206 lines
6.6 KiB
C
206 lines
6.6 KiB
C
#include <kernel/kernel.h>
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#include <kernel/multiboot.h>
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#include <kernel/mem.h>
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#include <kernel/serial.h>
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#include <kernel/idt.h>
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#include <kernel/pic.h>
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#include <kernel/pit.h>
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#include <kernel/elf.h>
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#include <kernel/task.h>
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#include <kernel/ps2.h>
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#include <stdint.h>
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kernel_ctx_t ctx = {0};
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struct idt_entry idt[256] = {0};
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struct idtr idtr = {0};
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tss_t tss = {0};
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extern uint32_t isr_stub_table[32];
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extern void pit_isr(void);
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extern void ps2_isr(void);
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extern void jmp_user_mode(uint32_t esp, uint32_t eip);
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extern void flush_tss(uint32_t segment_selector);
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extern void task_switch(task_t *task);
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extern void syscall(void);
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extern void syscall_isr(void);
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extern gdt_t gdt[6];
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extern uint32_t boot_page_dir[1024];
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extern uint32_t boot_page_tab[1024];
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#define FD_STDIN 0
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#define FD_STDOUT 1
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void syscall_write(stack_frame_t r) {
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uint32_t fd = r.edi;
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uint8_t *buf = (uint8_t *)r.esi;
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if (fd == FD_STDOUT) {
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LOG("%s", buf);
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}
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}
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void syscall_read(stack_frame_t r) {
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uint32_t fd = r.edi;
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uint8_t *buf = (uint8_t *)r.esi;
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uint32_t len = r.edx;
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if (fd == FD_STDOUT) {
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// Not yet
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} else if (fd == FD_STDIN) {
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// for some reason interrupts are disabled
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asm volatile ("sti" ::);
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while (ctx.current_task->stdin[ctx.current_task->stdin_len - 1] != '\n') cpu_relax;
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if (ctx.current_task->stdin_len > 0) ctx.current_task->stdin[--ctx.current_task->stdin_len] = 0;
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memcpy(buf, ctx.current_task->stdin, len);
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for (int i = 0; i < 0x1000; i++) ctx.current_task->stdin[i] = 0;
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ctx.current_task->stdin_len = 0;
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}
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}
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void syscall_reboot(stack_frame_t r) {
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(void)r;
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ps2_reboot;
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}
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void syscall_uptime(stack_frame_t r) {
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uint64_t *buf = (uint64_t *)r.esi;
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*buf = ctx.ticks;
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}
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void exception_handler(int_stack_frame_t r) {
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LOG("Exception 0x%X (0x%X) has occurred\nEAX: 0x%08X\nECX: 0x%08X\nEDX: 0x%08X\nEBX: 0x%08X\nESI: 0x%08X\nEDI: 0x%08X\nEBP: 0x%08X\nESP: 0x%08X\n",
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r.int_no, r.err_code, r.eax, r.ecx, r.edx, r.ebx, r.esi, r.edi, r.ebp, r.esp+24);
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LOG("\nEIP: 0x%08X\nCS: 0x%08X\nEFLAGS: 0x%08X\n",
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r.eip, r.cs, r.eflags);
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for (;;) {}
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}
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void sleep(int delay) {
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uint64_t end = ctx.ticks + delay;
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while (ctx.ticks < end)
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cpu_relax;
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}
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void idt_init(void) {
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for (int i = 0; i < 32; i++) {
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idt_encode_entry(idt, i, isr_stub_table[i], GDT_SEGMENT_SELECTOR(GDT_KERNEL_CODE, RING0), TRAP_GATE_32 | INT_RING0 | INT_PRESENT);
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}
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idt_encode_entry(idt, 32, (uint32_t)pit_isr, GDT_SEGMENT_SELECTOR(GDT_KERNEL_CODE, RING0), TRAP_GATE_32 | INT_RING0 | INT_PRESENT);
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idt_encode_entry(idt, 0x21, (uint32_t)ps2_isr, GDT_SEGMENT_SELECTOR(GDT_KERNEL_CODE, RING0), TRAP_GATE_32 | INT_RING0 | INT_PRESENT);
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idt_encode_entry(idt, 0x80, (uint32_t)syscall_isr, GDT_SEGMENT_SELECTOR(GDT_USER_CODE, RING3), TRAP_GATE_32 | INT_RING3 | INT_PRESENT);
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idtr.size = (sizeof(struct idt_entry) * 256) - 1;
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idtr.base = (uint32_t) idt;
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asm volatile ("lidt %0" :: "m"(idtr));
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}
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void kernel(multiboot_info_t *info) {
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if (!CHECK_FLAG(info->flags, 3)) goto halt; // Modules
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if (!CHECK_FLAG(info->flags, 6)) goto halt; // Memory map
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if (!CHECK_FLAG(info->flags, 12)) goto halt; // VBE data
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if (serial_port_init(COM1)) ctx.log_method = LOG_COM1;
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LOG("Kernel log being sent to COM1\n");
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ctx.multi_mmap = (multi_mmap_t *)(info->memmapaddress + KERNEL_VMA);
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ctx.multi_mmap_size = info->memmaplength;
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if (!mmap_init()) goto halt;
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LOG("%d bytes of RAM detected\nCreated a %d byte large physical memory map at 0x%08X\n", ctx.mmap_size*BLOCK_SIZE*8, ctx.mmap_size, (uint32_t)ctx.mmap);
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idt_init();
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pic_remap(PIC_1_START, PIC_2_START);
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ps2_init();
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asm volatile ("sti" ::);
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ctx.ticks = 0;
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pit_init();
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// Setup TSS
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uint32_t base = (uint32_t)&tss;
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uint32_t limit = base + sizeof(tss_t);
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gdt[5].base_low = base & 0xFFFF;
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gdt[5].base_middle = (base >> 16) & 0xFF;
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gdt[5].base_high = (base >> 24) & 0xFF;
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gdt[5].limit_low = limit & 0xFFFF;
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gdt[5].granularity = (limit >> 16) & 0x0F;
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gdt[5].granularity |= 0x40;
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gdt[5].access = 0x89;
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tss.ss0 = GDT_SEGMENT_SELECTOR(GDT_KERNEL_DATA, RING0);
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uint32_t esp0 = 0;
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asm volatile ("mov %%esp, %0" : "=r" (esp0));
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// Questionable
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tss.esp0 = esp0;
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tss.cs = GDT_SEGMENT_SELECTOR(GDT_USER_CODE, RING3);
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tss.ss = tss.ds = tss.es = tss.fs = tss.gs = GDT_SEGMENT_SELECTOR(GDT_USER_DATA, RING3);
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flush_tss(GDT_SEGMENT_SELECTOR(5, RING3));
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/*
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task_t task1 = {0};
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task_t task2 = {0};
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task1.cr3 = (uint32_t)boot_page_dir - KERNEL_VMA;
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task1.next = (uint32_t *)&task2;
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ctx.current_task = &task1;
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uint32_t *stack = mmap_find_first_free_block();
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asm volatile ("mov %%esp, %0" : "=r" (task1.esp));
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stack[1023] = 0x207;
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stack[1022] = 0x8;
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stack[1021] = (uint32_t)test;
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stack[1020] = 0xDEADBEEF;
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stack[1019] = 0xDEADBEEF;
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stack[1018] = 0xDEADBEEF;
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stack[1017] = 0xDEADBEEF;
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stack[1016] = 0xDEADBEEF;
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stack[1015] = 0xDEADBEEF;
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stack[1014] = 0xDEADBEEF;
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stack[1013] = 0xDEADBEEF;
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task2.esp = (uint32_t)stack + (0x1000 - 44);
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task2.cr3 = (uint32_t)boot_page_dir - KERNEL_VMA;
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task2.next = 0;
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*/
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multi_mod_t *init = (multi_mod_t *)(info->moduleaddress + KERNEL_VMA);
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elf_t *elf = (elf_t *)(init->mod_start+KERNEL_VMA);
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task_t task = {0};
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if (!task_init(&task, elf)) goto halt;
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ctx.current_task = &task;
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asm volatile ("mov %0, %%cr3" :: "r"(task.cr3));
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// Set the ring0 CS
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asm volatile (
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"movl $0x174, %%ecx \n\t"
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"movl %0, %%eax \n\t"
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"xor %%edx, %%edx \n\t"
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"wrmsr"
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:
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: "r"(GDT_SEGMENT_SELECTOR(GDT_KERNEL_CODE, RING0))
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: "eax", "ecx", "edx"
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);
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// Set the ring0 stack
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uint32_t *k_stack = mmap_find_first_free_block();
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asm volatile (
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"movl $0x175, %%ecx \n\t"
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"movl %0, %%eax \n\t"
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"xor %%edx, %%edx \n\t"
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"wrmsr"
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:
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: "r"((uint32_t)k_stack + 0x1000)
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: "eax", "ecx", "edx"
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);
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// Set the ring0 syscall entry
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asm volatile (
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"movl $0x176, %%ecx \n\t"
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"movl %0, %%eax \n\t"
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"xor %%edx, %%edx \n\t"
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"wrmsr"
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:
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: "r"(syscall)
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: "eax", "ecx", "edx"
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);
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LOG("Switching to ring 3... EIP: 0x%08X ESP: 0x%08X\n", task.eip, task.esp);
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jmp_user_mode(task.esp, task.eip);
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halt:
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for (;;) {}
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}
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