From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 E71A72D5401; Fri, 20 Jun 2025 15:21:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750432912; cv=none; b=qHa2nRY7T/Q5Bchya7VSqUyuZV1OT6lkZlWLNrjCzTkihrjlms7IZ+zOTXtnDOjaTzbC0+leIXltcEKIuArGtoiICdCRGsF3hF0evUk7DZL3SQZqqOSr+1Wd/fbY1kmHadZv4hMpfMWQ7cNDjgps8xV2niAzqazM8dZIx+Y1ZGE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750432912; c=relaxed/simple; bh=dXkDARLe97iucq+cYmZVbsCiWs5m/8DwxqHYS0wfhpY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QrZGSOzXgKkZtNfFtwdN3AVCHyBC2sal6q0I02XGCBPcbuFD5c6EkIL2YOv1lQyF1eIEsMzogw70ubYET8AstqP84Js+UGCaN7bN5oLBmBzaKrcnrE/3edjiMRZnEaoGWrIac/mbnSp701At8XgP7GFzpOqb/vg+n7NJYMu43/g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=r5iZH4X8; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="r5iZH4X8" Received: from [192.168.7.202] ([71.202.166.45]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 55KFKDv62532641 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Fri, 20 Jun 2025 08:20:13 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 55KFKDv62532641 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025052101; t=1750432820; bh=H1lU1VU9OB8WVDb9tMU+9NZuSja8f6u7jNZhQumnN1g=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=r5iZH4X8ZnjTARAjPmzjRmhhZMzHAn48uYs3t7MlalofsXZLyX4poAjKrLiqSocSQ /20Wd5K8r/qUuC52LAh+6g2DVS0FNSpQG2qe0470vq7o0ExU00ySE+bl7OzwQQN50c b/HBotYsb/qkn13W6f1JqVPqDqAVFgf3KU/LXe8fsx+fJmqWbU0eKGO/Egym1l4nIl B7yjwKHSy1I23esU/NWpqYbRdSnC0mrcguAbLGyqr6+CyjjHmqSA/g2VrXMSSxaJBr 1weomDC+1hVZyOqXS89lHhk1+kaIUZxrmY3o5Qi1lTb4UAZJKTS3WMr1C7jfOkIdQV 9rn/rb+4bOnRQ== Message-ID: <08758240-fd38-4d90-9efa-354274e8bb8e@zytor.com> Date: Fri, 20 Jun 2025 08:20:12 -0700 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv6 13/16] x86/traps: Handle LASS thrown #SS To: "Kirill A. Shutemov" , 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 References: <20250620135325.3300848-1-kirill.shutemov@linux.intel.com> <20250620135325.3300848-14-kirill.shutemov@linux.intel.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; keydata= xsDNBGUPz1cBDACS/9yOJGojBFPxFt0OfTWuMl0uSgpwk37uRrFPTTLw4BaxhlFL0bjs6q+0 2OfG34R+a0ZCuj5c9vggUMoOLdDyA7yPVAJU0OX6lqpg6z/kyQg3t4jvajG6aCgwSDx5Kzg5 Rj3AXl8k2wb0jdqRB4RvaOPFiHNGgXCs5Pkux/qr0laeFIpzMKMootGa4kfURgPhRzUaM1vy bsMsL8vpJtGUmitrSqe5dVNBH00whLtPFM7IbzKURPUOkRRiusFAsw0a1ztCgoFczq6VfAVu raTye0L/VXwZd+aGi401V2tLsAHxxckRi9p3mc0jExPc60joK+aZPy6amwSCy5kAJ/AboYtY VmKIGKx1yx8POy6m+1lZ8C0q9b8eJ8kWPAR78PgT37FQWKYS1uAroG2wLdK7FiIEpPhCD+zH wlslo2ETbdKjrLIPNehQCOWrT32k8vFNEMLP5G/mmjfNj5sEf3IOKgMTMVl9AFjsINLHcxEQ 6T8nGbX/n3msP6A36FDfdSEAEQEAAc0WWGluIExpIDx4aW5Aenl0b3IuY29tPsLBDQQTAQgA NxYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89XBQkFo5qAAhsDBAsJCAcFFQgJCgsFFgID AQAACgkQa70OVx2uN1HUpgv/cM2fsFCQodLArMTX5nt9yqAWgA5t1srri6EgS8W3F+3Kitge tYTBKu6j5BXuXaX3vyfCm+zajDJN77JHuYnpcKKr13VcZi1Swv6Jx1u0II8DOmoDYLb1Q2ZW v83W55fOWJ2g72x/UjVJBQ0sVjAngazU3ckc0TeNQlkcpSVGa/qBIHLfZraWtdrNAQT4A1fa sWGuJrChBFhtKbYXbUCu9AoYmmbQnsx2EWoJy3h7OjtfFapJbPZql+no5AJ3Mk9eE5oWyLH+ QWqtOeJM7kKvn/dBudokFSNhDUw06e7EoVPSJyUIMbYtUO7g2+Atu44G/EPP0yV0J4lRO6EA wYRXff7+I1jIWEHpj5EFVYO6SmBg7zF2illHEW31JAPtdDLDHYcZDfS41caEKOQIPsdzQkaQ oW2hchcjcMPAfyhhRzUpVHLPxLCetP8vrVhTvnaZUo0xaVYb3+wjP+D5j/3+hwblu2agPsaE vgVbZ8Fx3TUxUPCAdr/p73DGg57oHjgezsDNBGUPz1gBDAD4Mg7hMFRQqlzotcNSxatlAQNL MadLfUTFz8wUUa21LPLrHBkUwm8RujehJrzcVbPYwPXIO0uyL/F///CogMNx7Iwo6by43KOy g89wVFhyy237EY76j1lVfLzcMYmjBoTH95fJC/lVb5Whxil6KjSN/R/y3jfG1dPXfwAuZ/4N cMoOslWkfZKJeEut5aZTRepKKF54T5r49H9F7OFLyxrC/uI9UDttWqMxcWyCkHh0v1Di8176 jjYRNTrGEfYfGxSp+3jYL3PoNceIMkqM9haXjjGl0W1B4BidK1LVYBNov0rTEzyr0a1riUrp Qk+6z/LHxCM9lFFXnqH7KWeToTOPQebD2B/Ah5CZlft41i8L6LOF/LCuDBuYlu/fI2nuCc8d m4wwtkou1Y/kIwbEsE/6RQwRXUZhzO6llfoN96Fczr/RwvPIK5SVMixqWq4QGFAyK0m/1ap4 bhIRrdCLVQcgU4glo17vqfEaRcTW5SgX+pGs4KIPPBE5J/ABD6pBnUUAEQEAAcLA/AQYAQgA JhYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89ZBQkFo5qAAhsMAAoJEGu9DlcdrjdR4C0L /RcjolEjoZW8VsyxWtXazQPnaRvzZ4vhmGOsCPr2BPtMlSwDzTlri8BBG1/3t/DNK4JLuwEj OAIE3fkkm+UG4Kjud6aNeraDI52DRVCSx6xff3bjmJsJJMb12mWglN6LjdF6K+PE+OTJUh2F dOhslN5C2kgl0dvUuevwMgQF3IljLmi/6APKYJHjkJpu1E6luZec/lRbetHuNFtbh3xgFIJx 2RpgVDP4xB3f8r0I+y6ua+p7fgOjDLyoFjubRGed0Be45JJQEn7A3CSb6Xu7NYobnxfkwAGZ Q81a2XtvNS7Aj6NWVoOQB5KbM4yosO5+Me1V1SkX2jlnn26JPEvbV3KRFcwV5RnDxm4OQTSk PYbAkjBbm+tuJ/Sm+5Yp5T/BnKz21FoCS8uvTiziHj2H7Cuekn6F8EYhegONm+RVg3vikOpn gao85i4HwQTK9/D1wgJIQkdwWXVMZ6q/OALaBp82vQ2U9sjTyFXgDjglgh00VRAHP7u1Rcu4 l75w1xInsg== In-Reply-To: <20250620135325.3300848-14-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/20/2025 6:53 AM, Kirill A. Shutemov wrote: > From: Alexander Shishkin > > 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. > > Signed-off-by: Alexander Shishkin > Signed-off-by: Kirill A. Shutemov > --- > arch/x86/kernel/traps.c | 34 ++++++++++++++++++++++++++++------ > 1 file changed, 28 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index 0f558d3369a3..bd8f7e72b238 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -866,6 +860,34 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection) > cond_local_irq_disable(regs); > } > > +DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment) > +{ > + if (cpu_feature_enabled(X86_FEATURE_LASS)) { > + enum kernel_gp_hint hint = GP_NO_HINT; > + unsigned long gp_addr; > + > + if (user_mode(regs)) { > + gp_user_force_sig_segv(regs, X86_TRAP_GP, error_code, GPFSTR); > + return; > + } Please add the following FRED code: if (cpu_feature_enabled(X86_FEATURE_FRED) && fixup_exception(regs, X86_TRAP_SS, error_code, 0)) return; Because the following FRED fixup https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5105e7687ad3dffde77f6e4393b5530e83d672dc is otherwise skipped, it is interpreted as a LASS #SS before reaching the FRED fixup (which is indeed a userspace fault but triggered from a specific kernel IP as described in the commit changelog). The x86 selftest sigreturn_64 fails w/o the above fix. > + > + hint = get_kernel_gp_address(regs, &gp_addr); > + if (hint != GP_NO_HINT) { > + printk(GPFSTR ", %s 0x%lx", kernel_gp_hint_help[hint], GPFSTR? #define GPFSTR "general protection fault" It is misleading here, you need something like SSFSTR which tells exactly which exception caused it. Thanks! Xin