From patchwork Tue Jun 24 14:59:18 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kirill A. Shutemov" X-Patchwork-Id: 899787 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (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 E2BD92C15A6; Tue, 24 Jun 2025 14:59:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750777175; cv=none; b=gEOvk/zRl73N+1Opl2OfIM8WdDKeLxNNkSgaCEOtaTKzcdwzT3mIhPfqDhJtZnYNKI7uU4JZmhPBpc3U1zhTMudOYHAc3q2wU66CvvPO2/d9QLTcpFYwKAuFE8nCC1hE+VQcf0JFw5Sy6g+waNn9IqoashrwFqQ6CYB8y43IE6A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750777175; c=relaxed/simple; bh=gSrgyF7nkaMy9jgn9VB3Vel47cqINKRy4i1jm+eFhC4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SBRjZ7qehAVscQ/GB8mPupSJode605yRo8stBJHGBHa58QYOOgGt5fSdfeasuHcqimi9p9fnOclivyoUpp3yK8qBvQ7NyfRdEy9Ko0vwXFInWUakAQ62JLR2vf5F267btynKxvyiH0chGwslYgNxy0AsROzMzB626K9uFIfEK2Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.helo=mgamail.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=nyJv4hqX; arc=none smtp.client-ip=198.175.65.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.helo=mgamail.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="nyJv4hqX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1750777174; x=1782313174; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=gSrgyF7nkaMy9jgn9VB3Vel47cqINKRy4i1jm+eFhC4=; b=nyJv4hqX/s29oTdFDmRKiK+mBNGrOlQPXPaiwQElZPpoV0FIJwuXatS+ P7DfnLY4XZU9M+dCzTXLU/qut5iXWrZfj4JvbD7tt/z6tA1HUOSOY02Pr FZkEMyQDwZO9Baxg8ad28qrlbw68T+W7p9lmuMEmanCfu2pKz2tVI0tlv D1SDI04ICER/QVSvZQiYsuRk8WZbjwAE+HmyU0RGjHOHYhv79zGvaSMSq W9Jm5ZK2kjUsaQMgR1Ik/ql2Kho7qNikj8uPNaOpw7DExSBtcQGF5io6q 8fVsUve18Tzm0SB4Bt0JaNFGWh216uiEQg8zWGn6OdxGJNyjnCdg60ltH A==; X-CSE-ConnectionGUID: ukEm/ZceTCmB0pdDf+Musw== X-CSE-MsgGUID: em1l6HfsTr2T6YMUhj+Puw== X-IronPort-AV: E=McAfee;i="6800,10657,11474"; a="64080101" X-IronPort-AV: E=Sophos;i="6.16,262,1744095600"; d="scan'208";a="64080101" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2025 07:59:33 -0700 X-CSE-ConnectionGUID: IBEM0H0CSQuj9mNcu/owmg== X-CSE-MsgGUID: gbza5MI9RF2ZS2wYu+XWZw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,262,1744095600"; d="scan'208";a="152435086" Received: from black.fi.intel.com ([10.237.72.28]) by orviesa008.jf.intel.com with ESMTP; 24 Jun 2025 07:59:22 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id 71D81224; Tue, 24 Jun 2025 17:59:20 +0300 (EEST) From: "Kirill A. Shutemov" To: dave.hansen@intel.com Cc: acme@redhat.com, aik@amd.com, akpm@linux-foundation.org, alexander.shishkin@linux.intel.com, andrew.cooper3@citrix.com, ardb@kernel.org, ast@kernel.org, bp@alien8.de, brijesh.singh@amd.com, changbin.du@huawei.com, christophe.leroy@csgroup.eu, corbet@lwn.net, daniel.sneddon@linux.intel.com, dave.hansen@linux.intel.com, ebiggers@google.com, geert+renesas@glider.be, houtao1@huawei.com, hpa@zytor.com, jgg@ziepe.ca, jgross@suse.com, jpoimboe@kernel.org, kai.huang@intel.com, kees@kernel.org, kirill.shutemov@linux.intel.com, leitao@debian.org, linux-doc@vger.kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux@rasmusvillemoes.dk, luto@kernel.org, mcgrof@kernel.org, mhiramat@kernel.org, michael.roth@amd.com, mingo@kernel.org, mingo@redhat.com, namhyung@kernel.org, paulmck@kernel.org, pawan.kumar.gupta@linux.intel.com, peterz@infradead.org, rick.p.edgecombe@intel.com, rppt@kernel.org, sandipan.das@amd.com, shijie@os.amperecomputing.com, sohil.mehta@intel.com, tglx@linutronix.de, tj@kernel.org, tony.luck@intel.com, vegard.nossum@oracle.com, x86@kernel.org, xin3.li@intel.com, xiongwei.song@windriver.com, ytcoode@gmail.com Subject: [PATCH] x86/vsyscall: Do not require X86_PF_INSTR to emulate vsyscall Date: Tue, 24 Jun 2025 17:59:18 +0300 Message-ID: <20250624145918.2720487-1-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.47.2 In-Reply-To: <265eef27-aecb-479e-a293-c2e88d69e6ec@intel.com> References: <265eef27-aecb-479e-a293-c2e88d69e6ec@intel.com> Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 emulate_vsyscall() expects to see X86_PF_INSTR in PFEC on a vsyscall page fault, but the CPU does not report X86_PF_INSTR if neither X86_FEATURE_NX nor X86_FEATURE_SMEP are enabled. X86_FEATURE_NX should be enabled on nearly all 64-bit CPUs, except for early P4 processors that did not support this feature. Instead of explicitly checking for X86_PF_INSTR, compare the fault address to RIP. On machines with X86_FEATURE_NX enabled, issue a warning if RIP is equal to fault address but X86_PF_INSTR is absent. Originally-by: Dave Hansen Link: https://lore.kernel.org/all/bd81a98b-f8d4-4304-ac55-d4151a1a77ab@intel.com Signed-off-by: Kirill A. Shutemov Reported-by: Andrew Cooper Reviewed-by: Andrew Cooper --- arch/x86/entry/vsyscall/vsyscall_64.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c index c9103a6fa06e..0b0e0283994f 100644 --- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -124,7 +124,8 @@ bool emulate_vsyscall(unsigned long error_code, if ((error_code & (X86_PF_WRITE | X86_PF_USER)) != X86_PF_USER) return false; - if (!(error_code & X86_PF_INSTR)) { + /* Avoid emulation unless userspace was executing from vsyscall page: */ + if (address != regs->ip) { /* Failed vsyscall read */ if (vsyscall_mode == EMULATE) return false; @@ -136,13 +137,16 @@ bool emulate_vsyscall(unsigned long error_code, return false; } + + /* X86_PF_INSTR is only set when NX is supported: */ + if (cpu_feature_enabled(X86_FEATURE_NX)) + WARN_ON_ONCE(!(error_code & X86_PF_INSTR)); + /* * No point in checking CS -- the only way to get here is a user mode * trap to a high address, which means that we're in 64-bit user code. */ - WARN_ON_ONCE(address != regs->ip); - if (vsyscall_mode == NONE) { warn_bad_vsyscall(KERN_INFO, regs, "vsyscall attempted with vsyscall=none");