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- /*
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 2011 Wind River Systems,
- * written by Ralf Baechle <ralf@linux-mips.org>
- */
- #include <linux/compiler.h>
- #include <linux/errno.h>
- #include <linux/mm.h>
- #include <linux/mman.h>
- #include <linux/module.h>
- #include <linux/personality.h>
- #include <linux/random.h>
- #include <linux/sched.h>
- unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
- EXPORT_SYMBOL(shm_align_mask);
- /* gap between mmap and stack */
- #define MIN_GAP (128*1024*1024UL)
- #define MAX_GAP ((TASK_SIZE)/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_base(unsigned long rnd)
- {
- unsigned long gap = rlimit(RLIMIT_STACK);
- if (gap < MIN_GAP)
- gap = MIN_GAP;
- else if (gap > MAX_GAP)
- gap = MAX_GAP;
- return PAGE_ALIGN(TASK_SIZE - gap - rnd);
- }
- #define COLOUR_ALIGN(addr, pgoff) \
- ((((addr) + shm_align_mask) & ~shm_align_mask) + \
- (((pgoff) << PAGE_SHIFT) & shm_align_mask))
- enum mmap_allocation_direction {UP, DOWN};
- static unsigned long arch_get_unmapped_area_common(struct file *filp,
- unsigned long addr0, unsigned long len, unsigned long pgoff,
- unsigned long flags, enum mmap_allocation_direction dir)
- {
- struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
- unsigned long addr = addr0;
- int do_color_align;
- struct vm_unmapped_area_info info;
- if (unlikely(len > TASK_SIZE))
- return -ENOMEM;
- if (flags & MAP_FIXED) {
- /* Even MAP_FIXED mappings must reside within TASK_SIZE */
- if (TASK_SIZE - len < addr)
- return -EINVAL;
- /*
- * We do not accept a shared mapping if it would violate
- * cache aliasing constraints.
- */
- if ((flags & MAP_SHARED) &&
- ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
- return -EINVAL;
- return addr;
- }
- do_color_align = 0;
- if (filp || (flags & MAP_SHARED))
- do_color_align = 1;
- /* requesting a specific address */
- if (addr) {
- if (do_color_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.length = len;
- info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
- info.align_offset = pgoff << PAGE_SHIFT;
- if (dir == DOWN) {
- info.flags = VM_UNMAPPED_AREA_TOPDOWN;
- info.low_limit = PAGE_SIZE;
- info.high_limit = mm->mmap_base;
- addr = vm_unmapped_area(&info);
- if (!(addr & ~PAGE_MASK))
- return addr;
- /*
- * 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.
- */
- }
- info.flags = 0;
- info.low_limit = mm->mmap_base;
- info.high_limit = TASK_SIZE;
- return vm_unmapped_area(&info);
- }
- unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
- unsigned long len, unsigned long pgoff, unsigned long flags)
- {
- return arch_get_unmapped_area_common(filp,
- addr0, len, pgoff, flags, UP);
- }
- /*
- * There is no need to export this but sched.h declares the function as
- * extern so making it static here results in an error.
- */
- unsigned long arch_get_unmapped_area_topdown(struct file *filp,
- unsigned long addr0, unsigned long len, unsigned long pgoff,
- unsigned long flags)
- {
- return arch_get_unmapped_area_common(filp,
- addr0, len, pgoff, flags, DOWN);
- }
- unsigned long arch_mmap_rnd(void)
- {
- unsigned long rnd;
- rnd = (unsigned long)get_random_int();
- rnd <<= PAGE_SHIFT;
- if (TASK_IS_32BIT_ADDR)
- rnd &= 0xfffffful;
- else
- rnd &= 0xffffffful;
- return rnd;
- }
- void arch_pick_mmap_layout(struct mm_struct *mm)
- {
- unsigned long random_factor = 0UL;
- if (current->flags & PF_RANDOMIZE)
- random_factor = arch_mmap_rnd();
- if (mmap_is_legacy()) {
- mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
- mm->get_unmapped_area = arch_get_unmapped_area;
- } else {
- mm->mmap_base = mmap_base(random_factor);
- mm->get_unmapped_area = arch_get_unmapped_area_topdown;
- }
- }
- static inline unsigned long brk_rnd(void)
- {
- unsigned long rnd = get_random_int();
- rnd = rnd << PAGE_SHIFT;
- /* 8MB for 32bit, 256MB for 64bit */
- if (TASK_IS_32BIT_ADDR)
- rnd = rnd & 0x7ffffful;
- else
- rnd = rnd & 0xffffffful;
- return rnd;
- }
- unsigned long arch_randomize_brk(struct mm_struct *mm)
- {
- unsigned long base = mm->brk;
- unsigned long ret;
- ret = PAGE_ALIGN(base + brk_rnd());
- if (ret < mm->brk)
- return mm->brk;
- return ret;
- }
- int __virt_addr_valid(const volatile void *kaddr)
- {
- return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
- }
- EXPORT_SYMBOL_GPL(__virt_addr_valid);
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