entry64.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 + 8
SP_R2        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 16
SP_R3        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 24
SP_R4        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 32
SP_R5        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 40
SP_R6        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 48
SP_R7        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 56
SP_R8        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 64
SP_R9        =  STACK_FRAME_OVERHEAD + __PT_GPRS + 72
SP_R10       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 80
SP_R11       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 88
SP_R12       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 96
SP_R13       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 104
SP_R14       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 112
SP_R15       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 120
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

STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
STACK_SIZE  = 1 << STACK_SHIFT

_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)

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

	.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
	lg	%r10,\lc_from
	slg	%r10,\lc_to
	alg	%r10,\lc_sum
	stg	%r10,\lc_sum
	.endm
#endif

/*
 * 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
	stmg	%r12,%r15,\savearea
	larl	%r13,system_call
	.endm

        .macro  SAVE_ALL psworg,savearea,sync
	la	%r12,\psworg
	.if	\sync
	tm	\psworg+1,0x01		# test problem state bit
	jz	2f			# skip stack setup save
	lg	%r15,__LC_KERNEL_STACK	# problem state -> load ksp
	.else
	tm	\psworg+1,0x01		# test problem state bit
	jnz	1f			# from user -> load kernel stack
	clc	\psworg+8(8),BASED(.Lcritical_end)
	jhe	0f
	clc	\psworg+8(8),BASED(.Lcritical_start)
	jl	0f
	brasl	%r14,cleanup_critical
	tm	1(%r12),0x01		# retest problem state after cleanup
	jnz	1f
0:	lg	%r14,__LC_ASYNC_STACK	# are we already on the async. stack ?
	slgr	%r14,%r15
	srag	%r14,%r14,STACK_SHIFT
	jz	2f
1:	lg	%r15,__LC_ASYNC_STACK	# load async stack
	.endif
#ifdef CONFIG_CHECK_STACK
	j	3f
2:	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD
	jz	stack_overflow
3:
#endif
2:
	.endm

	.macro	CREATE_STACK_FRAME psworg,savearea
	aghi    %r15,-SP_SIZE		# make room for registers & psw
	mvc     SP_PSW(16,%r15),0(%r12)	# move user PSW to stack
	la	%r12,\psworg
	stg	%r2,SP_ORIG_R2(%r15)	# store original content of gpr 2
	icm	%r12,12,__LC_SVC_ILC
	stmg	%r0,%r11,SP_R0(%r15)	# store gprs %r0-%r11 to kernel stack
	st	%r12,SP_ILC(%r15)
	mvc	SP_R12(32,%r15),\savearea # move %r12-%r15 to stack
	la	%r12,0
	stg	%r12,__SF_BACKCHAIN(%r15)
        .endm

	.macro	RESTORE_ALL psworg,sync
	mvc	\psworg(16),SP_PSW(%r15) # move user PSW to lowcore
	.if !\sync
	ni	\psworg+1,0xfd		# clear wait state bit
	.endif
	lmg	%r0,%r15,SP_R0(%r15)	# load gprs 0-15 of user
	STORE_TIMER __LC_EXIT_TIMER
	lpswe	\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:
	tm	__THREAD_per+4(%r3),0xe8 # is the new process using per ?
	jz	__switch_to_noper		# if not we're fine
        stctg   %c9,%c11,__SF_EMPTY(%r15)# We are using per stuff
        clc     __THREAD_per(24,%r3),__SF_EMPTY(%r15)
        je      __switch_to_noper            # we got away without bashing TLB's
        lctlg   %c9,%c11,__THREAD_per(%r3)	# Nope we didn't
__switch_to_noper:
	lg	%r4,__THREAD_info(%r2)              # get thread_info of prev
	tm	__TI_flags+7(%r4),_TIF_MCCK_PENDING # machine check pending?
	jz	__switch_to_no_mcck
	ni	__TI_flags+7(%r4),255-_TIF_MCCK_PENDING # clear flag in prev
	lg	%r4,__THREAD_info(%r3)		    # get thread_info of next
	oi	__TI_flags+7(%r4),_TIF_MCCK_PENDING # set it in next
__switch_to_no_mcck:
        stmg    %r6,%r15,__SF_GPRS(%r15)# store __switch_to registers of prev task
	stg	%r15,__THREAD_ksp(%r2)	# store kernel stack to prev->tss.ksp
	lg	%r15,__THREAD_ksp(%r3)	# load kernel stack from next->tss.ksp
        lmg     %r6,%r15,__SF_GPRS(%r15)# load __switch_to registers of next task
	stg	%r3,__LC_CURRENT	# __LC_CURRENT = current task struct
	lctl	%c4,%c4,__TASK_pid(%r3) # load pid to control reg. 4
	lg	%r3,__THREAD_info(%r3)  # load thread_info from task struct
	stg	%r3,__LC_THREAD_INFO
	aghi	%r3,STACK_SIZE
	stg	%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
	llgh    %r7,__LC_SVC_INT_CODE # get svc number from lowcore
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
sysc_vtime:
	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
	jz	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:
	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
        slag    %r7,%r7,2         # *4 and test for svc 0
	jnz	sysc_nr_ok
	# svc 0: system call number in %r1
	cl	%r1,BASED(.Lnr_syscalls)
	jnl	sysc_nr_ok
	lgfr	%r7,%r1           # clear high word in r1
	slag    %r7,%r7,2         # svc 0: system call number in %r1
sysc_nr_ok:
	mvc	SP_ARGS(8,%r15),SP_R7(%r15)
sysc_do_restart:
	larl    %r10,sys_call_table
#ifdef CONFIG_S390_SUPPORT
	tm	__TI_flags+5(%r9),(_TIF_31BIT>>16)  # running in 31 bit mode ?
	jno	sysc_noemu
	larl    %r10,sys_call_table_emu  # use 31 bit emulation system calls
sysc_noemu:
#endif
	tm	__TI_flags+7(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
        lgf     %r8,0(%r7,%r10)   # load address of system call routine
        jnz     sysc_tracesys
        basr    %r14,%r8          # call sys_xxxx
        stg     %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 ?
        jno     sysc_leave
	tm	__TI_flags+7(%r9),_TIF_WORK_SVC
	jnz	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+7(%r9),_TIF_WORK_SVC
	jz	sysc_leave        # there is no work to do
#
# One of the work bits is on. Find out which one.
#
sysc_work:
	tm	__TI_flags+7(%r9),_TIF_MCCK_PENDING
	jo	sysc_mcck_pending
	tm	__TI_flags+7(%r9),_TIF_NEED_RESCHED
	jo	sysc_reschedule
	tm	__TI_flags+7(%r9),_TIF_SIGPENDING
	jo	sysc_sigpending
	tm	__TI_flags+7(%r9),_TIF_RESTART_SVC
	jo	sysc_restart
	tm	__TI_flags+7(%r9),_TIF_SINGLE_STEP
	jo	sysc_singlestep
	j	sysc_leave

#
# _TIF_NEED_RESCHED is set, call schedule
#	
sysc_reschedule:        
	larl    %r14,sysc_work_loop
        jg      schedule            # return point is sysc_return

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

#
# _TIF_SIGPENDING is set, call do_signal
#
sysc_sigpending:     
	ni	__TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
        la      %r2,SP_PTREGS(%r15) # load pt_regs
        sgr     %r3,%r3           # clear *oldset
	brasl	%r14,do_signal    # call do_signal
	tm	__TI_flags+7(%r9),_TIF_RESTART_SVC
	jo	sysc_restart
	tm	__TI_flags+7(%r9),_TIF_SINGLE_STEP
	jo	sysc_singlestep
	j	sysc_work_loop

#
# _TIF_RESTART_SVC is set, set up registers and restart svc
#
sysc_restart:
	ni	__TI_flags+7(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
	lg	%r7,SP_R2(%r15)        # load new svc number
        slag    %r7,%r7,2              # *4
	mvc	SP_R2(8,%r15),SP_ORIG_R2(%r15) # restore first argument
	lmg	%r2,%r6,SP_R2(%r15)    # load svc arguments
	j	sysc_do_restart        # restart svc

#
# _TIF_SINGLE_STEP is set, call do_single_step
#
sysc_singlestep:
	ni	__TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
	lhi	%r0,__LC_PGM_OLD_PSW
	sth	%r0,SP_TRAP(%r15)	# set trap indication to pgm check
	la	%r2,SP_PTREGS(%r15)	# address of register-save area
	larl	%r14,sysc_return	# load adr. of system return
	jg	do_single_step		# branch to do_sigtrap


#
# call syscall_trace before and after system call
# special linkage: %r12 contains the return address for trace_svc
#
sysc_tracesys:
	la	%r2,SP_PTREGS(%r15)    # load pt_regs
	la	%r3,0
	srl	%r7,2
	stg     %r7,SP_R2(%r15)
        brasl   %r14,syscall_trace
	lghi	%r0,NR_syscalls
	clg	%r0,SP_R2(%r15)
	jnh	sysc_tracenogo
	lg	%r7,SP_R2(%r15)   # strace might have changed the
	sll     %r7,2             #  system call
	lgf	%r8,0(%r7,%r10)
sysc_tracego:
	lmg     %r3,%r6,SP_R3(%r15)
	lg      %r2,SP_ORIG_R2(%r15)
        basr    %r14,%r8            # call sys_xxx
        stg     %r2,SP_R2(%r15)     # store return value
sysc_tracenogo:
	tm	__TI_flags+7(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
        jz      sysc_return
	la	%r2,SP_PTREGS(%r15)    # load pt_regs
	la	%r3,1
	larl	%r14,sysc_return    # return point is sysc_return
	jg	syscall_trace

#