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Cc:     rick.p.edgecombe@intel.com, Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v3 19/37] mm/mmap: Add shadow stack pages to memory accounting
Date:   Fri,  4 Nov 2022 15:35:46 -0700
Message-Id: <20221104223604.29615-20-rick.p.edgecombe@intel.com>
In-Reply-To: <20221104223604.29615-1-rick.p.edgecombe@intel.com>
References: <20221104223604.29615-1-rick.p.edgecombe@intel.com>
Precedence: bulk

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

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.

Account shadow stack pages to stack memory.

Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
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>

---

v3:
 - Remove unneeded VM_SHADOW_STACK check in accountable_mapping()
   (Kirill)

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 | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index f67606fbc464..4dc157869b34 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3298,6 +3298,8 @@ 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