entry.s

linux-2.6.15.6

/*
 *  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]),
 *		 Heiko Carstens <[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/asm-offsets.h>
#include <asm/unistd.h>
#include <asm/page.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_MCCK_PENDING | \
		 _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_MCCK_PENDING)

STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
STACK_SIZE  = 1 << STACK_SHIFT

#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  STORE_TIMER lc_offset
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
	stpt	\lc_offset
#endif
	.endm

#ifdef CONFIG_VIRT_CPU_ACCOUNTING
	.macro  UPDATE_VTIME lc_from,lc_to,lc_sum
	lm	%r10,%r11,\lc_from
	sl	%r10,\lc_to
	sl	%r11,\lc_to+4
	bc	3,BASED(0f)
	sl	%r10,BASED(.Lc_1)
0:	al	%r10,\lc_sum
	al	%r11,\lc_sum+4
	bc	12,BASED(1f)
	al	%r10,BASED(.Lc_1)
1:	stm	%r10,%r11,\lc_sum
	.endm
#endif

	.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	1(%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,STACK_SHIFT
	be	BASED(2f)
1:	l	%r15,__LC_ASYNC_STACK
	.endif
#ifdef CONFIG_CHECK_STACK
	b	BASED(3f)
2:	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD
	bz	BASED(stack_overflow)
3:
#endif
2:
	.endm

	.macro  CREATE_STACK_FRAME psworg,savearea
	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,__SF_BACKCHAIN(%r15)	# clear back chain
	.endm

	.macro  RESTORE_ALL psworg,sync
	mvc	\psworg(8),SP_PSW(%r15) # move user PSW to lowcore
	.if !\sync
	ni	\psworg+1,0xfd		# clear wait state bit
	.endif
	lm	%r0,%r15,SP_R0(%r15)	# load gprs 0-15 of user
	STORE_TIMER __LC_EXIT_TIMER
	lpsw	\psworg			# 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,__SF_EMPTY(%r15)	# We are using per stuff
        clc     __THREAD_per(12,%r3),__SF_EMPTY(%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:
	l	%r4,__THREAD_info(%r2)		# get thread_info of prev
	tm	__TI_flags+3(%r4),_TIF_MCCK_PENDING # machine check pending?
	bz	__switch_to_no_mcck-__switch_to_base(%r1)
	ni	__TI_flags+3(%r4),255-_TIF_MCCK_PENDING # clear flag in prev
	l	%r4,__THREAD_info(%r3)		# get thread_info of next
	oi	__TI_flags+3(%r4),_TIF_MCCK_PENDING # set it in next
__switch_to_no_mcck:
        stm     %r6,%r15,__SF_GPRS(%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,__SF_GPRS(%r15)# load __switch_to registers of next task
	st	%r3,__LC_CURRENT	# __LC_CURRENT = current task struct
	lctl	%c4,%c4,__TASK_pid(%r3) # load pid to control reg. 4
	l	%r3,__THREAD_info(%r3)  # load thread_info from task struct
	st	%r3,__LC_THREAD_INFO
	ahi	%r3,STACK_SIZE
	st	%r3,__LC_KERNEL_STACK	# __LC_KERNEL_STACK = new kernel stack
	br	%r14

__critical_start:
/*
 * SVC interrupt handler routine. System calls are synchronous events and
 * are executed with interrupts enabled.
 */

	.globl  system_call
system_call:
	STORE_TIMER __LC_SYNC_ENTER_TIMER
sysc_saveall:
	SAVE_ALL_BASE __LC_SAVE_AREA
        SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1
	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
	lh	%r7,0x8a	  # get svc number from lowcore
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
sysc_vtime:
	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
	bz	BASED(sysc_do_svc)
	UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
sysc_stime:
	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
sysc_update:
	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
#endif
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 __LC_RETURN_PSW,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_MCCK_PENDING
	bo	BASED(sysc_mcck_pending)
	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_MCCK_PENDING is set, call handler
#
sysc_mcck_pending:
	l	%r1,BASED(.Ls390_handle_mcck)
	la	%r14,BASED(sysc_work_loop)
	br	%r1			# TIF bit will be cleared by handler

#
# _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)
	tm	__TI_flags+3(%r9),_TIF_SINGLE_STEP
	bo	BASED(sysc_singlestep)
	b	BASED(sysc_work_loop)

#
# _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

#
# 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)