Kernel/Userspace: Start initial work on userspace and syscalls

kernel/arch/x86_64/IDT.cpp

@@ -148,6 +148,12 @@ namespace IDT
 		descriptor.flags = 0x8E;
 	}
 
+	static void register_syscall_handler(uint8_t index, void(*handler)())
+	{
+		register_interrupt_handler(index, handler);
+		s_idt[index].flags = 0xEE;
+	}
+
 	void register_irq_handler(uint8_t irq, void(*handler)())
 	{
 		s_irq_handlers[irq] = handler;
@@ -203,6 +209,8 @@ namespace IDT
 	extern "C" void irq14();
 	extern "C" void irq15();
 
+	extern "C" void syscall_asm();
+
 	void initialize()
 	{
 		s_idt = (GateDescriptor*)kmalloc(0x100 * sizeof(GateDescriptor));
@@ -262,6 +270,8 @@ namespace IDT
 		REGISTER_IRQ_HANDLER(14);
 		REGISTER_IRQ_HANDLER(15);
 
+		register_syscall_handler(0x80, syscall_asm);
+
 		flush_idt();
 	}
 

kernel/arch/x86_64/interrupts.S

@@ -34,6 +34,23 @@
 	popq %rax
 .endm
 
+.macro popaq_no_rax
+	popq %r15
+	popq %r14
+	popq %r13
+	popq %r12
+	popq %r11
+	popq %r10
+	popq %r9
+	popq %r8
+	popq %rsi
+	popq %rdi
+	popq %rbp
+	popq %rdx
+	popq %rcx
+	popq %rbx
+.endm
+
 isr_stub:
 	pushaq
 
@@ -138,3 +155,15 @@ irq 12
 irq 13
 irq 14
 irq 15
+
+.global syscall_asm
+syscall_asm:
+	cli
+	pushaq
+	movq %rax, %rdi
+	movq %rbx, %rsi
+	xchgq %rcx, %rdx
+	call cpp_syscall_handler
+	popaq_no_rax
+	addq $8, %rsp
+	iretq

kernel/arch/x86_64/linker.ld

@@ -11,7 +11,9 @@ SECTIONS
 	}
 	.rodata BLOCK(4K) : ALIGN(4K)
 	{
-		*(.rodata)
+		g_rodata_start = .;
+		*(.rodata.*)
+		g_rodata_end = .;
 	}
 	.data BLOCK(4K) : ALIGN(4K)
 	{
@@ -22,6 +24,15 @@ SECTIONS
 		*(COMMON)
 		*(.bss)
 	}
-
 	g_kernel_end = .;
+
+	. = 0x00A00000;
+
+	g_userspace_start = .;
+	.userspace BLOCK(4K) : ALIGN(4K)
+	{
+		*(.userspace)
+	}
+	g_userspace_end = .;
+
 }