hugetlb: introduce generic version of hugetlb_free_pgd_range
[linux/fpc-iii.git] / arch / x86 / mm / mmap.c
blob1e95d57760cf79becf81c012df564e42ae7122e2
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 <linux/compat.h>
34 #include <asm/elf.h>
36 #include "physaddr.h"
38 struct va_alignment __read_mostly va_align = {
39 .flags = -1,
42 unsigned long task_size_32bit(void)
44 return IA32_PAGE_OFFSET;
47 unsigned long task_size_64bit(int full_addr_space)
49 return full_addr_space ? TASK_SIZE_MAX : DEFAULT_MAP_WINDOW;
52 static unsigned long stack_maxrandom_size(unsigned long task_size)
54 unsigned long max = 0;
55 if (current->flags & PF_RANDOMIZE) {
56 max = (-1UL) & __STACK_RND_MASK(task_size == task_size_32bit());
57 max <<= PAGE_SHIFT;
60 return max;
63 #ifdef CONFIG_COMPAT
64 # define mmap32_rnd_bits mmap_rnd_compat_bits
65 # define mmap64_rnd_bits mmap_rnd_bits
66 #else
67 # define mmap32_rnd_bits mmap_rnd_bits
68 # define mmap64_rnd_bits mmap_rnd_bits
69 #endif
71 #define SIZE_128M (128 * 1024 * 1024UL)
73 static int mmap_is_legacy(void)
75 if (current->personality & ADDR_COMPAT_LAYOUT)
76 return 1;
78 return sysctl_legacy_va_layout;
81 static unsigned long arch_rnd(unsigned int rndbits)
83 if (!(current->flags & PF_RANDOMIZE))
84 return 0;
85 return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
88 unsigned long arch_mmap_rnd(void)
90 return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
93 static unsigned long mmap_base(unsigned long rnd, unsigned long task_size,
94 struct rlimit *rlim_stack)
96 unsigned long gap = rlim_stack->rlim_cur;
97 unsigned long pad = stack_maxrandom_size(task_size) + stack_guard_gap;
98 unsigned long gap_min, gap_max;
100 /* Values close to RLIM_INFINITY can overflow. */
101 if (gap + pad > gap)
102 gap += pad;
105 * Top of mmap area (just below the process stack).
106 * Leave an at least ~128 MB hole with possible stack randomization.
108 gap_min = SIZE_128M;
109 gap_max = (task_size / 6) * 5;
111 if (gap < gap_min)
112 gap = gap_min;
113 else if (gap > gap_max)
114 gap = gap_max;
116 return PAGE_ALIGN(task_size - gap - rnd);
119 static unsigned long mmap_legacy_base(unsigned long rnd,
120 unsigned long task_size)
122 return __TASK_UNMAPPED_BASE(task_size) + rnd;
126 * This function, called very early during the creation of a new
127 * process VM image, sets up which VM layout function to use:
129 static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
130 unsigned long random_factor, unsigned long task_size,
131 struct rlimit *rlim_stack)
133 *legacy_base = mmap_legacy_base(random_factor, task_size);
134 if (mmap_is_legacy())
135 *base = *legacy_base;
136 else
137 *base = mmap_base(random_factor, task_size, rlim_stack);
140 void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
142 if (mmap_is_legacy())
143 mm->get_unmapped_area = arch_get_unmapped_area;
144 else
145 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
147 arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base,
148 arch_rnd(mmap64_rnd_bits), task_size_64bit(0),
149 rlim_stack);
151 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
153 * The mmap syscall mapping base decision depends solely on the
154 * syscall type (64-bit or compat). This applies for 64bit
155 * applications and 32bit applications. The 64bit syscall uses
156 * mmap_base, the compat syscall uses mmap_compat_base.
158 arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base,
159 arch_rnd(mmap32_rnd_bits), task_size_32bit(),
160 rlim_stack);
161 #endif
164 unsigned long get_mmap_base(int is_legacy)
166 struct mm_struct *mm = current->mm;
168 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
169 if (in_compat_syscall()) {
170 return is_legacy ? mm->mmap_compat_legacy_base
171 : mm->mmap_compat_base;
173 #endif
174 return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;
177 const char *arch_vma_name(struct vm_area_struct *vma)
179 if (vma->vm_flags & VM_MPX)
180 return "[mpx]";
181 return NULL;
185 * mmap_address_hint_valid - Validate the address hint of mmap
186 * @addr: Address hint
187 * @len: Mapping length
189 * Check whether @addr and @addr + @len result in a valid mapping.
191 * On 32bit this only checks whether @addr + @len is <= TASK_SIZE.
193 * On 64bit with 5-level page tables another sanity check is required
194 * because mappings requested by mmap(@addr, 0) which cross the 47-bit
195 * virtual address boundary can cause the following theoretical issue:
197 * An application calls mmap(addr, 0), i.e. without MAP_FIXED, where @addr
198 * is below the border of the 47-bit address space and @addr + @len is
199 * above the border.
201 * With 4-level paging this request succeeds, but the resulting mapping
202 * address will always be within the 47-bit virtual address space, because
203 * the hint address does not result in a valid mapping and is
204 * ignored. Hence applications which are not prepared to handle virtual
205 * addresses above 47-bit work correctly.
207 * With 5-level paging this request would be granted and result in a
208 * mapping which crosses the border of the 47-bit virtual address
209 * space. If the application cannot handle addresses above 47-bit this
210 * will lead to misbehaviour and hard to diagnose failures.
212 * Therefore ignore address hints which would result in a mapping crossing
213 * the 47-bit virtual address boundary.
215 * Note, that in the same scenario with MAP_FIXED the behaviour is
216 * different. The request with @addr < 47-bit and @addr + @len > 47-bit
217 * fails on a 4-level paging machine but succeeds on a 5-level paging
218 * machine. It is reasonable to expect that an application does not rely on
219 * the failure of such a fixed mapping request, so the restriction is not
220 * applied.
222 bool mmap_address_hint_valid(unsigned long addr, unsigned long len)
224 if (TASK_SIZE - len < addr)
225 return false;
227 return (addr > DEFAULT_MAP_WINDOW) == (addr + len > DEFAULT_MAP_WINDOW);
230 /* Can we access it for direct reading/writing? Must be RAM: */
231 int valid_phys_addr_range(phys_addr_t addr, size_t count)
233 return addr + count <= __pa(high_memory);
236 /* Can we access it through mmap? Must be a valid physical address: */
237 int valid_mmap_phys_addr_range(unsigned long pfn, size_t count)
239 phys_addr_t addr = (phys_addr_t)pfn << PAGE_SHIFT;
241 return phys_addr_valid(addr + count - 1);
245 * Only allow root to set high MMIO mappings to PROT_NONE.
246 * This prevents an unpriv. user to set them to PROT_NONE and invert
247 * them, then pointing to valid memory for L1TF speculation.
249 * Note: for locked down kernels may want to disable the root override.
251 bool pfn_modify_allowed(unsigned long pfn, pgprot_t prot)
253 if (!boot_cpu_has_bug(X86_BUG_L1TF))
254 return true;
255 if (!__pte_needs_invert(pgprot_val(prot)))
256 return true;
257 /* If it's real memory always allow */
258 if (pfn_valid(pfn))
259 return true;
260 if (pfn >= l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN))
261 return false;
262 return true;