;
[bits 64]
+[section .text]
[global start64]
start64:
; Set kernel stack
GetRIP:
mov rax, [rsp]
ret
+
+[global GetCPUNum]
+GetCPUNum:
+ str ax
+ mov gs, ax
+ xor rax, rax
+ mov al, [gs:104] ; End of TSS
+ ret
+
+KSTACK_USERSTATE_SIZE equ (16+1+5)*8 ; GPRegs, CPU, IRET
+[global Proc_ReturnToUser]
+[extern Proc_GetCurThread]
+Proc_ReturnToUser:
+ ; RBP is the handler to use
+
+ call Proc_GetCurThread
+
+ ; EAX is the current thread
+ mov rbx, rax
+ mov rax, [rbx+40] ; Get Kernel Stack
+ sub rax, KSTACK_USERSTATE_SIZE
+
+ ;
+ ; NOTE: This can cause corruption if the signal happens while the user
+ ; has called a kernel operation.
+ ; Good thing this can only be called on a user fault.
+ ;
+
+ ; Get and alter User SP
+ mov rcx, [rax+KSTACK_USERSTATE_SIZE-3*8]
+ mov rdx, [rbx+60] ; Get Signal Number
+ mov [rcx-8], rdx
+ mov rax, User_Syscall_RetAndExit
+ mov [rcx-16], rax
+ sub rcx, 16
+
+ ; Restore Segment Registers
+ mov ax, 0x23
+ mov ds, ax
+ mov es, ax
+
+ push 0x23 ; SS
+ push rcx ; RSP
+ push 0x202 ; RFLAGS (IF and Rsvd)
+ push 0x1B ; CS
+ push rbp ; RIP
+
+ iret
+
+[section .usertext]
+User_Syscall_RetAndExit:
+ mov rdi, rax
+ jmp User_Syscall_Exit
+User_Syscall_Exit:
+ xor rax, rax
+ ; RDI: Return Value
+ int 0xAC
+
+[section .bss]
+[global gInitialKernelStack]
+ resd 1024*1 ; 1 Page
+gInitialKernelStack:
+