Modify vmalloc_fault() to handle additional page table level.
With 4-level paging, copying happens on p4d level, as we have pgd_none()
always false if p4d_t is folded.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/mm/fault.c | 27 ++++++++++++++++++++++++---
1 file changed, 24 insertions(+), 3 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 605fd5e8e048..1928ea02e182 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -435,6 +435,7 @@ void vmalloc_sync_all(void)
static noinline int vmalloc_fault(unsigned long address)
{
pgd_t *pgd, *pgd_ref;
+ p4d_t *p4d, *p4d_ref;
pud_t *pud, *pud_ref;
pmd_t *pmd, *pmd_ref;
pte_t *pte, *pte_ref;
@@ -458,17 +459,37 @@ static noinline int vmalloc_fault(unsigned long address)
if (pgd_none(*pgd)) {
set_pgd(pgd, *pgd_ref);
arch_flush_lazy_mmu_mode();
- } else {
+ } else if (CONFIG_PGTABLE_LEVELS > 4) {
+ /*
+ * With folded p4d, pgd_none() is always false. So pgd may
+ * point to empty page table entry and pgd_page_vaddr()
+ * will return garbage.
+ *
+ * We will do the correct sanity check on p4d level.
+ */
BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
}
+ /* With 4-level paging, copying happens on p4d level. */
+ p4d = p4d_offset(pgd, address);
+ p4d_ref = p4d_offset(pgd_ref, address);
+ if (p4d_none(*p4d_ref))
+ return -1;
+
+ if (p4d_none(*p4d)) {
+ set_p4d(p4d, *p4d_ref);
+ arch_flush_lazy_mmu_mode();
+ } else {
+ BUG_ON(p4d_pfn(*p4d) != p4d_pfn(*p4d_ref));
+ }
+
/*
* Below here mismatches are bugs because these lower tables
* are shared:
*/
- pud = pud_offset(pgd, address);
- pud_ref = pud_offset(pgd_ref, address);
+ pud = pud_offset(p4d, address);
+ pud_ref = pud_offset(p4d_ref, address);
if (pud_none(*pud_ref))
return -1;
--
2.11.0
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