syscalls

25 files changed, 183 insertions, 716 deletions

diff --git a/asm/GDT.asm b/asm/GDT.asm
deleted file mode 100644
index 444c313..0000000
--- a/asm/GDT.asm
+++ /dev/null
@@ -1,81 +0,0 @@
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;;;;;; Miguel's FoolOS Helper Functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;
-;   Global Descriptor Table
-;   we have the null descriptor and a code and data block for a start
-;
-;   0x08 code segment
-;   0x10 data segment
-;
-;    this file contains pure data
-;
-;
-;
-;
-
-global gdt_descriptor
-global gdt_start
-
-gdt_start:
-
-gdt_null:   ;null descriptor (2 x 4 bytes)
-    dd 0x0
-    dd 0x0
-
-gdt_code:
-    ; flags:
-    ; present: 1 / privilege: 00 / type: 1
-    ; code: 1 / conforming: 0 / readable: 1 / accessed: 0
-    ; granularity: 1 / 16-bit default: 1 / 64-bit seg: 0 / AVL: 0
-    dw 0xffff	    ;limit
-    dw 0x0	    ;base
-    db 0x0	    ;base
-    db 10011010b    ;flags
-    db 11001111b    ;flags & seg.limit
-    db 0x0	    ;base
-
-gdt_data:
-    ; flags:
-    ; code: 0 / expand down: 0 / writable: 1 / accessed: 0
-    dw 0xffff
-    dw 0x0
-    db 0x0
-    db 10010010b
-    db 11001111b
-    db 0x0
-
-gdt16_code:
-    ; flags:
-    ; present: 1 / privilege: 00 / type: 1
-    ; code: 1 / conforming: 0 / readable: 1 / accessed: 0
-    ; granularity: 1 / 16-bit default: 1 / 64-bit seg: 0 / AVL: 0
-    dw 0xffff	    ;limit
-    dw 0x0	    ;base
-    db 0x0	    ;base
-    db 10011010b    ;flags
-    db 10001111b    ;flags & seg.limit
-    db 0x0	    ;base
-
-gdt16_data:
-    ; flags:
-    ; code: 0 / expand down: 0 / writable: 1 / accessed: 0
-    dw 0xffff
-    dw 0x0
-    db 0x0
-    db 10010010b
-    db 10001111b
-    db 0x0
-
-gdt_end:
-
-gdt_descriptor:
-    dw gdt_end-gdt_start-1
-    dd gdt_start
-
-CODE_SEG equ gdt_code - gdt_start
-DATA_SEG equ gdt_data - gdt_start
-CODE16_SEG equ gdt16_code - gdt_start
-DATA16_SEG equ gdt16_data - gdt_start
-
-
diff --git a/asm/asm.h b/asm/asm.h
deleted file mode 100644
index 8433e4e..0000000
--- a/asm/asm.h
+++ /dev/null
@@ -1,27 +0,0 @@
-void pic_setup();
-
-void int_kb_handler();
-void int_mouse_handler();
-void int_default_handler();
-
-void int_syscall_handler();
-
-void int_irq0();
-void int_irq1();
-void int_irq2();
-void int_irq3();
-void int_irq4();
-void int_irq5();
-void int_irq6();
-void int_irq7();
-void int_irq8();
-void int_irq9();
-void int_irq10();
-void int_irq11();
-void int_irq12();
-void int_irq13();
-void int_irq14();
-void int_irq15();
-void int_irq16();
-void int_irq17();
-void int_irq18();
diff --git a/asm/gdt.h b/asm/gdt.h
new file mode 100644
index 0000000..f5bcbd3
--- /dev/null
+++ b/asm/gdt.h
@@ -0,0 +1 @@
+void asm_setup_gdt(uint32_t addr, uint32_t size)
diff --git a/asm/helpers.s b/asm/gdt.s
index 135443d..698dcf6 100644
--- a/asm/helpers.s
+++ b/asm/gdt.s
@@ -1,9 +1,9 @@
 //http://wiki.osdev.org/GDT_Tutorial
-.global setup_gdt
-.global tss_flush
+.global asm_setup_gdt
+//.global tss_flush
 
 // call as setup_gdt(GDT,sizeof(GDT))
-setup_gdt:
+asm_setup_gdt:
 
 	// re-fill gdt_descriptor with new GDT location and size
 	movl 4(%esp),%eax
@@ -32,10 +32,10 @@ setup_gdt:
 	tss_flush:
 
 	   movw $0x2B,%ax      # Load the index of our TSS structure - The index is
-                     # 0x28, as it is the 5th selector and each is 8 bytes
-                     # long, but we set the bottom two bits (making 0x2B)
-                     # so that it has an RPL of 3, not zero.
-	   ltr %ax            # Load 0x2B into the task state register.
+			       # 0x28, as it is the 5th selector and each is 8 bytes
+			       # long, but we set the bottom two bits (making 0x2B)
+			       # so that it has an RPL of 3, not zero.
+	   ltr %ax             # Load 0x2B into the task state register.
 
 	   ret
 
diff --git a/asm/int.h b/asm/int.h
index 4af9eac..33dd16e 100644
--- a/asm/int.h
+++ b/asm/int.h
@@ -14,4 +14,30 @@ void int12();
 void int13();
 void int14();
 void int15();
-void int128();
+
+void int128(); // syscalls
+void int129(); // scheduler
+void int255(); // unhandled
+
+void exc0();
+void exc1();
+void exc2();
+void exc3();
+void exc4();
+void exc5();
+void exc6();
+void exc7();
+void exc8();
+void exc9();
+void exc10();
+void exc11();
+void exc12();
+void exc13();
+void exc14();
+void exc15();
+void exc16();
+void exc17();
+void exc18();
+
+void asm_mouse_handler();
+void asm_kb_handler();
diff --git a/asm/int.s b/asm/int.s
index f6cb9e8..156c266 100644
--- a/asm/int.s
+++ b/asm/int.s
@@ -17,11 +17,48 @@
 .global int15
 
 .global int128
+.global int129
+.global int255
+
+.global exc0
+.global exc1
+.global exc2
+.global exc3
+.global exc4
+.global exc5
+.global exc6
+.global exc7
+.global exc8
+.global exc9
+.global exc10
+.global exc11
+.global exc12
+.global exc13
+.global exc14
+.global exc15
+.global exc16
+.global exc17
+.global exc18
 
 //temporary
 .global asm_mouse_handler
 .global asm_kb_handler
 
+asm_kb_handler:
+    push %eax
+    mov $0x0,%eax
+    in  $0x60,%al
+    pop %eax
+    ret
+
+asm_mouse_handler:
+    push %eax
+    mov $0x0,%eax
+    in  $0x60,%al
+    pop %eax
+    ret
+
+///////////////
 
 // nothing to ack
 .macro ack0
@@ -44,17 +81,9 @@
     pop %eax // load original
 .endm
 
-// ignore return value
-.macro ret0
-    add $4,%esp
-.endm
 
-// put return value in %eax
-.macro ret1
-    pop %eax
-.endm
 
-.macro intx ack retx num func
+.macro intx ack num func
 
     /* 
        Once we arrived here the stack already contains 3x 32bit values,
@@ -81,6 +110,8 @@
     push $0x666    //make room for potential C functions 'return value'.
                    //we use eax already for esp (so we can context switch)
 
+    push $0x0      //indicate if we want to return the value in ebx 0x0=NO
+
     pusha          //Push all standard registers 8 regs x 4bytes/32bit
     push %ds       //Push data segment
     push %es       //etc...
@@ -103,42 +134,64 @@
     pop %ds
     popa           
 
-    \retx          // potentially set return value to eax to return to the caller
+    cmp $0x0,(%esp)
+    je skip\num
+    pop %ebx
+    pop %ebx
+    jmp ret\num
+    skip\num:
+    add $8,%esp    // potentially set return value to eax to return to the caller
+    ret\num:
 
     iret           // pops the return instruction pointer, return code segment selector, and EFLAGS image from the stack
 
 .endm
 
-int0: intx ack1 ret0 $0 interrupt_handler
-int1: intx ack1 ret0 $1 interrupt_handler
-int2: intx ack1 ret0 $2 interrupt_handler
-int3: intx ack1 ret0 $3 interrupt_handler
-int4: intx ack1 ret0 $4 interrupt_handler
-int5: intx ack1 ret0 $5 interrupt_handler
-int6: intx ack1 ret0 $6 interrupt_handler
-int7: intx ack1 ret0 $7 interrupt_handler
-
-int8: intx ack2 ret0 $8 interrupt_handler
-int9: intx ack2 ret0 $9 interrupt_handler
-int10: intx ack2 ret0 $10 interrupt_handler
-int11: intx ack2 ret0 $11 interrupt_handler
-int12: intx ack2 ret0 $12 interrupt_handler
-int13: intx ack2 ret0 $13 interrupt_handler
-int14: intx ack2 ret0 $14 interrupt_handler
-int15: intx ack2 ret0 $15 interrupt_handler
-
-int128: intx ack0 ret1 $128 interrupt_handler
+.macro excx func
+    call \func
+    jmp .
+.endm
 
-asm_kb_handler:
-    push %eax
-    mov $0x0,%eax
-    in  $0x60,%al
-    pop %eax
-    ret
+int0: intx ack1 $0 interrupt_handler
+int1: intx ack1 $1 interrupt_handler
+int2: intx ack1 $2 interrupt_handler
+int3: intx ack1 $3 interrupt_handler
+int4: intx ack1 $4 interrupt_handler
+int5: intx ack1 $5 interrupt_handler
+int6: intx ack1 $6 interrupt_handler
+int7: intx ack1 $7 interrupt_handler
+
+int8: intx ack2  $8 interrupt_handler
+int9: intx ack2  $9 interrupt_handler
+int10: intx ack2 $10 interrupt_handler
+int11: intx ack2 $11 interrupt_handler
+int12: intx ack2 $12 interrupt_handler
+int13: intx ack2 $13 interrupt_handler
+int14: intx ack2 $14 interrupt_handler
+int15: intx ack2 $15 interrupt_handler
+
+int128: intx ack0 $128 interrupt_handler
+int129: intx ack0 $129 interrupt_handler
+
+int255: intx ack0 $255 interrupt_handler
+
+exc0: excx exception_handle_0
+exc1: excx exception_handle_1
+exc2: excx exception_handle_2
+exc3: excx exception_handle_3
+exc4: excx exception_handle_4
+exc5: excx exception_handle_5
+exc6: excx exception_handle_6
+exc7: excx exception_handle_7
+exc8: excx exception_handle_8
+exc9: excx exception_handle_9
+exc10: excx exception_handle_10
+exc11: excx exception_handle_11
+exc12: excx exception_handle_12
+exc13: excx exception_handle_13
+exc14: excx exception_handle_14
+exc15: excx exception_handle_15
+exc16: excx exception_handle_16
+exc17: excx exception_handle_17
+exc18: excx exception_handle_18
 
-asm_mouse_handler:
-    push %eax
-    mov $0x0,%eax
-    in  $0x60,%al
-    pop %eax
-    ret
diff --git a/asm/int_default_handler.asm b/asm/int_default_handler.asm
deleted file mode 100644
index 00aa1ac..0000000
--- a/asm/int_default_handler.asm
+++ /dev/null
@@ -1,15 +0,0 @@
-global int_default_handler
-[extern int_default]
-
-[bits 32]
-int_default_handler:
-
- pusha
-
- call int_default
-
- mov al, 0x20   ;Port number AND command number to Acknowledge IRQ
- out 0x20, al   ;Acknowledge IRQ, so we keep getting interrupts
-
- popa
- iret           ;Interrupt-Return
diff --git a/asm/int_irq.asm b/asm/int_irq.asm
deleted file mode 100644
index ac8eef8..0000000
--- a/asm/int_irq.asm
+++ /dev/null
@@ -1,155 +0,0 @@
-global int_irq0
-global int_irq1
-global int_irq2
-global int_irq3
-global int_irq4
-global int_irq5
-global int_irq6
-global int_irq7
-global int_irq8
-global int_irq9
-global int_irq10
-global int_irq11
-global int_irq12
-global int_irq13
-global int_irq14
-global int_irq15
-global int_irq16
-global int_irq17
-global int_irq18
-
-[extern exception_handle]
-[extern exception_handle_0]
-[extern exception_handle_1]
-[extern exception_handle_2]
-[extern exception_handle_3]
-[extern exception_handle_4]
-[extern exception_handle_5]
-[extern exception_handle_6]
-[extern exception_handle_7]
-[extern exception_handle_8]
-[extern exception_handle_9]
-[extern exception_handle_10]
-[extern exception_handle_11]
-[extern exception_handle_12]
-[extern exception_handle_13]
-[extern exception_handle_14]
-[extern exception_handle_15]
-[extern exception_handle_16]
-[extern exception_handle_17]
-[extern exception_handle_18]
-
-[bits 32]
-int_irq0:
-
- cli
- call exception_handle_0 ;this will never return due to panic!
- jmp $
-
-int_irq1:
-
- cli
- call exception_handle_1 ;this will never return due to panic!
- jmp $
-
-int_irq2:
-
- cli
- call exception_handle_2 ;this will never return due to panic!
- jmp $
-
-int_irq3:
-
- cli
- call exception_handle_3 ;this will never return due to panic!
- jmp $
-
-int_irq4:
-
- cli
- call exception_handle_4 ;this will never return due to panic!
- jmp $
-
-int_irq5:
-
- cli
- call exception_handle_5 ;this will never return due to panic!
- jmp $
-
-int_irq6:
-
- cli
- call exception_handle_6 ;this will never return due to panic!
- jmp $
-
-int_irq7:
-
- cli
- call exception_handle_7 ;this will never return due to panic!
- jmp $
-
-int_irq8:
-
- cli
- call exception_handle_8 ;this will never return due to panic!
- jmp $
-
-int_irq9:
-
- cli
- call exception_handle_9;this will never return due to panic!
- jmp $
-
-int_irq10:
-
- cli
- call exception_handle_10;this will never return due to panic!
- jmp $
-
-int_irq11:
-
- cli
- call exception_handle_11;this will never return due to panic!
- jmp $
-
-int_irq12:
-
- cli
- call exception_handle_12 ;this will never return due to panic!
- jmp $
-
-int_irq13:
-
- cli
- call exception_handle_13;this will never return due to panic!
- jmp $
-
-int_irq14:
-
- cli
- call exception_handle_14 ;this will never return due to panic!
- jmp $
-
-int_irq15:
-
- cli
- call exception_handle_15 ;this will never return due to panic!
- jmp $
-
-int_irq16:
-
- cli
- call exception_handle_16 ;this will never return due to panic!
- jmp $
-
-int_irq17:
-
- cli
- call exception_handle_17 ;this will never return due to panic!
- jmp $
-
-int_irq18:
-
- cli
- call exception_handle_18;this will never return due to panic!
- jmp $
diff --git a/asm/int_kb_handler.asm b/asm/int_kb_handler.asm
deleted file mode 100644
index cd1b32c..0000000
--- a/asm/int_kb_handler.asm
+++ /dev/null
@@ -1,24 +0,0 @@
-global int_kb_handler
-[extern keyboard_handle]
-[extern int_default]
-
-[bits 32]
-
-int_kb_handler:
-
-    pusha
-
-    mov eax,0x0
-    in al,0x60
-
-    push eax
-    call keyboard_handle
-
-    pop eax
-
-    mov al, 0x20   ;Port number AND command number to Acknowledge IRQ
-    out 0x20, al   ;Acknowledge IRQ, so we keep getting interrupts
-
-    popa
-
-iretd           ;Interrupt-Return
diff --git a/asm/int_mouse_handler.asm b/asm/int_mouse_handler.asm
deleted file mode 100644
index 9816950..0000000
--- a/asm/int_mouse_handler.asm
+++ /dev/null
@@ -1,16 +0,0 @@
-global int_mouse_handler
-[extern mouse_handler]
-
-[bits 32]
-int_mouse_handler: 
-  pusha
-
- call mouse_handler
-
- mov al, 0x20   ; Port number AND command number to Acknowledge IRQ
- out 0xa0, al   ; came from slave
- out 0x20, al   ; Acknowledge IRQ, so we keep getting interrupts
-
- popa
-
- iret           ;Interrupt-Return
diff --git a/asm/int_syscall_handler.asm b/asm/int_syscall_handler.asm
deleted file mode 100644
index 4031f3d..0000000
--- a/asm/int_syscall_handler.asm
+++ /dev/null
@@ -1,256 +0,0 @@
-global int_syscall_handler
-[extern task_fork]
-[extern task_exit]
-[extern task_wait]
-
-
-[extern syscall_exit]
-[extern syscall_write]
-[extern syscall_read]
-[extern syscall_readdir]
-[extern syscall_execve]
-[extern syscall_open]
-[extern syscall_close]
-[extern syscall_isatty]
-[extern syscall_lseek]
-[extern syscall_sbrk]
-[extern syscall_stat]
-[extern syscall_fork]
-[extern syscall_poll]
-[extern syscall_gettimeofday]
-[extern syscall_unhandled]
-
-[bits 32]
-
-pid: dd 0x0
-
-int_syscall_handler:
-
-cmp eax, 72
-je call_fork
-
-cmp eax, 60
-je call_exit
-
-cmp eax, 77
-je call_wait
-
- cli
-
-    push ebx
-    push ecx
-    push edx
-
-    cmp eax, 61
-    je call_write
-
-    cmp eax, 62
-    je call_read
-
-    cmp eax, 63
-    je call_readdir
-
-    cmp eax, 64
-    je call_execve
-
-    cmp eax, 65
-    je call_open
-
-    cmp eax, 66
-    je call_close
-
-    cmp eax, 68
-    je call_isatty
-
-    cmp eax, 69
-    je call_lseek
-
-    cmp eax, 70
-    je call_sbrk
-
-    cmp eax, 71
-    je call_timeofday
-
-    cmp eax, 74
-    je call_stat
-
-    cmp eax, 67
-    je call_stat
-
-    cmp eax, 79
-    je call_stat
-
-    cmp eax, 80
-    je call_poll
-
-    push eax
-    jmp call_unhandled
-
-
-done:
-
-
-
-done_blocking:
-
-    pop ebx
-    pop ecx
-    pop edx
-
-    mov ebx,eax 
-
-    sti
-
-    iret           ;Interrupt-Return
-
-call_wait:
-
-    cli
-
-    pusha          ;Push all standard registers
-
-    mov ebx, esp	;save current stack pointer in esp
-    mov esp, 0x7000	;now put the stack outside of virtual memory in kernel space!
-
-    push ebx      ;Push pointer to all the stuff we just pushed
-
-    call task_wait ;Call C code
-
-    mov esp, eax   ;Replace the stack with what the C code gave us
-
-    popa           ;Put the standard registers back
-
-    sti
-
-    iretd           ;Interrupt-Return
-    ;;;;
-
-call_exit:
-
-    cli
-
-    pusha          ;Push all standard registers
-
-    mov ebx, esp	;save current stack pointer in esp
-    mov esp, 0x7000	;now put the stack outside of virtual memory in kernel space!
-
-    push ebx      ;Push pointer to all the stuff we just pushed
-
-    call task_exit ;Call C code
-
-    mov esp, eax   ;Replace the stack with what the C code gave us
-
-    popa           ;Put the standard registers back
-
-    sti
-
-    iretd           ;Interrupt-Return
-    ;;;;
-
-call_fork:
-    
-    pusha		;Push all standard registers
-
-    push ds
-    push es
-    push fs
-    push gs
-
-    mov ebx, esp     ; pass it in
-    push ebx
-    call task_fork ;Call C code
-    pop ebx
-
-    pop ds
-    pop es
-    pop fs
-    pop gs
-
-    mov [pid],eax    ; save return val, so it survives popa
-
-    popa           ;Put the standard registers back
-
-    mov ebx,[pid]
-
-    iretd           ;Interrupt-Return
-
-call_timeofday:
-    call syscall_gettimeofday
-    jmp done
-
-call_stat:
-    call syscall_stat
-    jmp done
-
-call_write:
-    call syscall_write
-    jmp done
-
-call_open:
-    call syscall_open
-    jmp done
-
-call_readdir:
-    call syscall_readdir
-    jmp done
-
-call_close:
-    call syscall_close
-    jmp done
-
-call_isatty:
-    call syscall_isatty
-    jmp done
-
-call_lseek:
-    call syscall_lseek
-    jmp done
-
-call_sbrk:
-    call syscall_sbrk
-    jmp done
-
-call_poll:
-    call syscall_poll
-    jmp done
-
-call_unhandled:
-    call syscall_unhandled
-    jmp done ;this should never be called, since unhandled causes kernel panic
-
-
-    ;;; THIS CALLS NEED REENABLE INTERRUPTS BEFORE calling workers
-    ;; TODO: redesign this shit!
-call_read:
-
-    ;//mov al, 0x20   ;Port number AND command number to Acknowledge IRQ
-    ;//out 0x20, al     ;Acknowledge IRQ, so we keep getting interrupts
-    sti
-
-    call syscall_read
-
-    jmp done_blocking
-
-call_execve:
-
-    pusha
-
-    mov eax,esp
-    mov esp,0x7000
-
-    push ebx
-    push ecx
-    push edx
-
-    mov ebx,eax
-    call syscall_execve
-
-    pop eax
-    pop eax
-    pop eax
-
-    mov esp,ebx
-
-    popa
-
-    jmp done
diff --git a/asm/mp.asm b/asm/mp.asm
index 1c04f3f..e5cc26d 100644
--- a/asm/mp.asm
+++ b/asm/mp.asm
@@ -38,6 +38,7 @@ boot_32_pm:
     mov eax, 1		 ; semaphore	
     xchg eax, [LLOCK]
     cmp eax,1
+    hlt
     je $
     jmp $ ; loop forever here
 
diff --git a/asm/mp.h b/asm/mp.h
new file mode 100644
index 0000000..d050012
--- /dev/null
+++ b/asm/mp.h
@@ -0,0 +1 @@
+void smp_go();
diff --git a/asm/pic.asm b/asm/pic.asm
index 28b484c..901f854 100644
--- a/asm/pic.asm
+++ b/asm/pic.asm
@@ -4,7 +4,7 @@
 
 [bits 32]
 
-global pic_setup
+global asm_pic_setup
  
 %define ICW_1 0x11				; 00010001 binary. Enables initialization mode and we are sending ICW 4
  
@@ -17,7 +17,7 @@ global pic_setup
 %define IRQ_0	0x20				; IRQs 0-7 mapped to use interrupts 0x20-0x27
 %define IRQ_8	0x28				; IRQs 8-15 mapped to use interrupts 0x28-0x36
  
-pic_setup:
+asm_pic_setup:
  
 ; Send ICW 1 - Begin initialization -------------------------
  
diff --git a/asm/pic.h b/asm/pic.h
new file mode 100644
index 0000000..0daea2a
--- /dev/null
+++ b/asm/pic.h
@@ -0,0 +1 @@
+void asm_pic_setup();
diff --git a/asm/pit.h b/asm/pit.h
index 0bec3c4..d020de1 100644
--- a/asm/pit.h
+++ b/asm/pit.h
@@ -16,10 +16,10 @@
 #include <stdint.h>
 
 /** Init PIT - 25 times a second*/
-void pit_init();
+void asm_pit_init();
 
 /** install this interrupt handler to your Interrupt Vector Table */
-void pit_interrupt_handler();
+void asm_pit_tick();
 
 /** get number of ticks */
-uint32_t pit_get_ticks();
+uint32_t asm_pit_get_ticks();
diff --git a/asm/pit.s b/asm/pit.s
index 34b69ec..8e16d0b 100644
--- a/asm/pit.s
+++ b/asm/pit.s
@@ -1,16 +1,16 @@
-.global pit_init
-.global pit_interrupt_handler
-.global pit_get_ticks
+.global asm_pit_init
+.global asm_pit_tick
+.global asm_pit_get_ticks
 
 ticks:
 .int 0
 
-pit_get_ticks:
+asm_pit_get_ticks:
     
     mov (ticks),%eax
     ret
 
-pit_interrupt_handler:
+asm_pit_tick:
 
     push %eax // persist
 
@@ -18,38 +18,11 @@ pit_interrupt_handler:
     mov $ticks, %eax    
     incl (%eax)
 
-    // ACK IRQ
-    //mov $0x20,%al
-    //out %al,$0x20   
-
     pop %eax // load original
     
-    ///////
-
-    /*
-    pusha          //Push all standard registers
-    push %ds       //Push data segment
-    push %es       //etc...
-    push %fs
-    push %gs
-
-    mov %esp, %eax          // remember current %esp
-    movl $stack_top, %esp   // switch to our small scheduler stack
-
-    push %eax               // set original %esp as param and... 
-    call task_switch_next   // call scheduler
-    mov  %eax, %esp         // use %esp we got from scheduler
-
-    pop %gs
-    pop %fs
-    pop %es
-    pop %ds
-    popa           
-
-    iret // pops the return instruction pointer, return code segment selector, and EFLAGS image from the stack 
-*/
     ret
-pit_init:
+
+asm_pit_init:
 
     // configure ticking 25 times a second
     // 1193180 / 25 = 47727.2
diff --git a/asm/read_eip.asm b/asm/read_eip.asm
deleted file mode 100644
index 3341943..0000000
--- a/asm/read_eip.asm
+++ /dev/null
@@ -1,6 +0,0 @@
-; http://www.jamesmolloy.co.uk/tutorial_html/9.-Multitasking.html
-[bits 32]
-global read_eip
-read_eip:
-      pop eax
-       jmp eax
diff --git a/asm/start.h b/asm/start.h
index ff30326..7b31b76 100644
--- a/asm/start.h
+++ b/asm/start.h
@@ -14,8 +14,20 @@
   * The addresses for .smp and .multiboot are based on the assumption:
   * * 0x00000500 - 0x00007BFF : guaranteed free to use
   * * 0x00100000 - 0x00EFFFFF : free for use (if it exists) 
+  *
+  * References
+  * ----------
+  * * https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#Boot-information-format
+  * * http://wiki.osdev.org/Bare_Bones
   */
 
-/** This will be called by a multiboot compilant boot-loader (i.e. grub2) */
+/** This will be called by a multiboot compilant boot-loader (i.e. grub2).
+ *  Calls kernel_main() passing through eax and ebx:
+ *  * eax - magic number
+ *  * ebx - multiboot structure
+ * */
 void _start();
 
+/** 16-bit entry point for application processors */
+void _start_smp();
+
diff --git a/asm/start.s b/asm/start.s
index bb12a7c..1d881b4 100644
--- a/asm/start.s
+++ b/asm/start.s
@@ -1,7 +1,9 @@
-# https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#Boot-information-format
-# http://wiki.osdev.org/Bare_Bones
+.global _start
+.global _start_smp
+.global stack_top 
+.global stack_bottom
 
-# Fill Multiboot Haeder, init stack and call kernel_main passing to params:
+# Fill Multiboot Haeder, init stack and call kernel_main passing two params:
 # eax - magic number
 # ebx - multiboot structure
 
@@ -16,7 +18,9 @@
 # entry point for application processors at 0x7000
 .section .smp
 .code16
-call smp_go # TODO: align later before going C
+_start_smp:
+jmp .
+//call smp_go # TODO: align later before going C
 
 # Declare a header as in the Multiboot Standard. We put this into a special
 # section so we can force the header to be in the start of the final program.
@@ -56,12 +60,8 @@ stack_top:
 # bootloader will jump to this position once the kernel has been loaded. It
 # doesn't make sense to return from this function as the bootloader is gone.
 .section .text
-.global _start
-.global stack_top 
-.global stack_bottom
-.type _start, @function
-_start:
 
+_start:
 
 	# To set up a stack, we simply set the esp register to point to the top of
 	# our stack (as it grows downwards).
@@ -73,10 +73,11 @@ _start:
 
 	call kernel_main
 
-	# should never be reached
-
+	# turn off interrupts and halt.
+	# this should never be reached
 	cli
 	hlt
+
 .Lhang:
 	jmp .Lhang
 
diff --git a/asm/syscall.h b/asm/syscall.h
deleted file mode 100644
index 2cadce4..0000000
--- a/asm/syscall.h
+++ /dev/null
@@ -1,11 +0,0 @@
-/* 
- * Issue a System Call from Ring 3 / User Space 
- *
- * Accepts up to 3 parameters.
- * Check syscalls.h for details.
- */
-
-uint32_t syscall(uint32_t code,
-                 uint32_t param_1, 
-                 uint32_t param_2, 
-                 uint32_t param_3);
diff --git a/asm/syscall.s b/asm/syscall.s
deleted file mode 100644
index 388b6fa..0000000
--- a/asm/syscall.s
+++ /dev/null
@@ -1,17 +0,0 @@
-.global syscall
-
-syscall:
-
-	push %ebx // preserve (sysV abi convnetion)
-
-	mov 0x8(%esp),%eax    //syscall number
-	mov 0xC(%esp),%edx    //p1
-	mov 0x10(%esp),%ecx   //p2
-	mov 0x14(%esp),%ebx   //p3
-	
-	int $0x80
-	mov %ebx, %eax // set as return value
-
-	pop %ebx // preserve
-	ret
-
diff --git a/asm/task.s b/asm/task.s
index 4322da5..bf80025 100644
--- a/asm/task.s
+++ b/asm/task.s
@@ -7,6 +7,7 @@ task_pusha:
     push $userfunc
 
     push $0x666
+    push $0x0
 
     pusha
 
@@ -19,7 +20,7 @@ task_pusha:
 
 	now stack looks like:
 
-	param			 // esp+68
+	param			 // esp+72
 	returnaddy		
 
 	eflags			
@@ -44,7 +45,7 @@ task_pusha:
 
 	*/
 
-    mov 68(%esp),%eax // get address of alternative stack where we want to simulate the pusha
+    mov 72(%esp),%eax // get address of alternative stack where we want to simulate the pusha happened
 
     mov (%esp),%ecx
     mov %ecx,(%eax)
@@ -94,6 +95,9 @@ task_pusha:
     mov 60(%esp),%ecx
     mov %ecx,60(%eax)
 
+    mov 64(%esp),%ecx
+    mov %ecx,64(%eax)
+
     pop %gs
     pop %fs
     pop %es
@@ -105,5 +109,6 @@ task_pusha:
     pop %eax
     pop %eax
     pop %eax
+    pop %eax
 
     ret
diff --git a/asm/usermode.h b/asm/usermode.h
index 9b76db3..16597f2 100644
--- a/asm/usermode.h
+++ b/asm/usermode.h
@@ -1,7 +1,8 @@
-/*
- * Switch to User Mode and returin to function given by pointer
+/**
+ * @file
+ * Switch to User Mode and iret to function given by pointer
  * provide the address of a void func() that will be called without
- * any params.
+ * any params via iret.
  */
 
-void usermode(uint32_t func);
+void asm_usermode(uint32_t func);
diff --git a/asm/usermode.s b/asm/usermode.s
index 99cee49..71ecc1d 100644
--- a/asm/usermode.s
+++ b/asm/usermode.s
@@ -1,6 +1,6 @@
-.global usermode
+.global asm_usermode
 
-usermode:
+asm_usermode:
 
 	mov 0x4(%esp),%edx    //get adress of passed : void func()
 			      //to be called in ring 3