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kernel/linux-imx6_3.14.28/arch/sh/mm/mmap.c 3.9 KB
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  /*
   * arch/sh/mm/mmap.c
   *
   * Copyright (C) 2008 - 2009  Paul Mundt
   *
   * 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.
   */
  #include <linux/io.h>
  #include <linux/mm.h>
  #include <linux/mman.h>
  #include <linux/module.h>
  #include <asm/page.h>
  #include <asm/processor.h>
  
  unsigned long shm_align_mask = PAGE_SIZE - 1;	/* Sane caches */
  EXPORT_SYMBOL(shm_align_mask);
  
  #ifdef CONFIG_MMU
  /*
   * To avoid cache aliases, we map the shared page with same color.
   */
  static inline unsigned long COLOUR_ALIGN(unsigned long addr,
  					 unsigned long pgoff)
  {
  	unsigned long base = (addr + shm_align_mask) & ~shm_align_mask;
  	unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;
  
  	return base + off;
  }
  
  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_colour_align;
  	struct vm_unmapped_area_info info;
  
  	if (flags & MAP_FIXED) {
  		/* 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;
  	}
  
  	if (unlikely(len > TASK_SIZE))
  		return -ENOMEM;
  
  	do_colour_align = 0;
  	if (filp || (flags & MAP_SHARED))
  		do_colour_align = 1;
  
  	if (addr) {
  		if (do_colour_align)
  			addr = COLOUR_ALIGN(addr, pgoff);
  		else
  			addr = PAGE_ALIGN(addr);
  
  		vma = find_vma(mm, addr);
  		if (TASK_SIZE - len >= addr &&
  		    (!vma || addr + len <= vma->vm_start))
  			return addr;
  	}
  
  	info.flags = 0;
  	info.length = len;
  	info.low_limit = TASK_UNMAPPED_BASE;
  	info.high_limit = TASK_SIZE;
  	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 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_colour_align;
  	struct vm_unmapped_area_info info;
  
  	if (flags & MAP_FIXED) {
  		/* 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;
  	}
  
  	if (unlikely(len > TASK_SIZE))
  		return -ENOMEM;
  
  	do_colour_align = 0;
  	if (filp || (flags & MAP_SHARED))
  		do_colour_align = 1;
  
  	/* requesting a specific address */
  	if (addr) {
  		if (do_colour_align)
  			addr = COLOUR_ALIGN(addr, pgoff);
  		else
  			addr = PAGE_ALIGN(addr);
  
  		vma = find_vma(mm, addr);
  		if (TASK_SIZE - len >= addr &&
  		    (!vma || addr + len <= vma->vm_start))
  			return addr;
  	}
  
  	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
  	info.length = len;
  	info.low_limit = PAGE_SIZE;
  	info.high_limit = mm->mmap_base;
  	info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 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 = TASK_UNMAPPED_BASE;
  		info.high_limit = TASK_SIZE;
  		addr = vm_unmapped_area(&info);
  	}
  
  	return addr;
  }
  #endif /* CONFIG_MMU */
  
  /*
   * 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 count)
  {
  	if (addr < __MEMORY_START)
  		return 0;
  	if (addr + count > __pa(high_memory))
  		return 0;
  
  	return 1;
  }
  
  int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
  {
  	return 1;
  }