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X-CSE-ConnectionGUID: whX6K1FZQwm2BmLz21BpoQ== X-CSE-MsgGUID: s0tkY736TDSpVxjk7n0wRQ== X-IronPort-AV: E=McAfee;i="6700,10204,11336"; a="42345045" X-IronPort-AV: E=Sophos;i="6.13,265,1732608000"; d="scan'208";a="42345045" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2025 13:41:28 -0800 X-CSE-ConnectionGUID: 6H771ns0SpuSxG9hNzP1oQ== X-CSE-MsgGUID: Z+csMKT7SBO/Wvx19isNiQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="116528569" Received: from dnelso2-mobl.amr.corp.intel.com (HELO [10.125.111.17]) ([10.125.111.17]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2025 13:41:27 -0800 Message-ID: <239de2b9-0787-4105-a481-418dbd4d861e@intel.com> Date: Thu, 6 Feb 2025 13:41:29 -0800 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/15] kasan: x86: arm64: risc-v: KASAN tag-based mode for x86 To: "Christoph Lameter (Ampere)" , Jessica Clarke Cc: Maciej Wieczor-Retman , luto@kernel.org, xin@zytor.com, kirill.shutemov@linux.intel.com, palmer@dabbelt.com, tj@kernel.org, andreyknvl@gmail.com, brgerst@gmail.com, ardb@kernel.org, dave.hansen@linux.intel.com, jgross@suse.com, will@kernel.org, akpm@linux-foundation.org, arnd@arndb.de, corbet@lwn.net, dvyukov@google.com, richard.weiyang@gmail.com, ytcoode@gmail.com, tglx@linutronix.de, hpa@zytor.com, seanjc@google.com, paul.walmsley@sifive.com, aou@eecs.berkeley.edu, justinstitt@google.com, jason.andryuk@amd.com, glider@google.com, ubizjak@gmail.com, jannh@google.com, bhe@redhat.com, vincenzo.frascino@arm.com, rafael.j.wysocki@intel.com, ndesaulniers@google.com, mingo@redhat.com, catalin.marinas@arm.com, junichi.nomura@nec.com, nathan@kernel.org, ryabinin.a.a@gmail.com, dennis@kernel.org, bp@alien8.de, kevinloughlin@google.com, morbo@google.com, dan.j.williams@intel.com, julian.stecklina@cyberus-technology.de, peterz@infradead.org, kees@kernel.org, kasan-dev@googlegroups.com, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, linux-doc@vger.kernel.org, "Shutemov, Kirill" References: <8bd9c793-aac6-a330-ea8f-3bde0230a20b@gentwo.org> <72837fcd-97a8-c213-0098-c8f308c3415d@gentwo.org> <29A74A26-E922-4A4F-9B4A-8DB0336B99DF@jrtc27.com> <94f81328-a135-b99b-7f73-43fb77bd7292@gentwo.org> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/6/25 11:11, Christoph Lameter (Ampere) wrote: > I also see that KASAN_HW_TAGS exist but this means that the tags can only > be used with CONFIG_KASAN which is a kernel configuration for debug > purposes. > > What we are interested in is a *production* implementation with minimal > software overhead that will be the default on ARM64 if the appropriate > hardware is detected. Ahh, interesting. I'd assumed that once folks had in-hardware tag checks that they'd just turn on CONFIG_KASAN and be happy. Guess not! > That in turn will hopefully allow other software instrumentation > that is currently used to keep small objects secure and in turn > creates overhead. OK, so KASAN as-is is too broad. Are you saying that the kernel _currently_ have "software instrumentation" like SLAB redzoning/poisoning and you'd like to see MTE used to replace those? Are you just interested in small objects? What counts as small? I assume it's anything roughly