arch/um/sys-x86_64/syscalls.c

   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
  15 asmlinkage long sys_uname64(struct new_utsname __user * name)
  16 {
  17         int err;
  18
  19         down_read(&uts_sem);
  20         err = copy_to_user(name, utsname(), sizeof (*name));
  21         up_read(&uts_sem);
  22
  23         if (personality(current->personality) == PER_LINUX32)
  24                 err |= copy_to_user(&name->machine, "i686", 5);
  25
  26         return err ? -EFAULT : 0;
  27 }
  28
  29 long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
  30 {
  31         unsigned long *ptr = addr, tmp;
  32         long ret;
  33         int pid = task->mm->context.id.u.pid;
  34
  35         /*
  36          * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
  37          * be safe), we need to call arch_prctl on the host because
  38          * setting %fs may result in something else happening (like a
  39          * GDT or thread.fs being set instead).  So, we let the host
  40          * fiddle the registers and thread struct and restore the
  41          * registers afterwards.
  42          *
  43          * So, the saved registers are stored to the process (this
  44          * needed because a stub may have been the last thing to run),
  45          * arch_prctl is run on the host, then the registers are read
  46          * back.
  47          */
  48         switch (code) {
  49         case ARCH_SET_FS:
  50         case ARCH_SET_GS:
  51                 restore_registers(pid, &current->thread.regs.regs);
  52                 break;
  53         case ARCH_GET_FS:
  54         case ARCH_GET_GS:
  55                 /*
  56                  * With these two, we read to a local pointer and
  57                  * put_user it to the userspace pointer that we were
  58                  * given.  If addr isn't valid (because it hasn't been
  59                  * faulted in or is just bogus), we want put_user to
  60                  * fault it in (or return -EFAULT) instead of having
  61                  * the host return -EFAULT.
  62                  */
  63                 ptr = &tmp;
  64         }
  65
  66         ret = os_arch_prctl(pid, code, ptr);
  67         if (ret)
  68                 return ret;
  69
  70         switch (code) {
  71         case ARCH_SET_FS:
  72                 current->thread.arch.fs = (unsigned long) ptr;
  73                 save_registers(pid, &current->thread.regs.regs);
  74                 break;
  75         case ARCH_SET_GS:
  76                 save_registers(pid, &current->thread.regs.regs);
  77                 break;
  78         case ARCH_GET_FS:
  79                 ret = put_user(tmp, addr);
  80                 break;
  81         case ARCH_GET_GS:
  82                 ret = put_user(tmp, addr);
  83                 break;
  84         }
  85
  86         return ret;
  87 }
  88
  89 long sys_arch_prctl(int code, unsigned long addr)
  90 {
  91         return arch_prctl(current, code, (unsigned long __user *) addr);
  92 }
  93
  94 long sys_clone(unsigned long clone_flags, unsigned long newsp,
  95                void __user *parent_tid, void __user *child_tid)
  96 {
  97         long ret;
  98
  99         if (!newsp)
 100                 newsp = UPT_SP(&current->thread.regs.regs);
 101         current->thread.forking = 1;
 102         ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
 103                       child_tid);
 104         current->thread.forking = 0;
 105         return ret;
 106 }
 107
 108 void arch_switch_to(struct task_struct *from, struct task_struct *to)
 109 {
 110         if ((to->thread.arch.fs == 0) || (to->mm == NULL))
 111                 return;
 112
 113         arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
 114 }