diff mbox series

[v9,05/42] mm: Move VM_UFFD_MINOR_BIT from 37 to 38

Message ID 20230613001108.3040476-6-rick.p.edgecombe@intel.com
State New
Headers
Series Shadow stacks for userspace |

Commit Message

Edgecombe, Rick P June 13, 2023, 12:10 a.m. UTC 
  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.

Future patches will introduce a new VM flag VM_SHADOW_STACK that will be
VM_HIGH_ARCH_BIT_5. VM_HIGH_ARCH_BIT_1 through VM_HIGH_ARCH_BIT_4 are
bits 32-36, and bit 37 is the unrelated VM_UFFD_MINOR_BIT. For the sake
of order, make all VM_HIGH_ARCH_BITs stay together by moving
VM_UFFD_MINOR_BIT from 37 to 38. This will allow VM_SHADOW_STACK to be
introduced as 37.

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>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Peter Xu <peterx@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>
---
 include/linux/mm.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

David Hildenbrand June 14, 2023, 8:50 a.m. UTC | #1 
On 13.06.23 02:10, Rick Edgecombe wrote:
> 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.
> 
> Future patches will introduce a new VM flag VM_SHADOW_STACK that will be
> VM_HIGH_ARCH_BIT_5. VM_HIGH_ARCH_BIT_1 through VM_HIGH_ARCH_BIT_4 are
> bits 32-36, and bit 37 is the unrelated VM_UFFD_MINOR_BIT. For the sake
> of order, make all VM_HIGH_ARCH_BITs stay together by moving
> VM_UFFD_MINOR_BIT from 37 to 38. This will allow VM_SHADOW_STACK to be
> introduced as 37.
> 
> 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>
> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
> Acked-by: Peter Xu <peterx@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>
> ---
>   include/linux/mm.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 9ec20cbb20c1..6f52c1e7c640 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -370,7 +370,7 @@ extern unsigned int kobjsize(const void *objp);
>   #endif
>   
>   #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
> -# define VM_UFFD_MINOR_BIT	37
> +# define VM_UFFD_MINOR_BIT	38
>   # define VM_UFFD_MINOR		BIT(VM_UFFD_MINOR_BIT)	/* UFFD minor faults */
>   #else /* !CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
>   # define VM_UFFD_MINOR		VM_NONE

Reviewed-by: David Hildenbrand <david@redhat.com>
diff mbox series

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9ec20cbb20c1..6f52c1e7c640 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -370,7 +370,7 @@  extern unsigned int kobjsize(const void *objp);
 #endif
 
 #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
-# define VM_UFFD_MINOR_BIT	37
+# define VM_UFFD_MINOR_BIT	38
 # define VM_UFFD_MINOR		BIT(VM_UFFD_MINOR_BIT)	/* UFFD minor faults */
 #else /* !CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
 # define VM_UFFD_MINOR		VM_NONE