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X-CSE-ConnectionGUID: hiQ+PCM2S1avnaAzypLirA== X-CSE-MsgGUID: yq5Ai1tsRpCtKW4gDCY3fw== X-IronPort-AV: E=McAfee;i="6800,10657,11520"; a="60903623" X-IronPort-AV: E=Sophos;i="6.17,284,1747724400"; d="scan'208";a="60903623" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2025 06:28:26 -0700 X-CSE-ConnectionGUID: RvG1WbQvQdy6dQLlny3rTg== X-CSE-MsgGUID: gCS5TnjYQ6isOtqp7VNDUw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,284,1747724400"; d="scan'208";a="165831505" Received: from vpanait-mobl.ger.corp.intel.com (HELO wieczorr-mobl1.intel.com) ([10.245.245.54]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2025 06:28:02 -0700 From: Maciej Wieczor-Retman To: 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, ada.coupriediaz@arm.com, 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, maciej.wieczor-retman@intel.com, 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 Cc: 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 Subject: [PATCH v4 09/18] x86: KASAN raw shadow memory PTE init Date: Tue, 12 Aug 2025 15:23:45 +0200 Message-ID: <38129f9031dfefc3e9465a0bf06fd32256cdc157.1755004923.git.maciej.wieczor-retman@intel.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In KASAN's generic mode the default value in shadow memory is zero. During initialization of shadow memory pages they are allocated and zeroed. In KASAN's tag-based mode the default tag for the arm64 architecture is 0xFE which corresponds to any memory that should not be accessed. On x86 (where tags are 4-bit wide instead of 8-bit wide) that tag is 0xE so during the initializations all the bytes in shadow memory pages should be filled with it. Use memblock_alloc_try_nid_raw() instead of memblock_alloc_try_nid() to avoid zeroing out the memory so it can be set with the KASAN invalid tag. Signed-off-by: Maciej Wieczor-Retman --- Changelog v2: - Remove dense mode references, use memset() instead of kasan_poison(). arch/x86/mm/kasan_init_64.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 0539efd0d216..e8a451cafc8c 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -34,6 +34,18 @@ static __init void *early_alloc(size_t size, int nid, bo= ol should_panic) return ptr; } =20 +static __init void *early_raw_alloc(size_t size, int nid, bool should_pani= c) +{ + void *ptr =3D memblock_alloc_try_nid_raw(size, size, + __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid); + + if (!ptr && should_panic) + panic("%pS: Failed to allocate page, nid=3D%d from=3D%lx\n", + (void *)_RET_IP_, nid, __pa(MAX_DMA_ADDRESS)); + + return ptr; +} + static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr, unsigned long end, int nid) { @@ -63,8 +75,9 @@ static void __init kasan_populate_pmd(pmd_t *pmd, unsigne= d long addr, if (!pte_none(*pte)) continue; =20 - p =3D early_alloc(PAGE_SIZE, nid, true); - entry =3D pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL); + p =3D early_raw_alloc(PAGE_SIZE, nid, true); + memset(p, PAGE_SIZE, KASAN_SHADOW_INIT); + entry =3D pfn_pte(PFN_DOWN(__pa_nodebug(p)), PAGE_KERNEL); set_pte_at(&init_mm, addr, pte, entry); } while (pte++, addr +=3D PAGE_SIZE, addr !=3D end); } @@ -436,7 +449,7 @@ void __init kasan_init(void) * it may contain some garbage. Now we can clear and write protect it, * since after the TLB flush no one should write to it. */ - memset(kasan_early_shadow_page, 0, PAGE_SIZE); + memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); for (i =3D 0; i < PTRS_PER_PTE; i++) { pte_t pte; pgprot_t prot; --=20 2.50.1