[PATCH v2 19/39] mm/mmap: Add shadow stack pages to memory accounting

Rick Edgecombe
2022-09-29T22:33:28Z

From: Yu-cheng Yu <yu-cheng.yu@intel.com>

Account shadow stack pages to stack memory.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Kees Cook <keescook@chromium.org>

---

v2:
- Remove is_shadow_stack_mapping() and just change it to directly bitwise
and VM_SHADOW_STACK.

Yu-cheng v26:
- Remove redundant #ifdef CONFIG_MMU.

Yu-cheng v25:
- Remove #ifdef CONFIG_ARCH_HAS_SHADOW_STACK for is_shadow_stack_mapping().

mm/mmap.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index f0d2e9143bd0..8569ef09614c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1682,6 +1682,9 @@ static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
if (file && is_file_hugepages(file))
return 0;

+ if (vm_flags & VM_SHADOW_STACK)
+ return 1;
+
return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
}

@@ -3289,6 +3292,8 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
mm->exec_vm += npages;
else if (is_stack_mapping(flags))
mm->stack_vm += npages;
+ else if (flags & VM_SHADOW_STACK)
+ mm->stack_vm += npages;
else if (is_data_mapping(flags))
mm->data_vm += npages;
}
--
2.17.1