFLAGS_VM | stack[0];
m_if = (stack[0] & EFLAGS_IF) != 0;
regs->useresp = ((regs->useresp & 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
if (ip[1] == 60) { //INT 60 is used so that the real mode code can retrieve some regs from caller
regs->eax = m_ret->regs->eax;
regs->ebx = m_ret->regs->ebx;
regs->ecx = m_ret->regs->ecx;
regs->edx = m_ret->regs->edx;
regs->edi = m_ret->regs->edi;
regs->esi = m_ret->regs->esi;
regs->eip = (u16int)(regs->eip + 2);
return true;
}
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->useresp = ((regs->useresp & 0xFFFF) + 6) & 0xFFFF;
return false;
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);
}
}
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