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 A5D38B67F for ; Mon, 1 Sep 2025 21:29:17 +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=1756762159; cv=none; b=LxSnautJVnIXBIKVmSoEhrE+WoQnIRuCy4KpnfhOIfHuqyZzqLOeo7ZByKv2VaAsBQMCOrGXyKQbrdzaIajApnEhpuR89VI6MbVaTqe5P9ST+moq67/p0nguYqsm+2NgX+h51orFlJwV+YJso+HN2q9pgFjMpDO8Ia5kzjBtvr0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756762159; c=relaxed/simple; bh=552/6JCfc+JUxNZzimncP4Fs+dFS0i0A1bp0y7OqPfY=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=qFdfTM7UVUQzXlYnqkMULq//aV7rqRd/ocj9zzqAPoBqVN1Rp4/zXV+MCiowdLug0FNBku3Oai4vW6cXjeNIEq9G7snjduGWQXvoT8DU6NCiIPSxI3H4r7fbhuICV6KCxdlVAUe1PjvxGu2sEfcX7OLeFvWtK4/hqAmkQC5agTk= 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=WjM+pQrx; 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="WjM+pQrx" Received: from ehlo.thunderbird.net (c-76-133-66-138.hsd1.ca.comcast.net [76.133.66.138]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 581LS5Fb223203 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Mon, 1 Sep 2025 14:28:06 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 581LS5Fb223203 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025082201; t=1756762087; bh=552/6JCfc+JUxNZzimncP4Fs+dFS0i0A1bp0y7OqPfY=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=WjM+pQrxsjaHwPfu5TD4QjlSXAysuaTOWlWdBItkXSo83VaSviwaitzlJnp43OlSH IbSQ+zJTXkWoYyirIOanfielbrHFkyCx4pxC5LNqdmBUP+vSyv996TvuS9gw2IPcIN i+SbRviyHAtUh5GUjAOzjIGyKZUuzJuCC5cTMaoup38Cl6XwvceB56NML0McIubCFb I4pXhMPZ4/Qm1bZ4vIS2fiCZlutFM3d6tqrFozyze1gLQA85oDcFL/I4RsHR86iM1A M1odYRxp2gRjMObLBO2IDdFZ1ZpWWAc7cGcc1YrYxdQuNI8kpQ1bNof2+mB3n6bm+2 X1AV7tRuDlTYg== Date: Mon, 01 Sep 2025 14:28:04 -0700 From: "H. Peter Anvin" To: Marcos Del Sol Vives , kernel test robot CC: oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Peter Zijlstra , Kees Cook , "Xin Li (Intel)" , Sabyrzhan Tasbolatov Subject: Re: [PATCH v2] x86: add hintable NOPs emulation User-Agent: K-9 Mail for Android In-Reply-To: <51c25fb7-46be-4364-9371-6a7cb6b07625@orca.pet> References: <202508291620.bcfb3924-lkp@intel.com> <0ffa7c6e-f32f-4966-85df-3ee5f2426e9e@orca.pet> <33A549B7-B442-402C-A82C-862C0F509274@zytor.com> <51c25fb7-46be-4364-9371-6a7cb6b07625@orca.pet> Message-ID: <772C4DE8-8564-430D-9304-A39F88E07EBF@zytor.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On September 1, 2025 4:43:15 AM PDT, Marcos Del Sol Vives wrote: >El 31/08/2025 a las 21:32, H=2E Peter Anvin escribi=C3=B3: >> I'm really, *really* starting to question this approach=2E=20 >>=20 >> The right thing would be to not compile in endbr instructions on 32 bit= s, >> since they aren't supported by the kernel (if you try to enable CET/IBT >> you will crash instantly, because there is no endbr32 at the vdso syste= m >> can entry point right now=2E) >>=20 >> We are talking about a very small number of CPUs stuck between generati= on >> 5 and generation 6=2E Most likely we are talking about a much smaller n= umber >> than the i486 support we have been debating lately=2E=2E=2E > >I assume the kernel is currently simply ignoring the CET flag on ELF for >all 32-bit x86 binaries and libraries? > >Anyhow, seeing this is indeed becoming more tricky and error-prone, I'm >contating the sudo developer which is, so far, the only software that >has this issue=2E Yep=2E