1/* Copyright 2005 Andi Kleen, SuSE Labs. 2 * Licensed under GPL, v.2 3 */ 4#include <linux/mm.h> 5#include <linux/sched.h> 6#include <linux/random.h> 7#include <asm/ia32.h> 8 9/* Notebook: move the mmap code from sys_x86_64.c over here. */ 10 11void arch_pick_mmap_layout(struct mm_struct *mm) 12{ 13#ifdef CONFIG_IA32_EMULATION 14 if (current_thread_info()->flags & _TIF_IA32) 15 return ia32_pick_mmap_layout(mm); 16#endif 17 mm->mmap_base = TASK_UNMAPPED_BASE; 18 if (current->flags & PF_RANDOMIZE) { 19 /* Add 28bit randomness which is about 40bits of address space 20 because mmap base has to be page aligned. 21 or ~1/128 of the total user VM 22 (total user address space is 47bits) */ 23 unsigned rnd = get_random_int() & 0xfffffff; 24 mm->mmap_base += ((unsigned long)rnd) << PAGE_SHIFT; 25 } 26 mm->get_unmapped_area = arch_get_unmapped_area; 27 mm->unmap_area = arch_unmap_area; 28} 29