Merge branch 'x86/microcode' into x86/urgent, to pick up cleanup
[linux/fpc-iii.git] / arch / x86 / mm / mmap.c
blob7940166c799b787f1c9b01a08ce8920365b05cad
1 /*
2 * Flexible mmap layout support
4 * Based on code by Ingo Molnar and Andi Kleen, copyrighted
5 * as follows:
7 * Copyright 2003-2009 Red Hat Inc.
8 * All Rights Reserved.
9 * Copyright 2005 Andi Kleen, SUSE Labs.
10 * Copyright 2007 Jiri Kosina, SUSE Labs.
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
27 #include <linux/personality.h>
28 #include <linux/mm.h>
29 #include <linux/random.h>
30 #include <linux/limits.h>
31 #include <linux/sched/signal.h>
32 #include <linux/sched/mm.h>
33 #include <asm/elf.h>
35 struct va_alignment __read_mostly va_align = {
36 .flags = -1,
39 static unsigned long stack_maxrandom_size(void)
41 unsigned long max = 0;
42 if ((current->flags & PF_RANDOMIZE) &&
43 !(current->personality & ADDR_NO_RANDOMIZE)) {
44 max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT;
47 return max;
51 * Top of mmap area (just below the process stack).
53 * Leave an at least ~128 MB hole with possible stack randomization.
55 #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
56 #define MAX_GAP (TASK_SIZE/6*5)
58 static int mmap_is_legacy(void)
60 if (current->personality & ADDR_COMPAT_LAYOUT)
61 return 1;
63 if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
64 return 1;
66 return sysctl_legacy_va_layout;
69 unsigned long arch_mmap_rnd(void)
71 unsigned long rnd;
73 if (mmap_is_ia32())
74 #ifdef CONFIG_COMPAT
75 rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
76 #else
77 rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
78 #endif
79 else
80 rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
82 return rnd << PAGE_SHIFT;
85 static unsigned long mmap_base(unsigned long rnd)
87 unsigned long gap = rlimit(RLIMIT_STACK);
89 if (gap < MIN_GAP)
90 gap = MIN_GAP;
91 else if (gap > MAX_GAP)
92 gap = MAX_GAP;
94 return PAGE_ALIGN(TASK_SIZE - gap - rnd);
98 * This function, called very early during the creation of a new
99 * process VM image, sets up which VM layout function to use:
101 void arch_pick_mmap_layout(struct mm_struct *mm)
103 unsigned long random_factor = 0UL;
105 if (current->flags & PF_RANDOMIZE)
106 random_factor = arch_mmap_rnd();
108 mm->mmap_legacy_base = TASK_UNMAPPED_BASE + random_factor;
110 if (mmap_is_legacy()) {
111 mm->mmap_base = mm->mmap_legacy_base;
112 mm->get_unmapped_area = arch_get_unmapped_area;
113 } else {
114 mm->mmap_base = mmap_base(random_factor);
115 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
119 const char *arch_vma_name(struct vm_area_struct *vma)
121 if (vma->vm_flags & VM_MPX)
122 return "[mpx]";
123 return NULL;