-/*
- * Check whether a kernel address is valid (derived from arch/x86/).
- */
-int kern_addr_valid(unsigned long addr)
-{
- pgd_t *pgdp;
- p4d_t *p4dp;
- pud_t *pudp, pud;
- pmd_t *pmdp, pmd;
- pte_t *ptep, pte;
-
- addr = arch_kasan_reset_tag(addr);
- if ((((long)addr) >> VA_BITS) != -1UL)
- return 0;
-
- pgdp = pgd_offset_k(addr);
- if (pgd_none(READ_ONCE(*pgdp)))
- return 0;
-
- p4dp = p4d_offset(pgdp, addr);
- if (p4d_none(READ_ONCE(*p4dp)))
- return 0;
-
- pudp = pud_offset(p4dp, addr);
- pud = READ_ONCE(*pudp);
- if (pud_none(pud))
- return 0;
-
- if (pud_sect(pud))
- return pfn_valid(pud_pfn(pud));
-
- pmdp = pmd_offset(pudp, addr);
- pmd = READ_ONCE(*pmdp);
- if (pmd_none(pmd))
- return 0;
-
- if (pmd_sect(pmd))
- return pfn_valid(pmd_pfn(pmd));
-
- ptep = pte_offset_kernel(pmdp, addr);
- pte = READ_ONCE(*ptep);
- if (pte_none(pte))
- return 0;
-
- return pfn_valid(pte_pfn(pte));
-}
-