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kernel/linux-imx6_3.14.28/arch/arc/mm/mmap.c 1.89 KB
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  /*
   * ARC700 mmap
   *
   * (started from arm version - for VIPT alias handling)
   *
   * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
   *
   * 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.
   */
  
  #include <linux/fs.h>
  #include <linux/mm.h>
  #include <linux/mman.h>
  #include <linux/sched.h>
  #include <asm/cacheflush.h>
  
  #define COLOUR_ALIGN(addr, pgoff)			\
  	((((addr) + SHMLBA - 1) & ~(SHMLBA - 1)) +	\
  	 (((pgoff) << PAGE_SHIFT) & (SHMLBA - 1)))
  
  /*
   * 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.
   */
  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 D cache aliases.
  	 */
  	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 <= vma->vm_start))
  			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);
  }