[PATCH v8 08/27] mm: Introduce VM_SHSTK for shadow stack memory

From: Yu-cheng Yu
Date: Tue Aug 13 2019 - 17:02:51 EST


VM_SHSTK indicates a shadow stack memory area.
The shadow stack is implemented only for the 64-bit kernel.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
---
fs/proc/task_mmu.c | 3 +++
include/linux/mm.h | 8 ++++++++
2 files changed, 11 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 731642e0f5a0..09521579cc8e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -684,6 +684,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
[ilog2(VM_PKEY_BIT4)] = "",
#endif
#endif /* CONFIG_ARCH_HAS_PKEYS */
+#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+ [ilog2(VM_SHSTK)] = "ss",
+#endif
};
size_t i;

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0334ca97c584..bc58585014c9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -298,11 +298,13 @@ extern unsigned int kobjsize(const void *objp);
#define VM_HIGH_ARCH_BIT_2 34 /* bit only usable on 64-bit architectures */
#define VM_HIGH_ARCH_BIT_3 35 /* bit only usable on 64-bit architectures */
#define VM_HIGH_ARCH_BIT_4 36 /* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_BIT_5 37 /* bit only usable on 64-bit architectures */
#define VM_HIGH_ARCH_0 BIT(VM_HIGH_ARCH_BIT_0)
#define VM_HIGH_ARCH_1 BIT(VM_HIGH_ARCH_BIT_1)
#define VM_HIGH_ARCH_2 BIT(VM_HIGH_ARCH_BIT_2)
#define VM_HIGH_ARCH_3 BIT(VM_HIGH_ARCH_BIT_3)
#define VM_HIGH_ARCH_4 BIT(VM_HIGH_ARCH_BIT_4)
+#define VM_HIGH_ARCH_5 BIT(VM_HIGH_ARCH_BIT_5)
#endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */

#ifdef CONFIG_ARCH_HAS_PKEYS
@@ -340,6 +342,12 @@ extern unsigned int kobjsize(const void *objp);
# define VM_MPX VM_NONE
#endif

+#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
+# define VM_SHSTK VM_HIGH_ARCH_5
+#else
+# define VM_SHSTK VM_NONE
+#endif
+
#ifndef VM_GROWSUP
# define VM_GROWSUP VM_NONE
#endif
--
2.17.1