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/*

 *  linux/arch/m68k/kernel/process.c

 *

 *  Copyright (C) 1995  Hamish Macdonald

 */

/*

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

 */

#include <linux/errno.h>

#include <linux/sched.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/stddef.h>

#include <linux/unistd.h>

#include <linux/ptrace.h>

#include <linux/malloc.h>

#include <linux/user.h>

#include <linux/a.out.h>

#include <asm/segment.h>

#include <asm/system.h>

#include <asm/traps.h>

#include <asm/machdep.h>

asmlinkage void ret_from_exception(void);

/*

 * The idle loop on an m68k..

 */

asmlinkage int sys_idle(void)

{

        if (current->pid != 0)

                return -EPERM;

        /* endless idle loop with no priority at all */

        current->counter = -100;

        for (;;)

                schedule();

}

void hard_reset_now(void)

{

        if (mach_reset)

                mach_reset();

}

void show_regs(struct pt_regs * regs)

{

        printk("\n");

        printk("Format %02x  Vector: %04x  PC: %08lx  Status: %04x\n",

               regs->format, regs->vector, regs->pc, regs->sr);

        printk("ORIG_D0: %08lx  D0: %08lx  A1: %08lx\n",

               regs->orig_d0, regs->d0, regs->a1);

        printk("A0: %08lx  D5: %08lx  D4: %08lx\n",

               regs->a0, regs->d5, regs->d4);

        printk("D3: %08lx  D2: %08lx  D1: %08lx\n",

               regs->d3, regs->d2, regs->d1);

        if (!(regs->sr & PS_S))

                printk("USP: %08lx\n", rdusp());

}

/*

 * Free current thread data structures etc..

 */

void exit_thread(void)

{

}

void flush_thread(void)

{

        set_fs(USER_DS);

        current->tss.fs = USER_DS;

}

/*

 * "m68k_fork()".. By the time we get here, the

 * non-volatile registers have also been saved on the

 * stack. We do some ugly pointer stuff here.. (see

 * also copy_thread)

 */

asmlinkage int m68k_fork(struct pt_regs *regs)

{

        return do_fork(SIGCHLD, rdusp(), regs);

}

asmlinkage int m68k_clone(struct pt_regs *regs)

{

        unsigned long clone_flags;

        unsigned long newsp;

        /* syscall2 puts clone_flags in d1 and usp in d2 */

        clone_flags = regs->d1;

        newsp = regs->d2;

        if (!newsp)

          newsp  = rdusp();

        return do_fork(clone_flags, newsp, regs);

}

void release_thread(struct task_struct *dead_task)

{

}

void copy_thread(int nr, unsigned long clone_flags, unsigned long usp,

                 struct task_struct * p, struct pt_regs * regs)

{

        struct pt_regs * childregs;

        struct switch_stack * childstack, *stack;

        unsigned long stack_offset, *retp;

        stack_offset = PAGE_SIZE - sizeof(struct pt_regs);

        childregs = (struct pt_regs *) (p->kernel_stack_page + stack_offset);

        *childregs = *regs;

        childregs->d0 = 0;

        retp = ((unsigned long *) regs);

        stack = ((struct switch_stack *) retp) - 1;

        childstack = ((struct switch_stack *) childregs) - 1;

        *childstack = *stack;

        childstack->retpc = (unsigned long) ret_from_exception;

        p->tss.usp = usp;

        p->tss.ksp = (unsigned long)childstack;

        /* Copy the current fpu state */

        asm volatile ("fsave %0" : : "m" (p->tss.fpstate[0]) : "memory");

        if (p->tss.fpstate[0])

          asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"

                        "fmoveml %/fpiar/%/fpcr/%/fpsr,%1"

                        : : "m" (p->tss.fp[0]), "m" (p->tss.fpcntl[0])

                        : "memory");

        /* Restore the state in case the fpu was busy */

        asm volatile ("frestore %0" : : "m" (p->tss.fpstate[0]));

}

/* Fill in the fpu structure for a core dump.  */

int dump_fpu (struct user_m68kfp_struct *fpu)

{

  char fpustate[216];

  /* First dump the fpu context to avoid protocol violation.  */

  asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");

  if (!fpustate[0])

    return 0;

  asm volatile ("fmovem %/fpiar/%/fpcr/%/fpsr,%0"

                :: "m" (fpu->fpcntl[0])

                : "memory");

  asm volatile ("fmovemx %/fp0-%/fp7,%0"

                :: "m" (fpu->fpregs[0])

                : "memory");

  return 1;

}

/*

 * 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 = rdusp() & ~(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;

        dump->u_ar0 = (struct pt_regs *)(((int)(&dump->regs)) -((int)(dump)));

        dump->regs = *regs;

        dump->regs2 = ((struct switch_stack *)regs)[-1];

        /* dump floating point stuff */

        dump->u_fpvalid = dump_fpu (&dump->m68kfp);

}

/*

 * sys_execve() executes a new program.

 */

asmlinkage int sys_execve(char *name, char **argv, char **envp)

{

        int error;

        char * filename;

        struct pt_regs *regs = (struct pt_regs *) &name;

        error = getname(name, &filename);

        if (error)

                return error;

        error = do_execve(filename, argv, envp, regs);

        putname(filename);

        return error;

}