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bh=vQxW7nd7WTaydKIv2J5Y5kbM61+Nggklag6qseDgVeA=; b=2fExemH9AAagfWsJpScQi4fgIL MiKDwwjqp+cfhpZ6P1ExyRC9YDKwblxKGnzWf25kmk4iYzoHAKSK1L8x77dZx1ueTo7fuv4EgIuTq SUgOzZkc98ORksYE7NcjzjsOrYtGdByWAKx/QmYpiKeRiebJMoeELiG9gX6eQ3eHrY9NrKVap/RO2 XITlMawFAnTSkVjjtmvRXRNBAmU5GjUwX4XiYYqTXHHoLa9FufhVf/YrnCKka1h9hK6A6NCBYDCY8 tC1pRusLCBXO2ndInBKT6qapW1Yi2srX9qrkVpXjIkXQ/xZ8H8DVKz5nsS6fAuWcQOkGiHoIwUgjh NEmwwwZA==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rcfNq-0000000HEmM-23vn; Wed, 21 Feb 2024 05:43:06 +0000 Date: Tue, 20 Feb 2024 21:43:06 -0800 From: Christoph Hellwig To: Maxwell Bland Cc: linux-arm-kernel@lists.infradead.org, gregkh@linuxfoundation.org, agordeev@linux.ibm.com, akpm@linux-foundation.org, andreyknvl@gmail.com, andrii@kernel.org, aneesh.kumar@kernel.org, aou@eecs.berkeley.edu, ardb@kernel.org, arnd@arndb.de, ast@kernel.org, borntraeger@linux.ibm.com, bpf@vger.kernel.org, brauner@kernel.org, catalin.marinas@arm.com, christophe.leroy@csgroup.eu, cl@linux.com, daniel@iogearbox.net, dave.hansen@linux.intel.com, david@redhat.com, dennis@kernel.org, dvyukov@google.com, glider@google.com, gor@linux.ibm.com, guoren@kernel.org, haoluo@google.com, hca@linux.ibm.com, hch@infradead.org, john.fastabend@gmail.com, jolsa@kernel.org, kasan-dev@googlegroups.com, kpsingh@kernel.org, linux-arch@vger.kernel.org, linux@armlinux.org.uk, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, lstoakes@gmail.com, mark.rutland@arm.com, martin.lau@linux.dev, meted@linux.ibm.com, michael.christie@oracle.com, mjguzik@gmail.com, mpe@ellerman.id.au, mst@redhat.com, muchun.song@linux.dev, naveen.n.rao@linux.ibm.com, npiggin@gmail.com, palmer@dabbelt.com, paul.walmsley@sifive.com, quic_nprakash@quicinc.com, quic_pkondeti@quicinc.com, rick.p.edgecombe@intel.com, ryabinin.a.a@gmail.com, ryan.roberts@arm.com, samitolvanen@google.com, sdf@google.com, song@kernel.org, surenb@google.com, svens@linux.ibm.com, tj@kernel.org, urezki@gmail.com, vincenzo.frascino@arm.com, will@kernel.org, wuqiang.matt@bytedance.com, yonghong.song@linux.dev, zlim.lnx@gmail.com, awheeler@motorola.com Subject: Re: [PATCH 1/4] mm/vmalloc: allow arch-specific vmalloc_node overrides Message-ID: References: <20240220203256.31153-1-mbland@motorola.com> <20240220203256.31153-2-mbland@motorola.com> MIME-Version: 1.0 Content-Type: text/plain; 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See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D7CAD1C0010 X-Stat-Signature: yn8hti7eq84s8twhem9swyun41rsgtau X-Rspam-User: X-HE-Tag: 1708494202-634361 X-HE-Meta: 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 5TQpjK6c jytfs/MtD0K+mp9wffYI6X/VdU3NBa88gAJdpw3F5sv18yu8b9g+T29fDowAlvflXm8lXftkKANPlwzbZd6Be0sLCc9MdTZTSGeDyq50uJXyd3VmMfyXepHNsflfNrpome3zvyPOM7TnHgBBzR12YIEfOY45a1y6qVBtf86xZAePwxd8VfWsrwUl9KNqoYzCpAMJH6YmJhaomTfrMZXQfuBSpOCsPA45kreiCJrfOYZsqSeo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000524, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Feb 20, 2024 at 02:32:53PM -0600, Maxwell Bland wrote: > Present non-uniform use of __vmalloc_node and __vmalloc_node_range makes > enforcing appropriate code and data seperation untenable on certain > microarchitectures, as VMALLOC_START and VMALLOC_END are monolithic > while the use of the vmalloc interface is non-monolithic: in particular, > appropriate randomness in ASLR makes it such that code regions must fall > in some region between VMALLOC_START and VMALLOC_end, but this > necessitates that code pages are intermingled with data pages, meaning > code-specific protections, such as arm64's PXNTable, cannot be > performantly runtime enforced. That's not actually true. We have MODULE_START/END to separate them, which is used by mips only for now. > > The solution to this problem allows architectures to override the > vmalloc wrapper functions by enforcing that the rest of the kernel does > not reimplement __vmalloc_node by using __vmalloc_node_range with the > same parameters as __vmalloc_node or provides a __weak tag to those > functions using __vmalloc_node_range with parameters repeating those of > __vmalloc_node. I'm really not too happy about overriding the functions. Especially as the separation is a generally good idea and it would be good to move everyone (or at least all modern architectures) over to a scheme like this.