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/*
* linux/kernel/system_call.s
*
* (C) 1991 Linus Torvalds
*/
/*
* system_call.s contains the system-call low-level handling routines.
* This also contains the timer-interrupt handler, as some of the code is
* the same. The hd- and flopppy-interrupts are also here.
*
* NOTE: This code handles signal-recognition, which happens every time
* after a timer-interrupt and after each system call. Ordinary interrupts
* don't handle signal-recognition, as that would clutter them up totally
* unnecessarily.
*
* Stack layout in 'ret_from_system_call':
*
* 0(%esp) - %eax
* 4(%esp) - %ebx
* 8(%esp) - %ecx
* C(%esp) - %edx
* 10(%esp) - %fs
* 14(%esp) - %es
* 18(%esp) - %ds
* 1C(%esp) - %eip
* 20(%esp) - %cs
* 24(%esp) - %eflags
* 28(%esp) - %oldesp
* 2C(%esp) - %oldss
*/
SIG_CHLD = 17
EAX = 0x00
EBX = 0x04
ECX = 0x08
EDX = 0x0C
FS = 0x10
ES = 0x14
DS = 0x18
EIP = 0x1C
CS = 0x20
EFLAGS = 0x24
OLDESP = 0x28
OLDSS = 0x2C
state = 0 # these are offsets into the task-struct.
counter = 4
priority = 8
signal = 12
sigaction = 16 # MUST be 16 (=len of sigaction)
blocked = (33*16)
# offsets within sigaction
sa_handler = 0
sa_mask = 4
sa_flags = 8
sa_restorer = 12
nr_system_calls = 95 /* 72 */
/*
* Ok, I get parallel printer interrupts while using the floppy for some
* strange reason. Urgel. Now I just ignore them.
*/
.globl system_call,sys_fork,timer_interrupt,sys_execve,sys_execve2,sys_clone
.globl hd_interrupt,floppy_interrupt,parallel_interrupt
.globl device_not_available, coprocessor_error
.align 4
bad_sys_call:
movl $-1,%eax
iret
.align 4
reschedule:
pushl $ret_from_sys_call
jmp schedule
.align 4
system_call:
cmpl $nr_system_calls-1,%eax
ja bad_sys_call
push %ds
push %es
push %fs
pushl %edx
pushl %ecx # push %ebx,%ecx,%edx as parameters
pushl %ebx # to the system call
movl $0x10,%edx # set up ds,es to kernel space
mov %dx,%ds
mov %dx,%es
movl $0x17,%edx # fs points to local data space
mov %dx,%fs
pushl %eax #by wyj
call print_nr
popl %eax
call sys_call_table(,%eax,4)
pushl %eax
movl current,%eax
cmpl $0,state(%eax) # state
jne reschedule
cmpl $0,counter(%eax) # counter
je reschedule
ret_from_sys_call:
movl current,%eax # task[0] cannot have signals
cmpl task,%eax
je 3f
cmpw $0x0f,CS(%esp) # was old code segment supervisor ?
jne 3f
cmpw $0x17,OLDSS(%esp) # was stack segment = 0x17 ?
jne 3f
movl signal(%eax),%ebx
movl blocked(%eax),%ecx
notl %ecx
andl %ebx,%ecx
bsfl %ecx,%ecx
je 3f
btrl %ecx,%ebx
movl %ebx,signal(%eax)
incl %ecx
pushl %ecx
call do_signal
popl %eax
3: popl %eax
popl %ebx
popl %ecx
popl %edx
pop %fs
pop %es
pop %ds
iret
.align 4
coprocessor_error:
push %ds
push %es
push %fs
pushl %edx
pushl %ecx
pushl %ebx
pushl %eax
movl $0x10,%eax
mov %ax,%ds
mov %ax,%es
movl $0x17,%eax
mov %ax,%fs
pushl $ret_from_sys_call
jmp math_error
.align 2
device_not_available:
push %ds
push %es
push %fs
pushl %edx
pushl %ecx
pushl %ebx
pushl %eax
movl $0x10,%eax
mov %ax,%ds
mov %ax,%es
movl $0x17,%eax
mov %ax,%fs
pushl $ret_from_sys_call
clts # clear TS so that we can use math
movl %cr0,%eax
testl $0x4,%eax # EM (math emulation bit)
je math_state_restore
pushl %ebp
pushl %esi
pushl %edi
call math_emulate
popl %edi
popl %esi
popl %ebp
ret
.align 4
timer_interrupt:
push %ds # save ds,es and put kernel data space
push %es # into them. %fs is used by _system_call
push %fs
pushl %edx # we save %eax,%ecx,%edx as gcc doesn't
pushl %ecx # save those across function calls. %ebx
pushl %ebx # is saved as we use that in ret_sys_call
pushl %eax
movl $0x10,%eax
mov %ax,%ds
mov %ax,%es
movl $0x17,%eax
mov %ax,%fs
incl jiffies
movb $0x20,%al # EOI to interrupt controller #1
outb %al,$0x20
movl CS(%esp),%eax
andl $3,%eax # %eax is CPL (0 or 3, 0=supervisor)
pushl %eax
call do_timer # 'do_timer(long CPL)' does everything from
addl $4,%esp # task switching to accounting ...
jmp ret_from_sys_call
.align 4
sys_execve:
lea EIP(%esp),%eax
pushl %eax
call do_execve
addl $4,%esp
ret
.align 4
sys_execve2:
lea EIP(%esp),%eax
pushl %eax
call do_execve2
addl $4,%esp
ret
.align 4
sys_fork:
call find_empty_process
testl %eax,%eax
js 1f
push %gs
pushl %esi
pushl %edi
pushl %ebp
pushl %eax
pushl $0x0 #for flag
call copy_process
addl $24,%esp #for flag
1: ret
.align 4
sys_clone:
call find_empty_process
testl %eax,%eax
js 1f
pushl %eax
push %gs
pushl %esi
pushl %edi
pushl %ebp
pushl %eax
pushl $0x1 #for flag
call copy_process
addl $24,%esp #for flag
call do_clone
addl $4,%esp
1: ret
hd_interrupt:
pushl %eax
pushl %ecx
pushl %edx
push %ds
push %es
push %fs
movl $0x10,%eax
mov %ax,%ds
mov %ax,%es
movl $0x17,%eax
mov %ax,%fs
movb $0x20,%al
outb %al,$0xA0 # EOI to interrupt controller #1
jmp 1f # give port chance to breathe
1: jmp 1f
1: xorl %edx,%edx
xchgl do_hd,%edx
testl %edx,%edx
jne 1f
movl $unexpected_hd_interrupt,%edx
1: outb %al,$0x20
call *%edx # "interesting" way of handling intr.
pop %fs
pop %es
pop %ds
popl %edx
popl %ecx
popl %eax
iret
floppy_interrupt:
pushl %eax
pushl %ecx
pushl %edx
push %ds
push %es
push %fs
movl $0x10,%eax
mov %ax,%ds
mov %ax,%es
movl $0x17,%eax
mov %ax,%fs
movb $0x20,%al
outb %al,$0x20 # EOI to interrupt controller #1
xorl %eax,%eax
xchgl do_floppy,%eax
testl %eax,%eax
jne 1f
movl $unexpected_floppy_interrupt,%eax
1: call *%eax # "interesting" way of handling intr.
pop %fs
pop %es
pop %ds
popl %edx
popl %ecx
popl %eax
iret
parallel_interrupt:
pushl %eax
movb $0x20,%al
outb %al,$0x20
popl %eax
iret