diff options
Diffstat (limited to 'arch/powerpc/mm/pgtable.c')
| -rw-r--r-- | arch/powerpc/mm/pgtable.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index d3d61d29b4f1..db4a6253df92 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -30,6 +30,7 @@ #include <asm/pgalloc.h> #include <asm/tlbflush.h> #include <asm/tlb.h> +#include <asm/hugetlb.h> static inline int is_exec_fault(void) { @@ -299,3 +300,116 @@ unsigned long vmalloc_to_phys(void *va) return __pa(pfn_to_kaddr(pfn)) + offset_in_page(va); } EXPORT_SYMBOL_GPL(vmalloc_to_phys); + +/* + * We have 4 cases for pgds and pmds: + * (1) invalid (all zeroes) + * (2) pointer to next table, as normal; bottom 6 bits == 0 + * (3) leaf pte for huge page _PAGE_PTE set + * (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] indicate size of table + * + * So long as we atomically load page table pointers we are safe against teardown, + * we can follow the address down to the the page and take a ref on it. + * This function need to be called with interrupts disabled. We use this variant + * when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED + */ +pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, + bool *is_thp, unsigned *hpage_shift) +{ + pgd_t pgd, *pgdp; + pud_t pud, *pudp; + pmd_t pmd, *pmdp; + pte_t *ret_pte; + hugepd_t *hpdp = NULL; + unsigned pdshift = PGDIR_SHIFT; + + if (hpage_shift) + *hpage_shift = 0; + + if (is_thp) + *is_thp = false; + + pgdp = pgdir + pgd_index(ea); + pgd = READ_ONCE(*pgdp); + /* + * Always operate on the local stack value. This make sure the + * value don't get updated by a parallel THP split/collapse, + * page fault or a page unmap. The return pte_t * is still not + * stable. So should be checked there for above conditions. + */ + if (pgd_none(pgd)) + return NULL; + + if (pgd_huge(pgd)) { + ret_pte = (pte_t *)pgdp; + goto out; + } + if (is_hugepd(__hugepd(pgd_val(pgd)))) { + hpdp = (hugepd_t *)&pgd; + goto out_huge; + } + + /* + * Even if we end up with an unmap, the pgtable will not + * be freed, because we do an rcu free and here we are + * irq disabled + */ + pdshift = PUD_SHIFT; + pudp = pud_offset(&pgd, ea); + pud = READ_ONCE(*pudp); + + if (pud_none(pud)) + return NULL; + + if (pud_huge(pud)) { + ret_pte = (pte_t *)pudp; + goto out; + } + if (is_hugepd(__hugepd(pud_val(pud)))) { + hpdp = (hugepd_t *)&pud; + goto out_huge; + } + pdshift = PMD_SHIFT; + pmdp = pmd_offset(&pud, ea); + pmd = READ_ONCE(*pmdp); + /* + * A hugepage collapse is captured by pmd_none, because + * it mark the pmd none and do a hpte invalidate. + */ + if (pmd_none(pmd)) + return NULL; + + if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) { + if (is_thp) + *is_thp = true; + ret_pte = (pte_t *)pmdp; + goto out; + } + /* + * pmd_large check below will handle the swap pmd pte + * we need to do both the check because they are config + * dependent. + */ + if (pmd_huge(pmd) || pmd_large(pmd)) { + ret_pte = (pte_t *)pmdp; + goto out; + } + if (is_hugepd(__hugepd(pmd_val(pmd)))) { + hpdp = (hugepd_t *)&pmd; + goto out_huge; + } + + return pte_offset_kernel(&pmd, ea); + +out_huge: + if (!hpdp) + return NULL; + + ret_pte = hugepte_offset(*hpdp, ea, pdshift); + pdshift = hugepd_shift(*hpdp); +out: + if (hpage_shift) + *hpage_shift = pdshift; + return ret_pte; +} +EXPORT_SYMBOL_GPL(__find_linux_pte); |