The following commit has been merged into the x86/shstk branch of tip: Commit-ID: da6031de051337fc7ace0738553d509fd26cc85c Gitweb: https://git.kernel.org/tip/da6031de051337fc7ace0738553d509fd26cc85c Author: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx> AuthorDate: Mon, 12 Jun 2023 17:10:31 -07:00 Committer: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> CommitterDate: Thu, 15 Jun 2023 16:31:00 -07:00 mm: Move VM_UFFD_MINOR_BIT from 37 to 38 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. Co-developed-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Reviewed-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> Acked-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> Acked-by: Peter Xu <peterx@xxxxxxxxxx> Tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx> Tested-by: John Allen <john.allen@xxxxxxx> Tested-by: Kees Cook <keescook@xxxxxxxxxxxx> Link: https://lore.kernel.org/all/20230613001108.3040476-6-rick.p.edgecombe%40intel.com --- 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 9ec20cb..6f52c1e 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
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