[PATCH v12 15/26] mm: Fixup places that call pte_mkwrite() directly

Yu-cheng Yu
2020-09-18T19:23:33Z

A shadow stack page is made writable by pte_mkwrite_shstk(), which sets
_PAGE_DIRTY_HW. There are a few places that call pte_mkwrite() directly
and miss the maybe_mkwrite() fixup in the previous patch. Fix them with
maybe_mkwrite():

- do_anonymous_page() and migrate_vma_insert_page() check VM_WRITE directly
and call pte_mkwrite(), which is the same as maybe_mkwrite(). Change
them to maybe_mkwrite().

- In do_numa_page(), if the numa entry 'was-writable', then pte_mkwrite()
is called directly. Fix it by doing maybe_mkwrite().

- In change_pte_range(), pte_mkwrite() is called directly. Replace it with
maybe_mkwrite().

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
mm/memory.c | 5 ++---
mm/migrate.c | 3 +--
mm/mprotect.c | 2 +-
3 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 469af373ae76..c7c9d2d1118a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3374,8 +3374,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)

entry = mk_pte(page, vma->vm_page_prot);
entry = pte_sw_mkyoung(entry);
- if (vma->vm_flags & VM_WRITE)
- entry = pte_mkwrite(pte_mkdirty(entry));
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);

vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
&vmf->ptl);
@@ -4029,7 +4028,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
pte = pte_modify(old_pte, vma->vm_page_prot);
pte = pte_mkyoung(pte);
if (was_writable)
- pte = pte_mkwrite(pte);
+ pte = maybe_mkwrite(pte, vma);
ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
update_mmu_cache(vma, vmf->address, vmf->pte);

diff --git a/mm/migrate.c b/mm/migrate.c
index 941b89383cf3..dd55d8669de5 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2904,8 +2904,7 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
}
} else {
entry = mk_pte(page, vma->vm_page_prot);
- if (vma->vm_flags & VM_WRITE)
- entry = pte_mkwrite(pte_mkdirty(entry));
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
}

ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
diff --git a/mm/mprotect.c b/mm/mprotect.c
index ce8b8a5eacbb..a8edbcb3af99 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -135,7 +135,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
if (dirty_accountable && pte_dirty(ptent) &&
(pte_soft_dirty(ptent) ||
!(vma->vm_flags & VM_SOFTDIRTY))) {
- ptent = pte_mkwrite(ptent);
+ ptent = maybe_mkwrite(ptent, vma);
}
ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
pages++;
--
2.21.0