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imf21.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf21.hostedemail.com: domain of ada.coupriediaz@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ada.coupriediaz@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755779497; a=rsa-sha256; cv=none; b=X9p5SXjyWOLTTJRtj/x2eJVzeeI5RcrASug7q+U8jkTTUgfMyA65KXIMopuH1CCngF+Odb 6IKfQzDwafour0fLOCSUTTNbxCTj1B6oZ4i5wGKFr5MUkIk8ImM0BAVUNROlPP7PsaIBnY cVTT06qH0J/dOJ0JukDUXYopMIR1SPA= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2D09B168F; Thu, 21 Aug 2025 05:31:27 -0700 (PDT) Received: from [10.57.1.220] (unknown [10.57.1.220]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8ED163F63F; Thu, 21 Aug 2025 05:31:18 -0700 (PDT) Message-ID: <9eb211ee-94bf-431b-981c-e305c8ea5e0b@arm.com> Date: Thu, 21 Aug 2025 13:30:28 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 00/18] kasan: x86: arm64: KASAN tag-based mode for x86 To: Maciej Wieczor-Retman Cc: nathan@kernel.org, arnd@arndb.de, broonie@kernel.org, Liam.Howlett@oracle.com, urezki@gmail.com, will@kernel.org, kaleshsingh@google.com, rppt@kernel.org, leitao@debian.org, coxu@redhat.com, surenb@google.com, akpm@linux-foundation.org, luto@kernel.org, jpoimboe@kernel.org, changyuanl@google.com, hpa@zytor.com, dvyukov@google.com, kas@kernel.org, corbet@lwn.net, vincenzo.frascino@arm.com, smostafa@google.com, nick.desaulniers+lkml@gmail.com, morbo@google.com, andreyknvl@gmail.com, alexander.shishkin@linux.intel.com, thiago.bauermann@linaro.org, catalin.marinas@arm.com, ryabinin.a.a@gmail.com, jan.kiszka@siemens.com, jbohac@suse.cz, dan.j.williams@intel.com, joel.granados@kernel.org, baohua@kernel.org, kevin.brodsky@arm.com, nicolas.schier@linux.dev, pcc@google.com, andriy.shevchenko@linux.intel.com, wei.liu@kernel.org, bp@alien8.de, xin@zytor.com, pankaj.gupta@amd.com, vbabka@suse.cz, glider@google.com, jgross@suse.com, kees@kernel.org, jhubbard@nvidia.com, joey.gouly@arm.com, ardb@kernel.org, thuth@redhat.com, pasha.tatashin@soleen.com, kristina.martsenko@arm.com, bigeasy@linutronix.de, lorenzo.stoakes@oracle.com, jason.andryuk@amd.com, david@redhat.com, graf@amazon.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, mark.rutland@arm.com, dave.hansen@linux.intel.com, samuel.holland@sifive.com, kbingham@kernel.org, trintaeoitogc@gmail.com, scott@os.amperecomputing.com, justinstitt@google.com, kuan-ying.lee@canonical.com, maz@kernel.org, tglx@linutronix.de, samitolvanen@google.com, mhocko@suse.com, nunodasneves@linux.microsoft.com, brgerst@gmail.com, willy@infradead.org, ubizjak@gmail.com, peterz@infradead.org, mingo@redhat.com, sohil.mehta@intel.com, linux-mm@kvack.org, linux-kbuild@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, llvm@lists.linux.dev, kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Ada Couprie Diaz References: From: Ada Couprie Diaz Content-Language: en-US Organization: Arm Ltd. In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 8E6621C0003 X-Stat-Signature: istsg6se8ts9ek8rrszpnggq5kmc9rtr X-Rspam-User: X-HE-Tag: 1755779496-683342 X-HE-Meta: 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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: Hi, On 12/08/2025 14:23, Maciej Wieczor-Retman wrote: > [...] > ======= Testing > Checked all the kunits for both software tags and generic KASAN after > making changes. > > In generic mode the results were: > > kasan: pass:59 fail:0 skip:13 total:72 > Totals: pass:59 fail:0 skip:13 total:72 > ok 1 kasan > > and for software tags: > > kasan: pass:63 fail:0 skip:9 total:72 > Totals: pass:63 fail:0 skip:9 total:72 > ok 1 kasan I tested the series on arm64 and after fixing the build issues mentioned I was able to boot without issues and did not observe any regressions in the KASAN KUnit tests with either generic or software tags. So this is Tested-by: Ada Couprie Diaz (For arm64) I will note that the tests `kmalloc_memmove_negative_size` and `kmalloc_memmove_invalid_size` seem to be able to corrupt memory and lead to kernel crashes if `memmove()` is not properly instrumented, which I discovered while investigating [0]. > [...] > ======= Compilation > Clang was used to compile the series (make LLVM=1) since gcc doesn't > seem to have support for KASAN tag-based compiler instrumentation on > x86. Interestingly, while investigating [0], this comment slipped by me and I managed to compile your series for x86 with software tags using GCC, though it is a bit hacky. You need to update the CC_HAS_KASAN_SW_TAGS to pass `-mlam=u48` or `-mlam=u57`, as it is disabled by default, and pass `-march=arrowlake` for compilation (the support for software tags depends on the arch). You could then test with GCC (though the issue in [0] also applies to x86). Best, Ada [0]: https://groups.google.com/g/kasan-dev/c/v1PYeoitg88 > ======= Dependencies > The base branch for the series is the mainline kernel, tag 6.17-rc1. > > ======= Enabling LAM for testing > Since LASS is needed for LAM and it can't be compiled without it I > applied the LASS series [1] first, then applied my patches. > > [1] https://lore.kernel.org/all/20250707080317.3791624-1-kirill.shutemov@linux.intel.com/ > > Changes v4: > - Revert x86 kasan_mem_to_shadow() scheme to the same on used in generic > KASAN. Keep the arithmetic shift idea for the KASAN in general since > it makes more sense for arm64 and in risc-v. > - Fix inline mode but leave it unavailable until a complementary > compiler patch can be merged. > - Apply Dave Hansen's comments on series formatting, patch style and > code simplifications. > > Changes v3: > - Remove the runtime_const patch and setup a unified offset for both 5 > and 4 paging levels. > - Add a fix for inline mode on x86 tag-based KASAN. Add a handler for > int3 that is generated on inline tag mismatches. > - Fix scripts/gdb/linux/kasan.py so the new signed mem_to_shadow() is > reflected there. > - Fix Documentation/arch/arm64/kasan-offsets.sh to take new offsets into > account. > - Made changes to the kasan_non_canonical_hook() according to upstream > discussion. > - Remove patches 2 and 3 since they related to risc-v and this series > adds only x86 related things. > - Reorder __tag_*() functions so they're before arch_kasan_*(). Remove > CONFIG_KASAN condition from __tag_set(). > > Changes v2: > - Split the series into one adding KASAN tag-based mode (this one) and > another one that adds the dense mode to KASAN (will post later). > - Removed exporting kasan_poison() and used a wrapper instead in > kasan_init_64.c > - Prepended series with 4 patches from the risc-v series and applied > review comments to the first patch as the rest already are reviewed. > > Maciej Wieczor-Retman (16): > kasan: Fix inline mode for x86 tag-based mode > x86: Add arch specific kasan functions > kasan: arm64: x86: Make special tags arch specific > x86: Reset tag for virtual to physical address conversions > mm: x86: Untag addresses in EXECMEM_ROX related pointer arithmetic > x86: Physical address comparisons in fill_p*d/pte > x86: KASAN raw shadow memory PTE init > x86: LAM compatible non-canonical definition > x86: LAM initialization > x86: Minimal SLAB alignment > kasan: arm64: x86: Handle int3 for inline KASAN reports > kasan: x86: Apply multishot to the inline report handler > kasan: x86: Logical bit shift for kasan_mem_to_shadow > mm: Unpoison pcpu chunks with base address tag > mm: Unpoison vms[area] addresses with a common tag > x86: Make software tag-based kasan available > > Samuel Holland (2): > kasan: sw_tags: Use arithmetic shift for shadow computation > kasan: sw_tags: Support tag widths less than 8 bits > > Documentation/arch/arm64/kasan-offsets.sh | 8 ++- > Documentation/arch/x86/x86_64/mm.rst | 6 +- > MAINTAINERS | 4 +- > arch/arm64/Kconfig | 10 ++-- > arch/arm64/include/asm/kasan-tags.h | 9 +++ > arch/arm64/include/asm/kasan.h | 6 +- > arch/arm64/include/asm/memory.h | 14 ++++- > arch/arm64/include/asm/uaccess.h | 1 + > arch/arm64/kernel/traps.c | 17 +----- > arch/arm64/mm/kasan_init.c | 7 ++- > arch/x86/Kconfig | 4 +- > arch/x86/boot/compressed/misc.h | 1 + > arch/x86/include/asm/cache.h | 4 ++ > arch/x86/include/asm/kasan-tags.h | 9 +++ > arch/x86/include/asm/kasan.h | 71 ++++++++++++++++++++++- > arch/x86/include/asm/page.h | 24 +++++++- > arch/x86/include/asm/page_64.h | 2 +- > arch/x86/kernel/alternative.c | 4 +- > arch/x86/kernel/head_64.S | 3 + > arch/x86/kernel/setup.c | 2 + > arch/x86/kernel/traps.c | 4 ++ > arch/x86/mm/Makefile | 2 + > arch/x86/mm/init.c | 3 + > arch/x86/mm/init_64.c | 11 ++-- > arch/x86/mm/kasan_init_64.c | 19 +++++- > arch/x86/mm/kasan_inline.c | 26 +++++++++ > arch/x86/mm/pat/set_memory.c | 1 + > arch/x86/mm/physaddr.c | 1 + > include/linux/kasan-tags.h | 21 +++++-- > include/linux/kasan.h | 51 +++++++++++++++- > include/linux/mm.h | 6 +- > include/linux/mmzone.h | 1 - > include/linux/page-flags-layout.h | 9 +-- > lib/Kconfig.kasan | 3 +- > mm/execmem.c | 4 +- > mm/kasan/hw_tags.c | 11 ++++ > mm/kasan/report.c | 45 ++++++++++++-- > mm/kasan/shadow.c | 18 ++++++ > mm/vmalloc.c | 8 +-- > scripts/Makefile.kasan | 3 + > scripts/gdb/linux/kasan.py | 5 +- > scripts/gdb/linux/mm.py | 5 +- > 42 files changed, 381 insertions(+), 82 deletions(-) > mode change 100644 => 100755 Documentation/arch/arm64/kasan-offsets.sh > create mode 100644 arch/arm64/include/asm/kasan-tags.h > create mode 100644 arch/x86/include/asm/kasan-tags.h > create mode 100644 arch/x86/mm/kasan_inline.c >