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(p200300cbc704b2007d0323db0ad52d21.dip0.t-ipconnect.de. [2003:cb:c704:b200:7d03:23db:ad5:2d21]) by smtp.gmail.com with ESMTPSA id n5-20020a05600c294500b003f7ec896cefsm16882043wmd.8.2023.06.14.01.50.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Jun 2023 01:50:06 -0700 (PDT) Message-ID: <42a95041-e1a7-f343-8432-e2ce07af4e9e@redhat.com> Date: Wed, 14 Jun 2023 10:50:04 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v9 05/42] mm: Move VM_UFFD_MINOR_BIT from 37 to 38 Content-Language: en-US To: Rick Edgecombe , x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org, Andrew.Cooper3@citrix.com, christina.schimpe@intel.com, debug@rivosinc.com, szabolcs.nagy@arm.com, torvalds@linux-foundation.org, broonie@kernel.org Cc: Yu-cheng Yu , Axel Rasmussen , Peter Xu , Pengfei Xu References: <20230613001108.3040476-1-rick.p.edgecombe@intel.com> <20230613001108.3040476-6-rick.p.edgecombe@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230613001108.3040476-6-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On 13.06.23 02:10, Rick Edgecombe wrote: > From: Yu-cheng Yu > > 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 > Co-developed-by: Rick Edgecombe > Signed-off-by: Rick Edgecombe > Reviewed-by: Borislav Petkov (AMD) > Reviewed-by: Kees Cook > Reviewed-by: Axel Rasmussen > Acked-by: Mike Rapoport (IBM) > Acked-by: Peter Xu > Tested-by: Pengfei Xu > Tested-by: John Allen > Tested-by: Kees Cook > --- > 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 -- Cheers, David / dhildenb