[PATCH v22 18/28] mm/mmap: Add shadow stack pages to memory accounting

[Yu-cheng Yu]

Account shadow stack pages to stack memory.

Signed-off-by: Yu-cheng Yu <yu-cheng...@intel.com>
Reviewed-by: Kees Cook <keesc...@chromium.org>
---
 arch/x86/mm/pgtable.c   |  7 +++++++
 include/linux/pgtable.h | 11 +++++++++++
 mm/mmap.c               |  5 +++++
 3 files changed, 23 insertions(+)

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 0f4fbf51a9fc..948d28c29964 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -895,3 +895,10 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 
 #endif /* CONFIG_X86_64 */
 #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
+
+#ifdef CONFIG_ARCH_HAS_SHADOW_STACK
+bool arch_shadow_stack_mapping(vm_flags_t vm_flags)
+{
+       return (vm_flags & VM_SHSTK);
+}
+#endif
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index fb85ab22b5e5..e96130e18977 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1466,6 +1466,17 @@ static inline pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, 
struct vm_area_struct *vma
 #endif /* CONFIG_ARCH_MAYBE_MKWRITE */
 #endif /* CONFIG_MMU */
 
+#ifdef CONFIG_MMU
+#ifdef CONFIG_ARCH_HAS_SHADOW_STACK
+bool arch_shadow_stack_mapping(vm_flags_t vm_flags);
+#else
+static inline bool arch_shadow_stack_mapping(vm_flags_t vm_flags)
+{
+       return false;
+}
+#endif /* CONFIG_ARCH_HAS_SHADOW_STACK */
+#endif /* CONFIG_MMU */
+
 /*
  * Architecture PAGE_KERNEL_* fallbacks
  *
diff --git a/mm/mmap.c b/mm/mmap.c
index 3f287599a7a3..2ac67882ace2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1718,6 +1718,9 @@ static inline int accountable_mapping(struct file *file, 
vm_flags_t vm_flags)
        if (file && is_file_hugepages(file))
                return 0;
 
+       if (arch_shadow_stack_mapping(vm_flags))
+               return 1;
+
        return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
 }
 
@@ -3387,6 +3390,8 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t 
flags, long npages)
                mm->stack_vm += npages;
        else if (is_data_mapping(flags))
                mm->data_vm += npages;
+       else if (arch_shadow_stack_mapping(flags))
+               mm->stack_vm += npages;
 }
 
 static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
-- 
2.21.0