/*
 *  arch/s390/kernel/process.c
 *
 *  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),
 *
 *  Derived from "arch/i386/kernel/process.c"
 *    Copyright (C) 1995, Linus Torvalds
 */

/*
 * This file handles the architecture-dependent parts of process handling..
 */

#define __KERNEL_SYSCALLS__
#include <stdarg.h>

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/malloc.h>
#include <linux/vmalloc.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/config.h>
#include <linux/unistd.h>
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/init.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/misc390.h>

spinlock_t semaphore_wake_lock = SPIN_LOCK_UNLOCKED;

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

/*
 * The idle loop on a S390...
 */

static psw_t wait_psw;

#ifndef CONFIG_SMP
static
#endif
int cpu_idle(void *unused)
{
	/* endless idle loop with no priority at all */
        init_idle();
	current->priority = 0;
	current->counter = -100;
	wait_psw.mask = _WAIT_PSW_MASK;
	wait_psw.addr = (unsigned long) &&idle_wakeup | 0x80000000L;
	while(1) {
#ifdef CONFIG_SMP
                if (atomic_read(&global_bh_lock) == 0 &&
                    (bh_mask & bh_active)) {
#else
                if (bh_mask & bh_active) {
#endif
                        do_bottom_half();
                        continue;
                }
                if (current->need_resched) {
                        schedule();
                        check_pgt_cache();
                        continue;
                }

		/* load wait psw */
		asm volatile (
                        "lpsw %0"
                        : : "m" (wait_psw) );
idle_wakeup:
	}
}

asmlinkage int sys_idle(void)
{
	if (current->pid != 0)
		return -EPERM;
	cpu_idle(NULL);
	return 0;
}

/*
  As all the register will only be made displayable to the root
  user ( via printk ) or checking if the uid of the user is 0 from
  the /proc filesystem please god this will be secure enough DJB.
  The lines are given one at a time so as not to chew stack space in
  printk on a crash & also for the proc filesystem when you get
  0 returned you know you've got all the lines
 */

int sprintf_regs(int line,char *buff,struct task_struct * task,struct thread_struct *tss,struct pt_regs * regs)
{	
	int linelen=0;
	int regno,chaincnt;
	u32 backchain,prev_backchain,endchain;

	enum
	{
		sp_linefeed,
		sp_psw,
		sp_ksp,
		sp_gprs,
		sp_gprs1,
		sp_gprs2,
		sp_gprs3,
		sp_gprs4,
		sp_acrs,
		sp_acrs1,
		sp_acrs2,
		sp_acrs3,
		sp_acrs4,
		sp_kern_backchain,
		sp_kern_backchain1
	};

	if(task)
		tss=&task->tss;
	if(tss)
		regs=tss->regs;
	switch(line)
	{
	case sp_linefeed: linelen=sprintf(buff,"\n");
		break;
	case sp_psw:
		if(regs)
			linelen=sprintf(buff,"User PSW:    %08lx %08lx\n",
				(unsigned long) regs->psw.mask,
				(unsigned long) regs->psw.addr);
		else
			linelen=sprintf(buff,"pt_regs=NULL some info unavailable\n");
		break;
	case sp_ksp:
		if(task)
			linelen+=sprintf(&buff[linelen],"task: %08x ",(addr_t)task);
		if(tss)
			linelen+=sprintf(&buff[linelen],"tss: %08x ksp: %08x ",
					 (addr_t)tss,(addr_t)tss->ksp);
		if(regs)
			linelen+=sprintf(&buff[linelen],"pt_regs: %08x\n",(addr_t)regs);
		break;
	case sp_gprs:
		if(regs)
			linelen=sprintf(buff,"User GPRS:\n");
		break;
	case sp_gprs1 ... sp_gprs4:
		if(regs)
		{
			regno=(line-sp_gprs1)*4;
			linelen=sprintf(buff,"%08x  %08x  %08x  %08x\n",
					regs->gprs[regno], 
					regs->gprs[regno+1],
					regs->gprs[regno+2],
					regs->gprs[regno+3]);
		}
		break;
	case sp_acrs:
		if(regs)
			linelen=sprintf(buff,"User ACRS:\n");
		break;	
        case sp_acrs1 ... sp_acrs4:
		if(regs)
		{
			regno=(line-sp_acrs1)*4;
			linelen=sprintf(buff,"%08x  %08x  %08x  %08x\n",
					regs->acrs[regno],
					regs->acrs[regno+1],
					regs->acrs[regno+2],
					regs->acrs[regno+3]);
		}
		break;
	case sp_kern_backchain:
		if(tss&&tss->ksp&&regs)
			linelen=sprintf(buff,"Kernel BackChain  CallChain    BackChain  CallChain\n");
		break;
	default:
		if(tss&&tss->ksp&&regs)
		{
			
			backchain=(tss->ksp&PSW_ADDR_MASK);
			endchain=((backchain&(-8192))+8192);
			prev_backchain=backchain-1;
			line-=sp_kern_backchain1;
			for(chaincnt=0;;chaincnt++)
			{
				if((backchain==0)||(backchain>=endchain)
				   ||(chaincnt>=8)||(prev_backchain>=backchain))
					break;
				if((chaincnt>>1)==line)
				{
					linelen+=sprintf(&buff[linelen],"%s%08x   %08x     ",
							 (chaincnt&1) ? "":"       ",
							 backchain,*(u32 *)(backchain+56));
				}
				if((chaincnt>>1)>line)
					break;
				prev_backchain=backchain;
				backchain=(*((u32 *)backchain))&PSW_ADDR_MASK;
			}
			if(linelen)
				linelen+=sprintf(&buff[linelen],"\n");
		}
	}
	return(linelen);
}


void show_regs(struct task_struct * task,struct thread_struct *tss,struct pt_regs *regs)
{
	char buff[80];
	int line;
	
	for(line=0;sprintf_regs(line,buff,task,tss,regs);line++)
		printk(buff);
}

int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
        int clone_arg = flags | CLONE_VM;
        int retval;

        __asm__ __volatile__(
                "     sr    2,2\n"
                "     lr    3,%1\n"
                "     l     4,%6\n"     /* load kernel stack ptr of parent */
                "     svc   %b2\n"                     /* Linux system call*/
                "     cl    4,%6\n"    /* compare ksp's: child or parent ? */
                "     je    0f\n"                          /* parent - jump*/
                "     l     15,%6\n"            /* fix kernel stack pointer*/
                "     ahi   15,%7\n"
                "     xc    0(96,15),0(15)\n"           /* clear save area */
                "     lr    2,%4\n"                        /* load argument*/
                "     lr    14,%5\n"                      /* get fn-pointer*/
                "     basr  14,14\n"                             /* call fn*/
                "     svc   %b3\n"                     /* Linux system call*/
                "0:   lr    %0,2"
                : "=a" (retval)
                : "d" (clone_arg), "i" (__NR_clone), "i" (__NR_exit),
                  "d" (arg), "d" (fn), "i" (__LC_KERNEL_STACK) , "i" (-STACK_FRAME_OVERHEAD)
                : "2", "3", "4" );
        return retval;
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
}

void flush_thread(void)
{

        current->used_math = 0;
        current->flags &= ~PF_USEDFPU;
}

void release_thread(struct task_struct *dead_task)
{
}

int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
        struct task_struct * p, struct pt_regs * regs)
{
        struct stack_frame
          {
            unsigned long back_chain;
            unsigned long eos;
            unsigned long glue1;
            unsigned long glue2;
            unsigned long scratch[2];
            unsigned long gprs[10];    /* gprs 6 -15                       */
            unsigned long fprs[4];     /* fpr 4 and 6                      */
            unsigned long empty[4];
#if CONFIG_REMOTE_DEBUG
		gdb_pt_regs childregs;
#else
		pt_regs childregs;
#endif
		__u32   pgm_old_ilc;     /* single step magic from entry.S */
		__u32   pgm_svc_step;
          } *frame;

        frame = (struct stack_frame *) (2*PAGE_SIZE + (unsigned long) p) -1;
        frame = (struct stack_frame *) (((unsigned long) frame)&-8L);
        p->tss.regs = &frame->childregs;
        p->tss.ksp = (unsigned long) frame;
        frame->childregs = *regs;
        frame->childregs.gprs[15] = new_stackp;
        frame->eos = 0;

        /* new return point is ret_from_sys_call */
        frame->gprs[8] = ((unsigned long) &ret_from_fork) | 0x80000000;

        /* fake return stack for resume(), don't go back to schedule */
        frame->gprs[9]  = (unsigned long) frame;
	frame->pgm_svc_step=0; /* Nope we aren't single stepping an svc */
        /* save fprs, if used in last task */
	save_fp_regs(&p->tss.fp_regs);
        p->tss.user_seg = __pa((unsigned long) p->mm->pgd) | _SEGMENT_TABLE;
        p->tss.fs = USER_DS;
        /* Don't copy debug registers */
        memset(&p->tss.per_info,0,sizeof(p->tss.per_info));
        return 0;
}



asmlinkage int sys_fork(struct pt_regs regs)
{
        int ret;

        lock_kernel();
        ret = do_fork(SIGCHLD, regs.gprs[15], &regs);
        unlock_kernel();
        return ret;
}

asmlinkage int sys_clone(struct pt_regs regs)
{
        unsigned long clone_flags;
        unsigned long newsp;
        int ret;

        lock_kernel();
        clone_flags = regs.gprs[3];
        newsp = regs.gprs[2];
        if (!newsp)
                newsp = regs.gprs[15];
        ret = do_fork(clone_flags, newsp, &regs);
        unlock_kernel();
        return ret;
}

/*
 * This is trivial, and on the face of it looks like it
 * could equally well be done in user mode.
 *
 * Not so, for quite unobvious reasons - register pressure.
 * In user mode vfork() cannot have a stack frame, and if
 * done by calling the "clone()" system call directly, you
 * do not have enough call-clobbered registers to hold all
 * the information you need.
 */
asmlinkage int sys_vfork(struct pt_regs regs)
{
	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
                       regs.gprs[15], &regs);
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(struct pt_regs regs)
{
        int error;
        char * filename;

        lock_kernel();
        filename = getname((char *) regs.orig_gpr2);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
        error = do_execve(filename, (char **) regs.gprs[3], (char **) regs.gprs[4], &regs);
	if (error == 0)
		current->flags &= ~PF_DTRACE;
        putname(filename);
out:
        unlock_kernel();
        return error;
}


/*
 * fill in the FPU structure for a core dump.
 */
int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
{
	save_fp_regs(fpregs);
	return(TRUE);
}

/*
 * fill in the user structure for a core dump..
 */
void dump_thread(struct pt_regs * regs, struct user * dump)
{

/* changed the size calculations - should hopefully work better. lbt */
	dump->magic = CMAGIC;
	dump->start_code = 0;
	dump->start_stack = regs->gprs[15] & ~(PAGE_SIZE - 1);
	dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
	dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
	dump->u_dsize -= dump->u_tsize;
	dump->u_ssize = 0;
	if (dump->start_stack < TASK_SIZE)
		dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
	memcpy(&dump->regs.gprs[0],regs,sizeof(s390_regs));
	dump_fpu (regs, &dump->regs.fp_regs);
	memcpy(&dump->regs.per_info,&current->tss.per_info,sizeof(per_struct));
}