static int check_tlb_entry()

in mm/tlb.c [222:262]

• 39 lines of code
• 14 McCabe index (conditional complexity)

static int check_tlb_entry(unsigned w, unsigned e, bool dtlb)
{
	unsigned tlbidx = w | (e << PAGE_SHIFT);
	unsigned r0 = dtlb ?
		read_dtlb_virtual(tlbidx) : read_itlb_virtual(tlbidx);
	unsigned r1 = dtlb ?
		read_dtlb_translation(tlbidx) : read_itlb_translation(tlbidx);
	unsigned vpn = (r0 & PAGE_MASK) | (e << PAGE_SHIFT);
	unsigned pte = get_pte_for_vaddr(vpn);
	unsigned mm_asid = (get_rasid_register() >> 8) & ASID_MASK;
	unsigned tlb_asid = r0 & ASID_MASK;
	bool kernel = tlb_asid == 1;
	int rc = 0;

	if (tlb_asid > 0 && ((vpn < TASK_SIZE) == kernel)) {
		pr_err("%cTLB: way: %u, entry: %u, VPN %08x in %s PTE\n",
				dtlb ? 'D' : 'I', w, e, vpn,
				kernel ? "kernel" : "user");
		rc |= TLB_INSANE;
	}

	if (tlb_asid == mm_asid) {
		if ((pte ^ r1) & PAGE_MASK) {
			pr_err("%cTLB: way: %u, entry: %u, mapping: %08x->%08x, PTE: %08x\n",
					dtlb ? 'D' : 'I', w, e, r0, r1, pte);
			if (pte == 0 || !pte_present(__pte(pte))) {
				struct page *p = pfn_to_page(r1 >> PAGE_SHIFT);
				pr_err("page refcount: %d, mapcount: %d\n",
						page_count(p),
						page_mapcount(p));
				if (!page_count(p))
					rc |= TLB_INSANE;
				else if (page_mapcount(p))
					rc |= TLB_SUSPICIOUS;
			} else {
				rc |= TLB_INSANE;
			}
		}
	}
	return rc;
}