int arch_setup_additional_pages()

in kernel/vdso.c [114:195]

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

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
	struct mm_struct *mm = current->mm;
	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
	struct vm_area_struct *vma;
	unsigned long addr = 0;
	pgprot_t prot;
	int ret, vvar_page_num = 2;

	vdso_text_len = vdso_pages << PAGE_SHIFT;

	if(timer_mapping_base == EMPTY_VALUE)
		vvar_page_num = 1;
	/* Be sure to map the data page */
	vdso_mapping_len = vdso_text_len + vvar_page_num * PAGE_SIZE;
#ifdef CONFIG_CPU_CACHE_ALIASING
	vdso_mapping_len += L1_cache_info[DCACHE].aliasing_num - 1;
#endif

	if (mmap_write_lock_killable(mm))
		return -EINTR;

	addr = vdso_random_addr(vdso_mapping_len);
	vdso_base = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
	if (IS_ERR_VALUE(vdso_base)) {
		ret = vdso_base;
		goto up_fail;
	}

#ifdef CONFIG_CPU_CACHE_ALIASING
	{
		unsigned int aliasing_mask =
		    L1_cache_info[DCACHE].aliasing_mask;
		unsigned int page_colour_ofs;
		page_colour_ofs = ((unsigned int)vdso_data & aliasing_mask) -
		    (vdso_base & aliasing_mask);
		vdso_base += page_colour_ofs & aliasing_mask;
	}
#endif

	vma = _install_special_mapping(mm, vdso_base, vvar_page_num * PAGE_SIZE,
				       VM_READ | VM_MAYREAD, &vdso_spec[0]);
	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto up_fail;
	}

	/*Map vdata to user space */
	ret = io_remap_pfn_range(vma, vdso_base,
				 virt_to_phys(vdso_data) >> PAGE_SHIFT,
				 PAGE_SIZE, vma->vm_page_prot);
	if (ret)
		goto up_fail;

	/*Map timer to user space */
	vdso_base += PAGE_SIZE;
	prot = __pgprot(_PAGE_V | _PAGE_M_UR_KR | _PAGE_D |  _PAGE_C_DEV);
	ret = io_remap_pfn_range(vma, vdso_base, timer_mapping_base >> PAGE_SHIFT,
				 PAGE_SIZE, prot);
	if (ret)
		goto up_fail;

	/*Map vdso to user space */
	vdso_base += PAGE_SIZE;
	mm->context.vdso = (void *)vdso_base;
	vma = _install_special_mapping(mm, vdso_base, vdso_text_len,
				       VM_READ | VM_EXEC |
				       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
				       &vdso_spec[1]);
	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto up_fail;
	}

	mmap_write_unlock(mm);
	return 0;

up_fail:
	mm->context.vdso = NULL;
	mmap_write_unlock(mm);
	return ret;
}