X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=Kernel%2Farch%2Fx86_64%2Fstart64.asm;h=c1f1e58be0e474e6308e5676083555b6e8585d44;hb=9f407c493c33928e0f19b834699d9694036ca42e;hp=67ba23c9532eb62ac25bec34965234c296f17255;hpb=43f12a083f112a410859597c5f45e78b1de2e7c8;p=tpg%2Facess2.git

diff --git a/Kernel/arch/x86_64/start64.asm b/Kernel/arch/x86_64/start64.asm
index 67ba23c9..c1f1e58b 100644
--- a/Kernel/arch/x86_64/start64.asm
+++ b/Kernel/arch/x86_64/start64.asm
@@ -3,5 +3,68 @@
 ;
 [bits 64]
 
+[section .text]
+[global start64]
 start64:
+	; Set kernel stack
+	; Call main
 	jmp $
+
+[global GetRIP]
+GetRIP:
+	mov rax, [rsp]
+	ret
+
+KSTACK_USERSTATE_SIZE	equ	(4+8+1+5)*4	; SRegs, 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 QWORD [rcx-16], User_Syscall_RetAndExit
+	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:
+