From de2ae10743172075f2d527780bdfd890ccddb8e7 Mon Sep 17 00:00:00 2001
From: John Hodge <tpg@mutabah.net>
Date: Tue, 24 Aug 2010 09:18:25 +0800
Subject: [PATCH] Fixed Proc_ReturnToUser's dependence on the structure of
 tThread

---
 Kernel/arch/x86/include/arch.h |  4 ++--
 Kernel/arch/x86/proc.asm       | 24 ++++++++++++++----------
 Kernel/arch/x86/proc.c         |  4 ++--
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/Kernel/arch/x86/include/arch.h b/Kernel/arch/x86/include/arch.h
index 0fec144e..eff85fc2 100644
--- a/Kernel/arch/x86/include/arch.h
+++ b/Kernel/arch/x86/include/arch.h
@@ -58,7 +58,7 @@ static inline int IS_LOCKED(struct sShortSpinlock *Lock) {
 static inline void SHORTLOCK(struct sShortSpinlock *Lock) {
 	 int	v = 1;
 	 int	IF;
-	// int	val = GetCPUNum() + 1;
+	// int	cpu = GetCPUNum() + 1;
 	
 	// Save interrupt state and clear interrupts
 	__ASM__ ("pushf;\n\tcli;\n\tpop %%eax" : "=a"(IF));
@@ -66,7 +66,7 @@ static inline void SHORTLOCK(struct sShortSpinlock *Lock) {
 	
 	// Wait for another CPU to release
 	while(v)
-		__ASM__("xchgl %%ecx, (%%edi)":"=c"(v):"a"(1),"D"(&Lock->Lock));
+		__ASM__("xchgl %%eax, (%%edi)":"=a"(v):"a"(1),"D"(&Lock->Lock));
 	
 	Lock->IF = IF;
 }
diff --git a/Kernel/arch/x86/proc.asm b/Kernel/arch/x86/proc.asm
index 80cc3cbb..e0598a55 100644
--- a/Kernel/arch/x86/proc.asm
+++ b/Kernel/arch/x86/proc.asm
@@ -150,13 +150,16 @@ SpawnTask:
 .parent:
 	ret
 
-;
+; void Proc_ReturnToUser(void *Method, Uint Parameter)
 ; Calls a user fault handler
 ;
 [global Proc_ReturnToUser]
 [extern Proc_GetCurThread]
 Proc_ReturnToUser:
-	; EBP is the handler to use
+	push ebp
+	mov ebp, esp
+	; [EBP+4]: handler to use
+	; [EBP+8]: parameter
 	
 	call Proc_GetCurThread
 	
@@ -204,10 +207,10 @@ Proc_ReturnToUser:
 	jnz .justKillIt
 	
 	; Get and alter User SP
-	mov ecx, edx
-	mov edx, [ebx+68]	; Get Signal Number from TCB (TODO: Get this from parameters)
-	mov [ecx+4], edx	; Parameter (Signal/Error Number)
-	mov [ecx], DWORD User_Syscall_RetAndExit	; Return Address
+	mov edi, edx
+	mov edx, [ebp+8]	; Get parameter
+	mov [edi+4], edx	; save to user stack
+	mov [edi], DWORD User_Syscall_RetAndExit	; Return Address
 	
 	; Restore Segment Registers
 	mov ax, 0x23
@@ -217,10 +220,11 @@ Proc_ReturnToUser:
 	mov gs, ax
 	
 	push 0x23	; SS
-	push ecx	; ESP
+	push edi	; ESP
 	push 0x202	; EFLAGS (IP and Rsvd)
 	push 0x1B	; CS
-	push ebp	; EIP
+	mov eax, [ebp+4]	; Method to call
+	push eax	; EIP
 	
 	iret
 	
@@ -233,7 +237,7 @@ Proc_ReturnToUser:
 	int 0xAC
 
 [global GetCPUNum]
-GetCPUNum:
+GetCPUNum:	; TODO: Store in debug registers
 	xor eax, eax
 	str ax
 	sub ax, 0x30
@@ -245,7 +249,7 @@ GetCPUNum:
 ; Export a place for the user to jump to to call a syscall
 ; - Allows the kernel to change the method easily
 User_Syscall:
-	xchg bx, bx
+	xchg bx, bx	; MAGIC BREAKPOINT
 	int 0xAC
 
 ; A place to return to and exit
diff --git a/Kernel/arch/x86/proc.c b/Kernel/arch/x86/proc.c
index 16af0da8..bfd0e8f7 100644
--- a/Kernel/arch/x86/proc.c
+++ b/Kernel/arch/x86/proc.c
@@ -48,7 +48,7 @@ extern int	giNextTID;
 extern tThread	gThreadZero;
 extern tThread	*Threads_CloneTCB(Uint *Err, Uint Flags);
 extern void	Isr8(void);	// Double Fault
-extern void	Proc_ReturnToUser(void);
+extern void	Proc_ReturnToUser(tVAddr Handler, Uint Argument);
 
 // === PROTOTYPES ===
 void	ArchThreads_Init(void);
@@ -829,7 +829,7 @@ void Proc_CallFaultHandler(tThread *Thread)
 {
 	// Rewinds the stack and calls the user function
 	// Never returns
-	__asm__ __volatile__ ("mov %0, %%ebp;\n\tcall Proc_ReturnToUser" :: "r"(Thread->FaultHandler));
+	Proc_ReturnToUser( Thread->FaultHandler, Thread->CurFaultNum );
 	for(;;);
 }
 
-- 
2.20.1