Kernel: Fix multiprocessor for i686

i686 is now actually ran with multiple processors.

kernel/arch/i686/Syscall.S

@@ -1,3 +1,57 @@
+// arguments in EAX, EBX, ECX, EDX, ESI, EDI
+.global asm_syscall_handler
+asm_syscall_handler:
+	# save segment registers
+	pushw %ds
+	pushw %es
+	pushw %fs
+	pushw %gs
+
+	# save general purpose registers
+	pushl %ebx
+	pushl %ecx
+	pushl %edx
+	pushl %edi
+	pushl %esi
+	pushl %ebp
+
+	# align stack and push arguments
+	pushl %esp
+	addl $32, (%esp)
+	pushl %edi
+	pushl %esi
+	pushl %edx
+	pushl %ecx
+	pushl %ebx
+	pushl %eax
+
+	# load kernel segments
+	movw $0x10, %ax
+	movw %ax, %ds
+	movw %ax, %es
+	movw %ax, %fs
+	movw $0x28, %ax
+	movw %ax, %gs
+
+	call cpp_syscall_handler
+	addl $28, %esp
+
+	# restore general purpose registers
+	popl %ebp
+	popl %esi
+	popl %edi
+	popl %edx
+	popl %ecx
+	popl %ebx
+
+	# restore segment registers
+	popw %gs
+	popw %fs
+	popw %es
+	popw %ds
+
+	iret
+
 .global sys_fork_trampoline
 sys_fork_trampoline:
 	pushl %ebp

kernel/arch/i686/interrupts.S

@@ -24,22 +24,6 @@
 	popw %gs
 .endm
 
-.macro pop_userspace_skip_eax
-	popl %edi
-	popl %esi
-	popl %ebp
-	addl $4, %esp
-	popl %ebx
-	popl %edx
-	popl %ecx
-	addl $4, %esp
-
-	popw %ds
-	popw %es
-	popw %fs
-	popw %gs
-.endm
-
 isr_stub:
 	push_userspace
 	load_kernel_segments
@@ -81,46 +65,21 @@ irq_stub:
 	addl $8, %esp
 	iret
 
-.global asm_reschedule_handler
-asm_reschedule_handler:
-	push_userspace
-	load_kernel_segments
+.global asm_yield_handler
+asm_yield_handler:
+	# This can only be called from kernel, so no segment saving is needed
+	pushal
 
 	movl %esp,     %eax # interrupt registers ptr
-	leal 40(%esp), %ebx # interrupt stack ptr
+	leal 32(%esp), %ebx # interrupt stack ptr
 
-	subl $12, %esp
+	subl $4, %esp
 	pushl %eax
 	pushl %ebx
-	call cpp_reschedule_handler
-	addl $20, %esp
+	call cpp_yield_handler
+	addl $12, %esp
 
-	pop_userspace
-	iret
-
-// arguments in EAX, EBX, ECX, EDX, ESI, EDI
-.global syscall_asm
-syscall_asm:
-	push_userspace
-
-	subl $8, %esp
-
-	pushl %esp
-	addl $48, (%esp)
-
-	pushl %edi
-	pushl %esi
-	pushl %edx
-	pushl %ecx
-	pushl %ebx
-	pushl %eax
-
-	load_kernel_segments
-
-	call cpp_syscall_handler
-	addl $36, %esp
-
-	pop_userspace_skip_eax
+	popal
 	iret
 
 .macro isr n
@@ -211,3 +170,4 @@ irq 28
 irq 29
 irq 30
 irq 31
+irq 32

kernel/kernel/IDT.cpp

@@ -332,6 +332,7 @@ done:
 	extern "C" void cpp_yield_handler(InterruptStack* interrupt_stack, InterruptRegisters* interrupt_registers)
 	{
 		ASSERT(!InterruptController::get().is_in_service(IRQ_YIELD));
+		ASSERT(!GDT::is_user_segment(interrupt_stack->cs));
 
 		Processor::enter_interrupt(interrupt_stack, interrupt_registers);
 		Scheduler::get().irq_reschedule();