2 * linux/arch/arm/mm/mmap.c
6 #include <linux/mman.h>
8 #include <linux/sched/signal.h>
9 #include <linux/sched/mm.h>
11 #include <linux/personality.h>
12 #include <linux/random.h>
13 #include <asm/cachetype.h>
15 #define COLOUR_ALIGN(addr,pgoff) \
16 ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
17 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
19 /* gap between mmap and stack */
20 #define MIN_GAP (128*1024*1024UL)
21 #define MAX_GAP ((TASK_SIZE)/6*5)
23 static int mmap_is_legacy(void)
25 if (current
->personality
& ADDR_COMPAT_LAYOUT
)
28 if (rlimit(RLIMIT_STACK
) == RLIM_INFINITY
)
31 return sysctl_legacy_va_layout
;
34 static unsigned long mmap_base(unsigned long rnd
)
36 unsigned long gap
= rlimit(RLIMIT_STACK
);
40 else if (gap
> MAX_GAP
)
43 return PAGE_ALIGN(TASK_SIZE
- gap
- rnd
);
47 * We need to ensure that shared mappings are correctly aligned to
48 * avoid aliasing issues with VIPT caches. We need to ensure that
49 * a specific page of an object is always mapped at a multiple of
52 * We unconditionally provide this function for all cases, however
53 * in the VIVT case, we optimise out the alignment rules.
56 arch_get_unmapped_area(struct file
*filp
, unsigned long addr
,
57 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
59 struct mm_struct
*mm
= current
->mm
;
60 struct vm_area_struct
*vma
;
62 int aliasing
= cache_is_vipt_aliasing();
63 struct vm_unmapped_area_info info
;
66 * We only need to do colour alignment if either the I or D
70 do_align
= filp
|| (flags
& MAP_SHARED
);
73 * We enforce the MAP_FIXED case.
75 if (flags
& MAP_FIXED
) {
76 if (aliasing
&& flags
& MAP_SHARED
&&
77 (addr
- (pgoff
<< PAGE_SHIFT
)) & (SHMLBA
- 1))
87 addr
= COLOUR_ALIGN(addr
, pgoff
);
89 addr
= PAGE_ALIGN(addr
);
91 vma
= find_vma(mm
, addr
);
92 if (TASK_SIZE
- len
>= addr
&&
93 (!vma
|| addr
+ len
<= vma
->vm_start
))
99 info
.low_limit
= mm
->mmap_base
;
100 info
.high_limit
= TASK_SIZE
;
101 info
.align_mask
= do_align
? (PAGE_MASK
& (SHMLBA
- 1)) : 0;
102 info
.align_offset
= pgoff
<< PAGE_SHIFT
;
103 return vm_unmapped_area(&info
);
107 arch_get_unmapped_area_topdown(struct file
*filp
, const unsigned long addr0
,
108 const unsigned long len
, const unsigned long pgoff
,
109 const unsigned long flags
)
111 struct vm_area_struct
*vma
;
112 struct mm_struct
*mm
= current
->mm
;
113 unsigned long addr
= addr0
;
115 int aliasing
= cache_is_vipt_aliasing();
116 struct vm_unmapped_area_info info
;
119 * We only need to do colour alignment if either the I or D
123 do_align
= filp
|| (flags
& MAP_SHARED
);
125 /* requested length too big for entire address space */
129 if (flags
& MAP_FIXED
) {
130 if (aliasing
&& flags
& MAP_SHARED
&&
131 (addr
- (pgoff
<< PAGE_SHIFT
)) & (SHMLBA
- 1))
136 /* requesting a specific address */
139 addr
= COLOUR_ALIGN(addr
, pgoff
);
141 addr
= PAGE_ALIGN(addr
);
142 vma
= find_vma(mm
, addr
);
143 if (TASK_SIZE
- len
>= addr
&&
144 (!vma
|| addr
+ len
<= vma
->vm_start
))
148 info
.flags
= VM_UNMAPPED_AREA_TOPDOWN
;
150 info
.low_limit
= FIRST_USER_ADDRESS
;
151 info
.high_limit
= mm
->mmap_base
;
152 info
.align_mask
= do_align
? (PAGE_MASK
& (SHMLBA
- 1)) : 0;
153 info
.align_offset
= pgoff
<< PAGE_SHIFT
;
154 addr
= vm_unmapped_area(&info
);
157 * A failed mmap() very likely causes application failure,
158 * so fall back to the bottom-up function here. This scenario
159 * can happen with large stack limits and large mmap()
162 if (addr
& ~PAGE_MASK
) {
163 VM_BUG_ON(addr
!= -ENOMEM
);
165 info
.low_limit
= mm
->mmap_base
;
166 info
.high_limit
= TASK_SIZE
;
167 addr
= vm_unmapped_area(&info
);
173 unsigned long arch_mmap_rnd(void)
177 rnd
= get_random_long() & ((1UL << mmap_rnd_bits
) - 1);
179 return rnd
<< PAGE_SHIFT
;
182 void arch_pick_mmap_layout(struct mm_struct
*mm
)
184 unsigned long random_factor
= 0UL;
186 if (current
->flags
& PF_RANDOMIZE
)
187 random_factor
= arch_mmap_rnd();
189 if (mmap_is_legacy()) {
190 mm
->mmap_base
= TASK_UNMAPPED_BASE
+ random_factor
;
191 mm
->get_unmapped_area
= arch_get_unmapped_area
;
193 mm
->mmap_base
= mmap_base(random_factor
);
194 mm
->get_unmapped_area
= arch_get_unmapped_area_topdown
;
199 * You really shouldn't be using read() or write() on /dev/mem. This
200 * might go away in the future.
202 int valid_phys_addr_range(phys_addr_t addr
, size_t size
)
204 if (addr
< PHYS_OFFSET
)
206 if (addr
+ size
> __pa(high_memory
- 1) + 1)
213 * Do not allow /dev/mem mappings beyond the supported physical range.
215 int valid_mmap_phys_addr_range(unsigned long pfn
, size_t size
)
217 return (pfn
+ (size
>> PAGE_SHIFT
)) <= (1 + (PHYS_MASK
>> PAGE_SHIFT
));
220 #ifdef CONFIG_STRICT_DEVMEM
222 #include <linux/ioport.h>
225 * devmem_is_allowed() checks to see if /dev/mem access to a certain
226 * address is valid. The argument is a physical page number.
227 * We mimic x86 here by disallowing access to system RAM as well as
228 * device-exclusive MMIO regions. This effectively disable read()/write()
231 int devmem_is_allowed(unsigned long pfn
)
233 if (iomem_is_exclusive(pfn
<< PAGE_SHIFT
))
235 if (!page_is_ram(pfn
))