#include <linux/version.h>
#include "config.h"
#include "../../mcctrl.h"

unsigned long
reserve_user_space_common(struct mcctrl_usrdata *usrdata, unsigned long start, unsigned long end);

int
reserve_user_space(struct mcctrl_usrdata *usrdata, unsigned long *startp, unsigned long *endp)
{
	struct vm_area_struct *vma;
	unsigned long start = 0L;
	unsigned long end;

#define	DESIRED_USER_END	0x800000000000
#define	GAP_FOR_MCEXEC		0x008000000000UL
	end = DESIRED_USER_END;
	down_write(&current->mm->mmap_sem);
	vma = find_vma(current->mm, 0);
	if (vma) {
		end = (vma->vm_start - GAP_FOR_MCEXEC) & ~(GAP_FOR_MCEXEC - 1);
	}

#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,5,0)
	up_write(&current->mm->mmap_sem);
#endif
	start = reserve_user_space_common(usrdata, start, end);
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,5,0)
	up_write(&current->mm->mmap_sem);
#endif

	if (IS_ERR_VALUE(start)) {
		return start;
	}
	*startp = start;
	*endp = end;
	return 0;
}