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AJvYcCVoLXfNllnVmih3EVsvw3IU+5vk/kr/KA4m5DaLTse9F/jKO3WVp0hHcRoZE49TOdIv7JflIMlNHA==@kvack.org X-Gm-Message-State: AOJu0YzJsNNb7fcwcmbiyBT4ZS8kWj3c4J88CPi5POxGiDSqSjgCStSv Q4XCGq/6oCTwI8xT19m1zduB6+Ywuu+p3S4EmO9b8cICu7tvDMywCk1IIPQBHLxaFPTZxr8CYUO F54lhc4i/GS2pIAie5yieSbdCfjWxJnwCr6RDWtda X-Gm-Gg: ASbGnctzSJlCs2sU384HnGglvIAV4uE840uFbkuM5Jci3lt7drKgGVvPk/piatTRjUZ wbla9a2UyBIfwJODfPVRkiLWTKQ0FmAmhhs2NGw0C0RwCqVkDYJeqUI/06cFCQIX9U64cGrduF6 6blSWNclmQu7Bmy/OKQN3+gvgrQIIEs/qNvAyJv1+csXAlpxmpZQJMIut1Lri+VohJ7yuQYXivT yEDvkitnIMlIj+jN2Ty855Ivwal6GkT7fumZLk2+2hIuuBAcsBpx+vFNGuutInm2Bbl/Y45NqJg A7t86U3BUdBpeJ8aLnXzAHD6S1vXpBFqcIHG X-Google-Smtp-Source: AGHT+IGGiGzNQ2eAyJqdaO9JyMrXkP7w+emfDXwZMPoyyY2gy1i/zUBgnLRf870LMq5UXpv/uG8YRTM2WfKUuwW/Bjc= X-Received: by 2002:ac8:5751:0:b0:4ec:f4be:6b12 with SMTP id d75a77b69052e-4eda4fd3621mr141844221cf.72.1762852106635; Tue, 11 Nov 2025 01:08:26 -0800 (PST) MIME-Version: 1.0 References: <56d9203b1fcb6281b0d29b44bc181530e5c72327.1761763681.git.m.wieczorretman@pm.me> In-Reply-To: <56d9203b1fcb6281b0d29b44bc181530e5c72327.1761763681.git.m.wieczorretman@pm.me> From: Alexander Potapenko Date: Tue, 11 Nov 2025 10:07:50 +0100 X-Gm-Features: AWmQ_bksKNIR8oRrvQW5ElnBBjqadCFUKWpQKwYmKonXZ13JEF-XHOSa5ehktsY Message-ID: Subject: Re: [PATCH v6 12/18] x86/mm: LAM compatible non-canonical definition To: Maciej Wieczor-Retman Cc: xin@zytor.com, peterz@infradead.org, kaleshsingh@google.com, kbingham@kernel.org, akpm@linux-foundation.org, nathan@kernel.org, ryabinin.a.a@gmail.com, dave.hansen@linux.intel.com, bp@alien8.de, morbo@google.com, jeremy.linton@arm.com, smostafa@google.com, kees@kernel.org, baohua@kernel.org, vbabka@suse.cz, justinstitt@google.com, wangkefeng.wang@huawei.com, leitao@debian.org, jan.kiszka@siemens.com, fujita.tomonori@gmail.com, hpa@zytor.com, urezki@gmail.com, ubizjak@gmail.com, ada.coupriediaz@arm.com, nick.desaulniers+lkml@gmail.com, ojeda@kernel.org, brgerst@gmail.com, elver@google.com, pankaj.gupta@amd.com, mark.rutland@arm.com, trintaeoitogc@gmail.com, jpoimboe@kernel.org, thuth@redhat.com, pasha.tatashin@soleen.com, dvyukov@google.com, jhubbard@nvidia.com, catalin.marinas@arm.com, yeoreum.yun@arm.com, mhocko@suse.com, lorenzo.stoakes@oracle.com, samuel.holland@sifive.com, vincenzo.frascino@arm.com, bigeasy@linutronix.de, surenb@google.com, ardb@kernel.org, Liam.Howlett@oracle.com, nicolas.schier@linux.dev, ziy@nvidia.com, kas@kernel.org, tglx@linutronix.de, mingo@redhat.com, broonie@kernel.org, corbet@lwn.net, andreyknvl@gmail.com, maciej.wieczor-retman@intel.com, david@redhat.com, maz@kernel.org, rppt@kernel.org, will@kernel.org, luto@kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-kbuild@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, linux-doc@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: mukj6t9pfpdyuiquatpij84knmww9sh6 X-Rspam-User: X-Rspamd-Queue-Id: 133AD8000B X-Rspamd-Server: rspam10 X-HE-Tag: 1762852107-233153 X-HE-Meta: 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 R7wasSwF BCgivCZOG2Yi6HdjsYJ1B7YHLPRG2Iqh1alDixatEJR1IphC/JFXlCEp/x0K9IVvd75PBZkjcDcKcwFVvm7sLjLGDxKc3nEQR9qAZCKWgkRExN5Tc3uTvGBt91lw0FMVOVYcriNFaIkj1BVeGbJuc70+c0kh+7QhNj7XL9zjIXO8RiVE4U2cB6q9QaZFY/kK71Y0pwf49zJf8fe/y8XnIkctD3q3wRRnM9CZVFMcxAbPkoH0XIEoLyW0L7rb2GH5dcJqbgkTMjXIfUNG8PXdCBttSjiQxUpfylUe5Njewnje9exV2L2DwMmo+YGzPtUD0X2Wq3oRfa941vQ1o2DcJ1Hr8xg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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, Oct 29, 2025 at 9:08=E2=80=AFPM Maciej Wieczor-Retman wrote: > > From: Maciej Wieczor-Retman > > For an address to be canonical it has to have its top bits equal to each > other. The number of bits depends on the paging level and whether > they're supposed to be ones or zeroes depends on whether the address > points to kernel or user space. > > With Linear Address Masking (LAM) enabled, the definition of linear > address canonicality is modified. Not all of the previously required > bits need to be equal, only the first and last from the previously equal > bitmask. So for example a 5-level paging kernel address needs to have > bits [63] and [56] set. > > Change the canonical checking function to use bit masks instead of bit > shifts. > > Signed-off-by: Maciej Wieczor-Retman Acked-by: Alexander Potapenko