entry.s

优龙2410linux2.6.8内核源代码

/*
 *  arch/s390/kernel/entry.S
 *    S390 low-level entry points.
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Schwidefsky ([e-mail]),
 *               Hartmut Penner ([e-mail]),
 *               Denis Joseph Barrow ([e-mail],[e-mail]),
 */

#include <linux/sys.h>
#include <linux/linkage.h>
#include <linux/config.h>
#include <asm/cache.h>
#include <asm/lowcore.h>
#include <asm/errno.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/offsets.h>
#include <asm/unistd.h>

/*
 * Stack layout for the system_call stack entry.
 * The first few entries are identical to the user_regs_struct.
 */
SP_PTREGS    =  STACK_FRAME_OVERHEAD
SP_ARGS      =  STACK_FRAME_OVERHEAD + __PT_ARGS
SP_PSW       =  STACK_FRAME_OVERHEAD + __PT_PSW
SP_R0        =  STACK_FRAME_OVERHEAD + __PT_GPRS
SP_R1        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 4
SP_R2        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 8
SP_R3        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 12
SP_R4        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 16
SP_R5        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 20
SP_R6        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 24
SP_R7        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 28
SP_R8        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 32
SP_R9        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 36
SP_R10       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 40
SP_R11       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 44
SP_R12       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 48
SP_R13       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 52
SP_R14       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 56
SP_R15       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 60
SP_ORIG_R2   =  STACK_FRAME_OVERHEAD + __PT_ORIG_GPR2
SP_ILC       =  STACK_FRAME_OVERHEAD + __PT_ILC
SP_TRAP      =  STACK_FRAME_OVERHEAD + __PT_TRAP
SP_SIZE      =  STACK_FRAME_OVERHEAD + __PT_SIZE

_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
		 _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED)

#define BASED(name) name-system_call(%r13)

/*
 * Register usage in interrupt handlers:
 *    R9  - pointer to current task structure
 *    R13 - pointer to literal pool
 *    R14 - return register for function calls
 *    R15 - kernel stack pointer
 */

	.macro	SAVE_ALL_BASE savearea
	stm	%r12,%r15,\savearea
	l	%r13,__LC_SVC_NEW_PSW+4	# load &system_call to %r13
	.endm

	.macro	SAVE_ALL psworg,savearea,sync
	la	%r12,\psworg
	.if	\sync
	tm	\psworg+1,0x01		# test problem state bit
	bz	BASED(2f)		# skip stack setup save
	l	%r15,__LC_KERNEL_STACK	# problem state -> load ksp
	.else
	tm	\psworg+1,0x01		# test problem state bit
	bnz	BASED(1f)		# from user -> load async stack
	clc	\psworg+4(4),BASED(.Lcritical_end)
	bhe	BASED(0f)
	clc	\psworg+4(4),BASED(.Lcritical_start)
	bl	BASED(0f)
	l	%r14,BASED(.Lcleanup_critical)
	basr	%r14,%r14
	tm	0(%r12),0x01		# retest problem state after cleanup
	bnz	BASED(1f)
0:	l	%r14,__LC_ASYNC_STACK	# are we already on the async stack ?
	slr	%r14,%r15
	sra	%r14,13
	be	BASED(2f)
1:	l	%r15,__LC_ASYNC_STACK
	.endif
2:	s	%r15,BASED(.Lc_spsize)	# make room for registers & psw
	mvc	SP_PSW(8,%r15),0(%r12)	# move user PSW to stack
	la	%r12,\psworg
	st	%r2,SP_ORIG_R2(%r15)	# store original content of gpr 2
	icm	%r12,12,__LC_SVC_ILC
	stm	%r0,%r11,SP_R0(%r15)	# store gprs %r0-%r11 to kernel stack
	st	%r12,SP_ILC(%r15)
	mvc	SP_R12(16,%r15),\savearea # move %r12-%r15 to stack
	la	%r12,0
	st	%r12,0(%r15)		# clear back chain
	.endm

	.macro  RESTORE_ALL sync
	mvc	__LC_RETURN_PSW(8),SP_PSW(%r15) # move user PSW to lowcore
	.if !\sync
	ni	__LC_RETURN_PSW+1,0xfd	# clear wait state bit
	.endif
	lm	%r0,%r15,SP_R0(%r15)	# load gprs 0-15 of user
	lpsw	__LC_RETURN_PSW		# back to caller
	.endm

/*
 * Scheduler resume function, called by switch_to
 *  gpr2 = (task_struct *) prev
 *  gpr3 = (task_struct *) next
 * Returns:
 *  gpr2 = prev
 */
        .globl  __switch_to
__switch_to:
        basr    %r1,0
__switch_to_base:
	tm	__THREAD_per(%r3),0xe8		# new process is using per ?
	bz	__switch_to_noper-__switch_to_base(%r1)	# if not we're fine
        stctl   %c9,%c11,24(%r15)		# We are using per stuff
        clc     __THREAD_per(12,%r3),24(%r15)
        be      __switch_to_noper-__switch_to_base(%r1)	# we got away w/o bashing TLB's
        lctl    %c9,%c11,__THREAD_per(%r3)	# Nope we didn't
__switch_to_noper:
        stm     %r6,%r15,24(%r15)       # store __switch_to registers of prev task
	st	%r15,__THREAD_ksp(%r2)	# store kernel stack to prev->tss.ksp
	l	%r15,__THREAD_ksp(%r3)	# load kernel stack from next->tss.ksp
	lm	%r6,%r15,24(%r15)	# load __switch_to registers of next task
	st	%r3,__LC_CURRENT	# __LC_CURRENT = current task struct
	l	%r3,__THREAD_info(%r3)  # load thread_info from task struct
	st	%r3,__LC_THREAD_INFO
	ahi	%r3,8192
	st	%r3,__LC_KERNEL_STACK	# __LC_KERNEL_STACK = new kernel stack
	br	%r14

/*
 * do_softirq calling function. We want to run the softirq functions on the
 * asynchronous interrupt stack.
 */
	.global do_call_softirq
do_call_softirq:
	stnsm	24(%r15),0xfc
	stm	%r12,%r15,28(%r15)
	lr	%r12,%r15
        basr    %r13,0
do_call_base:
	l	%r0,__LC_ASYNC_STACK
	slr     %r0,%r15
	sra	%r0,13
	be	0f-do_call_base(%r13)
	l	%r15,__LC_ASYNC_STACK
0:	sl	%r15,.Lc_overhead-do_call_base(%r13)
        st	%r12,0(%r15)	# store backchain
	l	%r1,.Ldo_softirq-do_call_base(%r13)
	basr	%r14,%r1
	lm	%r12,%r15,28(%r12)
	ssm	24(%r15)
	br	%r14
	
__critical_start:
/*
 * SVC interrupt handler routine. System calls are synchronous events and
 * are executed with interrupts enabled.
 */

	.globl  system_call
system_call:
	SAVE_ALL_BASE __LC_SAVE_AREA
        SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1
	lh	%r7,0x8a	  # get svc number from lowcore
sysc_do_svc:
	l	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
	sla	%r7,2             # *4 and test for svc 0
	bnz	BASED(sysc_nr_ok) # svc number > 0
	# svc 0: system call number in %r1
	cl	%r1,BASED(.Lnr_syscalls)
	bnl	BASED(sysc_nr_ok)
	lr	%r7,%r1           # copy svc number to %r7
	sla	%r7,2             # *4
sysc_nr_ok:
	mvc	SP_ARGS(4,%r15),SP_R7(%r15)
sysc_do_restart:
	tm	__TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
        l       %r8,sys_call_table-system_call(%r7,%r13) # get system call addr.
        bnz     BASED(sysc_tracesys)
        basr    %r14,%r8          # call sys_xxxx
        st      %r2,SP_R2(%r15)   # store return value (change R2 on stack)
                                  # ATTENTION: check sys_execve_glue before
                                  # changing anything here !!

sysc_return:
	tm	SP_PSW+1(%r15),0x01	# returning to user ?
	bno	BASED(sysc_leave)
	tm	__TI_flags+3(%r9),_TIF_WORK_SVC
	bnz	BASED(sysc_work)  # there is work to do (signals etc.)
sysc_leave:
        RESTORE_ALL 1

#
# recheck if there is more work to do
#
sysc_work_loop:
	tm	__TI_flags+3(%r9),_TIF_WORK_SVC
	bz	BASED(sysc_leave)      # there is no work to do
#
# One of the work bits is on. Find out which one.
#
sysc_work:
	tm	__TI_flags+3(%r9),_TIF_NEED_RESCHED
	bo	BASED(sysc_reschedule)
	tm	__TI_flags+3(%r9),_TIF_SIGPENDING
	bo	BASED(sysc_sigpending)
	tm	__TI_flags+3(%r9),_TIF_RESTART_SVC
	bo	BASED(sysc_restart)
	tm	__TI_flags+3(%r9),_TIF_SINGLE_STEP
	bo	BASED(sysc_singlestep)
	b	BASED(sysc_leave)

#
# _TIF_NEED_RESCHED is set, call schedule
#	
sysc_reschedule:        
        l       %r1,BASED(.Lschedule)
	la      %r14,BASED(sysc_work_loop)
	br      %r1		       # call scheduler

#
# _TIF_SIGPENDING is set, call do_signal
#
sysc_sigpending:     
	ni	__TI_flags+3(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
        la      %r2,SP_PTREGS(%r15)    # load pt_regs
        sr      %r3,%r3                # clear *oldset
        l       %r1,BASED(.Ldo_signal)
	basr	%r14,%r1               # call do_signal
	tm	__TI_flags+3(%r9),_TIF_RESTART_SVC
	bo	BASED(sysc_restart)
	b	BASED(sysc_leave)      # out of here, do NOT recheck

#
# _TIF_RESTART_SVC is set, set up registers and restart svc
#
sysc_restart:
	ni	__TI_flags+3(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
	l	%r7,SP_R2(%r15)        # load new svc number
	sla	%r7,2
	mvc	SP_R2(4,%r15),SP_ORIG_R2(%r15) # restore first argument
	lm	%r2,%r6,SP_R2(%r15)    # load svc arguments
	b	BASED(sysc_do_restart) # restart svc

#
# _TIF_SINGLE_STEP is set, call do_single_step
#
sysc_singlestep:
	ni	__TI_flags+3(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
	mvi	SP_TRAP+1(%r15),0x28	# set trap indication to pgm check
	la	%r2,SP_PTREGS(%r15)	# address of register-save area
	l	%r1,BASED(.Lhandle_per)	# load adr. of per handler
	la	%r14,BASED(sysc_return)	# load adr. of system return
	br	%r1			# branch to do_single_step

__critical_end:

#
# call trace before and after sys_call
#
sysc_tracesys:
        l       %r1,BASED(.Ltrace)
	la	%r2,SP_PTREGS(%r15)    # load pt_regs
	la	%r3,0
	srl	%r7,2
	st	%r7,SP_R2(%r15)
	basr	%r14,%r1
	clc	SP_R2(4,%r15),BASED(.Lnr_syscalls)
	bnl	BASED(sysc_tracenogo)
	l	%r7,SP_R2(%r15)        # strace might have changed the 
	sll	%r7,2                  #  system call
	l	%r8,sys_call_table-system_call(%r7,%r13)
sysc_tracego:
	lm	%r3,%r6,SP_R3(%r15)
	l	%r2,SP_ORIG_R2(%r15)
	basr	%r14,%r8          # call sys_xxx
	st	%r2,SP_R2(%r15)   # store return value
sysc_tracenogo:
	tm	__TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
        bz      BASED(sysc_return)
	l	%r1,BASED(.Ltrace)
	la	%r2,SP_PTREGS(%r15)    # load pt_regs
	la	%r3,1
	la	%r14,BASED(sysc_return)
	br	%r1

#
# a new process exits the kernel with ret_from_fork
#
        .globl  ret_from_fork
ret_from_fork:
	l	%r13,__LC_SVC_NEW_PSW+4
	l	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
        l       %r1,BASED(.Lschedtail)
	basr    %r14,%r1
        stosm   24(%r15),0x03     # reenable interrupts
	b	BASED(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
        l       %r1,BASED(.Lclone)
        br      %r1                   # branch to sys_clone

sys_fork_glue:  
        la      %r2,SP_PTREGS(%r15)    # load pt_regs
        l       %r1,BASED(.Lfork)
        br      %r1                   # branch to sys_fork

sys_vfork_glue: 
        la      %r2,SP_PTREGS(%r15)    # load pt_regs
        l       %r1,BASED(.Lvfork)
        br      %r1                   # branch to sys_vfork

sys_execve_glue:        
        la      %r2,SP_PTREGS(%r15)   # load pt_regs
        l       %r1,BASED(.Lexecve)
	lr      %r12,%r14             # save return address
        basr    %r14,%r1              # call sys_execve
        ltr     %r2,%r2               # check if execve failed
        bnz     0(%r12)               # it did fail -> store result in gpr2
        b       4(%r12)               # SKIP ST 2,SP_R2(15) after BASR 14,8
                                      # in system_call/sysc_tracesys

sys_sigreturn_glue:     
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as parameter
        l       %r1,BASED(.Lsigreturn)
        br      %r1                   # branch to sys_sigreturn

sys_rt_sigreturn_glue:     
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as parameter
        l       %r1,BASED(.Lrt_sigreturn)
        br      %r1                   # branch to sys_sigreturn

#
# 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:    
        lr      %r5,%r4               # move mask back
        lr      %r4,%r3               # move history1 parameter
        lr      %r3,%r2               # move history0 parameter
        la      %r2,SP_PTREGS(%r15)   # load pt_regs as first parameter