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syscalls.c

/*
 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright 2003 PathScale, Inc.
 *
 * Licensed under the GPL
 */

#include "linux/linkage.h"
#include "linux/personality.h"
#include "linux/utsname.h"
#include "asm/prctl.h" /* XXX This should get the constants from libc */
#include "asm/uaccess.h"
#include "os.h"

asmlinkage long sys_uname64(struct new_utsname __user * name)
{
      int err;

      down_read(&uts_sem);
      err = copy_to_user(name, utsname(), sizeof (*name));
      up_read(&uts_sem);

      if (personality(current->personality) == PER_LINUX32)
            err |= copy_to_user(&name->machine, "i686", 5);

      return err ? -EFAULT : 0;
}

long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
{
      unsigned long *ptr = addr, tmp;
      long ret;
      int pid = task->mm->context.id.u.pid;

      /*
       * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
       * be safe), we need to call arch_prctl on the host because
       * setting %fs may result in something else happening (like a
       * GDT or thread.fs being set instead).  So, we let the host
       * fiddle the registers and thread struct and restore the
       * registers afterwards.
       *
       * So, the saved registers are stored to the process (this
       * needed because a stub may have been the last thing to run),
       * arch_prctl is run on the host, then the registers are read
       * back.
       */
      switch (code) {
      case ARCH_SET_FS:
      case ARCH_SET_GS:
            restore_registers(pid, &current->thread.regs.regs);
            break;
      case ARCH_GET_FS:
      case ARCH_GET_GS:
            /*
             * With these two, we read to a local pointer and
             * put_user it to the userspace pointer that we were
             * given.  If addr isn't valid (because it hasn't been
             * faulted in or is just bogus), we want put_user to
             * fault it in (or return -EFAULT) instead of having
             * the host return -EFAULT.
             */
            ptr = &tmp;
      }

      ret = os_arch_prctl(pid, code, ptr);
      if (ret)
            return ret;

      switch (code) {
      case ARCH_SET_FS:
            current->thread.arch.fs = (unsigned long) ptr;
            save_registers(pid, &current->thread.regs.regs);
            break;
      case ARCH_SET_GS:
            save_registers(pid, &current->thread.regs.regs);
            break;
      case ARCH_GET_FS:
            ret = put_user(tmp, addr);
            break;
      case ARCH_GET_GS:
            ret = put_user(tmp, addr);
            break;
      }

      return ret;
}

long sys_arch_prctl(int code, unsigned long addr)
{
      return arch_prctl(current, code, (unsigned long __user *) addr);
}

long sys_clone(unsigned long clone_flags, unsigned long newsp,
             void __user *parent_tid, void __user *child_tid)
{
      long ret;

      if (!newsp)
            newsp = UPT_SP(&current->thread.regs.regs);
      current->thread.forking = 1;
      ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
                  child_tid);
      current->thread.forking = 0;
      return ret;
}

void arch_switch_to(struct task_struct *from, struct task_struct *to)
{
      if ((to->thread.arch.fs == 0) || (to->mm == NULL))
            return;

      arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
}

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