/* *  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 (schwidefsky@de.ibm.com), *               Hartmut Penner (hp@de.ibm.com), *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com), */#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/smp.h>#include <asm/ptrace.h>#include "asm-offsets.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_PSW       =  STACK_FRAME_OVERHEAD + PT_PSWMASKSP_R0        =  STACK_FRAME_OVERHEAD + PT_GPR0SP_R1        =  STACK_FRAME_OVERHEAD + PT_GPR1SP_R2        =  STACK_FRAME_OVERHEAD + PT_GPR2SP_R3        =  STACK_FRAME_OVERHEAD + PT_GPR3SP_R4        =  STACK_FRAME_OVERHEAD + PT_GPR4SP_R5        =  STACK_FRAME_OVERHEAD + PT_GPR5SP_R6        =  STACK_FRAME_OVERHEAD + PT_GPR6SP_R7        =  STACK_FRAME_OVERHEAD + PT_GPR7SP_R8        =  STACK_FRAME_OVERHEAD + PT_GPR8SP_R9        =  STACK_FRAME_OVERHEAD + PT_GPR9SP_R10       =  STACK_FRAME_OVERHEAD + PT_GPR10SP_R11       =  STACK_FRAME_OVERHEAD + PT_GPR11SP_R12       =  STACK_FRAME_OVERHEAD + PT_GPR12SP_R13       =  STACK_FRAME_OVERHEAD + PT_GPR13SP_R14       =  STACK_FRAME_OVERHEAD + PT_GPR14SP_R15       =  STACK_FRAME_OVERHEAD + PT_GPR15SP_AREGS     =  STACK_FRAME_OVERHEAD + PT_ACR0SP_ORIG_R2   =  STACK_FRAME_OVERHEAD + PT_ORIGGPR2/* Now the additional entries */SP_TRAP      =  (SP_ORIG_R2+GPR_SIZE)SP_SIZE      =  (SP_TRAP+4)/* * Base Address of this Module --- saved in __LC_ENTRY_BASE */       .globl entry_baseentry_base:#define BASED(name) name-entry_base(%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        stm     %r13,%r15,__LC_SAVE_AREA        basr    %r13,0                    #  temp base pointer0:	stam    %a2,%a4,__LC_SAVE_AREA+12        l       %r13,.Lentry_base-0b(%r13)# load &entry_base to %r13	.endm        .macro  SAVE_ALL psworg,sync      # system entry macro        tm      \psworg+1,0x01            # test problem state bit	.if	\sync        bz      BASED(1f)                 # skip stack setup save	.else        bnz     BASED(0f)                 # from user -> load kernel stack	l	%r14,__LC_ASYNC_STACK	  # are we already on the async stack ?	slr     %r14,%r15	sra	%r14,13	be	BASED(1f)        l       %r15,__LC_ASYNC_STACK     # load async. stack	b	BASED(1f)	.endif0:      l       %r15,__LC_KERNEL_STACK    # problem state -> load ksp	lam	%a2,%a4,BASED(.Lc_ac)	  # set ac.reg. 2 to primary space					  # and ac.reg. 4 to home space1:      s       %r15,BASED(.Lc_spsize)    # make room for registers & psw        n       %r15,BASED(.Lc0xfffffff8) # align stack pointer to 8        stm     %r0,%r12,SP_R0(%r15)      # store gprs 0-12 to kernel stack        st      %r2,SP_ORIG_R2(%r15)      # store original content of gpr 2        mvc     SP_R13(12,%r15),__LC_SAVE_AREA  # move R13-R15 to stack        stam    %a0,%a15,SP_AREGS(%r15)   # store access registers to kst.        mvc     SP_AREGS+8(12,%r15),__LC_SAVE_AREA+12 # store ac. regs        mvc     SP_PSW(8,%r15),\psworg    # move user PSW to stack        la      %r0,\psworg               # store trap indication        st      %r0,SP_TRAP(%r15)        xc      0(4,%r15),0(%r15)         # clear back chain        .endm        .macro  RESTORE_ALL sync          # system exit macro        mvc     __LC_RETURN_PSW(8),SP_PSW(%r15)  # move user PSW to lowcore        lam     %a0,%a15,SP_AREGS(%r15)   # load the access registers        lm      %r0,%r15,SP_R0(%r15)      # load gprs 0-15 of user        ni      __LC_RETURN_PSW+1,0xfd    # clear wait state bit        lpsw    __LC_RETURN_PSW           # back to caller        .endm        .macro  GET_CURRENT	l	%r9,BASED(.Lc0xffffe000)  # load pointer to task_struct to %r9	al	%r9,__LC_KERNEL_STACK        .endm/* * Scheduler resume function, called by switch_to *  gpr2 = (task_struct *) prev *  gpr3 = (task_struct *) next * Returns: *  gpr2 = prev */        .globl  resumeresume:        basr    %r1,0resume_base:	tm	__THREAD_per(%r3),0xe8		# new process is using per ?	bz	resume_noper-resume_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      resume_noper-resume_base(%r1)	# we got away w/o bashing TLB's        lctl    %c9,%c11,__THREAD_per(%r3)	# Nope we didn'tresume_noper:        stm     %r6,%r15,24(%r15)       # store resume 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	stam    %a2,%a2,__THREAD_ar2(%r2)	# store kernel access reg. 2	stam    %a4,%a4,__THREAD_ar4(%r2)	# store kernel access reg. 4	lam     %a2,%a2,__THREAD_ar2(%r3)	# load kernel access reg. 2	lam     %a4,%a4,__THREAD_ar4(%r3)	# load kernel access reg. 4	lm	%r6,%r15,24(%r15)	# load resume registers of next task	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_softirqdo_call_softirq:	stm	%r12,%r15,24(%r15)	lr	%r12,%r15        basr    %r13,0do_call_base:	l	%r0,__LC_ASYNC_STACK	slr     %r0,%r15	sra	%r0,13	be	0f-do_call_base(%r13)	l	%r15,__LC_ASYNC_STACK0:	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,%r15,24(%r12)	br	%r14	/* * SVC interrupt handler routine. System calls are synchronous events and * are executed with interrupts enabled. */	.globl  system_callsystem_call:	SAVE_ALL_BASE        SAVE_ALL __LC_SVC_OLD_PSW,1	lh	%r8,0x8a	  # get svc number from lowcore        sll     %r8,2        GET_CURRENT               # load pointer to task_struct to R9        stosm   24(%r15),0x03     # reenable interrupts        l       %r8,sys_call_table-entry_base(%r8,%r13) # get system call addr.        tm      __TASK_ptrace+3(%r9),0x02 # PT_TRACESYS        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) # no-> skip resched & signal## check, if reschedule is needed#        icm     %r0,15,__TASK_need_resched(%r9)        bnz     BASED(sysc_reschedule)        icm     %r0,15,__TASK_sigpending(%r9)        bnz     BASED(sysc_signal_return)sysc_leave:	stnsm   24(%r15),0xfc     # disable I/O and ext. interrupts        RESTORE_ALL 1## call do_signal before return#sysc_signal_return:             la      %r2,SP_PTREGS(%r15) # load pt_regs        sr      %r3,%r3           # clear *oldset        l       %r1,BASED(.Ldo_signal)	la      %r14,BASED(sysc_leave)        br      %r1               # return point is sysc_leave## call schedule with sysc_return as return-address#sysc_reschedule:                l       %r1,BASED(.Lschedule)	la      %r14,BASED(sysc_return)        br      %r1               # call scheduler, return to sysc_return## call trace before and after sys_call#sysc_tracesys:	la	%r11,BASED(sysc_return)## call syscall_trace before and after system call# special linkage: %r11 contains the return address for trace_svc#trace_svc:        l       %r1,BASED(.Ltrace)	l       %r7,BASED(.Lc_ENOSYS)	st      %r7,SP_R2(%r15)   # give sysc_trace an -ENOSYS retval        basr    %r14,%r1	l       %r2,SP_R2(%r15)	cr      %r2,%r7		  # compare with saved -ENOSYS	be      BASED(trace_svc_go) # strace changed the syscall ?	sll     %r2,24	srl     %r2,22        l       %r8,sys_call_table-entry_base(%r2,%r13) # get system call addr.trace_svc_go:	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        l       %r1,BASED(.Ltrace)	lr	%r14,%r11	  # return point is in %r11        br      %r1## a new process exits the kernel with ret_from_fork#        .globl  ret_from_forkret_from_fork:          basr    %r13,0        l       %r13,.Lentry_base-.(%r13)  # setup base pointer to &entry_base        GET_CURRENT               # load pointer to task_struct to R9        stosm   24(%r15),0x03     # reenable interrupts        sr      %r0,%r0           # child returns 0        st      %r0,SP_R2(%r15)   # store return value (change R2 on stack)        l       %r1,BASED(.Lschedtail)	la      %r14,BASED(sysc_return)        br      %r1               # call schedule_tail, return to 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_clonesys_fork_glue:          la      %r2,SP_PTREGS(%r15)    # load pt_regs        l       %r1,BASED(.Lfork)        br      %r1                   # branch to sys_forksys_vfork_glue:         la      %r2,SP_PTREGS(%r15)    # load pt_regs        l       %r1,BASED(.Lvfork)        br      %r1                   # branch to sys_vforksys_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