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process.c

/*
 *  linux/arch/m68k/kernel/process.c
 *
 *  Copyright (C) 1995  Hamish Macdonald
 *
 *  68060 fixes by Jesper Skov
 */

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

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/reboot.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/setup.h>
#include <asm/pgtable.h>

/*
 * Initial task/thread structure. Make this a per-architecture thing,
 * because different architectures tend to have different
 * alignment requirements and potentially different initial
 * setup.
 */
static struct fs_struct init_fs = INIT_FS;
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
struct mm_struct init_mm = INIT_MM(init_mm);

EXPORT_SYMBOL(init_mm);

union thread_union init_thread_union
__attribute__((section(".data.init_task"), aligned(THREAD_SIZE)))
       = { INIT_THREAD_INFO(init_task) };

/* initial task structure */
struct task_struct init_task = INIT_TASK(init_task);

EXPORT_SYMBOL(init_task);

asmlinkage void ret_from_fork(void);


/*
 * Return saved PC from a blocked thread
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
      struct switch_stack *sw = (struct switch_stack *)tsk->thread.ksp;
      /* Check whether the thread is blocked in resume() */
      if (in_sched_functions(sw->retpc))
            return ((unsigned long *)sw->a6)[1];
      else
            return sw->retpc;
}

/*
 * The idle loop on an m68k..
 */
static void default_idle(void)
{
      if (!need_resched())
#if defined(MACH_ATARI_ONLY) && !defined(CONFIG_HADES)
            /* block out HSYNC on the atari (falcon) */
            __asm__("stop #0x2200" : : : "cc");
#else
            __asm__("stop #0x2000" : : : "cc");
#endif
}

void (*idle)(void) = default_idle;

/*
 * The idle thread. There's no useful work to be
 * done, so just try to conserve power and have a
 * low exit latency (ie sit in a loop waiting for
 * somebody to say that they'd like to reschedule)
 */
void cpu_idle(void)
{
      /* endless idle loop with no priority at all */
      while (1) {
            while (!need_resched())
                  idle();
            preempt_enable_no_resched();
            schedule();
            preempt_disable();
      }
}

void machine_restart(char * __unused)
{
      if (mach_reset)
            mach_reset();
      for (;;);
}

void machine_halt(void)
{
      if (mach_halt)
            mach_halt();
      for (;;);
}

void machine_power_off(void)
{
      if (mach_power_off)
            mach_power_off();
      for (;;);
}

void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);

void show_regs(struct pt_regs * regs)
{
      printk("\n");
      printk("Format %02x  Vector: %04x  PC: %08lx  Status: %04x    %s\n",
             regs->format, regs->vector, regs->pc, regs->sr, print_tainted());
      printk("ORIG_D0: %08lx  D0: %08lx  A2: %08lx  A1: %08lx\n",
             regs->orig_d0, regs->d0, regs->a2, 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());
}

/*
 * Create a kernel thread
 */
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
      int pid;
      mm_segment_t fs;

      fs = get_fs();
      set_fs (KERNEL_DS);

      {
      register long retval __asm__ ("d0");
      register long clone_arg __asm__ ("d1") = flags | CLONE_VM | CLONE_UNTRACED;

      retval = __NR_clone;
      __asm__ __volatile__
        ("clrl %%d2\n\t"
         "trap #0\n\t"        /* Linux/m68k system call */
         "tstl %0\n\t"        /* child or parent */
         "jne 1f\n\t"               /* parent - jump */
         "lea %%sp@(%c7),%6\n\t"    /* reload current */
         "movel %6@,%6\n\t"
         "movel %3,%%sp@-\n\t"      /* push argument */
         "jsr %4@\n\t"        /* call fn */
         "movel %0,%%d1\n\t"        /* pass exit value */
         "movel %2,%%d0\n\t"        /* exit */
         "trap #0\n"
         "1:"
         : "+d" (retval)
         : "i" (__NR_clone), "i" (__NR_exit),
           "r" (arg), "a" (fn), "d" (clone_arg), "r" (current),
           "i" (-THREAD_SIZE)
         : "d2");

      pid = retval;
      }

      set_fs (fs);
      return pid;
}
EXPORT_SYMBOL(kernel_thread);

void flush_thread(void)
{
      unsigned long zero = 0;
      set_fs(USER_DS);
      current->thread.fs = __USER_DS;
      if (!FPU_IS_EMU)
            asm volatile (".chip 68k/68881\n\t"
                        "frestore %0@\n\t"
                        ".chip 68k" : : "a" (&zero));
}

/*
 * "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, 0, NULL, NULL);
}

asmlinkage int m68k_vfork(struct pt_regs *regs)
{
      return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0,
                   NULL, NULL);
}

asmlinkage int m68k_clone(struct pt_regs *regs)
{
      unsigned long clone_flags;
      unsigned long newsp;
      int __user *parent_tidptr, *child_tidptr;

      /* syscall2 puts clone_flags in d1 and usp in d2 */
      clone_flags = regs->d1;
      newsp = regs->d2;
      parent_tidptr = (int __user *)regs->d3;
      child_tidptr = (int __user *)regs->d4;
      if (!newsp)
            newsp = rdusp();
      return do_fork(clone_flags, newsp, regs, 0,
                   parent_tidptr, child_tidptr);
}

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
             unsigned long unused,
             struct task_struct * p, struct pt_regs * regs)
{
      struct pt_regs * childregs;
      struct switch_stack * childstack, *stack;
      unsigned long *retp;

      childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;

      *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_fork;

      p->thread.usp = usp;
      p->thread.ksp = (unsigned long)childstack;
      /*
       * Must save the current SFC/DFC value, NOT the value when
       * the parent was last descheduled - RGH  10-08-96
       */
      p->thread.fs = get_fs().seg;

      if (!FPU_IS_EMU) {
            /* Copy the current fpu state */
            asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");

            if (!CPU_IS_060 ? p->thread.fpstate[0] : p->thread.fpstate[2])
              asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"
                        "fmoveml %/fpiar/%/fpcr/%/fpsr,%1"
                        : : "m" (p->thread.fp[0]), "m" (p->thread.fpcntl[0])
                        : "memory");
            /* Restore the state in case the fpu was busy */
            asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
      }

      return 0;
}

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

int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
{
      char fpustate[216];

      if (FPU_IS_EMU) {
            int i;

            memcpy(fpu->fpcntl, current->thread.fpcntl, 12);
            memcpy(fpu->fpregs, current->thread.fp, 96);
            /* Convert internal fpu reg representation
             * into long double format
             */
            for (i = 0; i < 24; i += 3)
                  fpu->fpregs[i] = ((fpu->fpregs[i] & 0xffff0000) << 15) |
                                   ((fpu->fpregs[i] & 0x0000ffff) << 16);
            return 1;
      }

      /* First dump the fpu context to avoid protocol violation.  */
      asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");
      if (!CPU_IS_060 ? !fpustate[0] : !fpustate[2])
            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;
}
EXPORT_SYMBOL(dump_fpu);

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

/* 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 user_regs_struct *)((int)&dump->regs - (int)dump);
      sw = ((struct switch_stack *)regs) - 1;
      dump->regs.d1 = regs->d1;
      dump->regs.d2 = regs->d2;
      dump->regs.d3 = regs->d3;
      dump->regs.d4 = regs->d4;
      dump->regs.d5 = regs->d5;
      dump->regs.d6 = sw->d6;
      dump->regs.d7 = sw->d7;
      dump->regs.a0 = regs->a0;
      dump->regs.a1 = regs->a1;
      dump->regs.a2 = regs->a2;
      dump->regs.a3 = sw->a3;
      dump->regs.a4 = sw->a4;
      dump->regs.a5 = sw->a5;
      dump->regs.a6 = sw->a6;
      dump->regs.d0 = regs->d0;
      dump->regs.orig_d0 = regs->orig_d0;
      dump->regs.stkadj = regs->stkadj;
      dump->regs.sr = regs->sr;
      dump->regs.pc = regs->pc;
      dump->regs.fmtvec = (regs->format << 12) | regs->vector;
      /* dump floating point stuff */
      dump->u_fpvalid = dump_fpu (regs, &dump->m68kfp);
}
EXPORT_SYMBOL(dump_thread);

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(char __user *name, char __user * __user *argv, char __user * __user *envp)
{
      int error;
      char * filename;
      struct pt_regs *regs = (struct pt_regs *) &name;

      lock_kernel();
      filename = getname(name);
      error = PTR_ERR(filename);
      if (IS_ERR(filename))
            goto out;
      error = do_execve(filename, argv, envp, regs);
      putname(filename);
out:
      unlock_kernel();
      return error;
}

unsigned long get_wchan(struct task_struct *p)
{
      unsigned long fp, pc;
      unsigned long stack_page;
      int count = 0;
      if (!p || p == current || p->state == TASK_RUNNING)
            return 0;

      stack_page = (unsigned long)task_stack_page(p);
      fp = ((struct switch_stack *)p->thread.ksp)->a6;
      do {
            if (fp < stack_page+sizeof(struct thread_info) ||
                fp >= 8184+stack_page)
                  return 0;
            pc = ((unsigned long *)fp)[1];
            if (!in_sched_functions(pc))
                  return pc;
            fp = *(unsigned long *) fp;
      } while (count++ < 16);
      return 0;
}

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