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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47763e4d7f2sm16568475e9.4.2025.11.06.05.53.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Nov 2025 05:53:59 -0800 (PST) Date: Thu, 6 Nov 2025 13:53:56 +0000 From: David Laight To: Christophe Leroy Cc: Alexander Viro , Christian Brauner , Jan Kara , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , "Andre Almeida" , Andrew Morton , Eric Dumazet , Kuniyuki Iwashima , Paolo Abeni , Willem de Bruijn , "David S. Miller" , Jakub Kicinski , Simon Horman , Daniel Borkmann , Dave Hansen , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v4 00/10] powerpc: Implement masked user access Message-ID: <20251106135356.51721903@pumpkin> In-Reply-To: References: X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 6 Nov 2025 12:31:18 +0100 Christophe Leroy wrote: > This is a rebase on top of commit 6ec821f050e2 (tag: core-scoped-uaccess) > from tip tree. > > Thomas, Peter, could you please take non-powerpc patches (1, 2, 3) > in tip tree for v6.19, then Maddy will take powerpc patches (4-10) > into powerpc-next for v6.20. > > Masked user access avoids the address/size verification by access_ok(). > Allthough its main purpose is to skip the speculation in the > verification of user address and size hence avoid the need of spec > mitigation, it also has the advantage to reduce the amount of > instructions needed so it also benefits to platforms that don't > need speculation mitigation, especially when the size of the copy is > not know at build time. ... Any thoughts on doing the same changes to 32bit x86? I think it just requires that TASK_SIZE_MASK be reduced by 4k and then the address 'mask' code written. David