linux-2.6.33/get_unmapped_area() の履歴(No.1)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• linux-2.6.33/get_unmapped_area() へ行く。
  • 1 (2010-10-15 (金) 11:04:53)

参照元†

• linux-2.6.33/HAVE_ARCH_UNMAPPED_AREA
• linux-2.6.33/do_mmap_pgoff()

説明†

• パス: linux-2.6.33/mm/mmap.c

• FIXME: これは何？
  • 説明

引数†

• struct file *filp
  • linux-2.6.33/file
• unsigned long addr
• unsigned long len
• unsigned long pgoff
• unsigned long flags

返り値†

参考†

実装†

/* Get an address range which is currently unmapped.
 * For shmat() with addr=0.
 *
 * Ugly calling convention alert:
 * Return value with the low bits set means error value,
 * ie
 *	if (ret & ~PAGE_MASK)
 *		error = ret;
 *
 * This function "knows" that -ENOMEM has the bits set.
 */
#ifndef HAVE_ARCH_UNMAPPED_AREA

• • linux-2.6.33/HAVE_ARCH_UNMAPPED_AREA

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;
	unsigned long start_addr;

• • linux-2.6.33/mm_struct
  • linux-2.6.33/vm_area_struct

	if (len > TASK_SIZE)
		return -ENOMEM;

• • linux-2.6.33/TASK_SIZE

	if (flags & MAP_FIXED)
		return addr;

• • linux-2.6.33/MAP_FIXED

	if (addr) {
		addr = PAGE_ALIGN(addr);

• • linux-2.6.33/PAGE_ALIGN()

		vma = find_vma(mm, addr);

• • linux-2.6.33/find_vma()

		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}
	if (len > mm->cached_hole_size) {
	        start_addr = addr = mm->free_area_cache;
	} else {
	        start_addr = addr = TASK_UNMAPPED_BASE;
	        mm->cached_hole_size = 0;

• • linux-2.6.33/TASK_UNMAPPED_BASE

	}

full_search:
	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {

• • linux-2.6.33/find_vma()

		/* At this point:  (!vma || addr < vma->vm_end). */
		if (TASK_SIZE - len < addr) {
			/*
			 * Start a new search - just in case we missed
			 * some holes.
			 */
			if (start_addr != TASK_UNMAPPED_BASE) {
				addr = TASK_UNMAPPED_BASE;
			        start_addr = addr;
				mm->cached_hole_size = 0;
				goto full_search;
			}
			return -ENOMEM;
		}
		if (!vma || addr + len <= vma->vm_start) {
			/*
			 * Remember the place where we stopped the search:
			 */
			mm->free_area_cache = addr + len;
			return addr;
		}
		if (addr + mm->cached_hole_size < vma->vm_start)
		        mm->cached_hole_size = vma->vm_start - addr;
		addr = vma->vm_end;
	}
}
#endif	

コメント†