LXR linux/arch/x86/um/syscalls

   1/*
   2 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3 * Copyright 2003 PathScale, Inc.
   4 *
   5 * Licensed under the GPL
   6 */
   7
   8#include "linux/linkage.h"
   9#include "linux/personality.h"
  10#include "linux/utsname.h"
  11#include "asm/prctl.h" /* XXX This should get the constants from libc */
  12#include "asm/uaccess.h"
  13#include "os.h"
  14
  15long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
  16{
  17        unsigned long *ptr = addr, tmp;
  18        long ret;
  19        int pid = task->mm->context.id.u.pid;
  20
  21        /*
  22         * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
  23         * be safe), we need to call arch_prctl on the host because
  24         * setting %fs may result in something else happening (like a
  25         * GDT or thread.fs being set instead).  So, we let the host
  26         * fiddle the registers and thread struct and restore the
  27         * registers afterwards.
  28         *
  29         * So, the saved registers are stored to the process (this
  30         * needed because a stub may have been the last thing to run),
  31         * arch_prctl is run on the host, then the registers are read
  32         * back.
  33         */
  34        switch (code) {
  35        case ARCH_SET_FS:
  36        case ARCH_SET_GS:
  37                ret = restore_registers(pid, &current->thread.regs.regs);
  38                if (ret)
  39                        return ret;
  40                break;
  41        case ARCH_GET_FS:
  42        case ARCH_GET_GS:
  43                /*
  44                 * With these two, we read to a local pointer and
  45                 * put_user it to the userspace pointer that we were
  46                 * given.  If addr isn't valid (because it hasn't been
  47                 * faulted in or is just bogus), we want put_user to
  48                 * fault it in (or return -EFAULT) instead of having
  49                 * the host return -EFAULT.
  50                 */
  51                ptr = &tmp;
  52        }
  53
  54        ret = os_arch_prctl(pid, code, ptr);
  55        if (ret)
  56                return ret;
  57
  58        switch (code) {
  59        case ARCH_SET_FS:
  60                current->thread.arch.fs = (unsigned long) ptr;
  61                ret = save_registers(pid, &current->thread.regs.regs);
  62                break;
  63        case ARCH_SET_GS:
  64                ret = save_registers(pid, &current->thread.regs.regs);
  65                break;
  66        case ARCH_GET_FS:
  67                ret = put_user(tmp, addr);
  68                break;
  69        case ARCH_GET_GS:
  70                ret = put_user(tmp, addr);
  71                break;
  72        }
  73
  74        return ret;
  75}
  76
  77long sys_arch_prctl(int code, unsigned long addr)
  78{
  79        return arch_prctl(current, code, (unsigned long __user *) addr);
  80}
  81
  82long sys_clone(unsigned long clone_flags, unsigned long newsp,
  83               void __user *parent_tid, void __user *child_tid)
  84{
  85        long ret;
  86
  87        if (!newsp)
  88                newsp = UPT_SP(&current->thread.regs.regs);
  89        current->thread.forking = 1;
  90        ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
  91                      child_tid);
  92        current->thread.forking = 0;
  93        return ret;
  94}
  95
  96void arch_switch_to(struct task_struct *to)
  97{
  98        if ((to->thread.arch.fs == 0) || (to->mm == NULL))
  99                return;
 100
 101        arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
 102}
 103