mm/mmap: Add shadow stack pages to memory accounting

The x86 Control-flow Enforcement Technology (CET) feature includes a new
type of memory called shadow stack. This shadow stack memory has some
unusual properties, which requires some core mm changes to function
properly.

Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/all/20230613001108.3040476-20-rick.p.edgecombe%40intel.com

diff --git a/mm/internal.h b/mm/internal.h
index a7d9e980429a5511afdea566c26b8faa35ac2e12..018f5c342f90799819c672c4cb5dd8bac64be483 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -538,14 +538,14 @@ static inline bool is_exec_mapping(vm_flags_t flags)
 }
 
 /*
- * Stack area - automatically grows in one direction
+ * Stack area (including shadow stacks)
  *
  * VM_GROWSUP / VM_GROWSDOWN VMAs are always private anonymous:
  * do_mmap() forbids all other combinations.
  */
 static inline bool is_stack_mapping(vm_flags_t flags)
 {
-       return (flags & VM_STACK) == VM_STACK;
+       return ((flags & VM_STACK) == VM_STACK) || (flags & VM_SHADOW_STACK);
 }
 
 /*