x86/um/syscalls_64.c

0001 /*
0002  * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
0003  * Copyright 2003 PathScale, Inc.
0004  *
0005  * Licensed under the GPL
0006  */
0007
0008 #include <linux/sched.h>
0009 #include <linux/sched/mm.h>
0010 #include <linux/syscalls.h>
0011 #include <linux/uaccess.h>
0012 #include <asm/prctl.h> /* XXX This should get the constants from libc */
0013 #include <registers.h>
0014 #include <os.h>
0015
0016 long arch_prctl(struct task_struct *task, int option,
0017         unsigned long __user *arg2)
0018 {
0019     unsigned long *ptr = arg2, tmp;
0020     long ret;
0021     int pid = task->mm->context.id.u.pid;
0022
0023     /*
0024      * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
0025      * be safe), we need to call arch_prctl on the host because
0026      * setting %fs may result in something else happening (like a
0027      * GDT or thread.fs being set instead).  So, we let the host
0028      * fiddle the registers and thread struct and restore the
0029      * registers afterwards.
0030      *
0031      * So, the saved registers are stored to the process (this
0032      * needed because a stub may have been the last thing to run),
0033      * arch_prctl is run on the host, then the registers are read
0034      * back.
0035      */
0036     switch (option) {
0037     case ARCH_SET_FS:
0038     case ARCH_SET_GS:
0039         ret = restore_pid_registers(pid, &current->thread.regs.regs);
0040         if (ret)
0041             return ret;
0042         break;
0043     case ARCH_GET_FS:
0044     case ARCH_GET_GS:
0045         /*
0046          * With these two, we read to a local pointer and
0047          * put_user it to the userspace pointer that we were
0048          * given.  If addr isn't valid (because it hasn't been
0049          * faulted in or is just bogus), we want put_user to
0050          * fault it in (or return -EFAULT) instead of having
0051          * the host return -EFAULT.
0052          */
0053         ptr = &tmp;
0054     }
0055
0056     ret = os_arch_prctl(pid, option, ptr);
0057     if (ret)
0058         return ret;
0059
0060     switch (option) {
0061     case ARCH_SET_FS:
0062         current->thread.arch.fs = (unsigned long) ptr;
0063         ret = save_registers(pid, &current->thread.regs.regs);
0064         break;
0065     case ARCH_SET_GS:
0066         ret = save_registers(pid, &current->thread.regs.regs);
0067         break;
0068     case ARCH_GET_FS:
0069         ret = put_user(tmp, arg2);
0070         break;
0071     case ARCH_GET_GS:
0072         ret = put_user(tmp, arg2);
0073         break;
0074     }
0075
0076     return ret;
0077 }
0078
0079 SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
0080 {
0081     return arch_prctl(current, option, (unsigned long __user *) arg2);
0082 }
0083
0084 void arch_switch_to(struct task_struct *to)
0085 {
0086     if ((to->thread.arch.fs == 0) || (to->mm == NULL))
0087         return;
0088
0089     arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
0090 }
0091
0092 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
0093         unsigned long, prot, unsigned long, flags,
0094         unsigned long, fd, unsigned long, off)
0095 {
0096     if (off & ~PAGE_MASK)
0097         return -EINVAL;
0098
0099     return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
0100 }