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05c594b135
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/*
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* linux/kernel/system_call.s
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*
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* (C) 1991 Linus Torvalds
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*/
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/*
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* system_call.s contains the system-call low-level handling routines.
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* This also contains the timer-interrupt handler, as some of the code is
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* the same. The hd- and flopppy-interrupts are also here.
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*
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* NOTE: This code handles signal-recognition, which happens every time
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* after a timer-interrupt and after each system call. Ordinary interrupts
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* don't handle signal-recognition, as that would clutter them up totally
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* unnecessarily.
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*
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* Stack layout in 'ret_from_system_call':
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*
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* 0(%esp) - %eax
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* 4(%esp) - %ebx
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* 8(%esp) - %ecx
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* C(%esp) - %edx
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* 10(%esp) - %fs
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* 14(%esp) - %es
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* 18(%esp) - %ds
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* 1C(%esp) - %eip
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* 20(%esp) - %cs
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* 24(%esp) - %eflags
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* 28(%esp) - %oldesp
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* 2C(%esp) - %oldss
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*/
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SIG_CHLD = 17
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EAX = 0x00
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EBX = 0x04
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ECX = 0x08
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EDX = 0x0C
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FS = 0x10
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ES = 0x14
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DS = 0x18
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EIP = 0x1C
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CS = 0x20
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EFLAGS = 0x24
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OLDESP = 0x28
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OLDSS = 0x2C
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state = 0 # these are offsets into the task-struct.
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counter = 4
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priority = 8
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signal = 12
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sigaction = 16 # MUST be 16 (=len of sigaction)
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blocked = (33*16)
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# offsets within sigaction
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sa_handler = 0
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sa_mask = 4
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sa_flags = 8
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sa_restorer = 12
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nr_system_calls = 92 /* 72 */
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/*
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* Ok, I get parallel printer interrupts while using the floppy for some
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* strange reason. Urgel. Now I just ignore them.
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*/
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.globl system_call,sys_fork,timer_interrupt,sys_execve,sys_execve2
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.globl hd_interrupt,floppy_interrupt,parallel_interrupt
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.globl device_not_available, coprocessor_error
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.align 4
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bad_sys_call:
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movl $-1,%eax
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iret
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.align 4
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reschedule:
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pushl $ret_from_sys_call
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jmp schedule
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.align 4
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system_call:
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cmpl $nr_system_calls-1,%eax
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ja bad_sys_call
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push %ds
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push %es
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push %fs
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pushl %edx
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pushl %ecx # push %ebx,%ecx,%edx as parameters
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pushl %ebx # to the system call
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movl $0x10,%edx # set up ds,es to kernel space
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mov %dx,%ds
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mov %dx,%es
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movl $0x17,%edx # fs points to local data space
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mov %dx,%fs
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call sys_call_table(,%eax,4)
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pushl %eax
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movl current,%eax
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cmpl $0,state(%eax) # state
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jne reschedule
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cmpl $0,counter(%eax) # counter
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je reschedule
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ret_from_sys_call:
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movl current,%eax # task[0] cannot have signals
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cmpl task,%eax
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je 3f
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cmpw $0x0f,CS(%esp) # was old code segment supervisor ?
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jne 3f
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cmpw $0x17,OLDSS(%esp) # was stack segment = 0x17 ?
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jne 3f
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movl signal(%eax),%ebx
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movl blocked(%eax),%ecx
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notl %ecx
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andl %ebx,%ecx
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bsfl %ecx,%ecx
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je 3f
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btrl %ecx,%ebx
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movl %ebx,signal(%eax)
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incl %ecx
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pushl %ecx
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call do_signal
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popl %eax
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3: popl %eax
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popl %ebx
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popl %ecx
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popl %edx
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pop %fs
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pop %es
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pop %ds
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iret
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.align 4
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coprocessor_error:
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push %ds
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push %es
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push %fs
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pushl %edx
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pushl %ecx
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pushl %ebx
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pushl %eax
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movl $0x10,%eax
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mov %ax,%ds
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mov %ax,%es
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movl $0x17,%eax
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mov %ax,%fs
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pushl $ret_from_sys_call
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jmp math_error
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.align 2
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device_not_available:
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push %ds
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push %es
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push %fs
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pushl %edx
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pushl %ecx
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pushl %ebx
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pushl %eax
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movl $0x10,%eax
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mov %ax,%ds
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mov %ax,%es
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movl $0x17,%eax
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mov %ax,%fs
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pushl $ret_from_sys_call
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clts # clear TS so that we can use math
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movl %cr0,%eax
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testl $0x4,%eax # EM (math emulation bit)
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je math_state_restore
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pushl %ebp
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pushl %esi
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pushl %edi
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call math_emulate
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popl %edi
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popl %esi
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popl %ebp
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ret
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.align 4
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timer_interrupt:
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push %ds # save ds,es and put kernel data space
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push %es # into them. %fs is used by _system_call
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push %fs
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pushl %edx # we save %eax,%ecx,%edx as gcc doesn't
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pushl %ecx # save those across function calls. %ebx
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pushl %ebx # is saved as we use that in ret_sys_call
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pushl %eax
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movl $0x10,%eax
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mov %ax,%ds
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mov %ax,%es
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movl $0x17,%eax
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mov %ax,%fs
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incl jiffies
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movb $0x20,%al # EOI to interrupt controller #1
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outb %al,$0x20
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movl CS(%esp),%eax
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andl $3,%eax # %eax is CPL (0 or 3, 0=supervisor)
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pushl %eax
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call do_timer # 'do_timer(long CPL)' does everything from
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addl $4,%esp # task switching to accounting ...
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jmp ret_from_sys_call
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.align 4
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sys_execve:
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lea EIP(%esp),%eax
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pushl %eax
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call do_execve
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addl $4,%esp
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ret
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.align 4
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sys_execve2:
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lea EIP(%esp),%eax
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pushl %eax
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call do_execve2
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addl $4,%esp
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ret
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.align 4
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sys_fork:
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call find_empty_process
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testl %eax,%eax
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js 1f
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push %gs
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pushl %esi
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pushl %edi
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pushl %ebp
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pushl %eax
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call copy_process
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addl $20,%esp
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1: ret
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hd_interrupt:
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pushl %eax
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pushl %ecx
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pushl %edx
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push %ds
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push %es
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push %fs
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movl $0x10,%eax
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mov %ax,%ds
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mov %ax,%es
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movl $0x17,%eax
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mov %ax,%fs
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movb $0x20,%al
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outb %al,$0xA0 # EOI to interrupt controller #1
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jmp 1f # give port chance to breathe
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1: jmp 1f
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1: xorl %edx,%edx
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xchgl do_hd,%edx
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testl %edx,%edx
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jne 1f
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movl $unexpected_hd_interrupt,%edx
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1: outb %al,$0x20
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call *%edx # "interesting" way of handling intr.
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pop %fs
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pop %es
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pop %ds
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popl %edx
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popl %ecx
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popl %eax
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iret
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floppy_interrupt:
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pushl %eax
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pushl %ecx
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pushl %edx
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push %ds
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push %es
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push %fs
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movl $0x10,%eax
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mov %ax,%ds
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mov %ax,%es
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movl $0x17,%eax
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mov %ax,%fs
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movb $0x20,%al
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outb %al,$0x20 # EOI to interrupt controller #1
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xorl %eax,%eax
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xchgl do_floppy,%eax
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testl %eax,%eax
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jne 1f
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movl $unexpected_floppy_interrupt,%eax
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1: call *%eax # "interesting" way of handling intr.
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pop %fs
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pop %es
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pop %ds
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popl %edx
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popl %ecx
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popl %eax
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iret
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parallel_interrupt:
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pushl %eax
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movb $0x20,%al
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outb %al,$0x20
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popl %eax
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iret
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