From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Date: Mon, 20 Feb 2023 11:23:28 +0000 Subject: Re: [PATCH v6 13/41] mm: Make pte_mkwrite() take a VMA Message-Id: List-Id: References: <20230218211433.26859-1-rick.p.edgecombe@intel.com> <20230218211433.26859-14-rick.p.edgecombe@intel.com> In-Reply-To: <20230218211433.26859-14-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable 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 Cc: linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, Michal Simek , Dinh Nguyen , linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, xen-devel@lists.xenproject.org On 18.02.23 22:14, Rick Edgecombe wrote: > 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. >=20 > One of these unusual properties is that shadow stack memory is writable, > but only in limited ways. These limits are applied via a specific PTE > bit combination. Nevertheless, the memory is writable, and core mm code > will need to apply the writable permissions in the typical paths that > call pte_mkwrite(). >=20 > In addition to VM_WRITE, the shadow stack VMA's will have a flag denoting > that they are special shadow stack flavor of writable memory. So make > pte_mkwrite() take a VMA, so that the x86 implementation of it can know to > create regular writable memory or shadow stack memory. >=20 > Apply the same changes for pmd_mkwrite() and huge_pte_mkwrite(). >=20 > No functional change. >=20 > Cc: linux-doc@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-alpha@vger.kernel.org > Cc: linux-snps-arc@lists.infradead.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-csky@vger.kernel.org > Cc: linux-hexagon@vger.kernel.org > Cc: linux-ia64@vger.kernel.org > Cc: loongarch@lists.linux.dev > Cc: linux-m68k@lists.linux-m68k.org > Cc: Michal Simek > Cc: Dinh Nguyen > Cc: linux-mips@vger.kernel.org > Cc: openrisc@lists.librecores.org > Cc: linux-parisc@vger.kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > Cc: linux-riscv@lists.infradead.org > Cc: linux-s390@vger.kernel.org > Cc: linux-sh@vger.kernel.org > Cc: sparclinux@vger.kernel.org > Cc: linux-um@lists.infradead.org > Cc: xen-devel@lists.xenproject.org > Cc: linux-arch@vger.kernel.org > Cc: linux-mm@kvack.org > Tested-by: Pengfei Xu > Suggested-by: David Hildenbrand > Signed-off-by: Rick Edgecombe >=20 > --- > Hi Non-x86 Arch=E2=80=99s, >=20 > x86 has a feature that allows for the creation of a special type of > writable memory (shadow stack) that is only writable in limited specific > ways. Previously, changes were proposed to core MM code to teach it to > decide when to create normally writable memory or the special shadow stack > writable memory, but David Hildenbrand suggested[0] to change > pXX_mkwrite() to take a VMA, so awareness of shadow stack memory can be > moved into x86 code. >=20 > Since pXX_mkwrite() is defined in every arch, it requires some tree-wide > changes. So that is why you are seeing some patches out of a big x86 > series pop up in your arch mailing list. There is no functional change. > After this refactor, the shadow stack series goes on to use the arch > helpers to push shadow stack memory details inside arch/x86. >=20 > Testing was just 0-day build testing. >=20 > Hopefully that is enough context. Thanks! >=20 > [0] https://lore.kernel.org/lkml/0e29a2d0-08d8-bcd6-ff26-4bea0e4037b0@red= hat.com/#t >=20 > v6: > - New patch > --- > Documentation/mm/arch_pgtable_helpers.rst | 9 ++++++--- > arch/alpha/include/asm/pgtable.h | 6 +++++- > arch/arc/include/asm/hugepage.h | 2 +- > arch/arc/include/asm/pgtable-bits-arcv2.h | 7 ++++++- > arch/arm/include/asm/pgtable-3level.h | 7 ++++++- > arch/arm/include/asm/pgtable.h | 2 +- > arch/arm64/include/asm/pgtable.h | 4 ++-- > arch/csky/include/asm/pgtable.h | 2 +- > arch/hexagon/include/asm/pgtable.h | 2 +- > arch/ia64/include/asm/pgtable.h | 2 +- > arch/loongarch/include/asm/pgtable.h | 4 ++-- > arch/m68k/include/asm/mcf_pgtable.h | 2 +- > arch/m68k/include/asm/motorola_pgtable.h | 6 +++++- > arch/m68k/include/asm/sun3_pgtable.h | 6 +++++- > arch/microblaze/include/asm/pgtable.h | 2 +- > arch/mips/include/asm/pgtable.h | 6 +++--- > arch/nios2/include/asm/pgtable.h | 2 +- > arch/openrisc/include/asm/pgtable.h | 2 +- > arch/parisc/include/asm/pgtable.h | 6 +++++- > arch/powerpc/include/asm/book3s/32/pgtable.h | 2 +- > arch/powerpc/include/asm/book3s/64/pgtable.h | 4 ++-- > arch/powerpc/include/asm/nohash/32/pgtable.h | 2 +- > arch/powerpc/include/asm/nohash/32/pte-8xx.h | 2 +- > arch/powerpc/include/asm/nohash/64/pgtable.h | 2 +- > arch/riscv/include/asm/pgtable.h | 6 +++--- > arch/s390/include/asm/hugetlb.h | 4 ++-- > arch/s390/include/asm/pgtable.h | 4 ++-- > arch/sh/include/asm/pgtable_32.h | 10 ++++++++-- > arch/sparc/include/asm/pgtable_32.h | 2 +- > arch/sparc/include/asm/pgtable_64.h | 6 +++--- > arch/um/include/asm/pgtable.h | 2 +- > arch/x86/include/asm/pgtable.h | 6 ++++-- > arch/xtensa/include/asm/pgtable.h | 2 +- > include/asm-generic/hugetlb.h | 4 ++-- > include/linux/mm.h | 2 +- > mm/debug_vm_pgtable.c | 16 ++++++++-------- > mm/huge_memory.c | 6 +++--- > mm/hugetlb.c | 4 ++-- > mm/memory.c | 4 ++-- > mm/migrate_device.c | 2 +- > mm/mprotect.c | 2 +- > mm/userfaultfd.c | 2 +- > 42 files changed, 106 insertions(+), 69 deletions(-) That looks painful but IMHO worth it :) Acked-by: David Hildenbrand --=20 Thanks, David / dhildenb