From nobody Wed Oct 8 08:32:39 2025 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) (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 A19F226FD8F; Tue, 1 Jul 2025 09:59:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.10 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751363966; cv=none; b=YXpgNyTcSq3V7khxph5nxKPlJe52wq70azp2deTZOwKZVCXis7in5pKfUbQh5vTbK1jyoBasKIXz5Hsswido3V18r2L7F+F8FFga2jEnzbJFjSKp4NoLkdm25qiiS70MRju+E1kWj04nh6err9rEmHYxlSybRJRtnEmkoInlKn0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751363966; c=relaxed/simple; bh=qO+8BSDMXd1kOh4db6N91L5SEjVjt9oi3Mr4Xl+KkEE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lwxD3QuzyRn1TG745MShYJ7qm30JsrUeuYrWGcX1GLiqBBXYK43mk9CBfUEX2Ahn9iLsXPIZ5d1bEAEl6rLPq3NqH3Kz8IIjpKZK8SsvXisD3D/BggeWaSgTBsc4j4wITfBTPMuVi/PBJYJGdHeqVI+yPf/PJkBCu63p1mSz9uw= 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=WmaMpHVG; arc=none smtp.client-ip=198.175.65.10 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="WmaMpHVG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1751363965; x=1782899965; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=qO+8BSDMXd1kOh4db6N91L5SEjVjt9oi3Mr4Xl+KkEE=; b=WmaMpHVGop6nEsng66U5j/rGLfp6s+xASHTJvTDP0HKupiRdPkOuBcco x7v/AioGDfewyMmkm0oEzddI72nJx6jh/TCTKyDTWhepuUCVdMmPJL42G 52SvoLlU4ughO6r2uH21n+YPfGPI+KTCy3d831Xze+sgdwsTtvm7Be2cv tN6gF89CaZu4Ndg3hiexe8q6G8Nqiw8HT7AX3IMzcRLDD3WsHbNFqDrsY i+UWX2mz+BF0MtvhFmrZQTfGLnZWQhpCBwkf6T0KlUjfzkMHTXQZTBRXg IOVlZSmGcsNcMrx7ENhJYl5fG44jwyow/3aJ2DJdxyoYbltfI5FKphYAI w==; X-CSE-ConnectionGUID: INofQOkhR8uKwSMrC/jCHA== X-CSE-MsgGUID: B+hk4MSjQXmi70Z6aharZg== X-IronPort-AV: E=McAfee;i="6800,10657,11480"; a="71048766" X-IronPort-AV: E=Sophos;i="6.16,279,1744095600"; d="scan'208";a="71048766" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Jul 2025 02:59:23 -0700 X-CSE-ConnectionGUID: aOqy9tIvQbafvLKOgawDGg== X-CSE-MsgGUID: auP5LPesQ/m7qenBhDetrg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,279,1744095600"; d="scan'208";a="177390854" Received: from black.fi.intel.com ([10.237.72.28]) by fmviesa002.fm.intel.com with ESMTP; 01 Jul 2025 02:59:01 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id DDBB9893; Tue, 01 Jul 2025 12:58:50 +0300 (EEST) From: "Kirill A. Shutemov" To: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Ard Biesheuvel , "Paul E. McKenney" , Josh Poimboeuf , Xiongwei Song , Xin Li , "Mike Rapoport (IBM)" , Brijesh Singh , Michael Roth , Tony Luck , Alexey Kardashevskiy , Alexander Shishkin Cc: Jonathan Corbet , Sohil Mehta , Ingo Molnar , Pawan Gupta , Daniel Sneddon , Kai Huang , Sandipan Das , Breno Leitao , Rick Edgecombe , Alexei Starovoitov , Hou Tao , Juergen Gross , Vegard Nossum , Kees Cook , Eric Biggers , Jason Gunthorpe , "Masami Hiramatsu (Google)" , Andrew Morton , Luis Chamberlain , Yuntao Wang , Rasmus Villemoes , Christophe Leroy , Tejun Heo , Changbin Du , Huang Shijie , Geert Uytterhoeven , Namhyung Kim , Arnaldo Carvalho de Melo , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" Subject: [PATCHv8 14/17] x86/traps: Handle LASS thrown #SS Date: Tue, 1 Jul 2025 12:58:43 +0300 Message-ID: <20250701095849.2360685-15-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.47.2 In-Reply-To: <20250701095849.2360685-1-kirill.shutemov@linux.intel.com> References: <20250701095849.2360685-1-kirill.shutemov@linux.intel.com> 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" LASS throws a #GP for any violations except for stack register accesses, in which case it throws a #SS instead. Handle this similarly to how other LASS violations are handled. In case of FRED, before handling #SS as LASS violation, kernel has to check if there's a fixup for the exception. It can address #SS due to invalid user context on ERETU. See 5105e7687ad3 ("x86/fred: Fixup fault on ERETU by jumping to fred_entrypoint_user") for more details. Co-developed-by: Alexander Shishkin Signed-off-by: Alexander Shishkin Signed-off-by: Kirill A. Shutemov --- arch/x86/kernel/traps.c | 39 +++++++++++++++++++++++++++++++++------ 1 file changed, 33 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index ceb091f17a5b..f9ca5b911141 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -418,12 +418,6 @@ DEFINE_IDTENTRY_ERRORCODE(exc_segment_not_present) SIGBUS, 0, NULL); } =20 -DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment) -{ - do_error_trap(regs, error_code, "stack segment", X86_TRAP_SS, SIGBUS, - 0, NULL); -} - DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check) { char *str =3D "alignment check"; @@ -866,6 +860,39 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection) cond_local_irq_disable(regs); } =20 +#define SSFSTR "stack segment fault" + +DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment) +{ + if (user_mode(regs)) + goto error_trap; + + if (cpu_feature_enabled(X86_FEATURE_FRED) && + fixup_exception(regs, X86_TRAP_SS, error_code, 0)) + return; + + if (cpu_feature_enabled(X86_FEATURE_LASS)) { + enum kernel_exc_hint hint; + unsigned long exc_addr; + + hint =3D get_kernel_exc_address(regs, &exc_addr); + if (hint !=3D EXC_NO_HINT) { + printk(SSFSTR ", %s 0x%lx", kernel_exc_hint_help[hint], + exc_addr); + } + + if (hint !=3D EXC_NON_CANONICAL) + exc_addr =3D 0; + + die_addr(SSFSTR, regs, error_code, exc_addr); + return; + } + +error_trap: + do_error_trap(regs, error_code, "stack segment", X86_TRAP_SS, SIGBUS, + 0, NULL); +} + static bool do_int3(struct pt_regs *regs) { int res; --=20 2.47.2