entry64.s

linux-2.6.15.6

# a new process exits the kernel with ret_from_fork
#
        .globl  ret_from_fork
ret_from_fork:
	lg	%r13,__LC_SVC_NEW_PSW+8
	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
	tm	SP_PSW+1(%r15),0x01	# forking a kernel thread ?
	jo	0f
	stg	%r15,SP_R15(%r15)	# store stack pointer for new kthread
0:	brasl   %r14,schedule_tail
        stosm   24(%r15),0x03     # reenable interrupts
	j	sysc_return

#
# clone, fork, vfork, exec and sigreturn need glue,
# because they all expect pt_regs as parameter,
# but are called with different parameter.
# return-address is set up above
#
sys_clone_glue: 
        la      %r2,SP_PTREGS(%r15)    # load pt_regs
        jg      sys_clone              # branch to sys_clone

#ifdef CONFIG_S390_SUPPORT
sys32_clone_glue: 
        la      %r2,SP_PTREGS(%r15)    # load pt_regs
        jg      sys32_clone            # branch to sys32_clone
#endif

sys_fork_glue:  
        la      %r2,SP_PTREGS(%r15)    # load pt_regs
        jg      sys_fork               # branch to sys_fork

sys_vfork_glue: 
        la      %r2,SP_PTREGS(%r15)    # load pt_regs
        jg      sys_vfork              # branch to sys_vfork

sys_execve_glue:        
        la      %r2,SP_PTREGS(%r15)   # load pt_regs
	lgr     %r12,%r14             # save return address
        brasl   %r14,sys_execve       # call sys_execve
        ltgr    %r2,%r2               # check if execve failed
        bnz     0(%r12)               # it did fail -> store result in gpr2
        b       6(%r12)               # SKIP STG 2,SP_R2(15) in
                                      # system_call/sysc_tracesys
#ifdef CONFIG_S390_SUPPORT
sys32_execve_glue:        
        la      %r2,SP_PTREGS(%r15)   # load pt_regs
	lgr     %r12,%r14             # save return address
        brasl   %r14,sys32_execve     # call sys32_execve
        ltgr    %r2,%r2               # check if execve failed
        bnz     0(%r12)               # it did fail -> store result in gpr2
        b       6(%r12)               # SKIP STG 2,SP_R2(15) in
                                      # system_call/sysc_tracesys
#endif

sys_sigreturn_glue:     
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as parameter
        jg      sys_sigreturn         # branch to sys_sigreturn

#ifdef CONFIG_S390_SUPPORT
sys32_sigreturn_glue:     
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as parameter
        jg      sys32_sigreturn       # branch to sys32_sigreturn
#endif

sys_rt_sigreturn_glue:     
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as parameter
        jg      sys_rt_sigreturn      # branch to sys_sigreturn

#ifdef CONFIG_S390_SUPPORT
sys32_rt_sigreturn_glue:     
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as parameter
        jg      sys32_rt_sigreturn    # branch to sys32_sigreturn
#endif

#
# sigsuspend and rt_sigsuspend need pt_regs as an additional
# parameter and they have to skip the store of %r2 into the
# user register %r2 because the return value was set in 
# sigsuspend and rt_sigsuspend already and must not be overwritten!
#

sys_sigsuspend_glue:    
        lgr     %r5,%r4               # move mask back
        lgr     %r4,%r3               # move history1 parameter
        lgr     %r3,%r2               # move history0 parameter
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as first parameter
	la      %r14,6(%r14)          # skip store of return value
        jg      sys_sigsuspend        # branch to sys_sigsuspend

#ifdef CONFIG_S390_SUPPORT
sys32_sigsuspend_glue:    
	llgfr	%r4,%r4               # unsigned long			
        lgr     %r5,%r4               # move mask back
	lgfr	%r3,%r3               # int			
        lgr     %r4,%r3               # move history1 parameter
	lgfr	%r2,%r2               # int			
        lgr     %r3,%r2               # move history0 parameter
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as first parameter
	la      %r14,6(%r14)          # skip store of return value
        jg      sys32_sigsuspend      # branch to sys32_sigsuspend
#endif

sys_rt_sigsuspend_glue: 
        lgr     %r4,%r3               # move sigsetsize parameter
        lgr     %r3,%r2               # move unewset parameter
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as first parameter
	la      %r14,6(%r14)          # skip store of return value
        jg      sys_rt_sigsuspend     # branch to sys_rt_sigsuspend

#ifdef CONFIG_S390_SUPPORT
sys32_rt_sigsuspend_glue: 
	llgfr	%r3,%r3               # size_t			
        lgr     %r4,%r3               # move sigsetsize parameter
	llgtr	%r2,%r2               # sigset_emu31_t *
        lgr     %r3,%r2               # move unewset parameter
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as first parameter
	la      %r14,6(%r14)          # skip store of return value
        jg      sys32_rt_sigsuspend   # branch to sys32_rt_sigsuspend
#endif

sys_sigaltstack_glue:
        la      %r4,SP_PTREGS(%r15)   # load pt_regs as parameter
        jg      sys_sigaltstack       # branch to sys_sigreturn

#ifdef CONFIG_S390_SUPPORT
sys32_sigaltstack_glue:
        la      %r4,SP_PTREGS(%r15)   # load pt_regs as parameter
        jg      sys32_sigaltstack_wrapper # branch to sys_sigreturn
#endif

/*
 * Program check handler routine
 */

        .globl  pgm_check_handler
pgm_check_handler:
/*
 * First we need to check for a special case:
 * Single stepping an instruction that disables the PER event mask will
 * cause a PER event AFTER the mask has been set. Example: SVC or LPSW.
 * For a single stepped SVC the program check handler gets control after
 * the SVC new PSW has been loaded. But we want to execute the SVC first and
 * then handle the PER event. Therefore we update the SVC old PSW to point
 * to the pgm_check_handler and branch to the SVC handler after we checked
 * if we have to load the kernel stack register.
 * For every other possible cause for PER event without the PER mask set
 * we just ignore the PER event (FIXME: is there anything we have to do
 * for LPSW?).
 */
	STORE_TIMER __LC_SYNC_ENTER_TIMER
	SAVE_ALL_BASE __LC_SAVE_AREA
        tm      __LC_PGM_INT_CODE+1,0x80 # check whether we got a per exception
        jnz     pgm_per                  # got per exception -> special case
	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1
	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
	jz	pgm_no_vtime
	UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
pgm_no_vtime:
#endif
	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
	lgf     %r3,__LC_PGM_ILC	 # load program interruption code
	lghi	%r8,0x7f
	ngr	%r8,%r3
pgm_do_call:
        sll     %r8,3
        larl    %r1,pgm_check_table
        lg      %r1,0(%r8,%r1)		 # load address of handler routine
        la      %r2,SP_PTREGS(%r15)	 # address of register-save area
	larl	%r14,sysc_return
        br      %r1			 # branch to interrupt-handler

#
# handle per exception
#
pgm_per:
        tm      __LC_PGM_OLD_PSW,0x40    # test if per event recording is on
        jnz     pgm_per_std              # ok, normal per event from user space
# ok its one of the special cases, now we need to find out which one
        clc     __LC_PGM_OLD_PSW(16),__LC_SVC_NEW_PSW
        je      pgm_svcper
# no interesting special case, ignore PER event
	lmg	%r12,%r15,__LC_SAVE_AREA
	lpswe   __LC_PGM_OLD_PSW

#
# Normal per exception
#
pgm_per_std:
	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1
	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
	jz	pgm_no_vtime2
	UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
pgm_no_vtime2:
#endif
	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
	lg	%r1,__TI_task(%r9)
	mvc	__THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
	mvc	__THREAD_per+__PER_address(8,%r1),__LC_PER_ADDRESS
	mvc	__THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
	oi	__TI_flags+7(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
	lgf     %r3,__LC_PGM_ILC	 # load program interruption code
	lghi	%r8,0x7f
	ngr	%r8,%r3			 # clear per-event-bit and ilc
	je	sysc_return
	j	pgm_do_call

#
# it was a single stepped SVC that is causing all the trouble
#
pgm_svcper:
	SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1
	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
	jz	pgm_no_vtime3
	UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
pgm_no_vtime3:
#endif
	llgh    %r7,__LC_SVC_INT_CODE	# get svc number from lowcore
	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
	lg	%r1,__TI_task(%r9)
	mvc	__THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
	mvc	__THREAD_per+__PER_address(8,%r1),__LC_PER_ADDRESS
	mvc	__THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
	oi	__TI_flags+7(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
	stosm	__SF_EMPTY(%r15),0x03	# reenable interrupts
	j	sysc_do_svc

/*
 * IO interrupt handler routine
 */
        .globl io_int_handler
io_int_handler:
	STORE_TIMER __LC_ASYNC_ENTER_TIMER
	stck	__LC_INT_CLOCK
	SAVE_ALL_BASE __LC_SAVE_AREA+32
        SAVE_ALL __LC_IO_OLD_PSW,__LC_SAVE_AREA+32,0
	CREATE_STACK_FRAME __LC_IO_OLD_PSW,__LC_SAVE_AREA+32
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
	jz	io_no_vtime
	UPDATE_VTIME __LC_EXIT_TIMER,__LC_ASYNC_ENTER_TIMER,__LC_USER_TIMER
	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_ASYNC_ENTER_TIMER
io_no_vtime:
#endif
	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
        la      %r2,SP_PTREGS(%r15)    # address of register-save area
	brasl   %r14,do_IRQ            # call standard irq handler

io_return:
        tm      SP_PSW+1(%r15),0x01    # returning to user ?
#ifdef CONFIG_PREEMPT
	jno     io_preempt             # no -> check for preemptive scheduling
#else
        jno     io_leave               # no-> skip resched & signal
#endif
	tm	__TI_flags+7(%r9),_TIF_WORK_INT
	jnz	io_work                # there is work to do (signals etc.)
io_leave:
        RESTORE_ALL __LC_RETURN_PSW,0
io_done:

#ifdef CONFIG_PREEMPT
io_preempt:
	icm	%r0,15,__TI_precount(%r9)	
	jnz     io_leave
	# switch to kernel stack
	lg	%r1,SP_R15(%r15)
	aghi	%r1,-SP_SIZE
	mvc	SP_PTREGS(__PT_SIZE,%r1),SP_PTREGS(%r15)
        xc      __SF_BACKCHAIN(8,%r1),__SF_BACKCHAIN(%r1) # clear back chain
	lgr	%r15,%r1
io_resume_loop:
	tm	__TI_flags+7(%r9),_TIF_NEED_RESCHED
	jno	io_leave
	larl    %r1,.Lc_pactive
	mvc     __TI_precount(4,%r9),0(%r1)
        stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
	brasl   %r14,schedule          # call schedule
        stnsm   __SF_EMPTY(%r15),0xfc   # disable I/O and ext. interrupts
	xc      __TI_precount(4,%r9),__TI_precount(%r9)
	j	io_resume_loop
#endif

#
# switch to kernel stack, then check TIF bits
#
io_work:
	lg	%r1,__LC_KERNEL_STACK
	aghi	%r1,-SP_SIZE
	mvc	SP_PTREGS(__PT_SIZE,%r1),SP_PTREGS(%r15)
        xc      __SF_BACKCHAIN(8,%r1),__SF_BACKCHAIN(%r1) # clear back chain
	lgr	%r15,%r1
#
# One of the work bits is on. Find out which one.
# Checked are: _TIF_SIGPENDING, _TIF_NEED_RESCHED and _TIF_MCCK_PENDING
#
io_work_loop:
	tm	__TI_flags+7(%r9),_TIF_MCCK_PENDING
	jo	io_mcck_pending
	tm	__TI_flags+7(%r9),_TIF_NEED_RESCHED
	jo	io_reschedule
	tm	__TI_flags+7(%r9),_TIF_SIGPENDING
	jo	io_sigpending
	j	io_leave

#
# _TIF_MCCK_PENDING is set, call handler
#
io_mcck_pending:
	larl	%r14,io_work_loop
	jg	s390_handle_mcck	# TIF bit will be cleared by handler

#
# _TIF_NEED_RESCHED is set, call schedule
#	
io_reschedule:        
	stosm   __SF_EMPTY(%r15),0x03	# reenable interrupts
	brasl   %r14,schedule		# call scheduler
	stnsm   __SF_EMPTY(%r15),0xfc	# disable I/O and ext. interrupts
	tm	__TI_flags+7(%r9),_TIF_WORK_INT
	jz	io_leave		# there is no work to do
	j	io_work_loop

#
# _TIF_SIGPENDING is set, call do_signal
#