252 lines
6 KiB
C
252 lines
6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* linux/arch/arm/mm/mmap.c
|
|
*/
|
|
#include <linux/fs.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/shm.h>
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/sched/mm.h>
|
|
#include <linux/io.h>
|
|
#include <linux/personality.h>
|
|
#include <linux/random.h>
|
|
#include <asm/cachetype.h>
|
|
|
|
#define COLOUR_ALIGN(addr,pgoff) \
|
|
((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
|
|
(((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
|
|
|
|
/* gap between mmap and stack */
|
|
#define MIN_GAP (128*1024*1024UL)
|
|
#define MAX_GAP ((STACK_TOP)/6*5)
|
|
#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
|
|
|
|
static int mmap_is_legacy(struct rlimit *rlim_stack)
|
|
{
|
|
if (current->personality & ADDR_COMPAT_LAYOUT)
|
|
return 1;
|
|
|
|
if (rlim_stack->rlim_cur == RLIM_INFINITY)
|
|
return 1;
|
|
|
|
return sysctl_legacy_va_layout;
|
|
}
|
|
|
|
static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
|
|
{
|
|
unsigned long gap = rlim_stack->rlim_cur;
|
|
unsigned long pad = stack_guard_gap;
|
|
|
|
/* Account for stack randomization if necessary */
|
|
if (current->flags & PF_RANDOMIZE)
|
|
pad += (STACK_RND_MASK << PAGE_SHIFT);
|
|
|
|
/* Values close to RLIM_INFINITY can overflow. */
|
|
if (gap + pad > gap)
|
|
gap += pad;
|
|
|
|
if (gap < MIN_GAP)
|
|
gap = MIN_GAP;
|
|
else if (gap > MAX_GAP)
|
|
gap = MAX_GAP;
|
|
|
|
return PAGE_ALIGN(STACK_TOP - gap - rnd);
|
|
}
|
|
|
|
/*
|
|
* We need to ensure that shared mappings are correctly aligned to
|
|
* avoid aliasing issues with VIPT caches. We need to ensure that
|
|
* a specific page of an object is always mapped at a multiple of
|
|
* SHMLBA bytes.
|
|
*
|
|
* We unconditionally provide this function for all cases, however
|
|
* in the VIVT case, we optimise out the alignment rules.
|
|
*/
|
|
unsigned long
|
|
arch_get_unmapped_area(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
int do_align = 0;
|
|
int aliasing = cache_is_vipt_aliasing();
|
|
struct vm_unmapped_area_info info;
|
|
|
|
/*
|
|
* We only need to do colour alignment if either the I or D
|
|
* caches alias.
|
|
*/
|
|
if (aliasing)
|
|
do_align = filp || (flags & MAP_SHARED);
|
|
|
|
/*
|
|
* We enforce the MAP_FIXED case.
|
|
*/
|
|
if (flags & MAP_FIXED) {
|
|
if (aliasing && flags & MAP_SHARED &&
|
|
(addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
|
|
return -EINVAL;
|
|
return addr;
|
|
}
|
|
|
|
if (len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
if (addr) {
|
|
if (do_align)
|
|
addr = COLOUR_ALIGN(addr, pgoff);
|
|
else
|
|
addr = PAGE_ALIGN(addr);
|
|
|
|
vma = find_vma(mm, addr);
|
|
if (TASK_SIZE - len >= addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = 0;
|
|
info.length = len;
|
|
info.low_limit = mm->mmap_base;
|
|
info.high_limit = TASK_SIZE;
|
|
info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
|
|
info.align_offset = pgoff << PAGE_SHIFT;
|
|
return vm_unmapped_area(&info);
|
|
}
|
|
|
|
unsigned long
|
|
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
|
|
const unsigned long len, const unsigned long pgoff,
|
|
const unsigned long flags)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long addr = addr0;
|
|
int do_align = 0;
|
|
int aliasing = cache_is_vipt_aliasing();
|
|
struct vm_unmapped_area_info info;
|
|
|
|
/*
|
|
* We only need to do colour alignment if either the I or D
|
|
* caches alias.
|
|
*/
|
|
if (aliasing)
|
|
do_align = filp || (flags & MAP_SHARED);
|
|
|
|
/* requested length too big for entire address space */
|
|
if (len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED) {
|
|
if (aliasing && flags & MAP_SHARED &&
|
|
(addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
|
|
return -EINVAL;
|
|
return addr;
|
|
}
|
|
|
|
/* requesting a specific address */
|
|
if (addr) {
|
|
if (do_align)
|
|
addr = COLOUR_ALIGN(addr, pgoff);
|
|
else
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma(mm, addr);
|
|
if (TASK_SIZE - len >= addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
|
|
info.length = len;
|
|
info.low_limit = FIRST_USER_ADDRESS;
|
|
info.high_limit = mm->mmap_base;
|
|
info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
|
|
info.align_offset = pgoff << PAGE_SHIFT;
|
|
addr = vm_unmapped_area(&info);
|
|
|
|
/*
|
|
* A failed mmap() very likely causes application failure,
|
|
* so fall back to the bottom-up function here. This scenario
|
|
* can happen with large stack limits and large mmap()
|
|
* allocations.
|
|
*/
|
|
if (addr & ~PAGE_MASK) {
|
|
VM_BUG_ON(addr != -ENOMEM);
|
|
info.flags = 0;
|
|
info.low_limit = mm->mmap_base;
|
|
info.high_limit = TASK_SIZE;
|
|
addr = vm_unmapped_area(&info);
|
|
}
|
|
|
|
return addr;
|
|
}
|
|
|
|
unsigned long arch_mmap_rnd(void)
|
|
{
|
|
unsigned long rnd;
|
|
|
|
rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
|
|
|
|
return rnd << PAGE_SHIFT;
|
|
}
|
|
|
|
void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
|
|
{
|
|
unsigned long random_factor = 0UL;
|
|
|
|
if (current->flags & PF_RANDOMIZE)
|
|
random_factor = arch_mmap_rnd();
|
|
|
|
if (mmap_is_legacy(rlim_stack)) {
|
|
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
|
|
mm->get_unmapped_area = arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(random_factor, rlim_stack);
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* You really shouldn't be using read() or write() on /dev/mem. This
|
|
* might go away in the future.
|
|
*/
|
|
int valid_phys_addr_range(phys_addr_t addr, size_t size)
|
|
{
|
|
if (addr < PHYS_OFFSET)
|
|
return 0;
|
|
if (addr + size > __pa(high_memory - 1) + 1)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Do not allow /dev/mem mappings beyond the supported physical range.
|
|
*/
|
|
int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
|
|
{
|
|
return (pfn + (size >> PAGE_SHIFT)) <= (1 + (PHYS_MASK >> PAGE_SHIFT));
|
|
}
|
|
|
|
#ifdef CONFIG_STRICT_DEVMEM
|
|
|
|
#include <linux/ioport.h>
|
|
|
|
/*
|
|
* devmem_is_allowed() checks to see if /dev/mem access to a certain
|
|
* address is valid. The argument is a physical page number.
|
|
* We mimic x86 here by disallowing access to system RAM as well as
|
|
* device-exclusive MMIO regions. This effectively disable read()/write()
|
|
* on /dev/mem.
|
|
*/
|
|
int devmem_is_allowed(unsigned long pfn)
|
|
{
|
|
if (iomem_is_exclusive(pfn << PAGE_SHIFT))
|
|
return 0;
|
|
if (!page_is_ram(pfn))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
#endif
|