| /* |
| * Based on arch/arm/mm/mmap.c |
| * |
| * Copyright (C) 2012 ARM Ltd. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * 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. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include <linux/elf.h> |
| #include <linux/fs.h> |
| #include <linux/mm.h> |
| #include <linux/mman.h> |
| #include <linux/export.h> |
| #include <linux/shm.h> |
| #include <linux/sched.h> |
| #include <linux/io.h> |
| #include <linux/personality.h> |
| #include <linux/random.h> |
| |
| #include <asm/cputype.h> |
| |
| /* |
| * Leave enough space between the mmap area and the stack to honour ulimit in |
| * the face of randomisation. |
| */ |
| #define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1)) |
| #define MAX_GAP (STACK_TOP/6*5) |
| |
| static int mmap_is_legacy(void) |
| { |
| if (current->personality & ADDR_COMPAT_LAYOUT) |
| return 1; |
| |
| if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) |
| return 1; |
| |
| return sysctl_legacy_va_layout; |
| } |
| |
| static unsigned long mmap_rnd(void) |
| { |
| unsigned long rnd = 0; |
| |
| if (current->flags & PF_RANDOMIZE) |
| rnd = (long)get_random_int() & STACK_RND_MASK; |
| |
| return rnd << PAGE_SHIFT; |
| } |
| |
| static unsigned long mmap_base(void) |
| { |
| unsigned long gap = rlimit(RLIMIT_STACK); |
| |
| if (gap < MIN_GAP) |
| gap = MIN_GAP; |
| else if (gap > MAX_GAP) |
| gap = MAX_GAP; |
| |
| return PAGE_ALIGN(STACK_TOP - gap - mmap_rnd()); |
| } |
| |
| /* |
| * 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) |
| { |
| /* |
| * Fall back to the standard layout if the personality bit is set, or |
| * if the expected stack growth is unlimited: |
| */ |
| if (mmap_is_legacy()) { |
| mm->mmap_base = TASK_UNMAPPED_BASE; |
| mm->get_unmapped_area = arch_get_unmapped_area; |
| } else { |
| mm->mmap_base = mmap_base(); |
| mm->get_unmapped_area = arch_get_unmapped_area_topdown; |
| } |
| } |
| EXPORT_SYMBOL_GPL(arch_pick_mmap_layout); |
| |
| |
| /* |
| * You really shouldn't be using read() or write() on /dev/mem. This might go |
| * away in the future. |
| */ |
| int valid_phys_addr_range(unsigned long 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 << PAGE_SHIFT) + size) & ~PHYS_MASK); |
| } |
| |
| #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 |