From nobody Sun Dec 14 18:14:34 2025 Received: from mail-24417.protonmail.ch (mail-24417.protonmail.ch [109.224.244.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6CAE931A805; Wed, 29 Oct 2025 20:07:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=109.224.244.17 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761768470; cv=none; b=qvRuPQXDuI0zqR4qOC4nchwnuVa56na1lz6DB3cUFuleQgU+vbnc2ovFTQU2iUuZf5B3aU04PpQMlmxU8Fr7L6wUsW6wyML287SbDSwtoUEkgSS1S8jpmTr2m7GDVygV/KoG1j+HXs0PxvNvhuApYrZdqdVixhjtSsHFJXybJTs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761768470; c=relaxed/simple; bh=pG6PmCayk69IIjMpN+E9J4X5ppcFU9gBb5y0rPTdVEE=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=WCeOLXtUveypGp+U+RK3PoKigwLTRyW7oazbA5SKaRqVlpsnRyqh4LycjlGUBt+4j1BlFUnuimtvhbAQa3BPHdkqIypsfsOXAAwdsXq22+fKTUxMjE1fpPRcQMtwUXZlnZbdh73Ig4up4kZe4PdvtistQVpF9cY0MHADrEGVTEk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pm.me; spf=pass smtp.mailfrom=pm.me; dkim=pass (2048-bit key) header.d=pm.me header.i=@pm.me header.b=bjmx3g8O; arc=none smtp.client-ip=109.224.244.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pm.me Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pm.me Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pm.me header.i=@pm.me header.b="bjmx3g8O" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail3; t=1761768465; x=1762027665; bh=h7bOmcRxuqO6z3MZPe9zBvs6V2vz8fOGqA1RpHhG/FE=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector; b=bjmx3g8OlacQX7FEB7CB4gFpPcUTD0I5Kc1p43/y9uXqIMVnKJWIWOuru2SF/QQfu 6AiAPDukFzXStuxWTR5WDI0wUwQ3jAjKxjVKN/rW5W4cFnmYpLhh/SnXC+CNzfiPNN yCU0Y0WKKnfImz6JKMr3Dj0qQjo+Mp/U3OEVrV6kaX0VUG3dIxPsjjzPd48CTfn+MD HpUu7+z+rhYq8apG5mFFr/w3+YtjPLc59AwJlIe7QmemdTNU+aT/cA3JtTnT2ge0If nWKsUZ1l87vhw5I/ZZHp5y2xOcPYMO6CexFWC9kS9HmKpnu1vWPf8OvbB4AV2iSubm Hlcw1buJNqcCg== Date: Wed, 29 Oct 2025 20:07:38 +0000 To: 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, glider@google.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 From: Maciej Wieczor-Retman Cc: 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, m.wieczorretman@pm.me Subject: [PATCH v6 11/18] x86/kasan: KASAN raw shadow memory PTE init Message-ID: In-Reply-To: References: Feedback-ID: 164464600:user:proton X-Pm-Message-ID: 388931058df330f6e092950b7ef3ba7585e70752 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" From: Maciej Wieczor-Retman 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 Reviewed-by: Alexander Potapenko --- 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 998b6010d6d3..e69b7210aaae 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 2.51.0