@@ -889,4 +889,22 @@ inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma)
else
return pmd;
}
+
+inline bool pte_exclusive(pte_t pte, struct vm_area_struct *vma)
+{
+ if (vma->vm_flags & VM_SHSTK)
+ return pte_dirty_hw(pte);
+ else
+ return pte_dirty(pte);
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+inline bool pmd_exclusive(pmd_t pmd, struct vm_area_struct *vma)
+{
+ if (vma->vm_flags & VM_SHSTK)
+ return pmd_dirty_hw(pmd);
+ else
+ return pmd_dirty(pmd);
+}
+#endif
#endif /* CONFIG_X86_INTEL_SHADOW_STACK_USER */
@@ -1156,9 +1156,27 @@ static inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma)
{
return pmd;
}
+
+#ifdef CONFIG_MMU
+static inline bool pte_exclusive(pte_t pte, struct vm_area_struct *vma)
+{
+ return pte_dirty(pte);
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline bool pmd_exclusive(pmd_t pmd, struct vm_area_struct *vma)
+{
+ return pmd_dirty(pmd);
+}
+#endif
+#endif /* CONFIG_MMU */
#else
pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma);
pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma);
+bool pte_exclusive(pte_t pte, struct vm_area_struct *vma);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+bool pmd_exclusive(pmd_t pmd, struct vm_area_struct *vma);
+#endif
#endif
#endif /* _ASM_GENERIC_PGTABLE_H */
@@ -64,10 +64,12 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
* FOLL_FORCE can write to even unwritable pte's, but only
* after we've gone through a COW cycle and they are dirty.
*/
-static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
+static inline bool can_follow_write(pte_t pte, unsigned int flags,
+ struct vm_area_struct *vma)
{
return pte_write(pte) ||
- ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
+ ((flags & FOLL_FORCE) && (flags & FOLL_COW) &&
+ pte_exclusive(pte, vma));
}
static struct page *follow_page_pte(struct vm_area_struct *vma,
@@ -105,7 +107,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
}
if ((flags & FOLL_NUMA) && pte_protnone(pte))
goto no_page;
- if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) {
+ if ((flags & FOLL_WRITE) && !can_follow_write(pte, flags, vma)) {
pte_unmap_unlock(ptep, ptl);
return NULL;
}
@@ -1387,10 +1387,12 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
* FOLL_FORCE can write to even unwritable pmd's, but only
* after we've gone through a COW cycle and they are dirty.
*/
-static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
+static inline bool can_follow_write(pmd_t pmd, unsigned int flags,
+ struct vm_area_struct *vma)
{
return pmd_write(pmd) ||
- ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
+ ((flags & FOLL_FORCE) && (flags & FOLL_COW) &&
+ pmd_exclusive(pmd, vma));
}
struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
@@ -1403,7 +1405,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
assert_spin_locked(pmd_lockptr(mm, pmd));
- if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
+ if (flags & FOLL_WRITE && !can_follow_write(*pmd, flags, vma))
goto out;
/* Avoid dumping huge zero page */
can_follow_write_pte/pmd look for the (RO & DIRTY) PTE/PMD to verify an exclusive RO page still exists after a broken COW. A shadow stack PTE is RO & PAGE_DIRTY_SW when it is shared, otherwise RO & PAGE_DIRTY_HW. Introduce pte_exclusive() and pmd_exclusive() to also verify a shadow stack PTE is exclusive. Also rename can_follow_write_pte/pmd() to can_follow_write() to make their meaning clear; i.e. "Can we write to the page?", not "Is the PTE writable?" Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> --- arch/x86/mm/pgtable.c | 18 ++++++++++++++++++ include/asm-generic/pgtable.h | 18 ++++++++++++++++++ mm/gup.c | 8 +++++--- mm/huge_memory.c | 8 +++++--- 4 files changed, 46 insertions(+), 6 deletions(-)