/* Sanitise and restore the current VFP state from the provided structures. */
int vfp_restore_user_hwstate(struct user_vfp __user *ufp,
			     struct user_vfp_exc __user *ufp_exc)
{
	struct thread_info *thread = current_thread_info();
	struct vfp_hard_struct *hwstate = &thread->vfpstate.hard;
	unsigned long fpexc;
	int err = 0;

	/* Disable VFP to avoid corrupting the new thread state. */
	vfp_flush_hwstate(thread);

	/*
	 * Copy the floating point registers. There can be unused
	 * registers see asm/hwcap.h for details.
	 */
	err |= __copy_from_user(&hwstate->fpregs, &ufp->fpregs,
				sizeof(hwstate->fpregs));
	/*
	 * Copy the status and control register.
	 */
	__get_user_error(hwstate->fpscr, &ufp->fpscr, err);

	/*
	 * Sanitise and restore the exception registers.
	 */
	__get_user_error(fpexc, &ufp_exc->fpexc, err);

	/* Ensure the VFP is enabled. */
	fpexc |= FPEXC_EN;

	/* Ensure FPINST2 is invalid and the exception flag is cleared. */
	fpexc &= ~(FPEXC_EX | FPEXC_FP2V);
	hwstate->fpexc = fpexc;

	__get_user_error(hwstate->fpinst, &ufp_exc->fpinst, err);
	__get_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err);

	return err ? -EFAULT : 0;
}
Example #2
0
/*
 * For vfp_set() a read-modify-write is done on the VFP registers,
 * in order to avoid writing back a half-modified set of registers on
 * failure.
 */
static int vfp_set(struct task_struct *target,
			  const struct user_regset *regset,
			  unsigned int pos, unsigned int count,
			  const void *kbuf, const void __user *ubuf)
{
	int ret;
	struct thread_info *thread = task_thread_info(target);
	struct vfp_hard_struct new_vfp = thread->vfpstate.hard;
	const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
	const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);

	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				  &new_vfp.fpregs,
				  user_fpregs_offset,
				  user_fpregs_offset + sizeof(new_vfp.fpregs));
	if (ret)
		return ret;

	ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
				user_fpregs_offset + sizeof(new_vfp.fpregs),
				user_fpscr_offset);
	if (ret)
		return ret;

	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				 &new_vfp.fpscr,
				 user_fpscr_offset,
				 user_fpscr_offset + sizeof(new_vfp.fpscr));
	if (ret)
		return ret;

	vfp_sync_hwstate(thread);
	thread->vfpstate.hard = new_vfp;
	vfp_flush_hwstate(thread);

	return 0;
}