Kernel: Remove unnecessary stack pointer loading

Any time I started a thread I was loading the stack pointer which is
already correctly passed :D

kernel/arch/i686/Syscall.S

@@ -63,7 +63,7 @@ sys_fork_trampoline:
 
 	call read_ip
 	testl %eax, %eax
-	jz .reload_stack
+	jz .done
 
 	movl %esp, %ebx
 
@@ -79,9 +79,3 @@ sys_fork_trampoline:
 	popl %ebx
 	popl %ebp
 	ret
-
- .reload_stack:
-	call get_thread_start_sp
-	movl %eax, %esp
-	xorl %eax, %eax
-	jmp .done

kernel/arch/i686/Thread.S

@@ -7,9 +7,6 @@ read_ip:
 # void start_kernel_thread()
 .global start_kernel_thread
 start_kernel_thread:
-	call get_thread_start_sp
-	movl %eax, %esp
-
 	# STACK LAYOUT
 	#   on_exit arg
 	#   on_exit func
@@ -34,9 +31,6 @@ start_kernel_thread:
 
 .global start_userspace_thread
 start_userspace_thread:
-	call get_thread_start_sp
-	movl %eax, %esp
-
 	movw $(0x20 | 3), %bx
 	movw %bx, %ds
 	movw %bx, %es

kernel/arch/x86_64/Syscall.S

@@ -33,7 +33,7 @@ sys_fork_trampoline:
 
 	call read_ip
 	testq %rax, %rax
-	je .done
+	jz .done
 
 	movq %rax, %rsi
 	movq %rsp, %rdi

kernel/arch/x86_64/Thread.S

@@ -7,9 +7,6 @@ read_ip:
 # void start_kernel_thread()
 .global start_kernel_thread
 start_kernel_thread:
-	call get_thread_start_sp
-	movq %rax, %rsp
-
 	# STACK LAYOUT
 	#   on_exit arg
 	#   on_exit func
@@ -27,9 +24,5 @@ start_kernel_thread:
 
 .global start_userspace_thread
 start_userspace_thread:
-	call get_thread_start_sp
-	movq %rax, %rsp
-
 	swapgs
-
 	iretq

kernel/kernel/Thread.cpp

@@ -25,11 +25,6 @@ namespace Kernel
 		*(uintptr_t*)rsp = (uintptr_t)value;
 	}
 
-	extern "C" uintptr_t get_thread_start_sp()
-	{
-		return Thread::current().yield_registers().sp;
-	}
-
 	static pid_t s_next_tid = 1;
 
 	alignas(16) static uint8_t s_default_sse_storage[512];