76 строки
2.0 KiB
C
76 строки
2.0 KiB
C
|
/*
|
||
|
|
* Copyright 2010 Tilera Corporation. All Rights Reserved.
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU General Public License
|
||
|
|
* as published by the Free Software Foundation, version 2.
|
||
|
|
*
|
||
|
|
* This program is distributed in the hope that it will be useful, but
|
||
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
|
||
|
|
* NON INFRINGEMENT. See the GNU General Public License for
|
||
|
|
* more details.
|
||
|
|
*
|
||
|
|
* Taken from the i386 architecture and simplified.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/mm.h>
|
||
|
|
#include <linux/random.h>
|
||
|
|
#include <linux/limits.h>
|
||
|
|
#include <linux/sched.h>
|
||
|
|
#include <linux/mman.h>
|
||
|
|
#include <linux/compat.h>
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Top of mmap area (just below the process stack).
|
||
|
|
*
|
||
|
|
* Leave an at least ~128 MB hole.
|
||
|
|
*/
|
||
|
|
#define MIN_GAP (128*1024*1024)
|
||
|
|
#define MAX_GAP (TASK_SIZE/6*5)
|
||
|
|
|
||
|
|
static inline unsigned long mmap_base(struct mm_struct *mm)
|
||
|
|
{
|
||
|
|
unsigned long gap = rlimit(RLIMIT_STACK);
|
||
|
|
unsigned long random_factor = 0;
|
||
|
|
|
||
|
|
if (current->flags & PF_RANDOMIZE)
|
||
|
|
random_factor = get_random_int() % (1024*1024);
|
||
|
|
|
||
|
|
if (gap < MIN_GAP)
|
||
|
|
gap = MIN_GAP;
|
||
|
|
else if (gap > MAX_GAP)
|
||
|
|
gap = MAX_GAP;
|
||
|
|
|
||
|
|
return PAGE_ALIGN(TASK_SIZE - gap - random_factor);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This function, called very early during the creation of a new
|
||
|
|
* process VM image, sets up which VM layout function to use:
|
||
|
|
*/
|
||
|
|
void arch_pick_mmap_layout(struct mm_struct *mm)
|
||
|
|
{
|
||
|
|
#if !defined(__tilegx__)
|
||
|
|
int is_32bit = 1;
|
||
|
|
#elif defined(CONFIG_COMPAT)
|
||
|
|
int is_32bit = is_compat_task();
|
||
|
|
#else
|
||
|
|
int is_32bit = 0;
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Use standard layout if the expected stack growth is unlimited
|
||
|
|
* or we are running native 64 bits.
|
||
|
|
*/
|
||
|
|
if (!is_32bit || rlimit(RLIMIT_STACK) == RLIM_INFINITY) {
|
||
|
|
mm->mmap_base = TASK_UNMAPPED_BASE;
|
||
|
|
mm->get_unmapped_area = arch_get_unmapped_area;
|
||
|
|
mm->unmap_area = arch_unmap_area;
|
||
|
|
} else {
|
||
|
|
mm->mmap_base = mmap_base(mm);
|
||
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
||
|
|
mm->unmap_area = arch_unmap_area_topdown;
|
||
|
|
}
|
||
|
|
}
|