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Wed, 14 Jan 2026 19:57:26 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Andrey Konovalov Date: Thu, 15 Jan 2026 04:57:15 +0100 X-Gm-Features: AZwV_QhDwJPvCo2WidVMEEygaFIr8dW0DNnDeWkqySsg7Bs1utl1YydiVNaZwUw Message-ID: Subject: Re: [PATCH v8 13/14] x86/kasan: Logical bit shift for kasan_mem_to_shadow To: Maciej Wieczor-Retman Cc: Maciej Wieczor-Retman , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Vincenzo Frascino , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: A1B5540008 X-Stat-Signature: 36391186c45e65kjuzyc6jamqp694u69 X-Rspam-User: X-HE-Tag: 1768449447-790701 X-HE-Meta: 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 KVse1HNQ 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 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, Jan 14, 2026 at 5:52=E2=80=AFPM Maciej Wieczor-Retman wrote: > > I'm a fan of trying to keep as much arch code in the arch directories. > > How about before putting a call here instead like: > > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { > if (addr < (unsigned long)kasan_mem_to_shadow((void *)(0U= LL)) || > addr > (unsigned long)kasan_mem_to_shadow((void *)(~0= ULL))) > return; > } > > arch_kasan_non_canonical_hook() > There would be the generic non-arch part above (and anything shared that = might > make sense here in the future) and all the arch related code would be hid= den in > the per-arch helper. > > So then we could move the part below: > if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) && IS_ENABLED(CONFIG_ARM64))= { > if (addr < (unsigned long)kasan_mem_to_shadow((void *)(0x= FFULL << 56)) || > addr > (unsigned long)kasan_mem_to_shadow((void *)(~0= ULL))) > return; > } > to /arch/arm64. > > For x86 we'd need to duplicate the generic part into > arch_kasan_non_canonical_hook() call in /arch/x86. That seems quiet tidy = to me, > granted the duplication isn't great but it would keep the non-arch part a= s > shared as possible. What do you think? Sounds good to me too, thanks!