From: Rik van Riel <r...@redhat.com>
MPX only seems to be available on 64 bit CPUs, starting with Skylake
and Goldmont. Move VM_MPX into the 64 bit only portion of vma->vm_flags,
in order to free up a VMA flag.
Signed-off-by: Rik van Riel <r...@redhat.com>
---
arch/x86/Kconfig | 4 +++-
include/linux/mm.h | 8 ++++++--
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 781521b7cf9e..6dff14fadc6f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1756,7 +1756,9 @@ config X86_SMAP
config X86_INTEL_MPX
prompt "Intel MPX (Memory Protection Extensions)"
def_bool n
- depends on CPU_SUP_INTEL
+ # Note: only available in 64-bit mode due to VMA flags shortage
+ depends on CPU_SUP_INTEL && X86_64
+ select ARCH_USES_HIGH_VMA_FLAGS
---help---
MPX provides hardware features that can be used in
conjunction with compiler-instrumented code to check
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 46b9ac5e8569..7550eeb06ccf 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -208,10 +208,12 @@ extern unsigned int kobjsize(const void *objp);
#define VM_HIGH_ARCH_BIT_1 33 /* bit only usable on 64-bit
architectures */
#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_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)
#endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
#if defined(CONFIG_X86)
@@ -235,9 +237,11 @@ extern unsigned int kobjsize(const void *objp);
# define VM_MAPPED_COPY VM_ARCH_1 /* T if mapped copy of data
(nommu mmap) */
#endif
-#if defined(CONFIG_X86)
+#if defined(CONFIG_X86_INTEL_MPX)
/* MPX specific bounds table or bounds directory */
-# define VM_MPX VM_ARCH_2
+# define VM_MPX VM_HIGH_ARCH_BIT_4
+#else
+# define VM_MPX VM_NONE
#endif
#ifndef VM_GROWSUP
--
2.9.4
