void __init efi_memmap_insert()

in efi/memmap.c [290:378]

• 67 lines of code
• 15 McCabe index (conditional complexity)

void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
			      struct efi_mem_range *mem)
{
	u64 m_start, m_end, m_attr;
	efi_memory_desc_t *md;
	u64 start, end;
	void *old, *new;

	/* modifying range */
	m_start = mem->range.start;
	m_end = mem->range.end;
	m_attr = mem->attribute;

	/*
	 * The EFI memory map deals with regions in EFI_PAGE_SIZE
	 * units. Ensure that the region described by 'mem' is aligned
	 * correctly.
	 */
	if (!IS_ALIGNED(m_start, EFI_PAGE_SIZE) ||
	    !IS_ALIGNED(m_end + 1, EFI_PAGE_SIZE)) {
		WARN_ON(1);
		return;
	}

	for (old = old_memmap->map, new = buf;
	     old < old_memmap->map_end;
	     old += old_memmap->desc_size, new += old_memmap->desc_size) {

		/* copy original EFI memory descriptor */
		memcpy(new, old, old_memmap->desc_size);
		md = new;
		start = md->phys_addr;
		end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;

		if (m_start <= start && end <= m_end)
			md->attribute |= m_attr;

		if (m_start <= start &&
		    (start < m_end && m_end < end)) {
			/* first part */
			md->attribute |= m_attr;
			md->num_pages = (m_end - md->phys_addr + 1) >>
				EFI_PAGE_SHIFT;
			/* latter part */
			new += old_memmap->desc_size;
			memcpy(new, old, old_memmap->desc_size);
			md = new;
			md->phys_addr = m_end + 1;
			md->num_pages = (end - md->phys_addr + 1) >>
				EFI_PAGE_SHIFT;
		}

		if ((start < m_start && m_start < end) && m_end < end) {
			/* first part */
			md->num_pages = (m_start - md->phys_addr) >>
				EFI_PAGE_SHIFT;
			/* middle part */
			new += old_memmap->desc_size;
			memcpy(new, old, old_memmap->desc_size);
			md = new;
			md->attribute |= m_attr;
			md->phys_addr = m_start;
			md->num_pages = (m_end - m_start + 1) >>
				EFI_PAGE_SHIFT;
			/* last part */
			new += old_memmap->desc_size;
			memcpy(new, old, old_memmap->desc_size);
			md = new;
			md->phys_addr = m_end + 1;
			md->num_pages = (end - m_end) >>
				EFI_PAGE_SHIFT;
		}

		if ((start < m_start && m_start < end) &&
		    (end <= m_end)) {
			/* first part */
			md->num_pages = (m_start - md->phys_addr) >>
				EFI_PAGE_SHIFT;
			/* latter part */
			new += old_memmap->desc_size;
			memcpy(new, old, old_memmap->desc_size);
			md = new;
			md->phys_addr = m_start;
			md->num_pages = (end - md->phys_addr + 1) >>
				EFI_PAGE_SHIFT;
			md->attribute |= m_attr;
		}
	}
}