From nobody Sun Dec 14 18:14:35 2025 Received: from mail-24416.protonmail.ch (mail-24416.protonmail.ch [109.224.244.16]) (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 18C8127A462; Wed, 29 Oct 2025 20:08:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=109.224.244.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761768539; cv=none; b=bbmJ1inlZk6vNAe3nBIU+tXCXKGey3qfwVTp8m6gGSaqYPdX+oWyDGlgL/ikoV72XYKcqtqwwr4slLKy51bwJKv6Btsa6NxWrNNNJxzwnrAjSZNLoaATbHy7WWRIDmJrCqXYvWVgdV+6+Jz2ry5Fqj2PafUmRsVD6iHwlB47jxQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761768539; c=relaxed/simple; bh=Ih8wwv/hVIpNDdvgfkJCAuMYW2YA73jRDPxtzkA+aI4=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=VnvApwsTb/hrO6uZQMILsC20VnoECAimDIrP96qMvtNiMVtQQivRTW7uTsZ5Fi1LhrvIVzb32eBXHItDIl2eZkYMeJdXrnxtoy5b9PGOhECpsKXMm4N/rjeBkh37gFrXMYOdokclEYkB19GQM6cmdzDH+WxHyyGnKQUuq12IKQM= 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=f2ixPvRO; arc=none smtp.client-ip=109.224.244.16 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="f2ixPvRO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail3; t=1761768530; x=1762027730; bh=+vFEd2i7cGwKfB76083zqMnaJRzsau0IVtzvsF2hHkA=; 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=f2ixPvROXBBe3oYcnt46ZpuoD3whpqDkx+uWuzdhIU+YPbduMbbLBUYy3V19N8DdT lJCQaItYc4V04frYC10Qp8vC4v6QealyZOWFQ9x+4qrE9lklIogwUqZ4H130zyymmQ QuU0Jp39WS7X0fe1Z0N55I/Nb2bcW5EMWiLI8MAIscT6weHJpTE4qsZY5FWESEyQBa XhAFbluJjDjJ4OVPWlAMCFRWCe1eIQ5pzDu9nHbw1L5wWjcHpVsCvn8VHSo6rvjAi8 DZuZbhfARnsZ1Xh2scxFMiBarfrU81v14JAR7983upQVZyAIOMSBej2abjtKpLwF5M HwEJuccHvAyqQ== Date: Wed, 29 Oct 2025 20:08:43 +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 13/18] x86/mm: LAM initialization Message-ID: <96559d5a8e897f97879259bad3117db617e21377.1761763681.git.m.wieczorretman@pm.me> In-Reply-To: References: Feedback-ID: 164464600:user:proton X-Pm-Message-ID: 0e1842514ef97eaa33355f60d534577848d5c6b8 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 To make use of KASAN's tag based mode on x86, Linear Address Masking (LAM) needs to be enabled. To do that the 28th bit in CR4 has to be set. Set the bit in early memory initialization. When launching secondary CPUs the LAM bit gets lost. To avoid this add it in a mask in head_64.S. The bitmask permits some bits of CR4 to pass from the primary CPU to the secondary CPUs without being cleared. Signed-off-by: Maciej Wieczor-Retman Acked-by: Alexander Potapenko --- Changelog v6: - boot_cpu_has() -> cpu_feature_enabled() arch/x86/kernel/head_64.S | 3 +++ arch/x86/mm/init.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 21816b48537c..c5a0bfbe280d 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -209,6 +209,9 @@ SYM_INNER_LABEL(common_startup_64, SYM_L_LOCAL) * there will be no global TLB entries after the execution." */ movl $(X86_CR4_PAE | X86_CR4_LA57), %edx +#ifdef CONFIG_ADDRESS_MASKING + orl $X86_CR4_LAM_SUP, %edx +#endif #ifdef CONFIG_X86_MCE /* * Preserve CR4.MCE if the kernel will enable #MC support. diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 8bf6ad4b9400..a8442b255481 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -764,6 +764,9 @@ void __init init_mem_mapping(void) probe_page_size_mask(); setup_pcid(); =20 + if (cpu_feature_enabled(X86_FEATURE_LAM) && IS_ENABLED(CONFIG_KASAN_SW_TA= GS)) + cr4_set_bits_and_update_boot(X86_CR4_LAM_SUP); + #ifdef CONFIG_X86_64 end =3D max_pfn << PAGE_SHIFT; #else --=20 2.51.0