Re: [PATCH v28 16/32] x86/mm: Update maybe_mkwrite() for shadow stack
From: Yu, Yu-cheng
Date: Tue Aug 17 2021 - 14:36:38 EST
On 8/16/2021 10:03 AM, Borislav Petkov wrote:
On Thu, Jul 22, 2021 at 01:52:03PM -0700, Yu-cheng Yu wrote:
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 3364fe62b903..ba449d12ec32 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -610,6 +610,26 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma,
}
#endif
+pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_flags & VM_WRITE))
+ pte = pte_mkwrite(pte);
+ else if (likely(vma->vm_flags & VM_SHADOW_STACK))
+ pte = pte_mkwrite_shstk(pte);
+ return pte;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_flags & VM_WRITE))
+ pmd = pmd_mkwrite(pmd);
+ else if (likely(vma->vm_flags & VM_SHADOW_STACK))
+ pmd = pmd_mkwrite_shstk(pmd);
What are all those likely()ies here for?
I will remove those.
Thanks,
Yu-cheng