void flush_tlb_page()

in kernel/tlb.c [455:528]

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

void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
{
	pgd_t *pgd;
	p4d_t *p4d;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	struct mm_struct *mm = vma->vm_mm;
	void *flush = NULL;
	int r, w, x, prot, err = 0;
	struct mm_id *mm_id;

	address &= PAGE_MASK;

	pgd = pgd_offset(mm, address);
	if (!pgd_present(*pgd))
		goto kill;

	p4d = p4d_offset(pgd, address);
	if (!p4d_present(*p4d))
		goto kill;

	pud = pud_offset(p4d, address);
	if (!pud_present(*pud))
		goto kill;

	pmd = pmd_offset(pud, address);
	if (!pmd_present(*pmd))
		goto kill;

	pte = pte_offset_kernel(pmd, address);

	r = pte_read(*pte);
	w = pte_write(*pte);
	x = pte_exec(*pte);
	if (!pte_young(*pte)) {
		r = 0;
		w = 0;
	} else if (!pte_dirty(*pte)) {
		w = 0;
	}

	mm_id = &mm->context.id;
	prot = ((r ? UM_PROT_READ : 0) | (w ? UM_PROT_WRITE : 0) |
		(x ? UM_PROT_EXEC : 0));
	if (pte_newpage(*pte)) {
		if (pte_present(*pte)) {
			unsigned long long offset;
			int fd;

			fd = phys_mapping(pte_val(*pte) & PAGE_MASK, &offset);
			err = map(mm_id, address, PAGE_SIZE, prot, fd, offset,
				  1, &flush);
		}
		else err = unmap(mm_id, address, PAGE_SIZE, 1, &flush);
	}
	else if (pte_newprot(*pte))
		err = protect(mm_id, address, PAGE_SIZE, prot, 1, &flush);

	if (err) {
		if (err == -ENOMEM)
			report_enomem();

		goto kill;
	}

	*pte = pte_mkuptodate(*pte);

	return;

kill:
	printk(KERN_ERR "Failed to flush page for address 0x%lx\n", address);
	force_sig(SIGKILL);
}