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Wed, 26 Feb 2025 09:17:22 -0800 (PST) MIME-Version: 1.0 References: <20250224225246.3712295-1-jeffxu@google.com> <20250224225246.3712295-5-jeffxu@google.com> <899d39af-08d2-4cd9-9698-9741d37186b8@lucifer.local> In-Reply-To: From: Jeff Xu Date: Wed, 26 Feb 2025 09:17:10 -0800 X-Gm-Features: AQ5f1JqJf9n4Unmz6uj_lnvCtH51CFyB4M8cqMKOxzhVNsJkXQyDA1ITrfYaz_4 Message-ID: Subject: Re: [PATCH v7 4/7] mseal, system mappings: enable arm64 To: "Liam R. Howlett" , Lorenzo Stoakes , Jeff Xu , akpm@linux-foundation.org, keescook@chromium.org, jannh@google.com, torvalds@linux-foundation.org, vbabka@suse.cz, adhemerval.zanella@linaro.org, oleg@redhat.com, avagin@gmail.com, benjamin@sipsolutions.net, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-mm@kvack.org, jorgelo@chromium.org, sroettger@google.com, hch@lst.de, ojeda@kernel.org, thomas.weissschuh@linutronix.de, adobriyan@gmail.com, johannes@sipsolutions.net, pedro.falcato@gmail.com, hca@linux.ibm.com, willy@infradead.org, anna-maria@linutronix.de, mark.rutland@arm.com, linus.walleij@linaro.org, Jason@zx2c4.com, deller@gmx.de, rdunlap@infradead.org, davem@davemloft.net, peterx@redhat.com, f.fainelli@gmail.com, gerg@kernel.org, dave.hansen@linux.intel.com, mingo@kernel.org, ardb@kernel.org, mhocko@suse.com, 42.hyeyoo@gmail.com, peterz@infradead.org, ardb@google.com, enh@google.com, rientjes@google.com, groeck@chromium.org, mpe@ellerman.id.au, aleksandr.mikhalitsyn@canonical.com, mike.rapoport@gmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B62C41C0022 X-Stat-Signature: xt7x3m6o7zdhrx89n5usjoaxs498q9c8 X-Rspam-User: X-HE-Tag: 1740590243-685064 X-HE-Meta: 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 5uciAoC8 ZA2TXzJIdw3zlUa6k3AR/00nVfPj0j+lRi5p0UN/XPW6jE7d3LWpCQraldH0GeyMlpuHSa8fux9LOV6KUe8ogdz7b0L7E+HLfLC62WMsPXQqaam6p0q8PYb3qFqYABhGgGZ3LaYFVvDCzeowMTTItCzxl8Cr05RQS+6YGJgRFA7krA3frZtvbdUr4eg8YRNtHsosRAt5k4NTCzlrL2L2tZT9ms/P50Hr1dnmk6W5BVsQQUGbOYVJS6Fu6ABlMeMNfE9sckT7G0RZ3geXOmTEalzKWSteRTyx2r4Tn9LT5ZRVO62cghnrIsS7SH/h58AxRosUf X-Bogosity: Ham, tests=bogofilter, spamicity=0.000794, 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 Wed, Feb 26, 2025 at 9:12=E2=80=AFAM Liam R. Howlett wrote: > > * Lorenzo Stoakes [250226 00:26]: > > On Tue, Feb 25, 2025 at 02:26:50PM -0800, Jeff Xu wrote: > > > On Mon, Feb 24, 2025 at 10:20=E2=80=AFPM Lorenzo Stoakes > > > wrote: > > > > > > > > On Mon, Feb 24, 2025 at 10:52:43PM +0000, jeffxu@chromium.org wrote= : > > > > > From: Jeff Xu > > > > > > > > > > Provide support for CONFIG_MSEAL_SYSTEM_MAPPINGS on arm64, coveri= ng > > > > > the vdso, vvar, and compat-mode vectors and sigpage mappings. > > > > > > > > > > Production release testing passes on Android and Chrome OS. > > > > > > > > This is pretty limited (yes yes I know android is massive etc. but = we must > > > > account for all the weird and wonderful arm64 devices out there in = context of > > > > upstream :) > > > > > > > > Have you looking through all arm64-code relating to vdso, vvar, com= pat-mode > > > > vectors, sigpage mapping and ensured nothing kernel-side relies upo= n relocation? > > > > Some arches actually seem to want to do this. Pretty sure PPC does.= .. so a bit > > > > nervous of that. > > > > > > > Can you please point out where PPC munmap/mremap the vdso ? > > > > > > Previously, when you mentioned that, I thought you meant user space i= n > > > PPC, I didn't realize that you meant that kernel code in PPC. I > > > tried, but didn't find anything, hence asking. > > > > Jeff, please stick to replying to review. 'Have you looking through all > > arm64-code'. > > > > I ended up doing this myself yesterday and found no issues, as with x86= -64. > > > > I said I'm _pretty sure_ PPC does this. Liam mentioned something about > > it. We can discuss it, and I can find specifics if + when you try to ad= d > > this to PPC. > > > > PPC allows the vma to be munmapped then detects and falls back to the > slower method, iirc. > Is this code in the kernel or userspace? If PPC doesn't want to create vdso for all its userspace apps, we could instead "don't create" vdso during the execve call. > They were against the removal of the fallback; other archs also have > this infrastructure. Really, if we fixed the fallback to work for > all platforms then it would probably also remove the possibility of a > remap over the VDSO being a problem (if it is today, which still isn't > clear?). > Any past thread/communication about this that I can read ? Thanks -Jeff > Thanks, > Liam